JP6046370B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device.

  Due to global environmental problems, automobiles are required to reduce emissions. In particular, in recent years, there has been an increasing demand for reducing the amount of soot discharged from engines. In order to reduce the amount of soot emission, split fuel injection is effective in which fuel injection is performed a plurality of times for the same cylinder during one cycle. Conventionally, there has been known a fuel injection device that estimates the air-fuel ratio of each cylinder for each cylinder based on the output of the detection value of the air-fuel ratio sensor and calculates and corrects the variation in the injection amount of each fuel injection valve during low-load operation. (For example, Patent Document 1).

JP 2009-214411 A

  However, in the fuel injection valve, the actual fuel injection amount is likely to vary in a region where the fuel injection amount is small due to the structure, and the degree of variation further increases as the change with time progresses. In particular, when the actual fuel injection amount varies in a decreasing direction, the air-fuel ratio of the cylinder becomes lean, so that the generated torque is reduced and a torque step is generated between the other cylinders and the drivability is deteriorated. There is a problem of doing.

According to the first aspect of the present invention, there is provided an engine control apparatus for performing split fuel injection in which fuel is injected a plurality of times in one cycle by a fuel injection valve provided in each of a plurality of cylinders. Lean cylinder detection means for detecting a situation and detecting a cylinder that is leaner than a predetermined value as a lean generation cylinder among a plurality of cylinders based on the detection result; Based on a signal indicating the air-fuel ratio output from the air-fuel ratio sensor or the O2 sensor, the number-of-injections control means for reducing the number of times of fuel injection to the lean generation cylinder detected by the lean cylinder detecting means, Based on the extraction means for extracting the frequency component corresponding to the two rotation cycles of the engine and the signal output from the crank angle sensor, the angular acceleration of the crank Or a calculating means for calculating angular jerk, wherein the lean cylinder detecting means is leaner than the predetermined value based on a frequency component corresponding to the two rotation cycles extracted by the extracting means. First detection means for detecting, and second detection means for detecting a cylinder leaner than the predetermined value based on the angular acceleration or angular jerk calculated by the calculation means, and at least Switching to output one detection result of the detection result by the first detection means and the detection result by the second detection means as the lean generation cylinder according to the rotation speed or load of the engine having the plurality of cylinders The apparatus further comprises means .

  According to the present invention, it is detected that the air-fuel ratio of at least one cylinder is leaner than the air-fuel ratio of other cylinders due to deterioration of the fuel injection valve over time, and the number of fuel injections of the lean cylinder is determined. Decrease. As a result, it is possible to suppress the occurrence of an unexpected lean cylinder at the time of split fuel injection and to prevent deterioration of drivability.

The block diagram explaining the outline of the function of the engine control apparatus by embodiment of this invention The block diagram explaining the outline of the function of the engine control apparatus by embodiment of this invention The block diagram explaining the outline of the function of the engine control apparatus by 1st Embodiment The block diagram explaining the outline of the function of the engine control apparatus by 1st Embodiment The block diagram explaining the outline of the function of the engine control apparatus by 1st Embodiment The block diagram explaining the outline of the function of the engine control apparatus by 1st Embodiment The block diagram explaining the outline of the function of the engine control apparatus by 1st Embodiment 1 is a schematic configuration diagram showing an entire system of an engine control apparatus according to an embodiment of the present invention. The block diagram explaining the structure of the control unit of embodiment The block diagram explaining the function by CPU in the control unit by 1st Embodiment The figure which illustrates typically the function of the basic fuel injection amount calculating part by 1st-4th embodiment. The figure which illustrates typically the function of the air fuel ratio feedback correction value calculating part by 1st-4th embodiment. The figure which illustrates typically the function of the 2 rotation component calculating part by 1st-4th embodiment. The figure which illustrates typically the function of the 1st injection frequency correction cylinder calculating part by 1st-4th embodiment. The figure which illustrates typically the function of the injection frequency calculating part by 1st-4th embodiment. The figure which illustrates typically the function of the fuel-injection-amount calculating part by 1st-4th embodiment. The figure which illustrates typically the function of the fuel-injection time calculating part by 1st-4th embodiment. The figure which illustrates typically the function of the abnormality determination part by 1st-4th embodiment. The block diagram explaining the outline of the function of the engine control apparatus by 2nd Embodiment The block diagram explaining the outline of the function of the engine control apparatus by 2nd Embodiment The block diagram explaining the function by CPU in the control unit by 2nd Embodiment The figure which illustrates typically the function of the angular acceleration and angular jerk calculation part by 2nd-4th embodiment. The figure which illustrates typically the function of the 2nd injection frequency correction cylinder calculating part by 2nd-4th embodiment. The block diagram explaining the outline of the function of the engine control apparatus by 3rd Embodiment The block diagram explaining the function by CPU in the control unit by 3rd Embodiment The figure which illustrates typically the function of the lean determination system switching part by 3rd Embodiment. The block diagram explaining the outline of the function of the engine control apparatus by 1st Embodiment The block diagram explaining the function by CPU in the control unit by 4th Embodiment The figure which illustrates typically the function of the 3rd injection frequency correction cylinder calculating part by 4th Embodiment. The figure which illustrates typically the function of the 1st correction | amendment cylinder number calculating part by 4th Embodiment. The figure which illustrates typically the function of the 2nd correction | amendment cylinder number calculating part by 4th Embodiment.

  The present invention relates to an engine control apparatus that employs a split fuel injection system. When a lean-burning cylinder is detected, the number of fuel injections in that cylinder is reduced to reduce engine torque fluctuations. It is a thing. That is, as shown in the functional block diagram of the engine control apparatus of the embodiment of FIG. 1, the engine control apparatus performs divided fuel injection that injects fuel multiple times during one cycle for each of a plurality of cylinders. During implementation, the air-fuel ratio or engine operating status is detected. Based on the detection result, the engine control device detects a cylinder that is leaner than a predetermined value as a lean generation cylinder among the plurality of cylinders as a lean generation cylinder, and detects the detected lean generation cylinder The number of times of fuel injection is reduced. Then, as shown in the functional block diagram of the engine control apparatus of the embodiment of FIG. 2, the engine control apparatus performs the total in one cycle by the lean generation cylinder before and after reducing the number of fuel injections to the lean generation cylinder. The fuel injection amount per one split fuel injection is controlled so as to prevent the fuel injection amount from changing. Details will be described below.

-First embodiment-
An engine control apparatus according to a first embodiment of the present invention will be described with reference to the drawings. First, the outline of the engine control apparatus of the first embodiment will be described with reference to schematic functional block diagrams shown in FIGS. As shown in FIG. 3, the engine control apparatus according to the first embodiment extracts a frequency component corresponding to two engine rotation cycles based on a signal indicating the air-fuel ratio output from the air-fuel ratio sensor or the O2 sensor. To do. Then, the engine control device detects the lean generation cylinder based on the extracted frequency component corresponding to the two rotation cycles. That is, as shown in FIG. 4, the engine control apparatus according to the present embodiment extracts a phase spectrum and a power spectrum corresponding to two engine rotation cycles based on a signal indicating an air-fuel ratio, and based on the phase spectrum. Detect lean cylinders. Then, the engine control apparatus of the present embodiment determines whether or not the detected power spectrum of the lean generation cylinder is equal to or greater than a predetermined value, and when it is determined that the power spectrum of the lean generation cylinder is equal to or greater than a predetermined value, the number of fuel injections Is to decrease.

  As shown in FIG. 5, after the number of fuel injections to the lean generation cylinder is reduced, the engine control device again determines that the cylinder whose air-fuel ratio is leaner than a predetermined value compared to the air-fuel ratios of the other cylinders again. If it is not detected, the number of fuel injections for the lean generating cylinder is maintained. Further, as shown in FIG. 6, after the number of fuel injections to the lean generation cylinder is reduced, the engine control apparatus of the present embodiment makes the air-fuel ratio leaner than a predetermined value compared to the air-fuel ratio of the other cylinders. When the detected cylinder is detected again, the number of fuel injections of the lean generating cylinder is further reduced. As shown in FIG. 7, when the number of fuel injections to the lean generation cylinder is reduced to a predetermined number, the engine control apparatus of the present embodiment has a predetermined value compared to the air / fuel ratio of the other cylinders. If a leaner cylinder is detected again, it is notified that there is an abnormality. Hereinafter, the first embodiment will be specifically described.

  FIG. 8 is a schematic configuration diagram of the entire system of the engine control apparatus 100. The engine control apparatus 100 includes an air cleaner 1, an air flow sensor 2, an electronic throttle 3, an intake manifold 4, a collector 5, an accelerator 6, a fuel injection valve 7, a spark plug 8, an engine 9, a manifold 10, a three-way catalyst 11, and an upstream catalyst space. A fuel ratio sensor 12, an accelerator opening sensor 13, a water temperature sensor 14, a crank angle sensor 15, a control unit 16, a throttle opening sensor 17, an exhaust gas recirculation pipe 18, a valve 19, a catalyst downstream O2 sensor 20, and an intake air temperature sensor 29 are provided.

  The engine 9 according to the present embodiment is configured with multiple cylinders (for example, four cylinders). Air from the outside passes through the air cleaner 1 and flows into the cylinder through the intake manifold 4 and the collector 5. The air flow sensor 2 detects the amount of air that has flowed in through the air cleaner 1 (hereinafter referred to as intake air amount) and controls a signal indicating the intake air amount (hereinafter referred to as intake air amount signal), which will be described later. Output to unit 16.

  The electronic throttle 3 is controlled by the control unit 16 to adjust the amount of intake air that has passed through the air cleaner 1. The throttle opening sensor 17 is attached to the electronic throttle 3 and outputs a signal indicating the opening of the electronic throttle 3 (hereinafter referred to as an opening signal) to the control unit 16. The intake air temperature sensor 29 is provided upstream of the air cleaner 1, detects the temperature of the air from the outside (hereinafter referred to as intake air temperature), and generates a signal indicating the intake air temperature (hereinafter referred to as intake air temperature signal) as a control unit. 16 is output.

  The crank angle sensor 15 outputs a signal indicating that the rotation angle of the crankshaft in the engine 9 is every 10 degrees to the control unit 16 as a signal indicating the rotation speed of the crankshaft (hereinafter referred to as a rotation speed signal) for each fuel cycle. The water temperature sensor 14 detects the temperature of the cooling water for cooling the engine 9 and outputs a signal indicating the detected temperature of the cooling water (hereinafter referred to as a water temperature signal) to the control unit 16. The accelerator opening sensor 13 detects the depression amount of the accelerator 6 by the driver and outputs a signal indicating the detected depression amount (hereinafter referred to as a depression amount signal) to the control unit 16.

  The control unit 16 includes a CPU, a ROM, a RAM, and the like, which will be described later, and is an arithmetic circuit that controls each component of the engine control device 100 and executes various data processing. The control unit 16 includes an intake air amount signal from the air flow sensor 2, an opening signal from the accelerator opening sensor 13, a water temperature signal from the water temperature sensor 14, a rotation speed signal from the crank angle sensor 15, and a throttle opening sensor. The opening degree signal from 17 and the intake air temperature signal from the intake air temperature sensor 29 are input, and the operating state of the engine 9 is detected. The control unit 16 calculates the target air amount, the fuel injection amount, the ignition timing, and the main operation amount of the engine 9 at the ignition timing based on the detected operating state of the engine 9.

  The control unit 16 calculates the target throttle opening of the electronic throttle 3 based on the calculated target air amount, converts it into an electronic throttle drive signal, and outputs it to the electronic throttle 3. The control unit 16 converts the calculated fuel injection amount into a valve opening pulse signal and outputs it to the fuel injection valve (injector) 7. The control unit 16 outputs a drive signal for igniting the spark plug 8 to the spark plug 8 at the calculated ignition timing. Further, the control unit 16 detects a lean-combusting cylinder and performs processing (injection frequency / injection amount control processing) for controlling the number of fuel injections and the fuel injection amount in one cycle of the detected cylinder. Details of processing by the control unit 16 will be described later.

  The fuel injected from the fuel injection valve 7 in accordance with the control by the control unit 16 is mixed with the air flowing in through the intake manifold 4 and flows into the cylinder of the engine 9 to form an air-fuel mixture. The air-fuel mixture explodes due to sparks generated from the spark plug 8 at each ignition timing calculated by the control unit 16. The piston is pushed down by the combustion pressure due to the explosion of the air-fuel mixture, and the power of the engine 9 is generated. A part of the exhaust gas after the explosion of the air-fuel mixture is sent to the three-way catalyst 11 through the exhaust manifold 10, and the other part is recirculated to the intake side (upstream of the collector 5) through the exhaust gas recirculation pipe 18. The amount of exhaust gas recirculated through the exhaust gas recirculation pipe 18 is controlled by a valve 19.

  The catalyst upstream air-fuel ratio sensor 12 is provided in a flow path that communicates from the engine 9 to the three-way catalyst 11, and outputs a signal indicating the detected oxygen concentration, that is, the air-fuel ratio (hereinafter, air-fuel ratio signal) to the control unit 16. . The catalyst downstream O2 sensor 20 is provided in a flow path downstream of the three-way catalyst 11 and outputs a signal indicating whether the residual oxygen amount in the exhaust gas is rich or thin to the control unit 16.

Details of the control unit 16 according to the first embodiment will be described below.
FIG. 9 is a block diagram showing the configuration of the control unit 16. The control unit 16 includes a CPU 21, ROM 22, RAM 23, input circuit 24, input / output port 25, ignition signal output circuit 26, fuel injection valve drive circuit 27, and electronic throttle drive circuit 28. The input circuit 24 includes an intake air amount signal from the airflow sensor 2, an air-fuel ratio signal from the catalyst upstream air-fuel ratio sensor 12, an opening signal from the accelerator opening sensor 13, a water temperature signal from the water temperature sensor 14, and a crank angle sensor 15. , A rotational speed signal from the throttle opening sensor 17, an opening signal from the catalyst downstream O2 sensor 20, and an intake air temperature signal from the intake air temperature sensor 29 are input to perform signal processing such as noise removal of various signals. Do.

  When the signal processing such as noise removal is performed by the input circuit 24, the various signals are output to the input port of the input / output port 25 and stored in the RAM 23. The CPU 21 performs various arithmetic processes to be described later using various signals stored in the RAM 23. In the ROM 22, a control program in which contents of various arithmetic processes executed by the CPU 21 are described is written in advance. The calculation result obtained by the calculation process by the CPU 21, that is, a value indicating each actuator operation amount is temporarily stored in the RAM 23 and then transmitted to the output port of the input / output port 25.

  The values set in the output port include, for example, an operation signal for the spark plug 8, a drive signal for the fuel injection valve 7, a drive signal for realizing the target opening of the electronic throttle 3. The operation signal of the spark plug 8 is an ON / OFF signal that is ON when the primary coil in the ignition signal output circuit 26 is energized, and is OFF when it is not energized. The ignition timing of the spark plug 8 is when the operation signal of the spark plug 8 changes from ON to OFF. The drive signal of the fuel injection valve 7 is an ON / OFF signal that is turned on when the valve is opened and turned off when the valve is closed. The drive signal for the fuel injection valve 7 is amplified to a sufficient energy to open the fuel injection valve 7 by the fuel injection valve drive circuit 27 and sent to the fuel injection valve 7. A drive signal for realizing the target opening degree of the electronic throttle 3 is sent to the electronic throttle 3 through the electronic throttle drive circuit 28.

  Hereinafter, the lean cylinder detection process and the injection number / injection amount control process executed by the CPU 21 of the control unit 16 will be described using the block diagram shown in FIG. The lean cylinder detection process and the injection amount control process are performed by the CPU 21 executing a control program written in the ROM 22. The CPU 21 includes a basic fuel injection amount calculation unit 210, an air-fuel ratio feedback correction value calculation unit 211, a two-rotation component calculation unit 212, a first injection number correction cylinder calculation unit 213, an injection number calculation unit 214, a fuel injection An amount calculation unit 215, a fuel injection timing calculation unit 216, and an abnormality determination unit 217 are functionally provided.

  The basic fuel injection amount calculation unit 210 is based on the intake air amount Qa corresponding to the intake air amount signal input from the air flow sensor 2 and the crankshaft rotation speed Ne corresponding to the rotation speed signal input from the crank angle sensor 15. Thus, the injection pulse width Tp0 corresponding to the basic fuel injection amount is calculated. The air-fuel ratio feedback correction value calculation unit 211 calculates a correction value Alpha for correcting the fuel injection amount so as to be the target air-fuel ratio, based on the air-fuel ratio signal Rabf from the catalyst upstream air-fuel ratio sensor 12.

  The two-rotation component calculation unit 212 uses the air-fuel ratio signal Rabf from the catalyst upstream air-fuel ratio sensor 12 to calculate components of two rotation cycles of the engine 9, that is, a power spectrum Power and a phase spectrum Phase. The first injection number correction cylinder calculating unit 213 is a cylinder in which lean combustion is generated based on the two-rotation cycle component of the engine 9 calculated by the two-rotation component calculating unit 212 (hereinafter referred to as a lean generating cylinder). Is detected. Then, the first injection number correction cylinder calculation unit 213 specifies a cylinder for correcting the injection number among the detected lean generation cylinders, that is, a correction target cylinder. The number-of-injections calculation unit 214 calculates the number of injections Kai_n for each cylinder. Note that n represents a cylinder number. As will be described later, the injection number calculation unit 214 reduces the number of injections of the correction target cylinder set by the first injection number correction cylinder calculation unit 213 in order to eliminate lean combustion.

  Based on the calculated air-fuel ratio feedback correction value Alpha and the calculated number of injections Kai_n of each cylinder, the fuel injection amount calculation unit 215 has an injection pulse width corresponding to the fuel injection amount of each cylinder with respect to the basic injection fuel amount Tp0. TI_n_k is calculated. Note that n indicates a cylinder number, and k indicates an injection number (injection order) of the same cylinder in one cycle. The fuel injection timing calculation unit 216 calculates the injection timing IT_n_k of each cylinder from the number of injections Kai_n of each cylinder. Note that n indicates a cylinder number, and k indicates an injection number (order) of the same cylinder in one cycle. The abnormality determination unit 217 determines whether or not the cylinder is abnormal based on the number of injections Kai_n of each cylinder. If it is determined that there is an abnormality, the abnormality determination unit 217 sets the abnormality flag f_MIL to 1.

11 to 18, the basic fuel injection amount calculation unit 210, the air-fuel ratio feedback correction value calculation unit 211, the rotation component calculation unit 212, the first injection number correction cylinder calculation unit 213, and the injection number calculation unit 214 described above. Details of the fuel injection amount calculation unit 215, the fuel injection timing calculation unit 216, and the abnormality determination unit 217 will be described.
FIG. 11 is a diagram schematically illustrating the function of the basic fuel injection amount calculation unit 210. The basic fuel injection amount calculation unit 210 calculates the basic fuel injection amount Tp0 using the following equation (1). In Equation (1), Cyl represents the number of cylinders, and K0 is a coefficient determined based on the specifications of the injector (the relationship between the fuel injection pulse width and the fuel injection amount).
Tp0 = K0 × Qa / (Ne × Cyl) (1)

  FIG. 12 is a diagram schematically illustrating the function of the air-fuel ratio feedback correction value calculation unit 211. The air-fuel ratio feedback correction value calculation unit 211 calculates an air-fuel ratio feedback correction value Alpha by PI control based on the difference between the air-fuel ratio signal Rabf from the catalyst upstream air-fuel ratio sensor 12 and the target air-fuel ratio TgRabf. In the case where an O2 sensor is provided instead of the catalyst upstream air-fuel ratio sensor 12, the air-fuel ratio feedback correction value calculation unit 211 calculates an air-fuel ratio feedback correction value Alpha using a signal output from the O2 sensor.

  FIG. 13 is a diagram schematically illustrating the function of the two-rotation component calculation unit 212. The two-rotation component calculation unit 212 uses, for example, a fast Fourier transform (FFT), the power spectrum Power of two rotation components from the air-fuel ratio signal Rabf from the catalyst upstream air-fuel ratio sensor 12, and the phase spectrum of the two rotation components. A basic value Phase0 is calculated. The 2-rotation component calculation unit 212 may use a discrete Fourier transform DFT (Discrete Fourier Transform) instead of using the fast Fourier transform FFT. In this case, since only two rotation components can be calculated by appropriately selecting the coefficients, the calculation load is reduced as compared with the fast Fourier transform FFT that calculates the power spectrum and phase spectrum of all frequencies.

  The phase spectrum Phase of the two-rotation component is obtained from the phase spectrum basic value Phase0 of the two-rotation component in each of the calculations: Phase 0 → Phase 0-90 → Phase 0-180 → Phase 0-270 → Phase 0 → Phase 0-90 →. Is a value obtained by cyclic calculation as described above. The above cyclic calculation is performed for the purpose of fixing the reference point for calculating the phase. The two-rotation component calculation unit 212 uses a combustion cycle (180 deg) as a calculation cycle, and the two-rotation component uses a period during which the engine rotates twice as one cycle (360 deg). Accordingly, the reference point of the phase is fixed so that the period during which the engine rotates twice, that is, one cycle when the two-rotation component calculation unit 212 calculates four times for each combustion cycle.

FIG. 14 is a diagram schematically illustrating the function of the first injection number correcting cylinder calculating unit 213. The first injection number correcting cylinder calculating unit 213 detects the lean generation cylinder based on the phase spectrum Phase calculated by the two-rotation component calculating unit 212 according to the following conditions (a1) to (d1), and detects the detected lean A cylinder number of the generation cylinder (hereinafter referred to as a lean generation cylinder number) N_lean_cyl is set. Note that K1a_Phase, K1b_Phase, K2a_Phase, K2b_Phase, K3a_Phase, K3b_Phase, K4a_Phase, K4b_Phase, and N1 are values determined empirically according to the characteristics of the engine 9.
(A1) When K1a_Phase ≦ Phase ≦ K1b_Phase is satisfied N1 times continuously, the first injection number correcting cylinder calculating unit 213 sets the lean generation cylinder number N_lean_cyl to 1.
(B1) When K2a_Phase ≦ Phase ≦ K2b_Phase is satisfied N1 times continuously, the first injection number correcting cylinder calculating unit 213 sets the lean generation cylinder number N_lean_cyl to 2.
(C1) When K3a_Phase ≦ Phase ≦ K3b_Phase is satisfied N1 times continuously, the first injection number correcting cylinder calculating unit 213 sets the lean generation cylinder number N_lean_cyl to 3.
(D1) When K4a_Phase ≦ Phase ≦ K4b_Phase is established N1 times continuously, the first injection number correcting cylinder calculating unit 213 sets the lean generation cylinder number N_lean_cyl to 4.
When the number of injections Kai_n of the nth cylinder calculated by the number-of-injections calculation unit 214 described later changes from the value of the number of injections Kai_n calculated in the previous calculation cycle, the first injection number correction cylinder calculation unit. In step S213, the number of times N1 is reset to zero.

When the lean generation cylinder number N_lean_cyl is set as described above, the first injection number correction cylinder calculation unit 213 is based on the power spectrum Power calculated by the two-rotation component calculation unit 212 and satisfies the following condition (e1) The correction target cylinder is specified from the lean generation cylinders according to .about. (H1), and the detected cylinder number of the correction target cylinder (hereinafter referred to as the correction target cylinder number) N_hos_cyl is set. K1_Power, K2_Power, K3_Power, and K4_Power are values determined empirically according to the characteristics of the engine 9.
(E1) When the lean generation cylinder number N_lean_cyl = 1 and K1_Power ≦ Power, the first injection number correcting cylinder calculating unit 213 sets the correction target cylinder number N_hos_cyl to 1.
(F1) When the lean generation cylinder number N_lean_cyl = 2 and K2_Power ≦ Power, the first injection number correction cylinder calculation unit 213 sets the correction target cylinder number N_hos_cyl to 2.
(G1) When the lean generation cylinder number N_lean_cyl = 3 and K3_Power ≦ Power, the first injection number correction cylinder calculation unit 213 sets the correction target cylinder number N_hos_cyl to 3.
(H1) When the lean generation cylinder number N_lean_cyl = 4 and K4_Power ≦ Power, the first injection number correction cylinder calculation unit 213 sets the correction target cylinder number N_hos_cyl to 4.

FIG. 15 is a diagram schematically illustrating the function of the injection number calculation unit 214. The number-of-injections calculation unit 214 calculates the number of injections Kai_n (n indicates the cylinder number) of the correction target cylinder according to the following conditions (i1) to (l1). In other words, the injection number calculation unit 214 decreases the number of injections of the correction target cylinder according to the following conditions (i1) to (l1). In the present embodiment, the initial values of Kai_1, Kai_2, Kai_3, and Kai_4 are all set to 6. That is, the initial number of injections performed by the same cylinder per cycle is six. Further, the lower limit value of the number of injections Kai_n is 1 in all cases.
(I1) When the correction target cylinder number N_hos_cyl = 1, the injection number calculation unit 214 decreases the value of the injection number Kai_1 of the first cylinder by one.
(J1) When the correction target cylinder number N_hos_cyl = 2, the injection number calculation unit 214 decreases the value of the injection number Kai_2 of the second cylinder by one.
(K1) When the correction target cylinder number N_hos_cyl = 3, the injection number calculation unit 214 decreases the value of the injection number Kai_3 of the third cylinder by one.
(L1) When the correction target cylinder number N_hos_cyl = 4, the injection number calculation unit 214 decreases the value of the injection number Kai_4 of the fourth cylinder by one.

FIG. 16 is a diagram schematically illustrating the function of the fuel injection amount calculation unit 215. The fuel injection amount calculation unit 215 calculates the k-th injection amount TI_n_k of the nth cylinder using the following equation (2).
TI_n_k = (Tp0 × Alpha) / Kai_n (2)

  For example, when the number of injections Kai_1 = 5, the number of injections in one cycle of the first cylinder is five. In this case, the fuel injection amount calculation unit 215 causes the fuel injection amount to be divided into five equal parts so that TI_1_1 = TI_1_2 = TI_1_3 = TI_1_4 = TI_1_5.

FIG. 17 is a diagram schematically illustrating the function of the fuel injection timing calculation unit 216. The fuel injection timing calculation unit 216 uses the following equations (3) to (8) according to the value of the number of injections Kai_n calculated by the injection number calculation unit 214, and the kth injection timing of the nth cylinder. IT_n_k is calculated. Each parameter is a value determined empirically according to the characteristics of the engine 9.
When Kai_n = 6,
IT_n_1 = K_IT_n_1a, IT_n_2 = K_IT_n_2a,
IT_n_3 = K_IT_n_3a, IT_n_4 = K_IT_n_4a,
IT_n_5 = K_IT_n_5a, IT_n_6 = K_IT_n_6a (3)
When Kai_n = 5,
IT_n_1 = K_IT_n_1b, IT_n_2 = K_IT_n_2b,
IT_n_3 = K_IT_n_3b, IT_n_4 = K_IT_n_4b,
IT_n_5 = K_IT_n_5b (4)
When Kai_n = 4,
IT_n_1 = K_IT_n_1c, IT_n_2 = K_IT_n_2c,
IT_n_3 = K_IT_n_3c, IT_n_4 = K_IT_n_4c (5)
When Kai_n = 3,
IT_n_1 = K_IT_n_1d, IT_n_2 = K_IT_n_2d,
IT_n_3 = K_IT_n_3d (6)
When Kai_n = 2,
IT_n_1 = K_IT_n_1e, IT_n_2 = K_IT_n_2e (7)
When Kai_n = 1
IT_n_1 = K_IT_n_1f (8)

FIG. 18 is a diagram schematically illustrating the function of the abnormality determination unit 217. The abnormality determination unit 217 determines whether or not the cylinder is abnormal by using the following equation (9). If the abnormality is determined to be abnormal, the abnormality notification flag f_MIL is set to 1, and if it is determined to be normal, the abnormality is determined to be abnormal. The notification flag f_MIL is set to 0. When the abnormality notification flag f_MIL is set to 1, for example, an abnormality notification lamp (not shown) is turned on. In the equation (9), it is preferable that NG_Kai is determined so as to be the number of injections that becomes the exhaust amount (especially soot) determined to be abnormal.
When Kai_n> NG_Kai, f_MIL = 0
When Kai_n ≦ NG_Kai, f_MIL = 1 (9)

According to the first embodiment described above, the following operational effects can be obtained.
(1) The engine control device 100 that performs split fuel injection that injects fuel a plurality of times in one cycle for each of a plurality of cylinders provided in the multi-cylinder engine 9 performs first injection number correction cylinder calculation A unit 213 and an injection number calculation unit 214. The first injection number correcting cylinder calculating unit 213 detects a cylinder that is leaner than a predetermined value as a lean generation cylinder among the plurality of cylinders compared to the air-fuel ratio of the other cylinders. The number-of-injections calculation unit 214 decreases the number of fuel injections to the lean generation cylinder detected by the first number-of-injection correction cylinders calculation unit 213. By reducing the number of fuel injections to the lean generation cylinder, the fuel injection amount per one time, that is, the valve opening time is increased. For this reason, the variation in the actual combustion injection amount with respect to the injection signal due to the change over time can be made relatively small, and the deterioration of the operation performance can be prevented.
Further details will be described. In general, a spark ignition type fuel injection valve has a large variation in injection amount in a region where the time width of an applied injection pulse is short, that is, in a region where the valve opening time is short. For this reason, it is designed to be used for a valve opening time longer than the allowable variation in the injection amount. In a new fuel injection valve, even if the variation in fuel injection amount is a valve opening time that is less than the allowable value, the variation in injection amount may become unacceptably large due to secular change. Therefore, lean combustion occurs in a cylinder equipped with an injection valve in which the injection amount decreases due to secular change, and the torque step increases. Therefore, in the present invention, for the cylinder that performs lean combustion, the valve opening time per injection is increased by reducing the number of fuel injections so that the variation in the injection amount does not increase. Thereby, generation | occurrence | production of a torque level | step difference can be suppressed.

(2) The fuel injection amount calculation unit 215 is configured to prevent a change in the total fuel injection amount in one cycle by the lean generation cylinder before and after the number of fuel injections to the lean generation cylinder is decreased by the injection number calculation unit 214. The fuel injection amount per divided fuel injection is controlled. Thereby, a required torque can be obtained.

(3) After the number of fuel injections to the lean generating cylinder is reduced, a combustion state, for example, a cylinder in which the air-fuel ratio is leaner than a predetermined value compared to the air-fuel ratio of other cylinders is not detected again The fuel injection number calculation unit 214 maintains the number of fuel injections for the lean generation cylinder. Therefore, when the lean generation cylinder is not detected, the number of fuel injections of the same cylinder in one cycle can be maintained.

(4) After the number of times of fuel injection to the lean generation cylinder is reduced, when a combustion state, for example, a cylinder in which the air / fuel ratio is leaner than a predetermined value compared to the air / fuel ratio of other cylinders is detected again The fuel injection number calculation unit 214 further reduces the number of fuel injections of the lean generation cylinder. When the lean generating cylinder maintains lean combustion, the number of fuel injections is further decreased to increase the fuel injection amount per split fuel injection. Therefore, the actual fuel injection amount relative to the injection signal is reduced. Variation can be reduced.

(5) When the number of fuel injections to the lean generation cylinder is reduced to a predetermined number, a combustion state, for example, a cylinder in which the air-fuel ratio is leaner than a predetermined value compared to the air-fuel ratio of other cylinders is detected again When it is done, the abnormality determination unit 217 notifies that it is abnormal. When the number of fuel injections in the same cylinder during one cycle is reduced, soot emission generally increases. Therefore, when the number of fuel injections is reduced to a predetermined number (NG_Kai), it can be notified that exhaust has deteriorated.

(6) The two-rotation component calculation unit 212 extracts a frequency component corresponding to the two-rotation period of the multi-cylinder engine 9 based on the air-fuel ratio signal. The first injection number correcting cylinder calculating unit 213 detects the lean generation cylinder based on the frequency component corresponding to the two rotation period extracted by the two rotation component calculating unit 212. When the air-fuel ratio of at least one cylinder is performing lean combustion, the waveform of the air-fuel ratio signal output from the catalyst upstream air-fuel ratio sensor 12 oscillates in one cycle period, that is, the engine two-rotation period. The first injection number correcting cylinder calculating unit 213 can detect the lean generation cylinder based on the above phenomenon.

(7) The two-rotation component calculation unit 212 extracts a phase spectrum and a power spectrum corresponding to the two-rotation period of the multi-cylinder engine 9 based on the signal indicating the air-fuel ratio. The first injection number correction cylinder calculation unit 213 detects a lean generation cylinder based on the phase spectrum extracted by the two-rotation component calculation unit 212, and determines whether or not the detected power spectrum of the lean generation cylinder is equal to or greater than a predetermined value. To do. The fuel injection number calculation unit 214 reduces the number of fuel injections when the first injection number correction cylinder calculation unit 213 determines that the power spectrum of the lean generation cylinder is equal to or greater than a predetermined value. The waveform of the air-fuel ratio signal when the air-fuel ratio of at least one cylinder is performing lean combustion is a specific reference point (for example, specific The phase from the intake stroke top dead center of the cylinder) changes. For this reason, it is possible to detect the lean generation cylinder from the value of the phase spectrum among the components of the two rotation cycles of the engine 9 obtained by Fourier transforming the air-fuel ratio signal. In addition, the amplitude of the vibration phenomenon of the above waveform changes depending on the lean degree of the lean-burning cylinder. That is, the larger the lean degree, the larger the amplitude of the waveform. Therefore, it is possible to obtain the lean degree of the lean generation cylinder from the value of the power spectrum having a correlation with the amplitude among the components of the two rotation cycles of the engine 9 obtained by Fourier transforming the air-fuel ratio signal. Therefore, the lean generation cylinder is detected based on the phase spectrum corresponding to the two rotation cycles of the engine 9, and when the power spectrum is larger to some extent among the detected lean generation cylinders, it is determined that the lean degree is large and the correction target cylinder is Can be identified.

-Second Embodiment-
An engine control apparatus according to the second embodiment will be described with reference to FIGS. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first embodiment. The present embodiment is different from the first embodiment in that the lean generation cylinder is detected using the angular acceleration and the angular jerk based on the rotation speed signal output from the crank angle sensor.

  First, the outline of the engine control apparatus according to the second embodiment will be described with reference to schematic functional block diagrams shown in FIGS. As shown in FIG. 19, the engine control apparatus according to the second embodiment calculates the angular acceleration or angular jerk of the crank based on the signal output from the crank angle sensor, and calculates the calculated angular acceleration or angular acceleration. A lean generation cylinder is detected based on the jerk. In this case, as shown in FIG. 20, the engine control device calculates the average angular acceleration or average angular jerk of each cylinder when each cylinder of the engine is in a predetermined cycle, and the calculated average angular acceleration is predetermined. When it is determined whether or not the calculated average angular jerk is out of the predetermined range, and it is determined that the average angular acceleration is equal to or less than the predetermined value, or the calculated average angular jerk is out of the predetermined range. The cylinder is detected as a lean generation cylinder. Hereinafter, the second embodiment will be specifically described.

  FIG. 21 shows the functions of the CPU 21 of the control unit 16 in the second embodiment. The CPU 21 according to the second embodiment replaces the two-rotation component calculation unit 212 and the first injection number correction cylinder calculation unit 213 included in the CPU 21 according to the first embodiment with an angular acceleration / angular jerk calculation unit 218, A second injection number correcting cylinder calculating unit 219 is functionally provided. The angular acceleration / angular acceleration calculation unit 218 calculates the angular acceleration dNe_n and the angular jerk ddNe_n from the rotation speed Ne of the crankshaft corresponding to the signal output from the crank angle sensor 15. Note that n indicates a cylinder number. Further, the second injection number correcting cylinder calculating unit 219 sets the correction target cylinder number N_hos_cyl of the correction target cylinder using the angular acceleration dNe_n and the angular jerk ddNe_n calculated by the angular acceleration / angular jerk calculating unit 218. To do.

  FIG. 22 is a diagram schematically illustrating the function of the angular acceleration / angular jerk calculation unit 218. The angular acceleration / angular acceleration calculation unit 218 uses the crank shaft rotational speed Ne corresponding to the rotational speed signal from the crank angle sensor 15 to average the rotational speed between 90 deg and 270 deg after the compression top dead center of the nth cylinder. Avg_Ne_n is calculated. Note that n changes in the ignition order. The angular acceleration / angular acceleration calculation unit 218 calculates the difference between the current average rotational speed Avg_Ne_n and the average rotational speed Avg_Ne_n of the previous ignition sequence (previous) as the angular acceleration dNe_n of the nth cylinder. For example, when the ignition order is from the first cylinder → the third cylinder → the fourth cylinder → the second cylinder, the angular acceleration / angular acceleration calculation unit 218 determines that the average rotational speed Avg_Ne_1 of the current first cylinder and the ignition order are The difference from the previous average rotational speed Avg_Ne_2 of the second cylinder is defined as the angular acceleration dNe_1 of the first cylinder. Further, the angular acceleration / angular acceleration calculation unit 218 calculates the difference between the current angular acceleration dNe_n and the previous angular acceleration dNe_n as the angular jerk ddNe_n of the nth cylinder.

FIG. 23 is a diagram schematically illustrating the function of the second injection number correction cylinder calculation unit 219. Based on the angular acceleration dNe_n or the angular jerk ddNe_n calculated by the angular acceleration / angular jerk calculating unit 218, the second injection number correcting cylinder calculating unit 219 performs correction according to the following conditions (a2) to (d2). The number N_hos_cyl is set. K1_dNe, K1_ddNe, K2_ddNe, and N2 are values that are determined empirically according to the characteristics of the engine 9.
(A2) When dNe_1 ≦ K1_dNe is established N2 times continuously, or ddNe_1 ≦ K1_ddNe is established N2 times continuously, or ddNe_1 ≧ K2_ddNe is established N2 times continuously, the second injection number correcting cylinder calculating unit 219 The correction target cylinder number N_hos_cyl is set to 1.
(B2) When dNe_2 ≦ K1_dNe is established N2 times continuously, or ddNe_2 ≦ K1_ddNe is established N2 times continuously, or ddNe_2 ≧ K2_ddNe is established N2 times continuously, the second injection number correcting cylinder calculating unit 219 The correction target cylinder number N_hos_cyl is set to 2.
(C2) When dNe_3 ≦ K1_dNe is established N2 times continuously, or ddNe_3 ≦ K1_ddNe is established N2 times continuously, or ddNe_3 ≧ K2_ddNe is established N2 times continuously, the second injection number correction cylinder calculating unit 219 The correction target cylinder number N_hos_cyl is set to 3.
(D2) When dNe_4 ≦ K1_dNe is established N2 times continuously, or ddNe_4 ≦ K1_ddNe is established N2 times continuously, or ddNe_4 ≧ K2_ddNe is established N2 times continuously, the second injection number correcting cylinder calculating unit 219 The correction target cylinder number N_hos_cyl is set to 4.

According to the second embodiment described above, in addition to the functions and effects (1) to (5) obtained by the first embodiment, the following functions and effects are obtained.
(1) The angular acceleration / angular jerk calculating unit 218 calculates the angular acceleration or angular jerk of the crank based on the signal output from the crank angle sensor. The second injection number correcting cylinder calculating unit 219 detects the lean generation cylinder based on the angular acceleration or the angular jerk calculated by the angular acceleration / angular jerk calculating unit 218. When the air-fuel ratio of at least one cylinder is lean burning, the torque generated by the combustion of the lean generation cylinder is smaller than the torque generated by the combustion of the other cylinders, that is, the cylinders that are not lean burning. There is a correlation between the torque generated by the engine 9 and the rotational angular acceleration or rotational angular jerk of the engine 9. That is, when the generated torque is small, the rotational angular acceleration and the rotational angular jerk are small. When the generated torque is restored, the rotational angular acceleration is also restored to the original value (that is, a normal value), and the rotational angular jerk is once increased and then restored to the original value. The second injection number correcting cylinder calculating unit 219 can detect the lean generation cylinder based on the above phenomenon.

(2) The angular acceleration / angular jerk calculating unit 218 calculates the average angular acceleration or average angular jerk of each cylinder when the cylinders of the multi-cylinder engine 9 are in a predetermined cycle, and calculates the calculated average angle. It is determined whether the acceleration is equal to or less than a predetermined value or the calculated average angular jerk is out of a predetermined range. When the average angular acceleration is determined to be equal to or less than the predetermined value by the angular acceleration / angular jerk calculation unit 218 or the average angular jerk calculated by the angular acceleration / angular jerk calculation unit 218 is outside the predetermined range, the second The injection number correcting cylinder calculating unit 219 detects the cylinder as a lean generation cylinder. The torque generated by the combustion of the lean generation cylinder is smaller than the generation torque of the other cylinders that are not lean burning, and the rotation angular acceleration and the rotation angle jerk of the engine 9 change accordingly. In order to clearly correspond the torque generated by the combustion of each cylinder to the angular acceleration and the angular jerk, the angular acceleration / angular jerk calculating unit 218 is configured so that each cylinder of the engine 9 has a predetermined cycle (for example, an expansion stroke). The average angular acceleration or average jerk of the cylinder is calculated. When the average angular acceleration or the average angular jerk changes, the second injection number correcting cylinder calculating unit 219 generates a cylinder in which the generated torque has changed from the interval calculated by the angular acceleration / angular jerk calculating unit 218, that is, lean generation A cylinder can be detected. Specifically, when a certain cylinder becomes lean combustion, the angular acceleration corresponding to the torque generated by the combustion of the cylinder becomes small. Therefore, the second injection frequency correction cylinder calculation unit 219 has an average angular acceleration equal to or less than a predetermined value. The lean generation cylinder can be detected in response to the fact. In addition, since the angular jerk increases once and then returns to a normal value, the second injection frequency correction cylinder calculation unit 219 determines whether the average angular jerk is out of the predetermined range. The generated cylinder can be detected.

-Third embodiment-
An engine control apparatus according to a third embodiment will be described with reference to FIGS. In the following description, the same components as those in the first and second embodiments are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first and second embodiments. In this embodiment, depending on the operating region of the engine, correction is made using one of angular acceleration and angular jerk based on the air-fuel ratio signal from the catalyst upstream air-fuel ratio sensor and the rotational speed signal output from the crank angle sensor. It differs from the first and second embodiments in that the cylinder is set.

  First, the outline of the engine control apparatus according to the third embodiment will be described with reference to the schematic functional block diagram shown in FIG. The engine control apparatus according to the third embodiment extracts a frequency component corresponding to the two rotation cycles of the engine based on a signal indicating the air-fuel ratio output from the air-fuel ratio sensor or the O2 sensor, and outputs it from the crank angle sensor. Based on the signal, the angular acceleration or angular jerk of the crank is calculated. Then, the cylinder that is leaner than the predetermined value based on the frequency component corresponding to the rotation period and the cylinder that is leaner than the predetermined value are detected based on the angular acceleration or the angular jerk. One of these results is output as a lean generation cylinder at least according to the engine speed or load (that is, the operating region). The third embodiment will be specifically described below.

  FIG. 25 shows the functions of the CPU 21 of the control unit 16 in the third embodiment. The CPU 21 has a basic fuel injection amount calculation unit 210, an air-fuel ratio feedback correction value calculation unit 211, a rotation component calculation unit 212, a first injection number correction cylinder calculation unit 213, an injection having the same functions as those in the first embodiment. The number calculation unit 214, the fuel injection amount calculation unit 215, the fuel injection timing calculation unit 216, the abnormality determination unit 217, the angular acceleration / angular jerk calculation unit 218, and the second function having the same functions as those of the second embodiment. In addition to the injection number correcting cylinder calculating unit 219, a lean determination method switching unit 220 and a switch 221 are functionally provided. Therefore, in the following description, the function of the lean determination method switching unit 220 is mainly performed.

FIG. 26 is a diagram schematically illustrating the function of the lean determination method switching unit 220. The lean determination method switching unit 220 sets the lean determination method switching flag f_ch_lean using the following equation (10). When the lean determination method switching flag f_ch_lean is set to 1, the correction set by the second injection number correction cylinder calculation unit 219 using the rotation speed Ne of the crankshaft corresponding to the rotation speed signal from the crank angle sensor 15 The number of injections of the target cylinder N_hos_cyl is corrected. When the lean determination method switching flag f_ch_lean is set to 0, the number of injections of the correction target cylinder specified by the first injection number correction cylinder calculating unit 213 is corrected using the air-fuel ratio signal from the catalyst upstream air-fuel ratio sensor 12. Is done.
F_ch_lean = 1 when Tp ≦ K1_Tp and Ne ≦ K1_Ne
In other cases, f_ch_lean = 0 (10)

  In the above equation (10), K1_Tp is determined according to the detection accuracy of the two rotation components of the air-fuel ratio signal from the catalyst upstream air-fuel ratio sensor 12, and K1_Ne is calculated from the rotation speed signal from the crank angle sensor 15. Preferably, it is determined according to the detection accuracy of the angular acceleration and angular jerk. The above expression (10) represents that the lean generation cylinder is detected using the angular acceleration and the angular jerk when the engine 9 is operated at a relatively low load and low rotation. That is, the inertial force increases as the engine 9 operates at a lower speed, and therefore the correlation between the combustion torque and the angular acceleration increases, and the detection accuracy of the lean generation cylinder by using the angular acceleration and the angular jerk increases. Is making use of. Further, Expression (10) represents that the lean generation cylinder is detected using the air-fuel ratio signal when the engine 9 is operated at a relatively high load and high rotation. That is, when the engine 9 is operating at a high load and high rotation, the degree to which the exhaust gas discharged from the exhaust valve diffuses during the period until it reaches the catalyst upstream air-fuel ratio sensor 12 is reduced. This makes use of the fact that the detection accuracy of the lean cylinder is increased by using.

  When the lean determination method switching flag f_ch_lean is set to 1 by the lean determination method switching unit 220, the switch 221 is switched, and the correction target cylinder number N_hos_cyl set by the second injection number correction cylinder calculation unit 219 is the number of injections. It is output to the calculation unit 214. Further, when the lean determination method switching flag f_ch_lean is set to 0 by the lean determination method switching unit 220, the switch 221 is switched, and the correction target cylinder number N_hos_cyl set by the first injection number correction cylinder calculation unit 213 is set. It is output to the injection number calculation unit 214.

According to the third embodiment described above, in addition to the functions and effects obtained by the first and second embodiments, the following functions and effects are obtained.
The lean determination method switching unit 220 switches the switch 221 in accordance with at least the rotational speed or load of the multi-cylinder engine 9, thereby detecting the result detected by the first injection number correcting cylinder calculating unit 213 and the second injection number correcting cylinder. One of the detection results detected by the calculation unit 219 is output as a lean generation cylinder. As described above, when the engine 9 is operating at a low load and a low rotation, the detection accuracy of the lean generation cylinder is improved by using the angular acceleration and the angular jerk, and the engine 9 is operated at a high load and high rotation. When the engine is operated with the air-fuel ratio signal, the detection accuracy of the lean generation cylinder can be improved by using the air-fuel ratio signal. That is, since the detection method of the lean generation cylinder is changed according to the operating state of the engine 9, the lean generation cylinder can be reliably detected.

-Fourth embodiment-
An engine control apparatus according to a fourth embodiment will be described with reference to FIGS. In the following description, the same components as those in the first and second embodiments are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first and second embodiments. In the present embodiment, the correction target cylinder is identified by using both the angular acceleration and the angular jerk based on the air-fuel ratio signal from the catalyst upstream air-fuel ratio sensor and the rotational speed signal from the crank angle sensor. Different from the second embodiment.

  First, the outline of the engine control apparatus of the fourth embodiment will be described with reference to the schematic functional block diagram shown in FIG. The engine control apparatus according to the fourth embodiment extracts a frequency component corresponding to the two rotation cycles of the engine based on a signal indicating the air-fuel ratio output from the air-fuel ratio sensor or the O2 sensor, and outputs it from the crank angle sensor. Based on the signal, the angular acceleration or angular jerk of the crank is calculated. Then, a cylinder that is leaner than a predetermined value based on a frequency component corresponding to two rotation cycles, and a cylinder that is leaner than a predetermined value based on angular acceleration or angular jerk The lean generation cylinder is detected using both of the detected results. The fourth embodiment will be specifically described below.

  FIG. 28 shows functions of the CPU 21 of the control unit 16 in the fourth embodiment. The CPU 21 includes a basic fuel injection amount calculation unit 210, an air-fuel ratio feedback correction value calculation unit 211, a rotation component calculation unit 212, an injection frequency calculation unit 214, and a fuel injection amount calculation unit that have the same functions as those in the first embodiment. 215, fuel injection timing calculation unit 216, abnormality determination unit 217, and angular acceleration / angular acceleration calculation unit 218 having the same functions as those of the second embodiment, a third injection number correction cylinder calculation unit 222 is functionally provided. Therefore, in the following description, the function of the third injection number correction cylinder calculation unit 222 is mainly performed.

FIG. 29 is a diagram schematically illustrating the function of the third injection number correcting cylinder calculating unit 222. As shown in FIG. 29, the third injection number correction cylinder calculation unit 222 includes a first correction cylinder number calculation unit 223 and a second correction cylinder number calculation unit 224. The third number-of-injection-correction cylinder calculation unit 222 is configured to set the first correction cylinder number N_hos_cyl_a detected by the first correction cylinder number calculation unit 223 and the second correction cylinder number N_hos_cyl_b detected by the second correction cylinder number calculation unit 224. Based on the following conditions (a3) to (d3), the correction target cylinder number N_hos_cyl is set. N4 is a value determined empirically in accordance with the characteristics of the engine 9. The first correction cylinder number calculation unit 223 and the second correction cylinder number calculation unit 224 will be described later.
(A3) When the first correction cylinder number N_hos_cyl_a = 1 and the second correction cylinder number N_hos_cyl_b = 1 are established N4 times consecutively, the third injection number correction cylinder calculating unit 222 sets the correction target cylinder number N_hos_cyl to 1 .
(B3) When the first correction cylinder number N_hos_cyl_a = 2 and the second correction cylinder number N_hos_cyl_b = 2 are established N4 times consecutively, the third injection number correction cylinder calculation unit 222 sets the correction target cylinder number N_hos_cyl to 2 .
(C3) When the first correction cylinder number N_hos_cyl_a = 3 and the second correction cylinder number N_hos_cyl_b = 3 are continuously established N4 times, the third injection number correction cylinder calculation unit 222 sets the correction target cylinder number N_hos_cyl to 3 .
(D3) When the first correction cylinder number N_hos_cyl_a = 4 and the second correction cylinder number N_hos_cyl_b = 4 are continuously established N4 times, the third injection number correction cylinder calculation unit 222 sets the correction target cylinder number N_hos_cyl to 4 .

FIG. 30 is a diagram schematically illustrating the function of the first correction cylinder number calculation unit 223. The first correction cylinder number calculation unit 223 detects the lean generation cylinder according to the following conditions (e3) to (h3) based on the phase spectrum Phase calculated by the two-rotation component calculation unit 212, and the lean generation cylinder number N_lean_cyl. Set. Note that K1a_Phase, K1b_Phase, K2a_Phase, K2b_Phase, K3a_Phase, K3b_Phase, K4a_Phase, K4b_Phase, and N1 are values determined empirically according to the characteristics of the engine 9.
(E3) When K1a_Phase ≦ Phase ≦ K1b_Phase is established N1 times continuously, the first correction cylinder number calculation unit 223 sets the lean generation cylinder number N_lean_cyl to 1.
(F3) When K2a_Phase ≦ Phase ≦ K2b_Phase is satisfied N1 times continuously, the first correction cylinder number calculation unit 223 sets the lean generation cylinder number N_lean_cyl to 2.
(G3) When K3a_Phase ≦ Phase ≦ K3b_Phase is satisfied N1 times continuously, the first correction cylinder number calculation unit 223 sets the lean generation cylinder number N_lean_cyl to 3.
(H3) When K4a_Phase ≦ Phase ≦ K4b_Phase is established N1 times continuously, the first correction cylinder number calculation unit 223 sets the lean generation cylinder number N_lean_cyl to 4.
When the injection number Kai_n of the nth cylinder calculated by the injection number calculation unit 214 is changed from the value of the injection number Kai_n calculated in the previous calculation cycle, the first injection number correction cylinder calculation unit 213 Reset the number of times N1 to zero.

When the lean generation cylinder number N_lean_cyl is set as described above, the first correction cylinder calculation unit 223 is based on the power spectrum Power calculated by the two-rotation component calculation unit 212 and satisfies the following conditions (i3) to ( The correction target cylinder is specified according to l3), and the first correction cylinder number N_hos_cyl_a is set. K1_Power, K2_Power, K3_Power, and K4_Power are values determined empirically according to the characteristics of the engine 9.
(I3) When the lean generation cylinder number N_lean_cyl = 1 and K1_Power ≦ Power, the first correction cylinder number calculation unit 223 sets the first correction cylinder number N_hos_cyl_a to 1.
(J3) When the lean generation cylinder number N_lean_cyl = 2 and K2_Power ≦ Power, the first correction cylinder number calculation unit 223 sets the first correction cylinder number N_hos_cyl_a to 2.
(K3) When the lean generation cylinder number N_lean_cyl = 3 and K3_Power ≦ Power, the first correction cylinder number calculation unit 223 sets the first correction cylinder number N_hos_cyl_a to 3.
(L3) When the lean generation cylinder number N_lean_cyl = 4 and K4_Power ≦ Power, the first correction cylinder number calculation unit 223 sets the first correction cylinder number N_hos_cyl_a to 4.

FIG. 31 is a diagram schematically illustrating the function of the second correction cylinder number calculation unit 224. The second correction cylinder number calculation unit 224 uses the rotational speed signal from the crank angle sensor 15 to calculate the following condition (m3) based on the angular acceleration and the angular jerk calculated by the angular acceleration / angular jerk calculation unit 218: ) To (p3), the second correction cylinder number N_hos_cly_b is set. K1_dNe, K1_ddNe, K2_ddNe, and N2 are values that are determined empirically according to the characteristics of the engine 9.
(M3) When dNe_1 ≦ K1_dNe is established N2 times continuously, or ddNe_1 ≦ K1_ddNe is established N2 times continuously, or ddNe_1 ≧ K2_ddNe is established N2 times continuously, the second correction cylinder number calculation unit 224 2 The correction cylinder number N_hos_cyl_b is set to 1.
(N3) When dNe_2 ≦ K1_dNe is established N2 times continuously, or ddNe_2 ≦ K1_ddNe is established N2 times continuously, or ddNe_2 ≧ K2_ddNe is established N2 times continuously, the second correction cylinder number calculation unit 224 2 The correction cylinder number N_hos_cyl_b is set to 2.
(O3) When dNe_3 ≦ K1_dNe is established N2 times continuously, or ddNe_3 ≦ K1_ddNe is established N2 times continuously, or ddNe_3 ≧ K2_ddNe is established N2 times continuously, the second correction cylinder number calculation unit 224 2 The correction cylinder number N_hos_cyl_b is set to 3.
(P3) When dNe_4 ≦ K1_dNe is established N2 times continuously, or ddNe_4 ≦ K1_ddNe is established N2 times continuously, or ddNe_4 ≧ K2_ddNe is established N2 times continuously, the second correction cylinder number calculation unit 224 2 The correction cylinder number N_hos_cyl_b is set to 4.

According to the fourth embodiment described above, the following functions and effects can be obtained in addition to the functions and effects obtained by the first and second embodiments.
The first correction cylinder number calculation unit 223 detects a cylinder that burns leaner than a predetermined value based on the frequency component corresponding to the two rotation period extracted by the two rotation component calculation unit 212, and the second correction cylinder number Based on the angular acceleration or the angular jerk calculated by the angular acceleration / angular jerk calculating unit 218, the calculating unit 224 detects a cylinder that is leaner than a predetermined value. Then, the third injection number correcting cylinder calculating unit 222 detects the lean generation cylinder by using both the detection result by the first correcting cylinder number calculating unit 223 and the detection result by the second correcting cylinder number calculating unit 224. did. In other words, both a method similar to the first injection number correction cylinder calculating unit 213 of the first embodiment and a method similar to the second injection number correction cylinder calculating unit 219 of the second embodiment. Since the lean generation cylinder can be detected by using, detection accuracy can be improved. In particular, when the engine 9 is operated at medium load and medium rotation, the detection accuracy of the lean generation cylinder based on the air-fuel ratio signal and the detection accuracy of the lean generation cylinder based on the angular acceleration and the angular jerk are improved. For this reason, when the engine 9 is operating at medium load and medium rotation, the detection accuracy of the lean generation cylinder by the third injection number correcting cylinder calculating unit 222 can be improved.

  In addition, the present invention is not limited to the above-described embodiment as long as the characteristics of the present invention are not impaired, and other forms conceivable within the scope of the technical idea of the present invention are also within the scope of the present invention. included. The embodiments and modifications used for the description may be configured by appropriately combining them.

1 Air cleaner, 2 Air flow sensor,
3 Electronic throttle, 4 Intake pipe,
5 collectors, 6 accelerators,
7 Fuel injection valve, 8 Spark plug,
9 engine, 10 exhaust pipe,
11 Three-way catalyst, 12 Catalyst upstream air-fuel ratio sensor,
13 accelerator opening sensor, 14 water temperature sensor,
15 Crank angle sensor, 16 Control unit,
17 throttle opening sensor, 18 exhaust recirculation pipe,
19 Exhaust gas recirculation amount control valve, 20 Catalyst downstream O2 sensor,
21 CPU, 22 ROM,
23 RAM, 24 input circuit,
25 I / O port, 26 Ignition output circuit,
27 fuel injection valve drive circuit, 28 electronic throttle drive circuit,
29 intake air temperature sensor, 210 basic combustion injection amount calculation unit,
211 Air-fuel ratio feedback correction value calculation unit, 212 Two-rotation component calculation unit,
213 first injection number correction cylinder calculation unit, 214 injection number calculation unit,
215 fuel injection amount calculation unit, 216 fuel injection timing calculation unit,
217 abnormality determination unit, 218 angular acceleration / angular jerk calculation unit,
219 second injection number correction cylinder calculation unit, 220 lean determination method switching unit,
221 switch, 222 third injection number correction cylinder calculation unit,
223 first correction cylinder number calculation unit, 224 second correction cylinder number calculation unit

Claims (1)

In a control device for an engine that performs split fuel injection that injects fuel a plurality of times in one cycle by a fuel injection valve provided in each of a plurality of cylinders,
The air-fuel ratio or engine operating condition is detected, and based on the detection result, a cylinder that is leaner than a predetermined value compared to the air-fuel ratio of the other cylinders is detected as a lean generation cylinder among the plurality of cylinders. Lean cylinder detecting means to
Injection number control means for reducing the number of fuel injections to the lean generation cylinder detected by the lean cylinder detection means ;
Extraction means for extracting a frequency component corresponding to two rotation cycles of the engine having the plurality of cylinders based on a signal indicating the air-fuel ratio output from the air-fuel ratio sensor or the O2 sensor;
Calculation means for calculating the angular acceleration or angular jerk of the crank based on the signal output from the crank angle sensor;
The lean cylinder detecting means includes first detecting means for detecting a cylinder that is leaner than the predetermined value based on a frequency component corresponding to the two rotation cycles extracted by the extracting means, and the calculating means. Second detecting means for detecting a cylinder that is leaner than the predetermined value based on the calculated angular acceleration or angular jerk,
One detection result of the detection result by the first detection means and the detection result by the second detection means is output as the lean generation cylinder according to at least the rotation speed or load of the engine having the plurality of cylinders. An engine control device further comprising switching means .

Images