WO2013153895A1 - Engine control device - Google Patents

Abstract

In the present invention, in split fuel injection for injecting fuel multiple times into the same cylinder during one cycle, deterioration of driving performance caused by leaning of the air-fuel ratio occurring due to time degradation of a fuel injection valve, etc., is suppressed. An engine control device is provided with the following: a lean cylinder detection means for detecting, as a cylinder in which leaning occurs, a cylinder from among a plurality of cylinders that is leaner than a prescribed value as compared to the air-fuel ratio of other cylinders; and a fuel injection frequency control means for reducing the frequency of fuel injection in the cylinder in which leaning occurs that was detected by the lean cylinder detection means.

Description

Engine control device

The present invention relates to a control device of an engine.

Due to global environmental problems, vehicles are required to reduce their emissions. In particular, in recent years, there has been an increasing demand for reducing the amount of soot emitted from engines. In order to reduce the amount of soot emissions, split fuel injection is effective in which multiple fuel injections are performed on the same cylinder in one cycle. Conventionally, a fuel injection system is known that estimates the air-fuel ratio of each cylinder based on the output of the detected value of the air-fuel ratio sensor for each cylinder and calculates and corrects the injection amount variation of the fuel injection valve of each cylinder at 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 is further increased as the temporal change progresses. In particular, when the actual fuel injection amount fluctuates in a decreasing direction, the air-fuel ratio of the cylinder becomes lean, so the generated torque decreases and a torque step occurs with other cylinders, resulting in deterioration of drivability. Have the problem of

According to a first aspect of the present invention, in a control device of an engine performing split fuel injection in which fuel is injected a plurality of times in one cycle to each of a plurality of cylinders provided in a multi-cylinder engine, Lean cylinder detection which detects the operating condition of the engine and detects a cylinder leaner than a predetermined value among the plurality of cylinders as a lean generation cylinder based on the detection result And an injection number control means for reducing the number of fuel injections to the lean generation cylinder detected by the lean cylinder detection 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 with time of the fuel injection valve etc., and the number of fuel injections of the cylinder being lean is Reduce. 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 the deterioration of the drivability.

A block diagram for explaining an outline of functions of an engine control apparatus according to an embodiment of the present invention A block diagram for explaining an outline of functions of an engine control apparatus according to an embodiment of the present invention A block diagram for explaining an outline of functions of an engine control apparatus according to a first embodiment A block diagram for explaining an outline of functions of an engine control apparatus according to a first embodiment A block diagram for explaining an outline of functions of an engine control apparatus according to a first embodiment A block diagram for explaining an outline of functions of an engine control apparatus according to a first embodiment A block diagram for explaining an outline of functions of an engine control apparatus according to a first embodiment The schematic block diagram which shows the whole system of the engine control system by embodiment of this invention Block diagram for explaining the configuration of the control unit of the embodiment Block diagram for explaining the function by the CPU in the control unit according to the first embodiment Diagram schematically illustrating the function of the basic fuel injection amount calculation unit according to the first to fourth embodiments Diagram schematically illustrating the function of the air-fuel ratio feedback correction value calculation unit according to the first to fourth embodiments Diagram schematically illustrating the function of the two-rotation component computing unit according to the first to fourth embodiments A diagram schematically illustrating the function of a first injection number correction cylinder calculation unit according to the first to fourth embodiments. A diagram schematically illustrating the function of the injection number calculation unit according to the first to fourth embodiments Diagram schematically illustrating the function of the fuel injection amount calculation unit according to the first to fourth embodiments Diagram schematically illustrating the function of a fuel injection timing calculation unit according to the first to fourth embodiments Diagram schematically illustrating the function of the abnormality determination unit according to the first to fourth embodiments Block diagram schematically illustrating the function of the engine control system according to the second embodiment Block diagram schematically illustrating the function of the engine control system according to the second embodiment Block diagram for explaining the function by the CPU in the control unit according to the second embodiment A diagram schematically illustrating functions of an angular acceleration and angular jerk computing unit according to the second to fourth embodiments. A diagram schematically illustrating the function of the second injection number correction cylinder calculation unit according to the second to fourth embodiments. Block diagram schematically illustrating functions of an engine control apparatus according to a third embodiment Block diagram for explaining the function by the CPU in the control unit according to the third embodiment Diagram schematically illustrating the function of the lean determination method switching unit according to the third embodiment A block diagram for explaining an outline of functions of an engine control apparatus according to a first embodiment Block diagram for explaining the function of the CPU in the control unit according to the fourth embodiment A diagram schematically illustrating the function of the third injection number correction cylinder calculation unit according to the fourth embodiment A diagram schematically illustrating the function of the first corrected cylinder number calculation unit according to the fourth embodiment A diagram schematically illustrating the function of the second corrected cylinder number calculation unit according to the fourth embodiment

The present invention relates to a control device for an engine adopting a split fuel injection method, and when a cylinder in lean combustion is detected, the number of fuel injections for that cylinder is reduced to reduce torque fluctuation of the engine. The That is, as shown in the functional block diagram of the engine control device according to the embodiment of FIG. 1, the engine control device performs split fuel injection for injecting fuel a plurality of times in one cycle for each of a plurality of cylinders. During operation, the air-fuel ratio or the operating condition of the engine is detected. The engine control device detects a cylinder that is leaner than a predetermined value among the plurality of cylinders based on the detection result as a lean generation cylinder, and detects the lean generation cylinder. To reduce the number of fuel injections. Then, as shown in the functional block diagram of the engine control device according to the embodiment of FIG. 2, the engine control device reduces the number of fuel injections to the lean generation cylinder before and after the reduction. The fuel injection amount per split fuel injection is controlled to prevent a change in the fuel injection amount. The 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, an outline of the engine control system according to the first embodiment will be described using 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 rotation cycles of the engine based on the signal indicating the air-fuel ratio output from the air-fuel ratio sensor or the O2 sensor. Do. Then, the engine control device detects the lean occurring cylinder based on the frequency component corresponding to the extracted two rotation cycle. That is, as shown in FIG. 4, the engine control apparatus of the present embodiment extracts a phase spectrum and a power spectrum corresponding to two rotation cycles of the engine based on the signal indicating the air-fuel ratio, and based on the phase spectrum. Detect lean cylinders. Then, the engine control device according to the present embodiment determines whether the detected power spectrum of the lean generation cylinder is equal to or more than a predetermined value, and determines that the power spectrum of the lean generation cylinder is equal to or more than the predetermined value. To reduce

As shown in FIG. 5, in the engine control apparatus, after the number of fuel injections to the lean generation cylinder is reduced, the cylinder whose air fuel ratio is leaner than the air fuel ratio of the other cylinders is again set to a predetermined value. If not detected, the number of fuel injections to the lean generation cylinder is maintained. Further, as shown in FIG. 6, in the engine control device of the present embodiment, after the number of fuel injections to the lean generation cylinder is reduced, the air fuel ratio is made leaner than the predetermined value compared to the air fuel ratio of the other cylinders. If a cylinder that has been detected is detected again, the number of fuel injections for the lean generation cylinder is further reduced. Then, as shown in FIG. 7, when the number of times of fuel injection to the lean generation cylinder is reduced to a predetermined number, the engine control device of the present embodiment has an air fuel ratio compared with the air fuel ratio of other cylinders. If a cylinder that is leaner than that is detected again, this is to notify that it is abnormal. The first embodiment will be specifically described below.

FIG. 8 is a schematic block diagram of the entire system of the engine control device 100. As shown in FIG. The engine control device 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. 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 downstream catalyst O2 sensor 20 and an intake air temperature sensor 29 are provided.

The engine 9 according to the present embodiment is configured of 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 an amount of air flowing through the air cleaner 1 (hereinafter referred to as an intake air amount), and controls a signal (hereinafter referred to as an intake air amount signal) indicative of the intake air amount. 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 degree sensor 17 is attached to the electronic throttle 3 and outputs a signal indicating the opening degree of the electronic throttle 3 (hereinafter referred to as an opening degree signal) to the control unit 16. The intake temperature sensor 29 is provided upstream of the air cleaner 1 and detects the temperature of air from the outside (hereinafter referred to as intake temperature), and a signal indicative of the intake temperature (hereinafter referred to as intake temperature signal) is a control unit. Output to 16

The crank angle sensor 15 outputs a signal at every 10 degrees of rotation angle of the crankshaft in the engine 9 to the control unit 16 for each fuel cycle as a signal indicating the rotation speed of the crankshaft (hereinafter, rotation speed signal). 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 is an arithmetic circuit that has a CPU, a ROM, a RAM, and the like, which will be described later, and controls each component of the engine control device 100 and executes various data processing. The control unit 16 controls the intake air amount from the air flow sensor 2, the opening degree signal from the accelerator opening degree sensor 13, the water temperature signal from the water temperature sensor 14, the rotational speed signal from the crank angle sensor 15, and the throttle opening degree sensor An operating state of the engine 9 is detected by inputting an opening degree signal from the engine 17 and an intake air temperature signal from the intake air temperature sensor 29. Then, 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 a target throttle opening degree 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 to the spark plug 8 a drive signal for igniting the spark plug 8 at the calculated ignition timing. Furthermore, the control unit 16 detects a cylinder in which lean combustion is occurring, and performs processing (injection number / injection amount control processing) for controlling the number of fuel injections and the fuel injection amount in one cycle of the detected cylinders. The details of the process by the control unit 16 will be described later.

The fuel injected from the fuel injection valve 7 according to 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 mixture is detonated by the spark generated from the spark plug 8 at each ignition timing calculated by the control unit 16. The combustion pressure resulting from the explosion of the mixture depresses the piston to generate power of the engine 9. A part of the exhaust after explosion of the 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 reflux 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 connecting the engine 9 to the three-way catalyst 11 and outputs a signal indicating the detected oxygen concentration, that is, an air-fuel ratio (hereinafter, air-fuel ratio signal) to the control unit 16 . The catalyst downstream O2 sensor 20 is provided in the flow passage downstream of the three-way catalyst 11, and outputs a signal indicating whether the amount of residual oxygen in the exhaust gas is thick or thin to the control unit 16.

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

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

Values set in the output port include, for example, an operation signal of the spark plug 8, a drive signal of the fuel injection valve 7, a drive signal for realizing the target opening degree of the electronic throttle 3, and the like. 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 flows, and OFF when it does not flow. The ignition timing of the spark plug 8 is when the actuation signal of the spark plug 8 turns from ON to OFF. The drive signal of the fuel injection valve 7 is an ON / OFF signal that is ON when the valve is open and OFF when the valve is closed. The drive signal of the fuel injection valve 7 is amplified to energy sufficient for opening the fuel injection valve 7 by the fuel injection valve drive circuit 27 and is 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.

The lean cylinder detection processing and the number of injections / injection amount control processing executed by the CPU 21 of the control unit 16 will be described below 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, and fuel injection. A quantity 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 rotational speed Ne of the crankshaft corresponding to the rotational speed signal input from the crank angle sensor 15 Then, the injection pulse width Tp0 corresponding to the basic fuel injection amount is calculated. Based on the air-fuel ratio signal Rabf from the catalyst upstream air-fuel ratio sensor 12, the air-fuel ratio feedback correction value calculation unit 211 calculates a correction value Alpha for correcting the fuel injection amount so as to achieve the target air-fuel ratio.

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 a two-rotation cycle of the engine 9, that is, a power spectrum Power and a phase spectrum Phase. The first injection number correction cylinder calculation unit 213 is a cylinder in which lean combustion is occurring based on the component of the two rotation cycle of the engine 9 calculated by the two rotation component calculation unit 212 (hereinafter referred to as a lean generation cylinder) To detect Then, the first injection number correction cylinder calculation unit 213 specifies a cylinder whose injection number is to be corrected among the detected lean occurring cylinders, that is, a correction target cylinder. The injection number calculation unit 214 calculates the injection number Kai_n of each cylinder. Here, n represents a cylinder number. 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, as described later.

Based on the calculated air-fuel ratio feedback correction value Alpha and the calculated number of times of injection Kai_n of each cylinder, the fuel injection amount calculation unit 215 has an injection pulse width equivalent to the fuel injection amount of each cylinder with respect to the basic injection fuel amount Tp0. Calculate TI_n_k. In addition, n shows a cylinder number and k shows the injection number (injection order) of the same cylinder in 1 cycle. The fuel injection timing calculation unit 216 calculates the injection timing IT_n_k of each cylinder from the number of times of injection Kai_n of each cylinder. In addition, n shows a cylinder number and k shows the injection number (order) of the same cylinder in 1 cycle. The abnormality determination unit 217 determines whether the cylinder is abnormal based on the number of times of injection Kai_n of each cylinder. If it is determined that an abnormality is present, the abnormality determination unit 217 sets the abnormality flag f_MIL to one.

The basic fuel injection amount calculation unit 210, the air fuel ratio feedback correction value calculation unit 211, the two-rotation component calculation unit 212, the first injection number correction cylinder calculation unit 213, and the injection number calculation unit 214 described above with reference to FIGS. The 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 view schematically showing the function of the basic fuel injection amount calculation unit 210. As shown in FIG. The basic fuel injection amount calculation unit 210 calculates a 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 showing the function of the air-fuel ratio feedback correction value calculation unit 211. As shown in FIG. The air-fuel ratio feedback correction value calculation unit 211 calculates the 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. When the 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 the air-fuel ratio feedback correction value Alpha using the signal output from the O2 sensor.

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

The phase spectrum Phase of the two-rotation component is calculated from Phase 0, Phase 0-90, Phase 0-180, Phase 0-270, Phase 0, Phase 0-90,... Is the value obtained by cyclic operation. The above cyclic operation is performed for the purpose of fixing the reference point for calculating the phase. The two-rotation component calculation unit 212 sets the combustion period (180 deg) as the calculation period, and the two-rotation component sets a period in which the engine makes two rotations as one period (360 deg). Therefore, the phase reference point 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 per combustion cycle.

FIG. 14 is a diagram schematically showing the function of the first injection number correction cylinder calculation unit 213. As shown in FIG. The first injection number correction cylinder calculation unit 213 detects a lean occurrence cylinder according to the following conditions (a1) to (d1) based on the phase spectrum Phase calculated by the two-rotation component calculation unit 212, and detects the detected lean The cylinder number of the generated cylinder (hereinafter referred to as a lean generated cylinder number) N_lean_cyl is set. 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) If K1a_Phase ≦ Phase ≦ K1b_Phase is satisfied N1 times consecutively, the first injection number correction cylinder calculating unit 213 sets the lean occurring cylinder number N_lean_cyl to one.
(B1) If K2a_Phase ≦ Phase ≦ K2b_Phase is satisfied N1 times consecutively, the first injection number correction cylinder calculating unit 213 sets the lean occurring cylinder number N_lean_cyl to 2.
(C1) If K3a_Phase ≦ Phase ≦ K3b_Phase is satisfied N1 times consecutively, the first injection number correction cylinder calculating unit 213 sets the lean occurring cylinder number N_lean_cyl to 3.
(D1) If K4a_Phase ≦ Phase ≦ K4b_Phase is satisfied N1 times consecutively, the first injection number correction cylinder operation unit 213 sets the lean occurring cylinder number N_lean_cyl to four.
When the number of times of injection Kai_n of the n-th 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 213 resets the number of times N1 to zero.

When the lean occurring cylinder number N_lean_cyl is set as described above, the first injection number correction cylinder calculating unit 213 sets the following condition (e1) based on the power spectrum Power calculated by the two-rotation component calculating unit 212. The cylinder to be corrected is specified from among the lean occurring cylinders according to (h1), and the cylinder number of the cylinder to be corrected (hereinafter referred to as the cylinder number to be corrected) 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 occurring cylinder number N_lean_cyl = 1 and K1_Power ≦ Power, the first injection number correction cylinder calculating unit 213 sets the cylinder number N_hos_cyl to be corrected to 1.
(F1) When the lean occurring cylinder number N_lean_cyl = 2 and K2_Power ≦ Power, the first injection number correction cylinder calculating unit 213 sets the cylinder number N_hos_cyl to be corrected to 2.
(G1) When the lean occurring cylinder number N_lean_cyl = 3 and K3_Power ≦ Power, the first injection number correction cylinder calculating unit 213 sets the cylinder number N_hos_cyl to be corrected to 3.
(H1) When the lean occurring cylinder number N_lean_cyl = 4 and K4_Power ≦ Power, the first injection number correction cylinder calculating unit 213 sets the cylinder number N_hos_cyl to be corrected to 4.

FIG. 15 is a view schematically showing the function of the injection number calculation unit 214. As shown in FIG. The injection number calculation unit 214 calculates the number of times of injection Kai_n (n indicates a cylinder number) of the cylinder to be corrected according to the following conditions (i1) to (l1). That is, the injection number calculation unit 214 reduces the number of injections of the cylinder to be corrected according to the following conditions (i1) to (11). 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 number of injections implemented by the same cylinder per cycle is set to six as an initial value. Further, the lower limit value of the number of times of injection Kai_n is set to one.
(I1) When the correction target cylinder number N_hos_cyl = 1, the injection number calculation unit 214 decreases the value of the number of times of injection 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 reduces the value of the number of times of injection 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 number of times of injection 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 reduces the value of the number of times of injection Kai_4 of the fourth cylinder by one.

FIG. 16 is a diagram schematically showing the function of the fuel injection amount calculation unit 215. As shown in FIG. The fuel injection amount calculation unit 215 calculates the kth 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 makes the fuel injection amount equal to five and performs the fuel injection so that TI_1_1 = TI_1_2 = TI_1_3 = TI_1_4 = TI_1_5.

FIG. 17 schematically shows the function of the fuel injection timing calculation unit 216. As shown in FIG. The fuel injection timing calculation unit 216 uses the following equations (3) to (8) according to the value of the number of times of injection Kai_n calculated by the injection number calculation unit 214 to determine the kth injection timing of the nth cylinder Calculate IT_n_k.
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_3 c, IT_n_4 = K_IT_n_4 c (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 schematically shows the function of the abnormality determination unit 217. As shown in FIG. The abnormality determination unit 217 determines whether the cylinder is abnormal or not by using the following equation (9), and when it is determined that the cylinder is abnormal, the abnormality notification flag f_MIL is set to 1, and when it is determined that it is normal 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 Equation (9), it is preferable that NG_Kai be determined to be the number of injections that is the discharge amount of exhaust (especially soot) that is determined to be abnormal.
F_MIL = 0 when Kai_n> NG_Kai
F_MIL = 1 when Kai_n ≦ NG_Kai (9)

According to the first embodiment described above, the following effects can be obtained.
(1) The engine control device 100 performing split fuel injection for injecting fuel several times in one cycle for each of the plurality of cylinders provided in the multi-cylinder engine 9 performs the first injection number correction cylinder calculation And an injection number calculation unit 214. The first injection number correction cylinder calculation unit 213 detects, among the plurality of cylinders, a cylinder that is leaner than a predetermined value compared to the air-fuel ratio of the other cylinders as the lean generation cylinder. The injection number calculation unit 214 reduces the number of fuel injections to the lean occurring cylinder detected by the first injection number correction cylinder calculation unit 213. By reducing the number of fuel injections to the lean generation cylinder, the amount of fuel injection per injection, that is, the valve opening time increases. For this reason, it is possible to relatively reduce the variation of the actual combustion injection amount with respect to the injection signal caused by the change with time, and to prevent the deterioration of the driving performance.
Further details will be described. Generally, in the spark ignition type fuel injection valve, the variation of the injection amount is large in the region where the time width of the applied injection pulse is short, that is, the region where the valve opening time is short. Therefore, it is designed to be used in the valve opening time or more in which the dispersion of the injection quantity can be allowed. With a new fuel injection valve, even if the variation of the fuel injection amount is less than the allowable value for the valve opening time, the variation of the injection amount may become unacceptably large due to the secular change. Therefore, lean combustion occurs in a cylinder equipped with an injection valve whose injection amount decreases with age, and the torque step becomes large. Therefore, in the present invention, for the cylinder in which the lean combustion is performed, the valve opening time per injection is lengthened by reducing the number of times of fuel injection so that the variation in the injection amount does not increase. Thereby, the occurrence of the torque step can be suppressed.

(2) Before and after the number of times of fuel injection to the lean generation cylinder is reduced by the injection number calculation unit 214, the fuel injection amount calculation unit 215 prevents the change of the total fuel injection amount in one cycle by the lean generation cylinder. The amount of fuel injection per split fuel injection was controlled. Thereby, necessary torque can be obtained.

(3) After the number of fuel injections to the lean generation cylinder is reduced, the combustion state, for example, when the cylinder whose 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 to 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 fuel injections to the lean generation cylinder is reduced, a combustion state, for example, when a cylinder whose air-fuel ratio is leaner than a predetermined value compared with 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 generation cylinder maintains lean combustion, the fuel injection amount per split fuel injection is increased by further reducing the number of fuel injections, so that the actual fuel injection amount relative to the injection signal is Variations can be reduced.

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

(6) The two-rotation component calculation unit 212 extracts a frequency component corresponding to the two-rotation cycle of the multi-cylinder engine 9 based on the air-fuel ratio signal. Then, the first injection number correction cylinder calculating unit 213 detects the lean occurring cylinder based on the frequency component corresponding to the 2-rotation cycle extracted by the 2-rotation component calculating unit 212. When the air-fuel ratio of at least one cylinder is lean-burning, the waveform of the air-fuel ratio signal output from the catalyst upstream air-fuel ratio sensor 12 oscillates in one cycle cycle, that is, two engine rotation cycles. The first injection number correction cylinder calculation unit 213 can detect a lean occurring cylinder based on the above phenomenon.

(7) The two-rotation component calculation unit 212 extracts the phase spectrum and the power spectrum corresponding to the two-rotation cycle of the multi-cylinder engine 9 based on the signal indicating the air-fuel ratio. The first injection number correction cylinder calculating unit 213 detects a lean occurring cylinder based on the phase spectrum extracted by the two-rotation component calculating unit 212, and determines whether the detected power spectrum of the lean occurring cylinder is equal to or more than a predetermined value. Do. Then, 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 more than the predetermined value. The waveform of the air-fuel ratio signal when the air-fuel ratio of at least one cylinder is in lean combustion is a phenomenon that oscillates in one cycle period, that is, in two engine rotation cycles, a specific reference point (for example, The phase from the top dead center of the cylinder intake process changes. For this reason, it is possible to detect the lean occurring cylinder from the value of the phase spectrum among the components of the two rotation cycles of the engine 9 obtained by subjecting the air-fuel ratio signal to Fourier transform. In addition, the amplitude of the above-described vibration phenomenon of the waveform changes depending on the degree of leanness of the cylinder in lean combustion. That is, the greater the degree of leanness, the greater 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 among the detected lean generation cylinders, the correction target cylinder is determined to be large when the power spectrum is large to a certain extent. It can be identified.

-Second embodiment-
An engine control system according to a second embodiment will be described with reference to FIGS. 19-23. In the following description, the same components as in the first embodiment will be assigned the same reference numerals and differences will be mainly described. The points that are not particularly described are the same as in the first embodiment. The present embodiment differs from the first embodiment in that a lean occurring cylinder is detected using angular acceleration and angular jerk based on a rotational speed signal output from a crank angle sensor.

First, the outline of the engine control system according to the second embodiment will be described using schematic functional block diagrams shown in FIGS. As shown in FIG. 19, the engine control device 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 angle. A lean occurring cylinder is detected based on the acceleration. 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 the average angular acceleration below the value or the calculated average angular acceleration is outside the predetermined range, and the average angular acceleration is below the predetermined value or the calculated average angular acceleration is outside the predetermined range The cylinder is detected as a lean cylinder. The second embodiment will be specifically described below.

FIG. 21 shows functions of the CPU 21 of the control unit 16 in the second embodiment. The CPU 21 according to the second embodiment includes an angular acceleration / angular acceleration calculation unit 218, instead of the 2-rotation component calculation unit 212 and the first injection number correction cylinder calculation unit 213 of the CPU 21 according to the first embodiment. A second injection number correction cylinder calculation unit 219 is functionally provided. The angular acceleration and angular jerk calculation unit 218 calculates the angular acceleration dNe_n and the angular jerk ddNe_n from the rotational speed Ne of the crankshaft corresponding to the signal output from the crank angle sensor 15. In addition, n shows a cylinder number. Further, the second injection number correction cylinder calculation 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 and angular jerk calculation unit 218. Do.

FIG. 22 is a view schematically showing the function of the angular acceleration and angular jerk computing unit 218. As shown in FIG. The angular acceleration and angular jerk calculation unit 218 uses the rotational speed Ne of the crankshaft corresponding to the rotational speed signal from the crank angle sensor 15 to calculate an average rotational speed between 90 degrees and 270 degrees after compression top dead center of the nth cylinder. Calculate Avg_Ne_n. Here, n changes in the order of ignition. The angular acceleration and angular jerk calculation unit 218 calculates the difference between the current average rotation speed Avg_Ne_n and the average rotation speed Avg_Ne_n one time before (previous) the ignition order as the angular acceleration dNe_n of the n-th cylinder. For example, in the case where the firing order is No. 1 → No. 3 → No. 4 → No. 2 cylinder, the angular acceleration / angular acceleration calculation unit 218 calculates the firing order with the average rotation speed Avg_Ne_1 of No. 1 cylinder at this time. The difference from the previous average rotation speed Avg_Ne_2 of the second cylinder is set as the angular acceleration dNe_1 of the first cylinder. Further, the angular acceleration and angular jerk calculation unit 218 calculates the difference between the current angular acceleration dNe_n and the previous angular acceleration dNe_n as the angular acceleration ddNe_n of the n-th cylinder.

FIG. 23 schematically shows the function of the second injection number correction cylinder calculating unit 219. As shown in FIG. The second injection number correction cylinder operation unit 219 corrects the cylinder according to the following conditions (a2) to (d2) based on the angular acceleration dNe_n or the angular acceleration ddNe_n calculated by the angular acceleration / angular acceleration calculation unit 218. Set the number N_hos_cyl. K1_dNe, K1_ddNe, K2_ddNe and N2 are values determined empirically according to the characteristics of the engine 9.
(A2) dNe_1 ≦ K1_dNe holds N2 times consecutively, or ddNe_1 ≦ K1_ddNe holds N2 times continuously, or ddNe_1 ≧ K2_ddNe holds N2 times continuously, the second injection number correction cylinder calculating unit 219 The correction target cylinder number N_hos_cyl is set to 1.
(B2) In the case where dNe_2 ≦ K1_dNe holds N2 times consecutively, or ddNe_2 ≦ K1_ddNe holds N2 times continuously, or ddNe_2 ≧ K2_ddNe holds N2 times continuously, the second injection number correction cylinder calculating unit 219 The correction target cylinder number N_hos_cyl is set to 2.
(C2) dNe_3 ≦ K1_dNe holds N2 times consecutively, or ddNe_3 ≦ K1_ddNe holds N2 times continuously, or ddNe_3 ≧ K2_ddNe holds N2 times continuously, the second injection number correction cylinder calculation unit 219 The correction target cylinder number N_hos_cyl is set to 3.
(D2) dNe_4 ≦ K1_dNe holds N2 times consecutively, or ddNe_4 ≦ K1_ddNe holds N2 times continuously, or ddNe_4 ≧ K2_ddNe holds N2 times continuously, the second injection number correction cylinder calculation 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 effects of (1) to (5) obtained by the first embodiment, the following effects can be obtained.
(1) The angular acceleration and angular jerk calculation unit 218 calculates the angular acceleration or angular jerk of the crank based on the signal output from the crank angle sensor. Then, the second injection number correction cylinder calculating unit 219 detects the lean occurring cylinder based on the angular acceleration or the angular jerk calculated by the angular acceleration and 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 not lean-burning. There is a correlation between the generated torque of the engine 9 and the rotational angular acceleration or rotational angular acceleration of the engine 9. That is, when the generated torque becomes smaller, the rotational angular acceleration and the rotational angular jerk become smaller. When the generated torque recovers, the rotational angular acceleration also recovers to the original value (i.e., the normal value), and the rotational angular acceleration accelerates once and then returns to the original value. The second injection number correction cylinder calculating unit 219 can detect a lean occurring cylinder based on the above phenomenon.

(2) The angular acceleration / angular acceleration calculation unit 218 calculates the average angular acceleration or average angular acceleration of each cylinder when each cylinder of the multi-cylinder engine 9 is in a predetermined cycle, and 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 outside a predetermined range. Then, when it is determined that the average angular acceleration is equal to or less than a predetermined value by the angular acceleration and angular jerk calculation unit 218 or the average angular jerk calculated by the angular acceleration and angular jerk calculation unit 218 is outside the predetermined range, the second The injection number correction cylinder calculating unit 219 detects the cylinder as a lean generation cylinder. The torque generated by the combustion of the lean generating cylinder becomes smaller than the generated torque of the other cylinders not being lean-burned, and the rotational angular acceleration and rotational angular acceleration of the engine 9 also change accordingly. The angular acceleration and angular jerk computing unit 218 is provided for each cylinder of the engine 9 for a predetermined number of cycles (for example, an expansion stroke) in order to make the torque generated by combustion of each cylinder correspond clearly to angular acceleration and angular jerk. Calculate the average angular acceleration or average angular jerk of the cylinder. When the average angular acceleration or the average angular jerk changes, the second injection number correction cylinder calculation unit 219 determines from the section calculated by the angular acceleration and angular jerk calculation unit 218 the cylinder in which the generated torque has changed, that is, the lean generation The cylinder can be detected. Specifically, when a cylinder becomes lean combustion, the angular acceleration corresponding to the torque generated by the combustion of the cylinder decreases, so the second injection number correction cylinder calculating unit 219 determines that the average angular acceleration is less than or equal to a predetermined value. In accordance with that, it is possible to detect lean occurring cylinders. Further, since the angular jerk becomes small and then increases once and returns to the normal value, the second injection number correction cylinder calculating unit 219 makes the lean in response to the average angular jerk falling outside the predetermined range. Can detect the generated cylinder.

-Third embodiment-
An engine control system according to a third embodiment will be described with reference to FIGS. 24 to 26. In the following description, the same components as those in the first and second embodiments will be assigned the same reference numerals and differences will be mainly described. Points that are not particularly described are the same as in the first and second embodiments. In the present embodiment, one of 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 output from the crank angle sensor is used according to the operating range of the engine. This embodiment differs from the first and second embodiments in that cylinders are set.

First, an outline of the engine control system according to the third embodiment will be described using a schematic functional block diagram shown in FIG. The engine control apparatus according to the third embodiment extracts a frequency component corresponding to two rotation cycles of the engine based on the signal indicating the air-fuel ratio output from the air-fuel ratio sensor or the O2 sensor, and outputs the frequency component from the crank angle sensor The angular acceleration or angular acceleration of the crank is calculated based on the received signal. Then, based on the result of detection of a cylinder that is leaner than a predetermined value based on the frequency component corresponding to the rotation period and the angular acceleration or angular jerk, a cylinder that is leaner than a predetermined value is detected. According to at least the rotational speed or the load (i.e., the operating range) of the engine, one of the above results is output as a lean generation cylinder. The third embodiment will be specifically described below.

FIG. 25 shows 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 having the same function as that of the first embodiment, 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, and injection The angular acceleration and angular acceleration calculation unit 218 having the same function as that of the second embodiment and the second operation calculation unit 214, the fuel injection amount calculation unit 215, the fuel injection timing calculation unit 216, and the abnormality determination unit 217 In addition to the injection number correction cylinder calculation unit 219, the lean determination method switching unit 220 and the switch 221 are functionally provided. Therefore, in the following description, the function of the lean determination method switching unit 220 will be mainly described.

FIG. 26 is a diagram schematically showing the function of the lean determination method switching unit 220. As shown in FIG. The lean determination method switching unit 220 sets the lean determination method switching flag f_ch_lean using the following equation (10). If 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 calculation unit 213 is corrected using the air-fuel ratio signal from the catalyst upstream air-fuel ratio sensor 12 Be done.
F_ch_lean = 1 when Tp ≦ K1_Tp and Ne ≦ K1_Ne
F_ch_lean = 0 (10) in cases other than the above

In the above equation (10), K1_Tp is determined according to the detection accuracy of the two-rotation component 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 angular acceleration and angular jerk. The above equation (10) represents that when the engine 9 is operating at a relatively low load and a low rotation speed, the angular acceleration and the angular jerk are used to detect a lean occurring cylinder. That is, since the inertia force is stronger as the engine 9 is operated at lower rotation speed, the correlation between the combustion torque and the angular acceleration becomes higher, and the detection accuracy of the lean generation cylinder by using the angular acceleration and the angular jerk is high. It is used to become. Further, equation (10) represents that the air-fuel ratio signal is used to detect a lean occurring cylinder when the engine 9 is operating at a relatively high load and a high revolution. That is, when the engine 9 is operated at high load and high rotation, the degree of diffusion of exhaust gas discharged from the exhaust valve decreases in a period until it reaches the catalyst upstream air-fuel ratio sensor 12, so the air-fuel ratio signal It is used that the detection accuracy of the lean generation cylinder becomes high 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 calculating unit 219 is the injection number. 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 It is output to the injection number calculation unit 214.

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

-Fourth embodiment-
An engine control system according to the fourth embodiment will be described with reference to FIGS. In the following description, the same components as those in the first and second embodiments will be assigned the same reference numerals and differences will be mainly described. Points that are not particularly described are the same as in the first and second embodiments. In the present embodiment, the first, in that the cylinder to be corrected is identified 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. It differs from the second embodiment.

First, an outline of the engine control system according to the fourth embodiment will be described with reference to a schematic functional block diagram shown in FIG. The engine control apparatus according to the fourth embodiment extracts a frequency component corresponding to two rotation cycles of the engine based on the signal indicating the air-fuel ratio output from the air-fuel ratio sensor or the O2 sensor, and outputs the frequency component from the crank angle sensor The angular acceleration or angular acceleration of the crank is calculated based on the received signal. Then, based on the result of detection of 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. A lean occurrence cylinder is detected using both of the detection result. 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 has a basic fuel injection amount calculation unit 210 having the same function as that of the first embodiment, an air-fuel ratio feedback correction value calculation unit 211, a two-rotation component calculation unit 212, an injection number calculation unit 214, and a fuel injection amount calculation unit In addition to the fuel injection timing calculation unit 216, the abnormality determination unit 217, and the angular acceleration / angular acceleration calculation unit 218 having the same function as that of the second embodiment, a third injection number correction cylinder calculation unit And 222 are functionally provided. Therefore, in the following description, the function of the third injection number correction cylinder calculation unit 222 will be mainly described.

FIG. 29 schematically shows the function of the third injection number correction cylinder calculating unit 222. As shown in FIG. As shown in FIG. 29, the third injection number correction cylinder calculation unit 222 is configured to include a first correction cylinder number calculation unit 223 and a second correction cylinder number calculation unit 224. The third injection number correction cylinder calculating unit 222 generates the first correction cylinder number N_hos_cyl_a detected by the first correction cylinder number calculating unit 223 and the second correction cylinder number N_hos_cyl_b detected by the second correction cylinder number calculating unit 224. Based on the correction target cylinder number N_hos_cyl is set according to the following conditions (a3) to (d3). N4 is a value determined empirically according to the characteristics of the engine 9. Further, the description of the first correction cylinder number calculation unit 223 and the second correction cylinder number calculation unit 224 will be described later.
(A3) If the first correction cylinder number N_hos_cyl_a = 1 and the second correction cylinder number N_hos_cyl_b = 1 hold N4 times consecutively, the third injection number correction cylinder calculation unit 222 sets the correction target cylinder number N_hos_cyl to 1 .
(B3) If the first correction cylinder number N_hos_cyl_a = 2 and the second correction cylinder number N_hos_cyl_b = 2 are successively satisfied N4 times, the third injection number correction cylinder calculation unit 222 sets the correction target cylinder number N_hos_cyl to 2 .
(C3) If the first correction cylinder number N_hos_cyl_a = 3 and the second correction cylinder number N_hos_cyl_b = 3 hold N4 times consecutively, the third injection number correction cylinder calculation unit 222 sets the correction target cylinder number N_hos_cyl to 3. .
(D3) If the first correction cylinder number N_hos_cyl_a = 4 and the second correction cylinder number N_hos_cyl_b = 4 are successively satisfied 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 view schematically showing the function of the first correction cylinder number calculation unit 223. As shown in FIG. The first correction cylinder number calculation unit 223 detects a 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 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) If K1a_Phase ≦ Phase ≦ K1b_Phase is satisfied N1 times consecutively, the first correction cylinder number calculation unit 223 sets the lean occurring cylinder number N_lean_cyl to 1.
(F3) If K2a_Phase ≦ Phase ≦ K2b_Phase is satisfied N1 times consecutively, the first corrected cylinder number computing unit 223 sets the lean occurring cylinder number N_lean_cyl to 2.
(G3) If K3a_Phase ≦ Phase ≦ K3b_Phase is satisfied N1 times consecutively, the first correction cylinder number calculation unit 223 sets the lean occurring cylinder number N_lean_cyl to 3.
(H3) If K4a_Phase ≦ Phase ≦ K4b_Phase is satisfied N1 times consecutively, the first corrected cylinder number computing unit 223 sets the lean occurring cylinder number N_lean_cyl to 4.
When the number of times of injection Kai_n of the n-th cylinder calculated by the number-of-injections calculation unit 214 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 213 Reset N1 times to 0.

When the lean occurring cylinder number N_lean_cyl is set as described above, the first correction cylinder operation unit 223 sets the following conditions (i3) to (i) based on the power spectrum Power calculated by the two-rotation component operation unit 212. 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 occurring 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 occurring 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 occurring 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 occurring 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 view schematically showing the function of the second correction cylinder number calculation unit 224. As shown in FIG. 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 acceleration calculated by the angular acceleration and angular jerk calculation unit 218: The second corrected cylinder number N_hos_cly_b is set in accordance with) to (p3). K1_dNe, K1_ddNe, K2_ddNe and N2 are values determined empirically according to the characteristics of the engine 9.
(M3) dNe_1 ≦ K1_dNe holds N2 times consecutively, or ddNe_1 ≦ K1_ddNe holds N2 times continuously, or ddNe_1 ≧ K2_ddNe holds N2 times continuously, the second correction cylinder number calculation unit 224 2 Set the corrected cylinder number N_hos_cyl_b to 1.
(N3) dNe_2 ≦ K1_dNe holds N2 times consecutively, or ddNe_2 ≦ K1_ddNe holds N2 times continuously, or ddNe_2 ≧ K2_ddNe holds N2 times continuously, the second correction cylinder number calculation unit 224 2 Set the corrected cylinder number N_hos_cyl_b to 2.
(O3) dNe_3 ≦ K1_dNe holds N2 times consecutively, or ddNe_3 ≦ K1_ddNe holds N2 times continuously, or ddNe_3 ≧ K2_ddNe holds N2 times continuously, the second corrected cylinder number calculation unit 224 2 Set the corrected cylinder number N_hos_cyl_b to 3.
(P3) dNe_4 ≦ K1_dNe holds N2 times consecutively, or ddNe_4 ≦ K1_ddNe holds N2 times continuously, or ddNe_4 ≧ K2_ddNe holds N2 times continuously, the second correction cylinder number calculation unit 224 2 Set the corrected cylinder number N_hos_cyl_b to 4.

According to the fourth embodiment described above, in addition to the effects obtained by the first and second embodiments, the following effects can be obtained.
The first correction cylinder number calculation unit 223 detects a cylinder that is burning leaner than a predetermined value based on the frequency component corresponding to the 2-rotation cycle extracted by the 2-rotation component calculation unit 212, and the second correction cylinder number The calculation unit 224 detects a cylinder that is leaner than a predetermined value, based on the angular acceleration or the angular jerk calculated by the angular acceleration / angular jerk calculation unit 218. Then, the third injection number correction cylinder calculation unit 222 detects a lean occurring cylinder using both the detection result by the first correction cylinder number calculation unit 223 and the detection result by the second correction cylinder number calculation unit 224. did. In other words, both the method similar to the first injection number correction cylinder calculating unit 213 of the first embodiment and the method similar to the second injection number correction cylinder calculating unit 219 of the second embodiment The detection accuracy can be improved because the lean generated cylinders can be detected using 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 operated at medium load and medium rotation, the detection accuracy of the lean occurring cylinder by the third injection number correction cylinder calculating unit 222 can be improved.

Furthermore, the present invention is not limited to the above embodiment as long as the features of the present invention are not impaired, and other embodiments considered 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 in the description may be combined appropriately.

1 air cleaner, 2 air flow sensor,
3 electronic throttles, 4 intake pipes,
5 collectors, 6 accelerators,
7 fuel injection valves, 8 spark plugs,
9 engines, 10 exhaust pipes,
11 three-way catalyst, 12 catalyst upstream air-fuel ratio sensor,
13 accelerator opening sensor, 14 water temperature sensor,
15 crank angle sensors, 16 control units,
17 throttle opening sensor, 18 exhaust recirculation pipe,
19 Exhaust Reflow Adjustment Valve, 20 Catalyst Downstream O2 Sensor,
21 CPU, 22 ROM,
23 RAM, 24 input circuits,
25 input / output ports, 26 ignition output circuits,
27 fuel injection valve drive circuit, 28 electronic throttle drive circuit,
29 intake 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 judgment unit, 218 angular acceleration / angular acceleration calculation unit,
219 second injection number correction cylinder operation unit, 220 lean determination method switching unit,
221 switch, 222 third injection number correction cylinder operation unit,
223 first corrected cylinder number calculator, 224 second corrected cylinder number calculator

Claims (11)

1. In a control device of an engine that performs split fuel injection that injects fuel multiple times in one cycle to each of a plurality of cylinders provided in a multi-cylinder engine,
   The air-fuel ratio or the operating condition of the engine is detected, and based on the detection result, among the plurality of cylinders, a cylinder that is leaner than a predetermined value compared to the air-fuel ratio of other cylinders is detected as a lean occurring cylinder Lean cylinder detection means to
   And an injection number control means for reducing the number of fuel injections to the lean generation cylinder detected by the lean cylinder detection means.
2. In the engine control device according to claim 1,
   Before and after the number of times of fuel injection to the lean generation cylinder is reduced by the injection number control means, the divided fuel injection may be performed once to prevent a change in the total fuel injection amount in one cycle by the lean generation cylinder. An engine control device further comprising: fuel injection amount control means for controlling a fuel injection amount of the engine.
3. In the engine control device according to claim 1,
   And an extraction unit that extracts a frequency component corresponding to a two-rotation cycle of the multi-cylinder engine based on a signal indicating an air-fuel ratio output from an air-fuel ratio sensor or an O2 sensor.
   A control device of an engine, wherein the lean cylinder detection means detects the lean occurrence cylinder based on a frequency component corresponding to the two rotation cycle extracted by the extraction means.
4. In the engine control device according to claim 3,
   The extraction means extracts a phase spectrum and a power spectrum corresponding to a 2-rotation cycle of the multi-cylinder engine based on the signal indicating the air-fuel ratio.
   The lean cylinder detection means detects the lean generation cylinder based on the phase spectrum, and determines whether the detected power spectrum of the lean generation cylinder is equal to or greater than a predetermined value.
   The engine control device according to claim 1, wherein the number-of-injections control means decreases the number of fuel injections when the lean cylinder detection means determines that the power spectrum of the lean generation cylinders is equal to or greater than a predetermined value.
5. In the engine control device according to claim 1,
   It further comprises calculation means for calculating the angular acceleration or angular jerk of the crank based on the signal output from the crank angle sensor,
   A control device of an engine, wherein the lean cylinder detection means detects the lean generation cylinder based on the angular acceleration or angular jerk calculated by the calculation means.
6. In the engine control device according to claim 5,
   The calculation means calculates an average angular acceleration or average angular jerk of each cylinder when each cylinder of the multi-cylinder engine is in a predetermined cycle, and the calculated average angular acceleration is equal to or less than a predetermined value, or the calculation Determining whether the average angular jerk calculated by the means is outside a predetermined range;
   When it is determined that the average angular acceleration is equal to or less than a predetermined value by the calculation means, or the average angular jerk calculated by the calculation means is out of a predetermined range, the lean cylinder detection unit determines the cylinder as the lean generation cylinder A control device of an engine characterized by detecting as.
7. In the engine control device according to claim 1,
   Extracting means for extracting a frequency component corresponding to two rotation cycles of the multi-cylinder engine based on a signal indicating an air-fuel ratio output from an air-fuel ratio sensor or an O 2 sensor;
   And calculating means for calculating an angular acceleration or an angular jerk of the crank based on a signal output from the crank angle sensor.
   The lean cylinder detection means is a first detection means for detecting a cylinder that is leaner than the predetermined value based on a frequency component corresponding to the two-rotation cycle extracted by the extraction means; and the calculation means And second detecting means for detecting a cylinder leaner than the predetermined value based on the calculated angular acceleration or angular jerk.
   Switching means for outputting the detection result of one 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 at least the rotational speed or load of the multi-cylinder engine A control device for an engine, further comprising:
8. In the engine control device according to claim 1,
   Extracting means for extracting a frequency component corresponding to two rotation cycles of the multi-cylinder engine based on a signal indicating an air-fuel ratio output from an air-fuel ratio sensor or an O 2 sensor;
   And calculating means for calculating an angular acceleration or an angular jerk of the crank based on a signal output from the crank angle sensor.
   The lean cylinder detection means is a first detection means for detecting a cylinder that is leaner than the predetermined value based on a frequency component corresponding to the two-rotation cycle extracted by the extraction means; and the calculation means And second detecting means for detecting a cylinder leaner than the predetermined value based on the calculated angular acceleration or angular jerk.
   A control device of an engine, wherein the lean cylinder detection means detects the lean generated cylinder using both the detection result by the first detection means and the detection result by the second detection means.
9. In the engine control device according to claim 1,
   A cylinder whose air-fuel ratio is leaner than the predetermined value compared to the air-fuel ratio of other cylinders by the lean cylinder detection means after the number of times of fuel injection to the lean generation cylinder is reduced by the injection number control means In the case where the number of injections is not detected again, the control device for controlling the number of injections maintains the number of fuel injections to the lean occurring cylinder.
10. In the engine control device according to claim 1,
    A cylinder whose air-fuel ratio is leaner than the predetermined value compared to the air-fuel ratio of other cylinders by the lean cylinder detection means after the number of times of fuel injection to the lean generation cylinder is reduced by the injection number control means The engine control device according to claim 1, wherein the number-of-injections control means further reduces the number of fuel injections for the lean generated cylinders when the second detection is detected again.
11. In the engine control device according to claim 10,
    When the number of fuel injections to the lean occurring cylinder is reduced to a predetermined number by the injection number control means, the air / fuel ratio is leaner than the predetermined value by the lean cylinder detection means compared to the air / fuel ratio of the other cylinders. A control device for an engine, further comprising abnormality notification means for giving notification of abnormality when a cylinder being detected is detected again.

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