JP4429301B2 - Engine fuel injection control device - Google Patents

Description

  The present invention relates to control of fuel injection amount of an engine, and in particular, engine fuel injection control for reducing HC components contained in engine exhaust gas by reducing the combustion air-fuel ratio while suppressing fluctuations in engine speed. Relates to the device.

  The amount of fuel injected at the start of the engine is increased by increasing the amount of fuel to be injected at the time of taking the fuel vaporization rate in accordance with the temperature of the intake pipe into consideration to increase the fuel injection amount as the temperature of the intake pipe decreases. The fuel vaporization rate depends not only on the temperature of the intake pipe but also on the volatile components contained in the fuel. Currently, light (gasoline) fuel that contains many components that are easily vaporized and heavy (gasoline) fuel that has a relatively small amount of volatile components are generally used as fuel for automobiles. Such differences in fuel volatility appear as differences in fuel properties. Especially in overseas, the difference in fuel properties with the fuel used as automobile fuel is large, and the start of the engine is secured by setting the fuel increase at the start according to the worst heavy fuel, When the fuel is light fuel, the combustion air-fuel ratio becomes rich and a lot of HC components are discharged.

  In addition, due to manufacturing variations of injectors that inject fuel and pressure variations of the fuel pressure regulator, even if a predetermined fuel injection pulse is applied to the injector, the amount of fuel actually injected into the intake pipe varies from engine to engine. . Therefore, in these engines, the fuel injection pulse width is set to be wide so that the fuel amount to be injected does not become insufficient even in the engine having the lower limit value. In addition, there are variations in the components that make up the engine, such as the distribution variation from cylinder to surge cylinder to the intake pipe and the variation in compression ratio between cylinders. Increase the amount to ensure engine startability in the worst case. Increase after starting, including correction. Therefore, in an engine in which the fuel amount of the upper limit value is injected, the combustion air-fuel ratio becomes rich, so that a large amount of HC component is also discharged.

  Conventionally, in order to suppress the HC component, the fuel property determination technique (Patent Document 1) for determining whether the fuel is heavy fuel or light fuel from the increase in the engine speed, or the behavior of the exhaust air-fuel ratio, the fuel is heavy fuel. A fuel property determination technique for determining whether a fuel is light or light has been used.

JP-A-3-26841

  Generally, the fuel increase after the engine is started is a fuel increase value based on heavy fuel in order to ensure engine startability from cranking. For this reason, it is difficult to detect the difference in the engine speed increase, and the fuel property determination technique for determining the fuel property from the engine speed increase has a problem that the detection accuracy is low. Also, in order to detect the fuel property from the behavior of the exhaust air-fuel ratio, the fuel property can only be determined after the air-fuel ratio sensor is activated, so the determination result can be reflected once after the engine is stopped. There was a problem that it could only be judged after restart.

  The present invention is for solving the above-mentioned problems, and the object of the present invention is to determine the fuel property at the time of starting by obtaining the engine speed fluctuation without determining the fuel property by the increase of the engine speed. In addition, the engine rotational fluctuation is obtained only when the engine state, the operating state, etc. satisfy the predetermined start-up conditions, so that an accurate rotational fluctuation is obtained to determine the engine rotational fluctuation. The fuel increase correction is performed.

  In order to solve the above-described problems, an engine fuel control apparatus according to the present invention includes passage time acquisition means for acquiring a passage time in which a crankshaft passes a predetermined crank angle range including an explosion stroke of the engine. An engine rotation fluctuation parameter for each explosion is calculated based on the passage time acquired by the acquisition means, and the fuel injection amount is controlled based on the fluctuation parameter.

  The present invention acquires the passage time for the crankshaft to pass through a predetermined crank angle range including the explosion stroke of the engine without determining the fuel property by the engine speed increase, and the passage time acquired by the passage time acquisition means. Since the engine rotation fluctuation parameter for each explosion is calculated based on the time and the fuel injection amount is controlled based on the fluctuation parameter, the fuel injection quantity after the engine start can be accurately controlled.

  The engine fuel control apparatus of the present invention includes an engine state determination unit and a vehicle state determination unit, and the passage time acquisition unit acquires the passage time when the engine state determination unit and the vehicle state determination unit permit. It is characterized by. In the present invention, for example, when the engine water temperature is within a predetermined range and the vehicle is stopped in an idling state, the passage time acquisition means acquires the passage time. It is possible to accurately grasp fluctuations.

  Further, the passage time acquisition means in the fuel control apparatus for an engine according to the present invention comprises: elapsed time measuring means for measuring an elapsed time until the pulse signal from the crank angle sensor reaches a predetermined number of pulses; Has a correcting means for correcting the passing time to pass a predetermined crank angle. The crank angle that is rotated until the pulse signal from the crank angle sensor reaches the predetermined number of pulses has an error for each cylinder due to manufacturing errors and mounting errors of the plate that detects the crank angle. Since the passing time for passing the predetermined crank angle is corrected by the means, the measurement value in a state where there is no manufacturing error between the cylinders can be acquired.

  Furthermore, in the engine fuel control apparatus according to the present invention, the rotation variation parameter is a difference between the first differential value and the first differential value, which is the difference between the passage time in the previous explosion stroke and the passage time in the current explosion stroke. The present invention is characterized in that it has a secondary differential value, and the present invention uses the secondary differential value as a rotational fluctuation parameter, so that the rotational fluctuation with little influence when the engine speed increases or decreases in the steady state of the engine. It can be detected.

  Furthermore, the engine fuel control apparatus of the present invention acquires correction data in the engine rotation state at the time of fuel cut, and prohibits measurement of elapsed time by the elapsed time measurement means when the correction means does not acquire correction data. It is characterized by doing. Since the present invention acquires correction data in the engine rotation state at the time of fuel cut, even if an error due to engine aging occurs, correction data for correcting the error can be acquired, and accurate rotation is always performed. Change can be detected.

  In the present invention, since the engine rotational fluctuation is obtained only when the engine state, the operating state, etc. satisfy a predetermined start-up condition, the rotational fluctuation can be detected accurately. The fuel increase correction after the start is performed based on the fluctuation, and the HC component in the exhaust gas can be suppressed regardless of the fuel property while ensuring the good startability of the engine, and the exhaust reduction effect is high.

Hereinafter, an embodiment of an engine fuel control apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 shows the overall configuration of an engine control system including an engine fuel control apparatus according to the present invention.
The engine body 10 has a piston 12 in a combustion chamber 11 of each cylinder, and the piston 12 is connected to a crankshaft by a connecting rod 13. The engine body 10 is provided with a water temperature sensor 14 for detecting the temperature of engine coolant and a knock sensor 15 for detecting knocking, and a crank angle sensor 16 for detecting the crank angle is installed on the crankshaft. ing. A cam angle sensor 17 for detecting a cam angle is installed on the cam shaft, and cylinder discrimination is performed by the cam angle sensor 17.

  In the intake system of the engine, an air flow sensor 18 integrated with an air cleaner for detecting the intake air amount, a pressure sensor 19 for detecting the pressure in the intake pipe, a throttle valve 20 for controlling the intake air amount, and an opening degree of the throttle valve 20 are detected. A throttle opening sensor 21, an ISC valve 22 for adjusting the intake air amount by bypassing the throttle valve 20, an intake air temperature sensor 23 for detecting the intake air temperature, and a fuel injection valve 24 for injecting fuel are provided. The intake air passes through the intake valve 25 as an air-fuel mixture and is sucked into the combustion chamber 11, and sparks are generated from the spark plug 27 by the high voltage generated by the ignition coil 30 and burned. The combusted air-fuel mixture becomes exhaust gas and is discharged from the combustion chamber 11 when the engine exhaust valve 26 is opened.

  A three-way catalytic converter 29 and an air-fuel ratio sensor 28 are connected to the engine exhaust system, and the exhaust gas discharged from the exhaust valve 26 is purified through the exhaust gas and discharged to the atmosphere. Although not shown, when a transmission gear ratio or gear position sensor is installed and the transmission is an AT gear, the gear position is in the parking or neutral position or other position. Is also output. In order to detect the driving state of the vehicle, a vehicle speed sensor that detects the rotational speed of the wheel, a steering sensor that detects the operation angle of the steering wheel, a brake sensor that detects the operation amount of the brake pedal, and the like are installed. These sensor signals are input to an electronic control unit (hereinafter referred to as ECU) 50.

FIG. 2 shows an outline of the internal configuration of the electronic control unit (control unit).
The control unit 201 includes a calculation unit 202, an input unit 203, an output unit 204, a communication circuit 205, and the like. The input unit 203 includes an analog input circuit 206 that converts analog voltages from various sensors into digital signals by an A / D converter and loads them, a digital input circuit 207 that loads signals from an ignition switch that indicates an operation state, and a time interval of pulse signals And a pulse input circuit 208 for capturing a signal having the number of pulses within a predetermined time. Signals from the air flow sensor 18, accelerator pedal sensor, intake pipe pressure sensor 19, water temperature sensor 14, intake air temperature sensor 23, battery voltage, steering angle sensor, and the like are input to the analog input circuit 206, and pulse input is performed. The circuit 208 receives signals from a crank angle sensor 16 that detects the engine speed and crank angle, a cam angle sensor 17 that performs cylinder discrimination, a vehicle speed sensor that measures the wheel speed, and the like. Further, information signals such as a brake pedal switch, an electric load detection switch for detecting an electric load application state, a transmission gear ratio information, a gear position sensor, and the like are input to the input means 203.

  The arithmetic unit 202 includes an arithmetic unit (CPU) 209 that performs numerical / logical operations, a ROM 210 that stores programs and data executed by the CPU, a RAM 211 that temporarily stores data, and the like. Based on this, a control signal for opening and closing the fuel injection valve, an ignition control signal for the spark plug, a control signal for controlling the electronic control throttle to the target opening, and the like are output via the output means 204.

  In addition, the control unit 201 is provided with a communication circuit 205, which outputs data in the control unit 201 to an external scan tool or the like, and other control devices such as an ABS, an antitheft device, a travel position ( Communication with the GPS) information device is performed to correct the engine control output according to the engine operating state.

  FIG. 3 shows the internal block configuration of the fuel control apparatus for the engine. The fuel increase correction control after the engine is started will be described with reference to FIG.

  The crank angle measuring plate for detecting the crank angle has a processing error and a mounting error of the plate to the crankshaft, and further, a manufacturing error is also present in the engine crank. Therefore, even if the engine is rotating at a constant rotation speed, the elapsed time until the counter value of the output pulse from the crank angle sensor 16 reaches a predetermined value within the rotation range of the crankshaft including the explosion stroke of the engine. When measured, an error occurs between the cylinders during the measured elapsed time. Therefore, it is necessary to acquire correction value data for correcting an error in elapsed time due to the manufacturing error as described above.

  Therefore, the output from the crank angle sensor 16 in the rotation range of the crankshaft including the expansion stroke of the engine starting from a predetermined delay angle from the top dead center for each cylinder or each cylinder group during the fuel cut. The pulses are counted by the crank angle window counter 301, and the elapsed time until the predetermined number of pulses is reached is measured by the window elapsed time measuring means 302. The average value of the elapsed time for each measured cylinder is obtained, and the ratio of the elapsed time of each cylinder to the average value is stored in the detection error table 303 as correction value data.

  Then, when the engine after engine startup is rotating in a steady state, the number of explosions of the engine is counted by the explosion rotation counter 311 for each explosion, and the crankshaft rotation range including the engine explosion stroke The elapsed time until the counter value of the output pulse from the angle sensor 16 reaches a predetermined value is measured by the elapsed time measuring means 302 in the window. The measured elapsed time is corrected by the elapsed time correction unit 304 based on the correction value stored in the detection error table 303 and output to the buffer 305 and the primary differential value calculation unit 306 as the elapsed time D_TIME for each cylinder. The The elapsed time D_TIME can be referred to as a passing time during which the crankshaft passes a predetermined crank angle range. The crankshaft passes a predetermined crank angle range by the elapsed time measuring means 302 and the elapsed time correcting means 304 in the window. Passing time acquisition means for acquiring the passing time is configured.

  The primary differential value calculation means 306 calculates the difference between the elapsed time D_TIME and the elapsed time D_TIMEz before the first explosion stored in the buffer 305 to obtain the primary differential value DD_TIME. That is, the following calculation is performed, and the calculated primary differential value DD_TIME is output to the buffer 307 and the secondary differential value calculation means 308.

DD_TIME = D_TIME−D_TIMEz
D_TIMEz = D_TIME

  Further, the secondary differential value calculation means 308 calculates the difference between the calculated elapsed time DD_TIME and the previous primary differential value DD_TIMEz stored in the buffer 307 to obtain the secondary differential value DDD_TIME. That is, the following calculation is performed.

DDD_TIME = DD_TIME−DD_TIMEz
DD_TIMEz = DD_TIME

  Here, the primary differential value DD_TIME and the secondary differential value DDD_TIME are used as rotation fluctuation parameters representing engine fluctuation.

  The rotation fluctuation detecting means 309 compares the primary differential value DD_TIME calculated by the primary differential value calculating means 306 with a preset threshold value β1, and the primary differential value DD_TIME is larger than the threshold value β1 ( When DD_TIME> β1), the flag indicating that the rotation fluctuation has been detected is set, and the explosion number counter value CMBCNT_ from the time of engine start of the explosion number counter 311 is stored in the explosion number storage means 312. The difference P_DD from the threshold value β1 is stored in the buffers 314 and 315.

  The rotation fluctuation detecting means 310 compares the secondary differential value DDD_TIME calculated by the secondary differential value calculating means 308 with a preset threshold value β2, and the secondary differential value DDD_TIME is larger than the threshold value β2. When (DDD_TIME> β2), a flag indicating that the rotation fluctuation has been detected is set, and the explosion number counter value CMBCNT_ from the engine start is stored in the explosion number storage means 313, and the threshold value β2 Is stored in the buffers 317 and 318.

  The explosion number storage means 312 and 313 and the buffers 314, 315, 317, and 318 store the difference P_DD between the explosion number counter value CMBCNT_ [n], the primary differential value, and the threshold value during the past two rotations. [N] Each difference P_DDD [n] between the secondary differential value and the threshold value is stored. The necessity determination means 316, 319 determines whether it is necessary to correct the fuel with respect to the fuel increase reference value after the start according to the occurrence of the rotation fluctuation, and the fuel correction amount calculation means 320 needs to correct the fuel. If there is, calculate the fuel correction amount.

  FIG. 4 shows a state of fuel increase correction control (fuel correction method 1) after engine start in the first embodiment of the engine fuel control apparatus according to the present invention. As shown in (a), the fuel increase reference value A assuming light fuel and the fuel increase reference value B presuming heavy fuel are set in advance in the fuel increase value after engine startup, Based on the fuel increase reference values A and B, the fuel increase after starting the engine is performed by an attenuation timer or an attenuation counter. In the present embodiment, fuel increase correction control is performed by adding an increase correction value due to engine rotation fluctuations to a fuel increase reference value A based on light fuel, which will be described in detail with reference to FIG.

  After the engine is started, no change in rotation is detected, so fuel increase control is performed based on a preset fuel increase reference value A (t0 to t1).

When the primary differential value exceeds the threshold value β1 three times and three rotation fluctuations are detected at the time point t1, the maximum value of the difference between the counter values in which the rotation fluctuations are detected is calculated. That is, assuming that the latest explosion number counter value is CMBCNT_ [0] and the previous explosion number counter value is CMBCNT_ [2], the maximum difference value DCMBCNT is
DCMBCNT = CMBCNT_ [0] −CMBCNT_ [2]
Can be expressed as

  If the maximum value DCMBCNT of the difference is equal to or less than a predetermined value KCMBCNT (30 times in the experimental results), it is determined that the air-fuel ratio is lean and that the fuel increase correction is necessary.

Then, when it is determined that the fuel increase correction is necessary, the differences P_DD [0], P_DD [1], P_DD [2] between the first-order differential values and the threshold values for the three rotation fluctuations are added up. Then, the magnitude P_DDALL of the rotational fluctuation is obtained.
P_DDALL = P_DD [0] + P_DD [1] + P_DD [2]

  Then, based on the magnitude of the rotational fluctuation P_DDALL, an increase correction value Q1 is retrieved from a preset table value, and the increase correction value Q1 is added to the fuel increase reference value A (t1). Fuel increase control is performed based on the fuel increase reference value A obtained by adding the increase correction value Q1 (t1 to t2).

  When the second derivative exceeds the threshold β2 three times at the time t2, and three rotation fluctuations are detected, the maximum value of the difference between the counter values at which the rotation fluctuations are detected is calculated. If the maximum difference value DCMBCNT is equal to or less than a predetermined value KCMBCNT (30 times in the experimental results), it is determined that the air-fuel ratio is lean, and it is determined that fuel increase correction is necessary.

When it is determined that the fuel increase correction is necessary, the differences P_DDD [0], P_DDD [1], P_DDD [2] between the second-order differential values for which the rotational fluctuation is detected and the threshold value β2 are calculated. Summing up, the magnitude of rotational fluctuation P_DDDALL is obtained.
P_DDDALL = P_DDD [0] + P_DDD [1] + P_DDD [2]

  Then, based on the magnitude P_DDDALL of the rotational fluctuation, the increase correction value Q2 is obtained by searching from a preset table value, the increase correction value Q2 is further added to the fuel increase reference value A (t2), and thereafter Then, the fuel increase control is performed based on the fuel increase reference value A obtained by further adding the increase correction value Q2 (t2).

  If it is determined by the primary differential value and the secondary differential value that fuel increase correction is required at the same time, the larger increase correction value is selected and added to the fuel increase reference value A. In the present embodiment, the upper limit of fuel increase in the fuel increase correction control is set to a preset value.

  In the fuel increase control according to the present embodiment, the engine speed fluctuation is always detected, and the fuel correction reference value A is corrected based on the detected engine speed fluctuation correction. Therefore, the fuel quantity is corrected until the speed fluctuation no longer occurs. It is possible to reduce the rotational fluctuation after the engine is started. In this embodiment, the fuel increase correction control is performed based on the fuel increase reference value A assuming light fuel. However, the fuel increase correction control is performed based on the fuel increase reference value B assuming heavy fuel. May be performed.

  FIG. 5 shows a state of fuel increase control after the engine is started (fuel correction method 2) in the second embodiment of the engine fuel control apparatus, and the engine speed is changed to the fuel increase reference value A assuming light fuel. Fuel increase control is performed by adding a fuel increase correction value due to fluctuation. The method for determining whether or not the engine rotation fluctuation has been detected and the method for determining whether or not the fuel increase correction is necessary are the same as those in the first embodiment shown in FIG.

  After the engine is started, no change in rotation is detected, so fuel increase control is performed based on a preset fuel increase reference value A (t0 to t1).

  If the first derivative exceeds the threshold value β1 three times and three rotation fluctuations are detected at the time t1, the maximum value of the difference between the counter values in which the rotation fluctuation has occurred is calculated. If the maximum value DCMBCNT is equal to or less than a predetermined value KCMMBCNT (30 times in the experimental results), it is determined that the air-fuel ratio is lean and that the fuel increase correction is necessary. In the present embodiment, when it is determined that the fuel increase correction is necessary, in the present embodiment, an attenuation timer or an attenuation counter that performs the fuel increase control after starting the engine based on the fuel increase reference value A at the time t1. The operation is held and held at the fuel increase value Q1 of the fuel increase reference value A at time t1, and the fuel increase value is not decreased (t1 to t2). Thereafter, when the state in which no rotation fluctuation is detected continues for a predetermined number of explosions, the operation of the attenuation timer or the attenuation counter is resumed, and fuel increase control is performed based on the fuel increase reference value A (t2 to t3).

  At time t3, when the secondary differential value exceeds the threshold value β2 three times and three rotation fluctuations are detected, and it is determined that the fuel increase correction is necessary, the above-mentioned primary differential value is determined. The fuel increase control is performed in the same manner as when it is determined that the fuel increase correction is necessary in the values (t3 to t4, t4 to).

  The fuel increase control according to the present embodiment is performed within the range of the fuel increase reference value A that is set in advance, so there is no need to consider the upper limit of the fuel increase value.

  FIG. 6 shows a state of fuel increase control after starting the engine (fuel correction method 3) in the third embodiment of the fuel control apparatus for the engine, based on the fuel increase reference value A based on light fuel. Fuel increase control is performed, and in the fuel correction in the first embodiment, the increase correction value is added (increased) to the fuel increase reference value A. However, in this embodiment, the rotation fluctuation is detected for a predetermined period. If not, the fuel correction for reducing the fuel increase value is also performed. The method for determining whether or not the engine rotation fluctuation has been detected and the method for determining whether or not the fuel increase correction is necessary are the same as those in the first embodiment shown in FIG.

  After the engine is started, no change in rotation is detected, so fuel increase control is performed based on a preset fuel increase reference value A (t0 to t1).

  When the first derivative exceeds the threshold value β1 three times and three rotation fluctuations are detected at the time t1, the maximum value of the difference between the counter values where the rotation fluctuations are detected is calculated. If the maximum difference value DCMBCNT is equal to or less than the predetermined value KCMBCNT (30 times in the experimental results), it is determined that the air-fuel ratio is lean and that the fuel increase correction is necessary.

  When it is determined that the fuel increase correction is necessary, in this embodiment, the predetermined fuel increase value Q0 is set regardless of the difference between the differential value when the rotational fluctuation occurs and the threshold value β1. Fuel increase control is performed based on the fuel increase reference value A obtained by adding to the fuel increase reference value A (t1) and adding the increase correction value Q0 (t1 to t2).

  Thereafter, if no rotation fluctuation is detected between the predetermined number of explosions, the predetermined amount of decrease correction value Q1 is subtracted (t2), and thereafter the fuel control is performed based on the fuel increase reference value A obtained by subtracting the amount of decrease correction value Q1. If the rotation variation is not detected, the fuel increase reference value A is subtracted by the decrease correction value Q1 until the increase value becomes zero (t2 to t3, t3 to t4).

  At the time point t4, when the secondary differential value exceeds the threshold value β2 three times and three rotation fluctuations are detected, and it is determined that the fuel increase correction is necessary, the above-mentioned primary differential value is determined. The fuel increase value Q0 is added in the same manner as when it is determined that the fuel increase correction is necessary for the value (t4), and the fuel increase control is performed based on the fuel increase reference value A to which the increase correction value Q0 is added ( t4 ~).

  In this embodiment, the fuel amount is increased regardless of the difference between the rotational fluctuation and the threshold value. Therefore, when the rotational fluctuation is detected, the fuel amount can be increased immediately. When the rotational fluctuation is not detected continuously, There is an advantage that the rich state can be quickly eliminated by reducing the fuel increase after starting. The upper limit value of fuel increase in the fuel increase control is set to a value set separately.

  FIG. 7 shows a state of fuel increase control after starting the engine (fuel correction method 4) in the fourth embodiment of the fuel control apparatus for the engine. In this embodiment, the fuel increase reference is based on heavy fuel. Fuel correction based on the value B is performed.

  In the first to third embodiments (fuel correction methods 1 to 3), it is necessary to detect three rotation fluctuations until the engine rotation fluctuation is detected and the increase is made. If the fuel increase is performed after three rotation fluctuations, the effect of suppressing the rotation fluctuation is small.

  Therefore, in this embodiment, if the engine fluctuation is less than the threshold value β1 or β2, the fuel increase value is calculated from the fuel increase reference value B according to the difference between the engine speed and the target engine speed for ISC control. The fuel is gradually attenuated, and the fuel increase correction is performed as soon as the engine rotational fluctuation is detected. This will be specifically described with reference to FIG.

  When the primary differential value is equal to or less than the threshold value β1, the secondary differential value is equal to or less than the threshold value β2, and no engine rotation fluctuation is detected, the difference between the engine speed and the target engine speed for ISC control In accordance with the control, the fuel increase value is gradually decreased (t0 to t1). If no rotation fluctuation is detected, control is performed to decrease the fuel increase value until the fuel increase value becomes zero.

  When the primary differential value exceeds the threshold value β1 and the rotation fluctuation is detected at the time point t1, the fuel increase flag is set, and the difference between the primary differential value and the threshold value β1 is obtained. An increase correction value Q1 is retrieved from a preset table value, and the increase correction value Q1 is added to the fuel increase value at t1.

  When the secondary differential value exceeds the threshold value β2 and rotation fluctuation is detected at the time t2, the difference between the secondary differential value and the threshold value β2 is obtained, and the difference is increased from the preset table value by this difference. The correction amount Q2 is searched, and the increase correction value Q2 is added to the fuel increase value at t2.

  In this embodiment, the fuel increase is performed without depending on the sum of the difference between the rotation fluctuation and the threshold value when the rotation fluctuation is detected three times. Therefore, the fuel increase can be immediately performed when the rotation fluctuation is detected once. In addition, when the rotation fluctuation is not continuously detected, there is an advantage that the rich state can be quickly eliminated by reducing the fuel increase after the start. The upper limit value of fuel increase in the fuel increase correction control is set to a value set separately.

  FIG. 8 shows states of engine speed, air-fuel ratio control, etc. at the time of engine start in the engine fuel control apparatus according to the present invention, where (a) shows engine speed and (b) shows ignition after complete explosion. (C) shows the engine water temperature, (d) shows the control state when the accelerator is operated or the gear is put in before the air-fuel ratio control is started, and (e) shows the accelerator operated. The control state when the engine water temperature reaches a predetermined temperature or the air-fuel ratio sensor is activated to start the air-fuel ratio control is shown.

  The fuel increase correction control of the present invention described with reference to FIGS. 4 to 7 is contrary to the air-fuel ratio control. Therefore, in order to perform the fuel correction, the engine water temperature is within a predetermined temperature range and the air-fuel ratio control is performed. It is necessary not to. In addition, since the fuel increase correction is based on the assumption that the vehicle is stopped and in an idle state, in order to perform the fuel increase correction, the accelerator petal is in the fully closed position, and the gear position is in the mutual position. Yes, the vehicle speed must be zero. Then, correction value data needs to be stored in the detection error table 303 in FIG.

  That is, after the engine is started, if the engine state determination means determines that the engine water temperature is within a predetermined range and the air-fuel ratio control is not performed, the engine state flags 81a and 81b permitting the fuel increase correction control are set. Is done. Further, the vehicle state determination means is such that the accelerator petal is in the fully closed position and the throttle valve is closed, the idle SW is in the on state, the ISC control is being performed, the gear position is in the mutual position, and the vehicle is in the stopped state. When it is determined that (the vehicle speed is zero) and the battery voltage is within the predetermined voltage range, the vehicle state flags 82a and 82b permitting the fuel increase correction control are set.

Then, after the engine speed increases and exceeds the target speed for ISC control, fuel increase correction with respect to the fuel increase reference value is started at time t2 when the predetermined number of explosions has elapsed.
In (d), since the accelerator pedal is depressed and the throttle valve 20 is opened at the time t5, the vehicle state flag 82a is reset, the fuel increase correction control is terminated, and the rapid deceleration flag 83a is set. At the time t5 The fuel increase value after starting the engine is decreased by a preset amount every time the engine is ignited until the increase value becomes zero (t5 to t6).

  In (e), since the air-fuel ratio sensor is activated and the air-fuel ratio control is started at time t3, the engine state flag 81b is reset, the fuel increase correction control is terminated, and the gradual decrease flag 83b is set. The fuel increase value Q3 after the engine start at the time t3 is gradually decreased by the air-fuel ratio control (t3 to t4). That is, as shown in FIG. 10, the fuel increase value Q3 after the start at the time when the air-fuel ratio control is started is decreased when the air-fuel ratio sensor detects richness, and the fuel increase value Q3 decreases. Increases when the lean is detected, and the increase value is gradually decreased.

FIG. 9 shows a flowchart of the control operation of the engine fuel control apparatus according to the present invention.
In steps 901 to 908, it is determined whether the conditions for performing the fuel increase correction control are satisfied. That is, in step 901, it is determined whether air-fuel ratio control is not performed. If air-fuel ratio control is not performed, the process proceeds to step 902. In step 902, it is determined whether the accelerator pedal is fully closed. If the accelerator pedal is in the closed state, the process proceeds to step 903.

  In step 903, it is determined whether crank angle error detection is performed. If crank angle error detection is performed and correction value data is stored, the process proceeds to step 904. In step 904, it is determined whether the water temperature is within a predetermined range. If the water temperature is not within the predetermined range, the process is reset. If the water temperature is in the predetermined range, the process proceeds to step 905. In step 905, it is determined whether the engine speed is lower than the target engine speed for idle control and a predetermined number of complete explosions has elapsed. If this condition is satisfied, the process proceeds to step 906. In step 906, it is determined whether the gear position of the transmission is neutral. If the gear position of the transmission is neutral (parking or neutral position in the case of an AT vehicle), the process proceeds to step 907. When it is determined in step 907 that the vehicle speed is 0 (zero) and the battery voltage is greater than or equal to the lower limit value in step 908, a permission flag for detecting engine rotation fluctuation is set. In steps 909 to 917, fuel increase is performed. Correction control is executed.

  That is, in step 909, the window elapsed time is fetched, the elapsed time is corrected with the correction value stored in the detection error table 303 to obtain the elapsed time D_TIME, and the engine explosion number counter is incremented. In step 910, a difference between the previous elapsed time D_TIME and the current elapsed time D_TIME is calculated to calculate a primary differential value.

  In step 911, the primary differential value obtained in step 910 is compared with the threshold value β1, and when the primary differential value exceeds the threshold value β1, the difference between the primary differential value and the threshold value β1 and the number of explosions are determined in step 912. The counter is stored in the buffers 314, 315 and the like.

  In step 913, the secondary differential value is calculated from the difference between the primary differential value obtained last time in step 910 and the primary differential value obtained this time, and in step 914, the secondary differential value obtained in step 913 and the threshold value are calculated. When the secondary differential value exceeds the threshold value β2, the difference between the secondary differential value and the threshold value β2 and the explosion counter are stored in the buffers 317, 318 and the like.

  In step 916, when the primary differential value exceeds the threshold value β1 three times or when the secondary differential value exceeds the threshold value β2, the fuel correction method shown in FIGS. A fuel correction value for correcting the subsequent fuel increase value is calculated, and in step 917, the fuel correction value is added to or subtracted from the increase reference value, and engine fuel control is performed.

  When the conditions of steps 901 to 908 are not satisfied, the routine proceeds to step 918, where the fuel increase correction control is reset. That is, when the air-fuel ratio control is started, when the accelerator pedal is depressed and the slot valve is opened, when the water temperature rises and deviates from the predetermined range, the number of explosions is less than the predetermined number after starting. In this case, the fuel increase correction control is not performed when the gear position of the transmission is not neutral, when the vehicle speed is not zero, or when the battery voltage is equal to or lower than a predetermined voltage.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various changes in design can be made without departing from the spirit of the invention described in the claims. It is something that can be done.

1 is an overall configuration diagram of an engine control system including an engine fuel control device according to the present invention. The figure which shows the outline | summary of the internal structure of an electronic control apparatus (control unit). The internal block block diagram of the engine fuel control apparatus in this invention. The figure which shows the state (fuel correction method 1) of the fuel increase control after engine starting in 1st Embodiment of the fuel control apparatus of the engine which concerns on this invention. The figure which shows the state (fuel correction method 2) of the fuel increase control after engine starting in 2nd Embodiment of the fuel control apparatus of the engine which concerns on this invention. The figure which shows the state (fuel correction method 3) of the fuel increase control after engine starting in 3rd Embodiment of the fuel control apparatus of the engine which concerns on this invention. The figure which shows the state (fuel correction method 4) of the fuel increase control after engine starting in 4th Embodiment of the fuel control apparatus of the engine which concerns on this invention. The figure which shows the engine speed at the time of engine starting in the engine fuel control apparatus which concerns on this invention, an air fuel ratio control, an engine state, a vehicle state, etc. FIG. The flowchart which shows the control action of the fuel control apparatus of the engine which concerns on this invention. The figure which shows fuel control when an air fuel ratio sensor is activated, air fuel ratio control is started, and fuel increase correction | amendment control is stopped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Engine main body, 11 ... Combustion chamber, 12 ... Piston, 13 ... Connecting rod, 14 ... Water temperature sensor, 15 ... Knock sensor, 16 ... Crank angle sensor, 17 ... Cam angle sensor, 18 ... Air flow sensor, 19 ... Intake pipe Pressure sensor, 20 ... throttle valve, 21 ... throttle opening sensor, 22 ... ISC valve, 23 ... intake air temperature sensor, 24 ... fuel injection valve, 25 ... intake valve, 26 ... exhaust valve, 27 ... spark plug, 28 ... empty Fuel ratio sensor 29 ... Three-way catalytic converter 30 ... Ignition coil 50 ... Electronic control unit (hereinafter ECU) 201 ... Control unit 202 ... Calculation means 203 ... Input means 204 ... Output means 205 ... Communication circuit , 206 ... Analog input circuit, 207 ... Digital input circuit, 208 ... Pulse input circuit, 209 ... Arithmetic unit (CPU) DESCRIPTION OF SYMBOLS 301 ... Crank angle window counter, 302 ... In-window elapsed time measuring means, 303 ... Detection error table, 304 ... Elapsed time correction means, 305, 314, 315, 317, 318 ... Buffer, 306 ... First derivative calculation means 308 ... secondary differential value calculating means 309, 310 ... rotation fluctuation detecting means, 311 ... explosion number counter, 312, 313 ... explosion number storing means, 316 ... correction necessity judging means.

Claims (2)

In an engine fuel control device that controls the combustion state of an engine by controlling the fuel injection amount of the engine,
The fuel control device includes passage time acquisition means for acquiring a passage time for the crankshaft to pass through a predetermined crank angle range including an explosion stroke of the engine, and is configured to detect each explosion based on the passage time acquired by the passage time acquisition means. The engine rotation fluctuation parameter is calculated, and the fuel injection amount is controlled based on the fluctuation parameter .
When the engine water temperature is within a predetermined range and the air-fuel ratio control is not performed, the engine state determination unit that permits the passage time acquisition by the passage time acquisition unit, the throttle valve is closed, and the idle switch is on. Vehicle state determination means that permits acquisition of the passage time by the passage time acquisition means when the gear is not engaged,
The engine fuel control apparatus according to claim 1, wherein the passage time acquisition means acquires the passage time when the engine state determination means and the vehicle state determination means permit . The engine state determination unit prohibits acquisition of the passage time by the passage time acquisition unit when the engine water temperature is out of a predetermined range or when air-fuel ratio control is performed, and the vehicle state determination unit includes the throttle valve If There was an open state, the idle switch when turned off, or, according to claim 1, characterized in that prohibiting the acquisition of transit time due to the passage time acquisition means when the gear is put Engine fuel control device.

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