JP3560264B2 - Engine fuel injection control device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection control device for an engine that can easily obtain an initial explosion at the time of engine start and can smoothly shift from an initial explosion to a complete explosion.
[0002]
[Prior art]
As is well known, when starting the engine, it is necessary to control at a higher air-fuel ratio than normal, and the cranking speed gradually increases after the first initial explosion occurs, and eventually reaches the complete explosion speed At this point, control is switched to normal air-fuel ratio control.
[0003]
In this case, conventionally, the fuel injection amount was increased and corrected depending on the engine temperature such as the cooling water temperature, and the starting control was performed with the same air-fuel ratio from the cranking to the complete explosion. The air-fuel ratio becomes unnecessarily over-rich when transitioning from the initial explosion to a stable complete explosion state at the start, and the air-fuel ratio after the initial explosion due to a decrease in fuel supply due to fuel system vapor generation at high temperature start However, it was difficult to obtain a smooth start due to problems such as a lean start.
[0004]
For this reason, the applicant has previously disclosed in Japanese Unexamined Patent Application Publication No. 2-146240 that, when the engine is started, the fuel is supplied in the amount of the first-explosion start-up fuel injection until the engine speed exceeds the first-explosion engine speed set value. After that, it proposes a technology to smoothly transition from the first explosion to the complete explosion by supplying fuel at the start-up fuel injection amount for the complete explosion until the engine speed exceeds the set value for the complete explosion engine speed. .
[0005]
[Problems to be solved by the invention]
Normally, the fuel injection amount required for the first explosion is adjusted for the complete explosion to compensate for the amount of fuel injected from the injector that adheres to the intake manifold walls, intake valves, combustion chamber walls, etc. and does not contribute to combustion effectively. It must be set larger than the fuel injection amount.
[0006]
Therefore, according to the technology proposed by the present application, even if the engine is cranked and the first explosion occurs and burns in any one of the cylinders, the engine is initially operated until the engine speed exceeds the initial explosion engine speed set value. A large amount of fuel injection for the explosion will continue to be supplied to the engine, causing problems such as the spark plug getting wet and smoldering before reaching the complete explosion, and even if the first explosion occurs the mixture will be too rich and stall There was room for improvement for the problem.
[0007]
Further, depending on the setting of the first explosion fuel injection amount and the complete explosion fuel injection amount, a step may be generated between the first explosion fuel injection amount and the complete explosion fuel injection amount. However, there has been a problem that measures against engine speed fluctuations such as a stagnation in engine speed are not always sufficient.
[0008]
The present invention has been made in view of the above circumstances, and enables an initial explosion to be easily obtained at the time of engine start, and an engine capable of smoothly transitioning from the initial explosion to a complete explosion to ensure engine start. It is an object of the present invention to provide a fuel injection control device.
[0009]
[Means for Solving the Problems]
According to the first aspect of the present invention, as shown in the basic configuration diagram of FIG. 1 (a), an initial explosion fuel injection amount for obtaining an air-fuel ratio suitable for an initial explosion at the time of engine start is set according to an engine state. A first fuel injection amount setting means for setting an initial fuel injection amount for obtaining an appropriate air-fuel ratio from the first explosion to a complete explosion in accordance with an engine state; The initial fuel injection amount set by the fuel injection amount setting means Only when there is a history of complete explosion at the last engine start Before the cylinder discrimination at the time of engine start is completed, the fuel is injected asynchronously with the engine rotation. After the cylinder discrimination is completed, the starting fuel injection amount set by the starting fuel injection amount setting means is set to a predetermined engine rotation speed. Injection control means for injecting in synchronization with the engine rotation until the rotation speed exceeds the explosion determination rotation speed.
[0010]
According to a second aspect of the present invention, as shown in the basic configuration diagram of FIG. 1 (b), a fuel injection amount for the first explosion for obtaining an air-fuel ratio suitable for the first explosion at the time of starting the engine is set according to the engine state. First-explosion fuel injection amount setting means, and starting fuel injection amount setting means for setting a starting fuel injection amount for obtaining an appropriate air-fuel ratio from the first explosion to the complete explosion according to the engine state; There is a history of complete explosion at the last engine start, and When the crank angle signal is input a set number of times before the completion of the cylinder discrimination at the time of starting the engine, the fuel injection amount for the first explosion set by the first fuel injection amount setting means is injected. Injection control means for injecting the starting fuel injection amount set by the starting fuel injection amount setting means until the engine speed exceeds a preset complete explosion determination rotation speed.
[0013]
In other words, according to the first aspect of the present invention, when the engine is started, the fuel injection amount for the first explosion set according to the engine state before the cylinder discrimination is completed. Only when there is a history of complete explosion at the last engine start An air-fuel ratio suitable for the first explosion is obtained by injecting asynchronously with the engine rotation, and after the cylinder discrimination is completed, the starting fuel injection amount set according to the engine state is set to the complete combustion with the engine speed set in advance The fuel is injected in synchronization with the engine speed until the engine speed exceeds the judgment speed, and an appropriate air-fuel ratio from the first explosion to the complete explosion is obtained.
[0014]
According to the second aspect of the invention, when the engine is started, There is a history of complete explosion at the last engine start, and When the crank angle signal is input a set number of times before the cylinder discrimination is completed, the air-fuel ratio suitable for the first detonation is obtained by injecting the fuel injection amount for the first detonation set according to the engine state. After completion, the starting fuel injection amount set according to the engine state is injected until the engine speed exceeds a preset complete explosion determination rotational speed, and an appropriate air-fuel ratio from the initial explosion to the complete explosion is obtained.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 2 to 11 relate to the first embodiment of the present invention, FIG. 2 is a flowchart of a start-time all-cylinder simultaneous injection setting routine, FIGS. 3 to 5 are flowcharts of a Ti setting routine, and FIG. 6 is an engine control system. FIG. 7 is a front view of a crank rotor and a crank angle sensor, FIG. 8 is a front view of a cam rotor and a cam angle sensor, FIG. 9 is a circuit diagram of an electronic control system, and FIG. FIG. 11 is an explanatory diagram showing a switching state with the hour fuel injection control, and FIG. 11 is a time chart of the fuel injection.
[0018]
In FIG. 6, reference numeral 1 denotes an engine. In the figure, a cylinder block 1a is divided into two banks (a left bank on the right side and a right bank on the left side) around the crankshaft 1b. 1 shows a horizontally opposed four-cylinder engine in which 1, 1 and 3 cylinders are arranged and # 2 and # 4 cylinders are arranged in a left bank. Cylinder heads 2 are provided in both left and right banks of a cylinder block 1a of the engine 1, respectively. An intake port 2a and an exhaust port 2b are formed in each cylinder head 2.
[0019]
An intake manifold 3 is connected to the intake port 2a. A throttle chamber 5 is connected to an upstream gathering portion of the intake manifold 3 via an air chamber 4. An intake pipe 6 is connected upstream of the throttle chamber 5. An air cleaner 7 is attached via the air cleaner.
[0020]
A hot-wire type or hot-film type intake air amount sensor 8 is provided immediately downstream of the air cleaner 7 in the intake pipe 6, and a throttle valve 5a provided in the throttle chamber 5 is provided with a throttle valve 5a. A throttle sensor 9 having a built-in throttle opening sensor 9a for detecting the throttle opening and an idle switch 9b that is turned ON when the throttle valve is fully closed is provided in series.
[0021]
An idle speed control valve (ISCV) 11 for adjusting an idle air amount is interposed in a bypass passage 10 that communicates the upstream side and the downstream side of the throttle valve 5a, and communicates with the intake manifold 3. An intake pipe pressure / atmospheric pressure switching solenoid valve 12, which is turned on and off by an electronic control unit (ECU; see FIG. 9) 50 described later, is interposed in the passage of the intake pipe pressure / atmospheric pressure switching solenoid valve 12. The absolute pressure sensor 13 is connected.
[0022]
The intake pipe pressure / atmospheric pressure switching solenoid valve 12 includes an electromagnetic three-way valve having a port communicating with the absolute pressure sensor 13, a port communicating with the intake manifold 3, and an atmospheric port. The intake port pressure is introduced into the absolute pressure sensor 13 by closing the atmosphere port and opening the port communicating with the intake manifold 3, and communicates with the intake manifold 3 when measuring the atmospheric pressure. Atmospheric pressure is introduced into the absolute pressure sensor 13 by closing the port and releasing the atmospheric port.
[0023]
Further, an injector 14 is disposed immediately upstream of each intake port 2a of each cylinder of the intake manifold 3, and a spark plug 15a having a tip exposed to a combustion chamber is attached to the cylinder head 2 for each cylinder. ing. An ignition coil 15b is connected to the ignition plug 15a, and an igniter 16 is connected to the ignition coil 15b.
[0024]
The injector 14 is connected to a fuel tank 18 via a fuel supply path 17, and an in-tank type fuel pump 19 is provided in the fuel tank 18. The fuel from the fuel pump 19 is pumped from the injector 14 to the pressure regulator 21 via the fuel filter 20 interposed in the fuel supply path 17, and the excess fuel is returned from the pressure regulator 21 to the fuel tank 18. The fuel pressure to the injector 14 is adjusted to a predetermined pressure.
[0025]
On the other hand, a knock sensor 22 is attached to the cylinder block 1a of the engine 1, and a coolant temperature sensor 24 faces a cooling water passage 23 that connects the left and right banks of the cylinder block 1a. Further, an O2 sensor 26 faces the gathering portion of the exhaust manifold 25 communicating with the exhaust port 2b of the cylinder head 2, and a catalytic converter 27 is interposed downstream of the O2 sensor 26.
[0026]
A crank rotor 28 is mounted on a crankshaft 1b supported by the cylinder block 1a. A crank angle sensor 29 is provided on the outer periphery of the crank rotor 28. Further, a cam rotor 30 is connected to the camshaft 1c of the cylinder head 2, and a cam angle sensor 31 for cylinder identification is provided on the cam rotor 30.
[0027]
As shown in FIG. 7, the crank rotor 28 has projections 28a, 28b, 28c formed on its outer periphery, and these projections 28a, 28b, 28c are connected to the cylinders (# 1, # 2 and # 3, # 3). 4) formed before the compression top dead center (BTDC) θ1, θ2, θ3. In the present embodiment, θ1 = 97 ° CA, θ2 = 65 ° CA, and θ3 = 10 ° CA.
[0028]
As shown in FIG. 8, projections 30a, 30b, 30c for cylinder discrimination are formed on the outer periphery of the cam rotor 30, and the projections 30a are located after the compression top dead center (ATDC) θ4 of the # 3, # 4 cylinders. And the projection 30b is formed of three projections, and the first projection is formed at the position of ATDC θ5 of the # 1 cylinder. Further, the projection 30c is formed by two projections, and the first projection is formed at the position of ATDC θ6 of the # 2 cylinder. In the present embodiment, θ4 = 20 ° CA, θ5 = 5 ° CA, and θ6 = 20 ° CA.
[0029]
Then, as shown in the time chart of FIG. 11, each protrusion of the crank rotor 28 is detected by the crank angle sensor 29 including a magnetic sensor (such as an electromagnetic pickup), and θ1, θ2, θ3 (BTDC 97 °, 65 ° , 10 °) is output every 1/2 engine revolution (every 180 ° CA), while each protrusion of the cam rotor 30 between the θ3 crank pulse and the θ1 crank pulse is also formed of a magnetic sensor. Detected by the cam angle sensor 31, a predetermined number of cam pulses are output.
[0030]
An electronic control unit (ECU; see FIG. 9) 50, which will be described later, calculates the engine speed NE based on the input interval time of the crank pulse output from the crank angle sensor 29, and calculates the combustion stroke order of each cylinder ( For example, based on a pattern of # 1 cylinder → # 3 cylinder → # 2 cylinder → # 4 cylinder) and a value obtained by counting a cam pulse from the cam angle sensor 31 by a counter, a fuel injection target cylinder and an ignition target cylinder are determined. Perform cylinder discrimination.
[0031]
Next, an electronic control unit (ECU) 50 that performs electronic control of the engine 1 will be described with reference to FIG. The ECU 50 mainly includes two computers, a main computer 51 for performing fuel injection control, ignition timing control, idle speed control, and the like, and a sub-computer 52 dedicated to knock detection processing. A constant voltage circuit 53, a driving circuit 54 and an A / D converter 55 connected to the main computer 51, an A / D converter 56 connected to the sub computer 52, and a frequency filter for the A / D converter 56. Peripheral circuits such as an amplifier 58 connected through 57 are built in.
[0032]
The constant voltage circuit 53 is connected to a battery 60 via a first relay contact of a power supply relay 59 having two relay contacts, and the anode side of a diode 62 is connected to the battery 60 via an ignition switch 61. ing. The cathode side of the diode 62 is connected to one end of a relay coil of the power supply relay 59, and the other end of the relay coil is grounded.
[0033]
The constant voltage circuit 53 is not only connected to the battery 60 via the first relay contact of the power supply relay 59 but also directly connected to the battery 60, and the ignition switch 61 is turned on. Then, when the relay contact of the power supply relay 59 is closed, power is supplied from the constant voltage circuit 53 to each unit, and the constant voltage circuit 53 is always turned on regardless of whether the ignition switch 61 is ON or OFF. A power supply for backup is supplied to a backup RAM 68 of the main computer 51 described later.
[0034]
The fuel pump 19 is connected to the battery 60 via a relay contact of a fuel pump relay 63. The fuel pump relay 63 has a drive coil 54 having one end of a relay coil connected to the battery 60 via a second relay contact of the power supply relay 59 and the other end of the relay coil connected to the main computer 51. It is connected to the. A power supply line to each actuator extends from the second relay contact of the power supply relay 59.
[0035]
The main computer 51 is a microcomputer to which a CPU 65, a ROM 66, a RAM 67, a backup RAM 68, a counter / timer group 69, an SCI 70 as a serial communication interface, and an I / O interface 71 are connected via a bus line 72. The backup RAM 68 is constantly supplied with a backup power supply from the constant voltage circuit 53 to hold data.
[0036]
The counter / timer group 69 includes various counters such as a free-run counter, a counter for counting the input of a cam angle sensor signal, a fuel injection timer, an ignition timer, a periodic interrupt timer for generating a periodic interrupt, and a crank. Various timers such as a timer for measuring an input interval of an angle sensor signal and a watchdog timer for monitoring a system abnormality are collectively referred to for convenience. In the main computer 51, various other software counters and timers are used. Can be
[0037]
Input ports of the I / O interface 71 include an idle switch 9b, a crank angle sensor 29, a cam angle sensor 31, a neutral switch 32 that is turned on when a shift lever of a transmission (not shown) is set to a neutral position, an air conditioner switch 33, a starter. The switch 34 and the ignition switch 61 are connected. Further, via the A / D converter 55, the intake air amount sensor 8, the throttle opening sensor 9a, the absolute pressure sensor 13, the water temperature sensor 24, the O2 sensor 26 and the vehicle speed sensor 35 are connected, and the battery voltage VB is input and monitored.
[0038]
An igniter 16 is connected to an output port of the I / O interface 71, and an ISCV 11, an intake pipe pressure / atmospheric pressure switching solenoid valve 12, an injector 14, and a relay coil of a fuel pump relay 63 are driven by the drive coil. Further, after the ignition switch 61 is turned off, the power supply relay 59 is turned on for a predetermined time after the ignition switch 61 is turned off. A relay coil of the relay 59 is connected to the output port of the I / O interface 71 via the drive circuit 54 on the cathode side of the diode 62.
[0039]
On the other hand, the sub-computer 52 is a microcomputer to which a CPU 75, a ROM 76, a RAM 77, a counter / timer group 78, an SCI 79, and an I / O interface 80 are connected via a bus line 81, like the main computer 51. The main computer 51 and the sub-computer 52 are connected to each other by serial communication lines via the SCIs 70 and 79.
[0040]
A crank angle sensor 29 and a cam angle sensor 31 are connected to input ports of the I / O interface 80, and a knock sensor 22 is connected to the input port via an amplifier 58, a frequency filter 57, and an A / D converter 56. After the knock detection signal from the knock sensor 22 is amplified to a predetermined level by the amplifier 58, necessary frequency components are extracted by the frequency filter 57, and the digital signal is extracted by the A / D converter 56. Is converted and input.
[0041]
A predetermined output port of the I / O interface 80 in the sub-computer 52 is connected to a predetermined input port of the I / O interface 71 in the main computer 51. In the sub-computer 52, a signal from the knock sensor 22 is output. The presence / absence of knock occurrence is determined based on the I / O interface 80, and the result of this determination is output to the main computer 51 via the output port of the I / O interface 80.
[0042]
In the event of knocking, knock data transmitted from the sub-computer 52 through the serial line is read into the main computer 51, and the main computer 51 delays the ignition timing of the corresponding cylinder based on the knock data, thereby reducing the knock. It is designed to avoid it.
[0043]
That is, the sub-computer 52 sets a sample period of the signal from the knock sensor 22 based on the engine speed and the engine load, and performs high-speed A / D conversion of the signal from the knock sensor 22 in this sample period. The vibration waveform is faithfully converted into digital data, the presence or absence of knock is determined based on the data, and the determination result is output to the main computer 51.
[0044]
On the other hand, in the main computer 51, the CPU 65 processes a detection signal from sensors and switches input via the I / O interface 71, a battery voltage, and the like according to a control program stored in the ROM 66. Based on various data stored in the RAM 67 and the backup RAM 68, fixed data stored in the ROM 66, and the like, various control amounts such as a fuel injection amount, an ignition timing, and a duty ratio of a drive signal for the ISCV 11 are calculated, and various actuators are controlled. It drives to perform various controls such as air-fuel ratio learning control, ignition timing control, and idle speed control.
[0045]
That is, the drive circuit 54 turns on the fuel pump relay 63 to drive the fuel pump 19, and turns the intake pipe pressure / atmospheric pressure switching solenoid valve 12 on and off, and the absolute pressure sensor 13 detects the atmospheric pressure and the intake pipe pressure. Are alternately detected, and a drive pulse signal corresponding to the calculated fuel injection pulse width is output at a predetermined timing to the injector 14 of the corresponding cylinder to perform fuel injection control, and at a timing corresponding to the calculated ignition timing. It outputs an ignition signal to the igniter 16 to execute ignition timing control, and further outputs a duty control signal to the ISCV 11 to execute idle speed control and the like.
[0046]
Further, in the main computer 51, when detecting the start mode of the engine accompanying the turning on of the ignition switch 61, the starting fuel injection amount by the normal start control is synchronized with the rotation of the engine accompanying the cranking from the injector 14. Before the injection, the fuel injection amount for the first explosion is previously injected simultaneously and asynchronously in all cylinders, so that the first explosion is easily obtained, and after the first explosion, control is performed so as to smoothly reach the complete explosion. That is, by the main computer 51 and the respective sensors and actuators connected to the main computer 51, each function of the initial explosion fuel injection amount setting means, the starting fuel injection amount setting means, and the injection control means according to the present invention is provided. Is realized.
[0047]
Hereinafter, the air-fuel ratio control (fuel injection control) executed by the main computer 51 will be described with reference to the flowcharts shown in FIGS. Since the sub-computer 52 is a computer dedicated to knock detection processing, description of the control contents is omitted.
[0048]
First, when the ignition switch 61 is turned on and power is supplied to the ECU 50, the system is initialized (clearing each flag and each variable value), and a start-time all-cylinder simultaneous injection setting routine shown in FIG. 2 is executed.
[0049]
In the present embodiment, the start-time all-cylinder simultaneous injection setting routine is executed only once immediately after the power is turned on to the system and the initialization is completed, and the driver turns on the ignition switch 61 to directly execute the engine cranking. Therefore, even if the starter switch 34 is turned on, the process is completed before the engine is actually cranked, and the process is executed according to the state at the time of the previous engine start. It is determined whether or not to execute the simultaneous asynchronous injection of all cylinders prior to the engine-synchronous start-time injection by the Ti (fuel injection pulse width that determines the fuel injection amount) setting routine of FIG.
[0050]
That is, in the start-time all-cylinder simultaneous injection setting routine, first, in step S101, the state at the time of the previous engine start is determined by referring to the start-time all-cylinder simultaneous injection determination flag FST stored in the backup RAM 68. The start-time all-cylinder simultaneous injection determination flag FST is cleared (FST) when the set time elapses (when the complete explosion state continues for the set time or more) after the engine completely explodes and the control shifts from the start control to the normal control. ← 0), and the state at the time of the previous engine start can be determined based on the value of the start-time all-cylinder simultaneous injection determination flag FST.
[0051]
If FST = 1 in step S101 and there is a history that the explosion did not complete at the time of the previous engine start or that the ignition switch 61 was turned off without performing cranking, the routine is terminated as it is. If an excessive fuel supply is avoided and FST = 0, the previous engine start state has reached the complete explosion from the cranking through the initial explosion, and if there is a history that the complete explosion state has continued for the set time or more, the process proceeds to step S102 and thereafter. Then, a process for performing simultaneous injection to all cylinders asynchronously is performed.
[0052]
That is, in step S102, a basic value TSTRT is set based on the cooling water temperature TW detected by the water temperature sensor 24, and then the process proceeds to step S103, where the basic value TSTRT is set to the atmospheric pressure based on the atmospheric pressure ATM measured by the absolute pressure sensor 13. An atmospheric pressure correction coefficient KTSATM for correction is set.
[0053]
The basic value TSTRT is a fuel amount for obtaining an air-fuel ratio suitable for the first explosion by correcting a fuel component that adheres to an intake manifold wall surface, an intake valve, a combustion chamber wall surface, or the like and cannot contribute to combustion when the engine is started (described later). This is a base value for setting the start-up simultaneous injection pulse width of all cylinders (TSSTRT), which is determined based on the intake pipe negative pressure at the time of extremely low rotation at the beginning of cranking. As shown in step S102, the lower the cooling water temperature TW, the larger the value.
[0054]
Further, as shown in step S103, the atmospheric pressure correction coefficient KTSATM is set to KTSATM = 1.0 under the standard atmospheric pressure (760 mmHg), and a small value is set under conditions where the atmospheric pressure ATM is low, such as at high altitude. Then, the correction amount for the basic value TSTRT is reduced, and the correction amount for the basic value TSTRT is increased by setting a large value under a condition where the atmospheric pressure ATM is high such as in lowland.
[0055]
Thereafter, the process proceeds to step S104, in which a voltage correction coefficient TCSL for compensating the invalid injection time of the injector 14 is set based on the battery voltage VB. The voltage correction coefficient TCSL is set to a large value because the invalid injection time of the injector 14 increases as the battery voltage VB decreases.
[0056]
Next, proceeding to step S105, the basic explosion fuel injection is performed by multiplying the basic value TSTRT set in step S102 by the atmospheric pressure correction coefficient KTSATM set in step S103 and the voltage correction coefficient TCSL set in step S104. The start-time all-cylinder simultaneous injection pulse width TSSTRT for determining the amount is set (TSSTRT ← TSRT × KTSATM × TCSL), and the process proceeds to step S106.
[0057]
In step S106, the start-time simultaneous injection pulse width TSSTRT of all cylinders set in step S105 is set, and in step S107, the injectors 14 of all cylinders are simultaneously driven via the drive circuit 54. Then, in step S108, the start-time all-cylinder simultaneous injection determination flag is set (FST ← 1), and the routine ends.
[0058]
As a result, a fuel amount corresponding to the simultaneous injection pulse width TSSTRT of all cylinders at the time of starting is simultaneously injected into all cylinders, and this fuel is first drawn into the cylinders during an intake stroke at the time of cranking. The air-fuel ratio is reached, and the first explosion can be easily obtained.
[0059]
Following the above-described start-time all-cylinder simultaneous injection setting routine, the Ti setting routine of FIGS. 3 to 5 is executed at predetermined intervals, and is executed until the engine speed exceeds the complete explosion determination engine speed. In the control, a starting fuel injection amount for obtaining an appropriate air-fuel ratio from the first explosion to the complete explosion is set. In this routine, first, in step S201, it is determined whether or not cylinder determination based on a signal from the crank angle sensor 29 and a signal from the cam angle sensor 31 has been performed.
[0060]
In this cylinder discrimination, the crank pulse input from the crank angle sensor 29 is identified based on the input pattern of the cam pulse from the cam angle sensor 31 as to which one of the crank angles θ1, θ2, and θ3 is the signal. And the cylinder to be injected with fuel are determined from the input pattern of the cam pulse.
[0061]
That is, as shown in the time chart of FIG. 11, for example, if there is a cam pulse input between the previous crank pulse input and the present crank pulse input, the present crank pulse is a θ1 crank pulse. And the next input crank pulse can be identified as the θ2 crank pulse.
[0062]
Also, when there is no cam pulse input between the previous and current crank pulse inputs and there is a cam pulse input between the last and previous crank pulse inputs, the current crank pulse can be identified as a θ2 crank pulse, and the next input crank pulse The pulse can be identified as a θ3 crank pulse. Further, when there is no cam pulse input between the previous and current times and between the last and last crank pulse inputs, the currently input crank pulse can be identified as the θ3 crank pulse, and the next input crank pulse is It can be identified as a θ1 crank pulse.
[0063]
Further, when three cam pulses are input (θ5 cam pulse corresponding to the projection 30b) between the previous and current crank pulse inputs, the next compression top dead center is # 3 cylinder, When two cam pulses are input during the pulse input (θ6 cam pulse corresponding to the projection 30c), it can be determined that the next top dead center is the # 4 cylinder.
[0064]
If one cam pulse is input between the previous and current crank pulse inputs (θ4 cam pulse corresponding to the projection 30a) and the previous compression top dead center determination was for a # 4 cylinder, the next compression top dead center Is the # 1 cylinder. Similarly, if one cam pulse is input between the previous and current crank pulse inputs, and the previous compression top dead center determination was for the # 3 cylinder, the next compression top dead center is # It can be determined that there are two cylinders.
[0065]
When the cylinder discrimination has not been performed, the routine exits from the step S201, and when the cylinder discrimination has been performed, the process proceeds from the step S201 to the step S202, where the engine speed calculated based on the signal from the crank angle sensor 29 is determined. A basic fuel injection pulse width TP is calculated from NE and an intake air amount Q based on a signal from the intake air amount sensor 8 (TP ← K × Q / NE; K is an injector characteristic correction constant).
[0066]
Next, in step S203, the operation state of the starter switch (starter SW) 34 is detected. When the starter switch (starter SW) is ON (during start-up), in step S204, the fuel is supplied only during start-up during starter motor operation in order to improve engine startability. The starting increase coefficient KST for increasing the amount is set to a set value CKST (where CKST> 1.0). When the starting increase coefficient KST is OFF, the starting increase coefficient KST is set to 1.0 (no starting increase correction) in step S205, and the process proceeds to step S206.
[0067]
In step S206, a mixing ratio allocation coefficient KMR is set based on the basic fuel injection pulse width TP and the engine speed NE. The mixture ratio allocation coefficient KMR is a coefficient for ensuring fine controllability even when a difference occurs between the inherent characteristics of the injector 14 and the intake air amount sensor 8, and is a basic coefficient representing the engine load. For example, an optimum coefficient obtained by an experiment or the like is stored in a table or the like so that an appropriate air-fuel ratio can be obtained for each region of the engine operating state specified by the fuel injection pulse width TP and the engine speed NE.
[0068]
Thereafter, the process proceeds to step S207, where a full increase coefficient KFULL is set based on the throttle opening Th detected by the throttle opening sensor 9a, the basic fuel injection pulse width TP, and the engine speed NE. This full increase coefficient KFULL is an increase correction coefficient for improving the output performance by increasing the fuel in an operation state requiring an output, such as when the throttle valve is fully opened or under a high load, and the throttle opening Th is When the throttle valve is fully opened or when the basic fuel injection pulse width TP indicates a high load state, the table is set by referring to a table set in advance based on the engine speed NE with interpolation calculation and the like. When the throttle opening Th is other than the full opening and the engine load is other than the high load, KFULL ← 0 is set.
[0069]
Next, the process proceeds to step S208, and based on the coolant temperature TW representing the engine temperature, the fuel injection amount is increased and corrected to set the water temperature increase coefficient KTW for ensuring the operability in the cold state of the engine. In step S209, Similarly, a post-start increase coefficient KAS is set based on the cooling water temperature TW representing the engine temperature to ensure the stability of the engine speed immediately after the start of the engine.
[0070]
As shown in step S208, the water temperature increase coefficient KTW is set so that the fuel increase rate increases as the cooling water temperature TW, that is, the engine temperature, decreases, and the post-start increase coefficient KAS is determined in step S209. As shown in the figure, the initial value is set when the starter switch 34 is ON, and after the starter switch 34 is turned ON → OFF, the set value is decreased by 0 every time the routine is executed until the starter switch 34 becomes 0.
[0071]
In the following step S210, an after-idle increase coefficient KAI for preventing the backlash at the time of releasing the idle is set. This post-idle increase coefficient KAI is set to an initial value based on the cooling water temperature TW when the vehicle speed is equal to or lower than the set vehicle speed and when the throttle valve is fully closed to open, and then the routine is executed as shown in step S210. Each time, the set value is decreased by 0 until it becomes zero.
[0072]
Then, the process proceeds to step S211 to calculate various increase coefficients COEF that summarize the above coefficients (COEF ← KST × (1 + KMR + KFULL + KTW + KAS + KAI)). In addition to setting the air-fuel ratio feedback correction coefficient α for approximation, the variation in the production of the intake air amount measurement system such as the intake air amount sensor 8 and the fuel supply system such as the injector 14 or the deviation of the air-fuel ratio due to the change over time can be quickly determined. Then, a learning correction coefficient KBLRC for correction is set, and the process proceeds to step S213.
[0073]
In step S213, the basic fuel injection pulse width TP is corrected by the above-described various increase coefficients COEF, the air-fuel ratio feedback correction coefficient α, and the learning correction coefficient KBLRC, and an effective injection pulse width Te suitable for one injection per cylinder, one revolution is calculated. (Te ← TP × α × COEF × KBLRC).
[0074]
Thereafter, the process proceeds to step S214, and refers to a normal control discrimination flag F1 (initial value: 0: start control) for discriminating between the normal control and the start control. When the start-time control has been selected, the process proceeds to step S215, in which it is determined whether or not the engine has completely exploded, and a complete explosion determination rotation speed NST serving as a reference value when switching from the start-time control to the normal control is determined. When the control is updated with a preset set value NST1 (for example, 500 rpm) and F1 = 1 and the normal control is selected at the time of the previous execution of the routine, the process branches to step S216 to set the complete explosion determination rotation speed NST. The value is updated with the value NST2 (where NST1> NST2, for example, 300 rpm), and the process proceeds to step S217.
[0075]
The normal control discrimination flag F1 is set in a later-described step S219 during normal control, and is cleared in a later-described step S233 during start control. As described above, by providing the complete explosion determination rotation speed NST with hysteresis, control hunting when shifting from the start-time fuel injection control to the normal-time fuel injection control as shown in FIG. 10 is prevented.
[0076]
Next, in step 217, the engine speed NE is compared with the complete explosion determination rotation speed NST. When NE> NST, the routine proceeds to step S218 and thereafter to execute normal fuel injection control, and when NE ≦ NST, Then, the flow branches to step S223 and thereafter to execute the start-time fuel injection control.
[0077]
In the following description, first, the fuel injection control at the start will be described, and then the fuel injection control at the normal time will be described.
[0078]
When branching from step S217 to step S223, a voltage correction pulse width TS set based on the battery voltage VB to correct the invalid injection time of the injector 14 is added to the effective injection pulse width Te set in step S213. Then, the starting injection pulse width Ti0 is calculated (Ti0 ← Te + TS), and in step S224, the basic value TCST is set by referring to the basic value table TBLCST with interpolation calculation based on the cooling water temperature TW. The basic value TCST is a base value for calculating the cold start pulse width TiST at the time of starting, and is set to a larger value as the cooling water temperature TW is lower, as shown in step S224.
[0079]
In a succeeding step S225, a rotation correction coefficient TCSN is set by referring to a table or the like based on the engine speed NE, and in a step S226, a time correction coefficient TKCS is set. As shown in step S226, when the starter switch 34 is turned on, the time correction coefficient TKCS is fixed at TKCS = 1.0 for a predetermined time, and thereafter gradually decreases until it becomes zero. . Therefore, if the start-time injection control is not completed within a predetermined time after the starter switch 34 is turned on, the cold start pulse width TiST set in step S229 described below gradually decreases, and finally TiST = 0. .
[0080]
Next, the routine proceeds to step S227, where a voltage correction coefficient TCSL for compensating the ineffective injection time of the injector 14 based on the battery voltage VB is set by referring to a table or the like, and the routine proceeds to step S228, where the throttle opening correction coefficient TCSA is determined based on the throttle opening Th. Is set by referring to a table or the like. The throttle opening correction coefficient TCSA is set to a larger value so as to increase the throttle opening Th as the throttle opening Th becomes larger.
[0081]
Further, the process proceeds to step S229, and the basic value TCST set in step S224 is corrected by the correction coefficients TCSN, TKCS, TCSL, and TCSA to calculate a cold start pulse width TIST (TiST ← TCST × TCSN × TKCS × TCSL × TCSA), in step S230, the cold start pulse width TiST is compared with the starting injection pulse width Ti0 calculated in step S223, and the larger one is adopted as the final fuel injection pulse width Ti. From the cold start pulse width TiST to the start injection pulse width TiO, the connection of the fuel injection amount is smoothed, the sudden change of the fuel injection amount is prevented, the sudden change of the air-fuel ratio is suppressed, and the engine operability deteriorates due to the sudden change of the air-fuel ratio. Prevent engine stalls.
[0082]
That is, when Ti0 ≧ TiST, the process proceeds from step S230 to step S231 to set the starting injection pulse width Ti0 as the fuel injection pulse width Ti that determines the fuel injection amount for starting. When TiO <TiST, the process proceeds to step S230. The process proceeds from step S232 to step S232 to set the cold start pulse width TiST as the fuel injection pulse width Ti that determines the fuel injection amount for starting, and then proceeds from step S231 or step S232 to step S233 to set the normal-time control determination flag F1. Clear (F1 ← 0), proceed to step S222, set the fuel injection pulse width Ti, and exit the routine.
[0083]
In this start-time fuel injection control, as shown in FIG. 11, two injectors are assigned to each injector 14 as one group (for example, a group of # 1 cylinder and # 2 cylinder, a group of # 3 cylinder and # 4 cylinder). On the other hand, the fuel injection pulse width Ti at the time of starting set in step S222 is output as a drive pulse signal for each rotation of the engine, and group injection of two cylinders is performed.
[0084]
In other words, the above-mentioned start-up simultaneous injection pulse width of all cylinders TSSTRT is used to obtain a richer air-fuel ratio that makes it easy to obtain an initial explosion only at the first combustion in the engine start, and as a fuel injection amount for smoothly shifting to a complete explosion after the initial explosion In order to prevent the air-fuel ratio from being over-rich, it is possible to prevent engine stall and rotation fluctuation without causing fogging or smoldering on the spark plug 15a.
[0085]
Eventually, when the engine speed NE increases and NE> NST, the engine is determined to be in the complete explosion state in step S217, and the process proceeds from step S217 to step S218 to perform normal fuel injection control.
[0086]
In the normal fuel injection control, the fuel injection pulse width Ti is set by adding the voltage correction pulse width TS for compensating the invalid injection time of the injector 14 to the value obtained by doubling the effective injection pulse width Te (Ti ← 2). × Te + TS). In other words, in the normal fuel injection control, sequential injection (one cylinder-by-cylinder injection every two engine revolutions) is performed. On the other hand, twice the amount of fuel (2 × Te) is required.
[0087]
After that, the routine proceeds to step S219, where the normal control discrimination flag F1 is set (F1 ← 1). In step S220, after shifting from the start control to the normal control, it is checked whether or not a set time has elapsed. If the set time has not elapsed after the shift, the process jumps to step S222. Accordingly, the above-described start-time all-cylinder simultaneous injection determination flag FST is maintained in the set state (FST = 1) until the set time elapses after shifting to the normal fuel injection control, and the engine is stopped in this state. Then, at the next start-up, the asynchronous start-time simultaneous injection of all cylinders in the above-described start-time simultaneous injection simultaneous cylinder setting routine (see FIG. 2) is canceled by FST = 1. If the set time has elapsed after the transition to the normal control, the process proceeds to step S221 to perform the simultaneous injection of all cylinders at the start of the next engine start. Is cleared (FST ← 0), and the process proceeds to step S222. Then, in step S222, the fuel injection pulse width Ti set in step S218 is set, and the routine exits.
[0088]
In the normal fuel injection control, the fuel injection pulse width Ti set in step S222 is output as a drive pulse signal to the injector 14 of the fuel injection target cylinder at a predetermined timing, and the fuel metered from the injector 14 to a predetermined amount. Is injected.
[0089]
In the present embodiment, the fuel injection amount for obtaining the air-fuel ratio suitable for the first explosion, that is, the fuel corresponding to the simultaneous injection pulse width TSSTRT of all cylinders at the start is injected only once before engine cranking. However, the injection may be performed several times before the cylinder discrimination at the time of starting the engine is completed.
[0090]
FIGS. 12 and 13 are flowcharts of a start-time all-cylinder simultaneous injection setting routine according to the second embodiment of the present invention.
[0091]
In the present embodiment, when the set number of crank pulses is input from the crank angle sensor 29 before the cylinder discrimination based on the signals from the crank angle sensor 29 and the cam angle sensor 31 at the time of starting the engine, It is determined whether or not to execute simultaneous start-time all-cylinder injection prior to normal start-up injection synchronized with engine rotation by the Ti setting routine of FIGS. 3 to 5 described in the first embodiment. Is what you do.
[0092]
The start-time all-cylinder simultaneous injection setting routine of this embodiment is shown in FIGS. 12 and 13. When the ignition switch 61 is turned on and the system is initialized, and the engine is cranked, the crank angle is increased with the rotation of the crank rotor 28. The process is executed every time a crank pulse output from the sensor 29 is input.
[0093]
In this routine, first, it is checked whether or not the cylinder discrimination has been completed in step S301. If the cylinder discrimination has not been completed, the process exits the routine as it is. If the cylinder discrimination has been completed, the process proceeds to step S302 to perform backup. The state at the time of the previous engine start is checked with reference to the start-time all-cylinder simultaneous injection determination flag FST in the RAM 68.
[0094]
When FST = 1, the process exits the routine from step S302, and when FST = 0, the process proceeds from step S302 to step S303, where the pulse input number setting value ns is set based on the cooling water temperature TW by referring to a table or the like. Since the cranking rotational speed is low and the rotational fluctuation is large at low water temperature, the pulse input count setting value ns takes into account the erroneous input of the crank pulse and the delay in the determination of the cylinder determination, and as shown in FIG. It is sometimes large and small at high water temperatures.
[0095]
Next, proceeding to step S304, when the count value C for counting the number of crank pulse inputs is counted up (C ← C + 1), it is checked in step S305 whether or not the count value C has reached the pulse input count set value ns. , C <ns, the routine exits. If C ≧ ns, the routine proceeds to step S306, where a basic value TSTRT, which is the base value of the simultaneous start all cylinder simultaneous injection pulse width TSSTRT, is set based on the cooling water temperature TW. At step S307, an atmospheric pressure correction coefficient KTSATM for atmospheric pressure correction of the basic value TSTRT is set based on the atmospheric pressure ATM.
[0096]
Thereafter, the process proceeds to step S308, where the correction coefficient KTSNS is set based on the pulse input count setting value ns. As shown in step S308, when the value of ns = 0 is set to KTSNS = 1 (all cylinders are simultaneously injected at the first crank pulse input), the value of the pulse input count setting value ns increases as shown in step S308. As a result, the asynchronous start injection amount is gradually reduced in the direction of decreasing the amount. For example, KTSNS = 0 at ns = 5 (no simultaneous injection of all cylinders at start at high water temperature).
[0097]
In a succeeding step S309, a voltage correction coefficient TCSL for compensating for the invalid injection time of the injector 14 that changes according to the battery voltage VB is set. In a step S310, the above-mentioned atmospheric pressure correction coefficient KTSATM, the above correction coefficient KTSNS, When the start-time all-cylinder simultaneous injection pulse width TSSTRT is set by multiplying the voltage correction coefficient TCSL (TSSTRT ← TSRT × KTSATM × KTSNS × TCSL), the start-time all-cylinder simultaneous injection pulse width TSSTRT is set in step S311. set.
[0098]
When the injectors 14 of all the cylinders are simultaneously driven via the drive circuit 54 in step S312, the count value C is cleared in step S313 (C ← 0), and in step S314, control is shifted to normal start-up control. In order to start, the all-cylinder simultaneous injection discrimination flag is set at startup (FST ← 1), and the routine exits.
[0099]
In this embodiment, as in the first embodiment described above, only the first combustion at the start of the engine is set to a richer air-fuel ratio that makes it easier to obtain the first explosion, and after the first explosion, the fuel injection amount is used to smoothly shift to the complete explosion. Although it is possible to prevent the fuel ratio from being over-rich, fine adjustment is made by the number of crank pulse inputs so that simultaneous injection of all cylinders is performed according to the engine state immediately before the cylinder discrimination is completed and the normal start-up control is started. It is possible to reliably supply the fuel effective for the initial combustion and to eliminate unnecessary fuel consumption.
[0113]
【The invention's effect】
As described above, according to the present invention, the amount of fuel that cannot be contributed to combustion by adhering to the intake manifold wall surface, the intake valve, the combustion chamber wall surface, and the like is corrected in the initial stage of the start-up control until the first explosion occurs. In order to prevent over-rich air-fuel ratio by preventing excessive fuel supply after the first explosion, engine stall and rotation fluctuations are prevented without causing ignition plug smoldering or smoldering. As a result, it is possible to improve the exhaust emission at the time of start by ensuring the start of the engine.
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram of the present invention.
FIG. 2 is a flowchart of a start-time all-cylinder simultaneous injection setting routine according to the first embodiment of the present invention;
FIG. 3 is a flowchart of a Ti setting routine (part 1);
FIG. 4 is a flowchart of a Ti setting routine (part 2);
FIG. 5 is a flowchart of a Ti setting routine (part 3);
FIG. 6 is a schematic configuration diagram of an engine control system according to the first embodiment;
FIG. 7 is a front view of the crank rotor and the crank angle sensor according to the first embodiment;
FIG. 8 is a front view of the cam rotor and the cam angle sensor according to the first embodiment;
FIG. 9 is a circuit diagram of an electronic control system according to the first embodiment;
FIG. 10 is an explanatory diagram showing a switching state between start-time fuel injection control and normal-time fuel injection control;
FIG. 11 is a time chart of fuel injection according to the first embodiment;
FIG. 12 is a flowchart of a start-time all-cylinder simultaneous injection setting routine (part 1) according to the second embodiment of the present invention;
FIG. 13 is a flowchart of a start-time all-cylinder simultaneous injection setting routine (part 2);
[Explanation of symbols]
1. Engine
51: main computer (first explosion fuel injection amount setting means, starting fuel injection amount setting means, injection control means)
NE: engine speed
NST: Complete explosion judgment rotation speed
TSSTRT… Simultaneous injection pulse width for all cylinders at startup (fuel injection amount for initial explosion)

Claims (2)

An initial explosion fuel injection amount setting means for setting an initial explosion fuel injection amount for obtaining an air-fuel ratio suitable for an initial explosion at the time of engine start according to the engine state;
Starting fuel injection amount setting means for setting a starting fuel injection amount for obtaining an appropriate air-fuel ratio from a first explosion to a complete explosion in accordance with an engine state;
The fuel injection amount for the initial explosion set by the fuel injection amount setting device for the first explosion is injected asynchronously with the engine rotation before the cylinder discrimination at the start of the engine is completed only when there is a history of complete explosion at the time of the previous engine start. After completion of the cylinder discrimination, injection control for injecting the starting fuel injection amount set by the starting fuel injection amount setting means in synchronization with the engine rotation until the engine rotation speed exceeds a preset complete explosion determination rotation speed. And a fuel injection control device for an engine. An initial explosion fuel injection amount setting means for setting an initial explosion fuel injection amount for obtaining an air-fuel ratio suitable for an initial explosion at the time of engine start according to the engine state;
Starting fuel injection amount setting means for setting a starting fuel injection amount for obtaining an appropriate air-fuel ratio from a first explosion to a complete explosion in accordance with an engine state;
If there is a history of complete explosion at the time of the previous engine start, and the crank angle signal is input a set number of times before the cylinder discrimination at the time of engine start is completed, the initial explosion set by the initial explosion fuel injection amount setting means Injection control for injecting the fuel injection amount and, after completion of the cylinder discrimination, injecting the starting fuel injection amount set by the starting fuel injection amount setting means until the engine speed exceeds a preset complete explosion determination rotation speed. And a fuel injection control device for an engine.

Images