JP2013209929A - Start control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve start control capable of securing favorable startability in an engine mounted on a vehicle or the like.SOLUTION: If a misfire state is determined at an engine start when a condition (oil-tight leakage estimation condition) where large oil-tight leakage of an injector is estimated while the engine is stopped, a fuel injection amount by the injector is corrected to reduce the amount. Thereby, an air-fuel ratio of an air fuel mixture at the engine start can be optimized to improve startability. Opening control of a throttle valve 5 may be concurrently performed to increase an intake air amount.

Description

  The present invention relates to a start control device for an internal combustion engine mounted on a vehicle or the like, and more particularly to measures against so-called oil-tight leakage, in which fuel leaks from a nozzle hole of a fuel injection valve while the engine is stopped.

  An internal combustion engine (hereinafter also referred to as an engine) mounted on a vehicle or the like, for example, guides an air-fuel mixture obtained by mixing air flowing through an intake passage and fuel injected from a fuel injection valve (hereinafter also referred to as an injector) into a combustion chamber. The air-fuel mixture is ignited with an ignition plug to burn and explode, and the crankshaft is rotated by energy (power) generated by the combustion and explosion of the air-fuel mixture. Such an engine is started by cranking the engine with a starter (motor) connected to a crankshaft, supplying fuel in accordance with the cranking, and igniting.

  In an engine that supplies fuel with an injector, it is known that fuel leaks from the injector nozzle hole while the engine is stopped (during soak), for example, so-called oil tight leakage may occur (for example, (See Patent Documents 1 to 3).

JP 2008-025521 A JP 2010-037984 A JP 2010-053787 A

  By the way, the oil tight leakage of the injector becomes large depending on the operating condition and the environmental condition when the engine is stopped. For example, if the fuel temperature (fuel temperature) and fuel pressure (fuel pressure) are high when the engine is stopped during low-speed and high-load driving or climbing, etc., or if the outside air temperature is high and the fuel temperature and fuel pressure are high, such as in summer In this case, the oil leakage of the injector is increased. When the oil tight leak of the injector increases, the concentration of HC (hydrocarbon) in the intake manifold (intake port) increases. If the air-fuel ratio of the air-fuel mixture becomes rich and exceeds the range of the combustible air-fuel ratio due to the increase in the HC concentration, the combustion state may deteriorate and the engine may fail to start.

  On the other hand, considering the operating conditions and environmental conditions when the engine is stopped as described above, for example, it is determined whether the oil leakage of the injector is large based on the fuel temperature and the fuel pressure. When combustion deterioration (engine start-up failure) is assumed, it is conceivable to reduce the fuel injection amount to suppress the richness of the air-fuel ratio.

  However, if the fuel injection amount at the time of starting the engine is uniformly reduced according to the assumed result of the oil leak, if the assumption is incorrect and the oil leak is not large, the air-fuel ratio of the air-fuel mixture Becomes leaner than an appropriate value, and on the contrary, the startability may be reduced.

  The present invention has been made in view of such a situation, and an object of the present invention is to realize start control capable of ensuring good startability in an internal combustion engine mounted on a vehicle or the like.

  The present invention relates to a start control device for an internal combustion engine that obtains power by burning an air-fuel mixture of intake air and fuel injected from a fuel injection valve in a combustion chamber. When the oil leak leakage assumption condition is satisfied, if the misfire state is determined when the engine is started, the technical feature is that the fuel injection amount by the fuel injection valve is corrected to decrease.

  According to the present invention, if the oil-tight leak of the fuel injection valve during engine stop is large and the oil-tight leak assumption condition is satisfied, and the misfire state is actually determined at the time of engine start, the fuel injection valve The fuel injection amount is corrected to decrease, and the richness of the air-fuel ratio of the air-fuel mixture is suppressed. As a result, the air-fuel ratio approaches an appropriate value within the combustible range, the deterioration of the combustion state is suppressed, and the engine speed (engine speed) increases rapidly. That is, the startability of the internal combustion engine is improved.

  On the other hand, if the misfire condition is not determined, the fuel decrease correction is not performed even if the oil leak assumption is satisfied. Therefore, even if the assumption is incorrect and the oil leak is not large, the fuel leak is not corrected. Therefore, the air-fuel ratio does not become leaner than the appropriate value due to the decrease correction.

  In the present invention, when the internal combustion engine has a plurality of cylinders and the fuel injection valve is provided for each cylinder, the determination of the misfire state is at least a first ignition for each cylinder. It is preferable to carry out after completion of. By so doing, it is possible to reduce the influence of the variation in the combustion state of each cylinder and to appropriately determine the misfire state due to the oil tight leakage of the injector.

  More specifically, from the output signal of the crank position sensor for detecting the crank angle of the internal combustion engine, it is possible to determine the rise of engine rotation due to ignition for each cylinder and determine the misfire state. In this case, taking into consideration that the combustion state due to the first ignition for each cylinder at the time of engine start tends to be somewhat unstable, the misfire state is determined after the second ignition for each cylinder is completed. Is preferred. The misfire state can also be determined by, for example, a cylinder internal pressure sensor or an ion current sensor.

  In the present invention, the fuel injection amount reduction correction amount is preferably set in accordance with the actual HC concentration in the intake manifold (intake port), that is, the magnitude of oil-tight leakage. A constant value set in advance may be corrected for reduction, and the amount of reduction correction can be set based on at least the engine water temperature. Further, the amount of decrease correction may be set in consideration of the intake air temperature and water temperature when the engine is started, and also the intake air temperature and water temperature when the engine is stopped.

  In this way, it becomes possible to suitably set the amount of fuel injection reduction in accordance with various conditions at the time of engine start including the magnitude of oil tight leakage, and the air-fuel ratio of the air-fuel mixture is made more appropriate. be able to. It should be noted that the fuel injection amount reduction correction is set so as to ensure a minimum injection amount that allows the engine to be started even if there is no oil tight leak.

  Further, in the present invention, it is preferable to execute a scavenging control that increases the intake air amount and promotes the scavenging of the air-fuel mixture if the misfire state is determined at the time of starting the engine when the oil tight leak assumption condition is satisfied. . In this way, even if the oil-tight leak of the fuel injection valve is large while the engine is stopped and the concentration of HC in the intake manifold (intake port) is high, the mixture of HC is quickly concentrated by cranking. Since scavenging is possible, it is advantageous for optimizing the air-fuel ratio when starting the engine.

  In addition, since the richness of the air-fuel ratio of the air-fuel mixture is suppressed by the increase in the intake air amount, it is possible to moderate the decrease in the fuel injection amount, and to optimize the air-fuel ratio when starting the engine. The torque can be increased while increasing the starting performance of the internal combustion engine.

  More specifically, a configuration in which the amount of intake air is increased by controlling (opening control) the opening of a throttle valve provided in an intake passage leading to a combustion chamber of an internal combustion engine at the time of engine start can be mentioned. . In this case, the opening of the throttle valve when the intake air amount is increased (during scavenging control) is controlled so that the intake passage on the downstream side of the intake flow of the throttle valve does not become negative pressure, and the new air amount is reduced. It is preferable to control so as to be maximized.

  In this case, the throttle valve opening may be set based on the engine water temperature and the engine speed. In this way, an increase in the intake air amount at the time of starting the engine can be appropriately set according to the conditions at the time of starting the engine, so that a stable scavenging effect can be obtained. That is, for example, the opening of the throttle valve may be increased in accordance with an increase in the cranking rotational speed when the engine is started.

  According to the present invention, when the oil-tight leak of the fuel injection valve is large while the engine is stopped and the oil-tight leak assumption condition is satisfied, if the misfire state is determined at the engine start, the fuel injection amount is corrected to decrease. Thus, the air-fuel ratio can be prevented from becoming excessively rich, and good startability can be ensured. If scavenging control for increasing the intake air amount is also performed, torque can be increased while optimizing the air-fuel ratio, and the startability of the internal combustion engine can be further improved.

It is a schematic block diagram which shows an example of the engine (internal combustion engine) to which this invention is applied. It is a block diagram which shows the structure of the control system of the engine shown in FIG. It is a flowchart which shows an example of the engine starting control which ECU performs. It is a figure which shows an example of the map which calculates | requires a water temperature fall determination value. 3 is a timing chart showing an example of changes in injection timing, ignition timing, and engine speed at start-up for each cylinder by start control according to the present invention. It is a figure which shows an example of the map which calculates | requires the throttle opening at the time of engine starting. 6 is a flowchart of a modified example in which the ignition timing is retarded when the engine is started. 4 is a timing chart showing changes in engine speed and the like when retarding the ignition timing. FIG. 6 is a view corresponding to FIG. 3 according to another embodiment that does not perform throttle opening control.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

-Configuration of internal combustion engine-
First, an internal combustion engine (hereinafter also referred to as an engine) to which the present invention is applied will be described. FIG. 1 is a diagram showing a schematic configuration of an engine to which the present invention is applied. FIG. 1 shows only the configuration of one cylinder of the engine.

  The engine 1 in this example is a port injection type four-cylinder gasoline engine mounted on a vehicle, and a piston 1c that reciprocates in the vertical direction is provided in a cylinder block 1a constituting each cylinder. The piston 1c is connected to the crankshaft 15 via the connecting rod 16, and the reciprocating motion of the piston 1c is converted into rotation of the crankshaft 15 by the connecting rod 16.

  The crankshaft 15 of the engine 1 is connected to a transmission (not shown) via a torque converter (or clutch) or the like, and transmits the power from the engine 1 to the drive wheels of the vehicle via the transmission. Can do.

  The transmission is, for example, a stepped automatic transmission that sets a gear position (for example, six forward speeds and one reverse speed) using a friction engagement element such as a clutch and a brake and a planetary gear mechanism. Each range (parking range P, reverse range R, neutral range N, drive range D) of the transmission is switched by operating the shift lever 50 (see FIG. 2). The shift operation position (P, R, N, D range) of the shift lever 50 is detected by the shift position sensor 41. The transmission may be a continuously variable transmission such as a belt type continuously variable transmission.

  The crankshaft 15 of the engine 1 is connected to a starter (motor) 10 that is started when the engine 1 is started, and the cranking of the engine 1 can be performed by starting the starter 10.

  A signal rotor 17 is attached to the crankshaft 15. A plurality of teeth (projections) 17a are provided on the outer peripheral surface of the signal rotor 17 at equal angles (in this example, for example, 10 ° CA (crank excessive)). Further, the signal rotor 17 has a missing tooth portion 17b in which two teeth 17a are missing.

  A crank position sensor 31 that detects a crank angle is disposed near the side of the signal rotor 17. The crank position sensor 31 is an electromagnetic pickup, for example, and generates a pulsed signal (voltage pulse) corresponding to the teeth 17a of the signal rotor 17 when the crankshaft 15 rotates. The engine speed Ne can be calculated from the output signal of the crank position sensor 31.

  A water temperature sensor 32 for detecting the coolant temperature of the engine cooling water is disposed in the cylinder block 1a of the engine 1. A cylinder head 1b is provided at the upper end of the cylinder block 1a, and a combustion chamber 1d is formed between the cylinder head 1b and the piston 1c. A spark plug 3 is disposed in the combustion chamber 1 d of the engine 1. The ignition timing of the spark plug 3 is adjusted by the igniter 4. The igniter 4 is controlled by an ECU (Electronic Control Unit) 200.

  An oil pan 18 for storing lubricating oil (engine oil) is provided below the cylinder block 1 a of the engine 1. Lubricating oil stored in the oil pan 18 is pumped up by an oil pump (not shown) through an oil strainer that removes foreign matters during operation of the engine 1, and the engine such as the piston 1 c, crankshaft 15, connecting rod 16, etc. It is supplied to each part and used for lubrication and cooling of each part. The lubricating oil supplied in this way is used for lubrication and cooling of each part of the engine, then returned to the oil pan 18 and stored in the oil pan 18 until it is pumped up again by the oil pump. .

  An intake passage 11 and an exhaust passage 12 are connected to the combustion chamber 1 d of the engine 1. A part of the intake passage 11 is formed by an intake port 11a and an intake manifold 11b. A surge tank 11 c is provided in the intake passage 11. A part of the exhaust passage 12 is formed by an exhaust port 12a and an exhaust manifold 12b.

  In the intake passage 11 of the engine 1, an air cleaner 7 that filters the intake air, a hot-wire air flow meter 33, an intake air temperature sensor 34 (built in the air flow meter 33), a throttle valve 5 for adjusting the intake air amount of the engine 1, etc. Is arranged.

  The throttle valve 5 is provided on the upstream side (upstream side of the intake flow) of the surge tank 11 c and is driven by the throttle motor 6. The opening of the throttle valve 5 is detected by a throttle opening sensor 35. The throttle opening of the throttle valve 5 is driven and controlled by the ECU 200.

  Specifically, the optimum intake air amount (target) according to the engine 1 operating state such as the engine speed Ne calculated from the output signal of the crank position sensor 31 and the accelerator pedal depression amount (accelerator opening) of the driver. The throttle opening of the throttle valve 5 is controlled so that the intake amount) is obtained. As an example, the target intake air amount may be determined by referring to this map by setting an optimal value corresponding to the engine speed Ne and the accelerator opening by experiment / calculation or the like and setting it as an intake air amount map. .

  More specifically, the actual throttle opening of the throttle valve 5 is detected using the throttle opening sensor 35, and the actual throttle opening matches the throttle opening (target throttle opening) at which the target intake air amount can be obtained. Thus, the throttle motor 6 of the throttle valve 5 is feedback-controlled. Such a control system for the throttle valve 5 is referred to as an “electronic throttle system” and can control the throttle opening independently of the driver's operation of the accelerator pedal. For example, it is possible to execute an increase control of the intake air amount when starting the engine, which will be described later.

A three-way catalyst 8 is disposed in the exhaust passage 12 of the engine 1. In the three-way catalyst 8, oxidation of CO and HC and reduction of NOx in the exhaust gas exhausted from the combustion chamber 1d to the exhaust passage 12 is performed, and these are made harmless CO ₂ , H ₂ O, and N ₂ . In this way, the exhaust gas is purified.

A front air-fuel ratio sensor 37 is disposed in the exhaust passage 12 upstream of the three-way catalyst 8 (upstream of the exhaust flow). The front air-fuel ratio sensor 37 is a sensor that exhibits linear characteristics with respect to the air-fuel ratio. A rear O ₂ sensor 38 is disposed in the exhaust passage 12 on the downstream side of the three-way catalyst 8. The rear O ₂ sensor 38 generates an electromotive force according to the oxygen concentration in the exhaust gas. When the output is higher than a voltage (comparison voltage) corresponding to the theoretical air-fuel ratio, the rear O ₂ sensor 38 determines that the output is rich. When the output is lower than the comparison voltage, it is determined as lean. The output signals of the front air-fuel ratio sensor 37 and the rear O ₂ sensor 38 are used for air-fuel ratio feedback control (for example, refer to the technique described in Japanese Patent Laid-Open No. 2010-007561).

  An intake valve 13 is provided between the intake passage 11 and the combustion chamber 1d. By opening and closing the intake valve 13, the intake passage 11 and the combustion chamber 1d are communicated or blocked. Further, an exhaust valve 14 is provided between the exhaust passage 12 and the combustion chamber 1d. By opening and closing the exhaust valve 14, the exhaust passage 12 and the combustion chamber 1d are communicated or blocked. The opening / closing drive of the intake valve 13 and the exhaust valve 14 is performed by each rotation of the intake camshaft 21 and the exhaust camshaft 22 to which the rotation of the crankshaft 15 is transmitted via a timing chain or the like.

  In the vicinity of the intake camshaft 21, a cam position sensor 39 is provided that generates a pulse signal when the piston 1c of a specific cylinder (for example, the first cylinder) reaches the compression top dead center (TDC). . The cam position sensor 39 is, for example, an electromagnetic pickup, and is disposed so as to face one tooth (not shown) on the outer peripheral surface of the rotor provided integrally with the intake camshaft 21. When the shaft 21 rotates, a pulse signal (voltage pulse) is output. Since the intake camshaft 21 (and the exhaust camshaft 22) rotates at a half speed of the crankshaft 15, the cam position sensor 39 becomes 1 each time the crankshaft 15 rotates twice (720 ° rotation). Two pulse signals are generated.

  In the intake passage 11, an injector (fuel injection valve) 2 is arranged for each cylinder so as to inject fuel into the intake port 11 a as an example. These injectors 2 are connected to a common delivery pipe 101, and fuel is supplied to the delivery pipe 101 from a fuel tank 104 of a fuel supply system 100 described later. The drive of the injector 2 is controlled by the ECU 200, and fuel injection is performed at a predetermined timing for each cylinder.

  Thus, the fuel injected from the injector 2 into the intake port 11a is mixed with intake air and introduced into the combustion chamber 1d in each cylinder as the intake valve 13 is opened. This air-fuel mixture is ignited by the spark plug 3 at the end of the compression stroke of the cylinder and burns and explodes. The piston 1c is pushed down by the high-temperature and high-pressure combustion gas generated at this time (expansion stroke), and driving torque is output from the crankshaft 15. The combustion gas is discharged to the exhaust passage 12 when the exhaust valve 14 is opened.

  The fuel supply system 100 includes a delivery pipe 101 commonly connected to the injector 2 of each cylinder, a fuel supply pipe 102 connected to the delivery pipe 101, a fuel pump (for example, an electric pump) 103, and a fuel tank 104. The fuel stored in the fuel tank 104 can be supplied to the delivery pipe 101 via the fuel supply pipe 102 by controlling the drive of the fuel pump 103 by the ECU 200 described below. Then, the fuel is supplied to the injector 2 of each cylinder by the fuel supply system 100 having such a configuration.

-ECU-
As shown in FIG. 2, the ECU 200 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, a backup RAM 204, and the like.

  The ROM 202 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 201 executes various arithmetic processes based on various control programs and maps stored in the ROM 202. The RAM 203 is a memory that temporarily stores calculation results of the CPU 201, data input from each sensor, and the backup RAM 204 is a nonvolatile memory that stores data to be saved when the engine 1 is stopped, for example. Memory.

  The CPU 201, the ROM 202, the RAM 203, and the backup RAM 204 are connected to each other via the bus 207, and are connected to the input interface 205 and the output interface 206.

The input interface 205 includes a crank position sensor 31, a water temperature sensor 32, an air flow meter 33, an intake air temperature sensor 34, a throttle opening sensor 35, an accelerator opening sensor 36 that outputs a detection signal corresponding to the depression amount of the accelerator pedal, a front Various sensors such as an air-fuel ratio sensor 37, a rear O ₂ sensor 38, a cam position sensor 39, and a shift position sensor 41 for detecting a shift operation position of the shift lever 50 are connected. Further, the ignition switch 40 is connected to the input interface 205, and when the ignition switch 40 is turned on, cranking of the engine 1 by the starter 10 is started.

  The output interface 206 is connected to the injector 2, the igniter 4 of the spark plug 3, the throttle motor 6 of the throttle valve 5, the starter 10, the fuel pump 103 of the fuel supply system 100, and the like.

  The ECU 200 controls the drive of the injector 2 (control of the fuel injection amount and injection timing), the control of the ignition timing by the spark plug 3, the throttle motor 6 of the throttle valve 5 based on the detection signals of the various sensors described above. Various controls of the engine 1 including drive control (control of intake air amount), air-fuel ratio feedback control, and the like are executed. Furthermore, the ECU 200 executes the following “engine start control”.

  With the program executed by the ECU 200 described above, the internal combustion engine start control device of the present invention is realized.

-Engine start control-
First, in the engine 1 including the injector 2, as described above, there may be an oil-tight leak in which fuel leaks from the injector 2 while the engine is stopped (during soak). The oil tight leakage of the injector 2 increases depending on operating conditions and environmental conditions when the engine was stopped last time. For example, when the fuel temperature / pressure is high when the engine is stopped in a low-speed / high-load operation state or in an uphill driving state, or when the outside air temperature is high and the fuel temperature / fuel pressure is high, such as in summer, the oil leak from the injector 2 Becomes larger. When the oil tight leak of the injector 2 increases, the concentration of HC in the intake manifold 11b (intake port 11a) increases. If the air-fuel ratio of the air-fuel mixture becomes rich and exceeds the range of the combustible air-fuel ratio due to the increase in the HC concentration, the combustion state deteriorates and the engine 1 becomes a start failure (misfire state). There is a case.

  Therefore, in the present embodiment, in consideration of such an oil-tight leak of the injector 2 when the engine is stopped, a misfire is actually caused at the time of starting the engine, which is assumed to be a condition where the oil-tight leak is large and the start is severe. If the state is determined, the fuel injection amount by the injector 2 for each cylinder is corrected to decrease and the intake air amount is increased to optimize the air-fuel ratio of the air-fuel mixture. Hereinafter, an example of the control (engine start control) will be described with reference to the flowchart of FIG.

  The control routine of FIG. 3 is executed by the ECU 200 and is started (START) when the ignition switch 40 is turned on (IG-ON). First, in step ST101, the water temperature and the intake air temperature at the time of engine start (at the time of restart) are recognized from the output signals of the water temperature sensor 32 and the intake air temperature sensor 34, the water temperature and the intake air temperature at the time of the engine restart, Based on the water temperature and the intake air temperature when the engine 1 is stopped, it is determined whether or not an oil-tight leak assumption condition of the injector 2 is satisfied.

  This oil-tight leak assumption is a condition where the oil-tight leak of the injector 2 is assumed to be large based on, for example, the fuel temperature and fuel pressure, taking into account the operating conditions and environmental conditions when the engine 1 is stopped. Is determined whether or not all of the following conditions J1, J2, and J3 are satisfied.

Condition J1: The water temperature at the previous engine stop is equal to or higher than a predetermined water temperature determination value, and the intake air temperature at the previous engine stop is equal to or higher than a predetermined intake temperature determination value. Condition J2: The water temperature at engine restart is The water temperature at the time of restarting the engine relative to the water temperature at the time of the last engine stop ([[ The water temperature at the time of previous stop]-[water temperature at the time of restart]) is equal to or higher than the water temperature decrease determination value set for each water temperature at the time of previous stop. Each condition J1 to J3 will be described.

(Condition J1)
When the water temperature and the intake air temperature when the engine 1 is stopped are high, the oil-tight leak of the injector 2 when the engine is stopped increases. In consideration of this point, it is assumed that the water temperature at the time of the previous engine stop is equal to or higher than a predetermined water temperature judgment value and the intake air temperature at the previous time of engine stop is equal to or higher than a predetermined intake air temperature judgment value. One of them.

  As for the water temperature judgment value when the engine is stopped, the relationship between the water temperature when the engine is stopped and the amount of oil-tight leak that may deteriorate the startability of the engine 1 is obtained by experiments, simulations, etc. Based on the relationship, the water temperature (water temperature at the time of stoppage) at which startability may deteriorate is obtained. Then, a suitable value (water temperature determination value) is set based on the result. Also, a value adapted to the intake air temperature determination value when the engine is stopped is set by the same processing.

  Here, the reason why the two parameters of the water temperature at the previous engine stop and the intake air temperature at the previous engine stop are used in the condition J1 will be described.

  For example, when the engine 1 is stopped after the engine is started until the water temperature reaches a warm-up temperature (a temperature at which the warm-up of the engine 1 can be considered to be completed: for example, about 80 ° C.), the water temperature is lower than the intake air temperature. Therefore, if the determination is made only with the water temperature, the determination does not reflect the actual temperature of the injector 2. Further, depending on the operating state of the engine 1, the intake air temperature may be lower than the water temperature. If the determination is made only with the intake air temperature (the temperature of the intake air near the air cleaner 7), an accurate determination can be made. There may not be. Considering such points, in this example, the condition J1 is set with the water temperature and the intake air temperature as parameters.

(Condition J2)
Considering the fact that the longer the engine stop time (soak time) from the previous engine stop to the restart time, the greater the oil-tight leakage of the injector 2, the water temperature at the time of engine restart is below a predetermined water temperature judgment value. In addition, it is assumed that one of the oil leak leakage assumption conditions is that the intake air temperature at the time of engine restart is equal to or lower than a predetermined intake air temperature determination value. That is, when the water temperature and the intake air temperature when the engine is stopped are equal to or higher than the above determination values, the longer the engine stop time (soak time), the lower the water temperature and the intake air temperature during the restart. In addition, the assumption that the intake air temperature is equal to or lower than the determination value is one of the conditions for oil leakage leakage.

  Note that the water temperature determination value and the intake air temperature determination value at the time of engine restart are set to suitable values through experiments and calculations in consideration of the relationship between the soak time and the amount of oil leak. Also in this condition J2, the condition J2 is set using the water temperature and the intake air temperature as parameters for the same reason as the condition J1 described above.

(Condition J3)
When the water temperature when the engine is stopped is, for example, 90 ° C. or higher and the oil temperature is 90 ° C. or higher, the water temperature tends not to decrease due to the influence of the temperature of the lubricating oil (oil temperature). In consideration of this point, in addition to the above condition J2, with respect to the water temperature, the water temperature drop value at the time of the engine restart relative to the water temperature at the time of the previous engine stop (the water temperature at the time of the previous engine stop)-[ It is a condition that the engine water temperature]) is equal to or higher than the water temperature decrease determination value set for each water temperature during stoppage. The water temperature decrease determination value used for this condition J3 is obtained with reference to the map (table) in FIG. 4 based on the water temperature when the engine is stopped.

  The map of FIG. 4 is a map of values (water temperature decrease determination value) adapted by experiment / calculation in consideration of the effect of the oil temperature, and is stored in the ROM 202 of the ECU 200. In the map shown in FIG. 4, when the water temperature is 90 ° C. or higher, the water temperature lowering determination value is set to a smaller value with respect to the side where the water temperature is lower than 90 ° C.

  In the map of FIG. 4, the water temperature decrease determination value between 80 ° C. and 90 ° C. is a constant value (10 ° C.). For the water temperature decrease determination value between 90 ° C. and 105 ° C., the water temperature decrease determination value is obtained by interpolation calculation.

  Here, as the oil-tight leak assumption condition of the injector 2, other conditions can be used as long as the deterioration of combustion at restart (engine start failure) due to the oil-tight leak of the injector 2 when the engine is stopped is assumed. It may be. For example, the water temperature difference between the previous engine stop and the engine restart may be a predetermined value or more and the intake air temperature at the restart may be a predetermined value or less. Further, in addition to such a condition, the above condition J3 may be set.

  Returning to the flowchart of FIG. 3, if the determination result in step ST101 is negative (NO), that is, if the oil-tight leak assumption condition is not satisfied, the process proceeds to step ST110. In step ST110, the engine 1 is started with the fuel injection amount and the intake air amount at the normal start (normal start control). Note that the fuel injection amount and the intake air amount at the normal start time are, for example, the injection amount map and the intake air amount for the normal start time based on the engine start conditions (water temperature, intake air temperature, correction values so far, etc.), respectively. Calculated from the map.

  As an example, as shown in the middle part of FIG. 5, fuel is injected in a predetermined order by the respective injectors 2 of the first to fourth cylinders during normal start. In the example shown in the figure, fuel injection is performed in the order of the fourth cylinder, the second cylinder, the first cylinder, and the third cylinder, and basically the intake port at a predetermined timing (for example, at the end of the expansion stroke) for each cylinder. Fuel is injected into 11a. This fuel is mixed with intake air to become an air-fuel mixture, and is introduced into the combustion chamber 1d in each cylinder when the intake valve 13 is opened at the end of the exhaust stroke.

  Also, in order to shorten the start time as much as possible, immediately after the start of cranking by the starter 10, the first (first) fuel injection for each cylinder is different from the above as shown in the left end of FIG. It is executed at the timing. In the example shown in the figure, when the intake camshaft 21 rotates with cranking and the cam position sensor 39 generates a pulse signal (cylinder identification signal) at the compression top dead center (TDC) of the first cylinder, fuel injection by the injector 2 is performed. Is started.

  At this time, that is, at the compression top dead center of the first cylinder, the cylinder that first reaches the ignition timing (indicated by a virtual line in the figure) is the third cylinder, but the third cylinder immediately shifts to the compression stroke. Fuel cannot be supplied. Therefore, first, the injector 2 of the fourth cylinder in the intake stroke is driven, and then the injector 2 of the second cylinder in the exhaust stroke is driven to inject fuel respectively. If the injection pulses overlap, the injection amount may vary due to fluctuations in the fuel pressure of the delivery pipe 101, so the injection pulses are slightly shifted.

  Thus, the fourth cylinder for injecting fuel first is in the intake stroke, and the second cylinder for injecting fuel is in the exhaust stroke, both of which are later than the original injection timing, but one of the injected fuels. The part is mixed and introduced into the cylinder. Further, the fuel is injected into the subsequent first cylinder at substantially the original injection timing, and the injection timing into the subsequent third cylinder is earlier than the original timing. In general, fuel vaporization tends to be worse at the time of starting, so it is preferable to inject early.

  After the first fuel injection for each cylinder, which is performed in the order of the fourth cylinder, the second cylinder, the first cylinder, and the third cylinder, the final stage of the compression stroke for each cylinder as shown in the upper part of FIG. From ignition to the expansion stroke, that is, ignition is performed by the spark plug 3 at a predetermined timing in the vicinity of the TDC (first ignition for each cylinder), and the air-fuel mixture burns and explodes (initial explosion). As a result, the rotation of the crankshaft 15 is accelerated, and the engine speed rises as shown by the phantom line graph in the lower part of FIG.

  On the other hand, if the determination result in step ST101 is affirmative (YES), that is, if the oil-tight leak assumption condition is satisfied, the process proceeds to step ST102. First, the normal start control (step ST110) and Similarly, start control is started with the fuel injection amount and intake air amount for normal start. Then, in step ST103, it is determined whether or not the mixture is in a misfire state in which the air-fuel mixture does not burn well even though ignition is performed for each cylinder as described above.

  That is, if the oil-tight leak is not large and the air-fuel ratio of the air-fuel mixture is within the flammable range, the initial explosion occurs by ignition of each cylinder as described above, and the engine speed rises, but the oil-tight leak is large. If the concentration of HC in the intake manifold 11b (intake port 11a) is high, the air-fuel ratio of the air-fuel mixture becomes excessively rich and a misfire may occur.

  When a misfire occurs, the engine speed does not easily rise as shown by the broken line in FIG. 5, so that, for example, if the engine speed does not reach a predetermined judgment value within a predetermined time from ignition, the engine is in a misfire state. Can be determined. Although not shown, for example, if the rate of change dNe / dt of the engine speed has not reached a predetermined determination value, it can be determined that the engine is misfired.

  Note that, as described above, the first fuel injection at the time of starting is not necessarily performed at a preferable timing, and the combustion state by the first ignition is likely to be somewhat unstable. Therefore, in this embodiment, the second ignition is finished for each cylinder. After that, the misfire state is determined from the output signal of the crank position sensor 31. However, a suitable timing for determining the misfire state is not limited thereto, and may be at least after the first ignition is completed for each cylinder.

  If the misfire state is not determined in step ST103 and the determination is negative (NO), the process proceeds to step 110 and normal start control is continued. On the other hand, if the determination is affirmative (YES), that is, if the misfire condition is determined when the oil-tight leak assumption condition of the injector 2 is satisfied, the routine proceeds to step ST104, where the opening of the throttle valve 5 (throttle throttle) The opening degree is set larger than that at the normal start, and the intake air amount is increased from the normal start (that is, the scavenging control is executed).

  The throttle opening at this time, that is, the opening of the throttle valve 5 at the time of executing the control (scavenging control) for increasing the intake air amount may be an opening at which the intake passage 11 does not become negative pressure. Specifically, a value (throttle opening) adapted by experiment / calculation or the like may be used with the cranking rotation speed at the time of engine start as a parameter. The throttle opening for correcting the intake air amount increase may be a constant value, or may be set variably according to the cranking rotational speed or the like, as will be described later.

  Note that the throttle opening at which the intake passage 11 does not become negative pressure means that the throttle opening within a range in which intake pipe negative pressure (intake manifold negative pressure) does not occur when the throttle valve 5 is opened larger than at normal start when the engine is started. For example, it is an opening obtained by adding a margin (open side value) to the lower limit opening of the throttle opening range in which the intake manifold negative pressure does not occur. The throttle opening is set such that the amount of fresh air is maximized (the scavenging effect is maximized) within a range where intake pipe negative pressure (intake manifold negative pressure) does not occur.

  Subsequently, in step ST105 of the flow of FIG. 3, the fuel injection amount by the injector 2 for each cylinder is decreased from that at the normal start. This reduced amount may be a preset constant amount or may be variable. When variable, for example, the water temperature (water temperature at engine start) obtained from the output signal of the water temperature sensor 32 or the intake air temperature is used as a parameter. It is sufficient to map values that are suitable by, for example, and determine the amount of reduction correction with reference to this map. It should be noted that the fuel injection amount after the reduction correction is at least as much as the engine 1 can be started.

  If the fuel injection amount for each cylinder is corrected so as to decrease, the air-fuel ratio of the air-fuel mixture becomes lean. Therefore, even if oil-tight leakage is large, the air-fuel ratio in the combustion chamber 1a in the cylinder is enriched. It can be effectively suppressed. Therefore, when ignited by the spark plug 3, the air-fuel mixture burns and explodes without being misfired (initial explosion), and the engine speed rises as shown by the solid line graph in the lower part of FIG. Then, the scavenging of the air-fuel mixture advances due to the cranking of the engine 1, and the engine speed rapidly increases in combination with the optimization of the air-fuel ratio.

  Thereafter, in step ST106 of the flowchart of FIG. 3, it is determined whether or not the engine speed Ne calculated from the output signal of the crank position sensor 31 has reached a predetermined determination value Thne, and the determination is negative (NO). Waits until the engine speed Ne at the start reaches this determination value Thne. Then, when the determination is affirmative (YES), that is, when the engine speed Ne at the start reaches the determination value Thne, the process proceeds to step ST107.

  The determination value Thne used for the determination in step ST106 is obtained by experiment / calculation, etc., of the engine speed at which HC can sufficiently scavenge a high-concentration mixture during cranking at the time of engine start. A value (for example, 1000 rpm) adapted to the result may be used.

  In step ST107, the reduction of the fuel injection amount is finished, the fuel injection amount by the injector 2 is returned to the normal control state, and the increase of the intake air amount is also finished, and the throttle valve 5 is controlled to the opening during the normal control. Return the intake air amount to the normal control state. Thereafter, this control routine is temporarily terminated (RETURN).

  As described above, in the present embodiment, when the oil-tight leak of the injector 2 during engine stop is large and the oil-tight leak assumption condition is satisfied, if the misfire state is determined at the engine start, the injector The fuel injection amount by 2 is corrected to decrease, and the scavenging of the air-fuel mixture having a high concentration of HC is promoted by the increase of the intake air amount (scavenging control). As a result, the air-fuel ratio of the air-fuel mixture becomes an appropriate value within the combustible range, and the combustion state is improved.

  In addition, by increasing the intake air amount, the amount of air-fuel mixture combusted in the cylinder increases, and the torque can be increased in combination with the improvement of the combustion state. As a result, as shown by the solid line graph in the lower part of FIG. 5, the initial explosion was obtained earlier compared to the case where fuel reduction and air volume increase were not performed (shown by the broken line graph), and the engine speed was It can be launched quickly. That is, even if the oil tight leak from the injector 2 is large, a good engine start can be realized.

  On the other hand, if the misfire condition is not determined, the fuel decrease correction and the air increase correction are not performed even if the oil leak assumption is satisfied. If not, the air-fuel ratio of the air-fuel mixture does not become leaner than an appropriate value or the engine speed does not increase due to the correction control as described above. In other words, there is no concern that the startability of the engine 1 will be lowered, the fuel consumption will be deteriorated, or that a sense of incongruity will be caused due to the correction control based on the prediction of oil leak.

  In the present embodiment, as described above, when the fuel injection amount is reduced and the intake air amount is increased as a countermeasure against oil tight leakage of the injector 2, the increased intake air amount may be a constant amount, It may be set to be variable.

  When the amount of intake air to be increased is set to be variable, the negative pressure (intake manifold negative pressure) in the intake passage increases as the cranking rotational speed at engine startup increases. As the cranking speed increases, the opening of the throttle valve 5 is increased and the intake air amount is gradually increased (or increased stepwise) so that the intake passage 11 does not become negative pressure. Also good.

  In this case, the map shown in FIG. 6 is referred to based on the water temperature obtained from the output signal of the water temperature sensor 32 (water temperature at the time of starting the engine) and the cranking rotation speed by the starter 10 (recognized from the output signal of the crank position sensor 31). Then, by setting the throttle opening θ of the throttle valve 5, the intake air amount may be gradually increased (or increased stepwise) in accordance with the cranking rotation speed.

  As an example, the map shown in FIG. 6 is a map obtained by mapping the throttle opening θ at which the intake passage 11 does not become negative pressure by experiment and calculation using the water temperature and the cranking rotation number as parameters. It is stored in the ROM 202 of the ECU 200. In the map of FIG. 6, the throttle opening θ is set to be larger as the water temperature is higher and the cranking rotational speed is higher.

-Modification of engine start control-
Next, a modified example of the engine start control described above will be described with reference to the flowchart of FIG. In this modification, paying attention to the fact that when the intake air amount is increased at the start of the engine as in the above embodiment, the engine speed at the completion of the start may rise higher than usual. Unnecessary rotation increase of the engine 1 is suppressed by timing retard control or the like.

  Therefore, the flowchart of FIG. 7 does not show the steps of reducing the fuel injection amount or increasing the intake air amount, but also in this modified example, the fuel injection amount decrease or the intake air amount increase is the same as in the above embodiment. The same is done.

  Also in this modification, the ECU 200 recognizes the water temperature and the intake air temperature when the engine is stopped every time the engine 1 is stopped based on the output signals of the water temperature sensor 32 and the intake air temperature sensor 34. The water temperature and intake air temperature when the engine is stopped are sequentially stored and updated in the RAM 203 or the like.

  The control routine of FIG. 7 is started when the ignition switch 40 is turned on (IG-ON). When this processing routine is started, first, in step ST201, it is determined whether or not an oil-tight leak assumption condition of the injector 2 is satisfied and a misfire state is determined. Since the determination process in step ST201 is the same as the determination process in steps ST101 and ST103 of FIG. 3, detailed description thereof is omitted here.

  If the determination result in step ST201 is negative (NO), that is, if the oil-tight leak assumption condition is not satisfied or the misfire state is not determined, the process proceeds to step ST210. On the other hand, if the determination result in step ST201 is affirmative (YES), that is, if the oil-tight leak assumption condition is satisfied and the misfire state is determined, the process proceeds to step ST202.

  In step ST202, it is determined whether or not the engine speed Ne calculated from the output signal of the crank position sensor 31 rises to a scavenging completion speed (the same value as the scavenging end determination value Thne: 1000 rpm, for example) or more. judge. When the determination result is negative (NO) (when the engine speed Ne does not increase to the scavenging completion speed), the process proceeds to step ST220.

  If the determination result in step ST202 is affirmative (YES), it is determined that the engine speed has rapidly increased due to fuel decrease correction and scavenging control (increase in intake air amount) at the time of engine start, and step ST203. Proceed to

  In step ST203, after completing the scavenging control at the time of engine start (increase in the amount of intake air), ignition retard control is performed in order to suppress the engine speed Ne from rising. Specifically, the ignition timing C (for example, −10 ° BTDC (10 ° [CA] retarded with respect to BTDC)) is set, and the ignition timing control (retarding control) of the spark plug 3 (igniter 4) is performed. Do.

  Next, in step ST204, it is determined whether or not one of the conditions “reaching the rotation increase end determination time ta (see FIG. 8)” or “predetermined time has elapsed after engine start” is satisfied. If the determination result is negative (NO), the retard control in step ST203 is continued. The rotation increase end determination time ta is from when the engine starts t1 (or when cranking starts) until the increase in the engine speed Ne ends when the fuel is reduced and the intake air amount is increased at the time of starting the engine. This time is adapted by experiment and calculation. Further, the elapsed time after the engine is started is, for example, the time until the engine speed is stabilized after the engine is started, and is adapted by experiments and calculations.

  Then, when the determination result in step ST204 is affirmative (YES), the process proceeds to step ST205. In step ST205, on the basis of the current engine speed Ne and the engine load factor kl calculated from the output signal of the crank position sensor 31, the ignition timing is calculated with reference to a map previously adapted by experiments and calculations. Then, a gradual change process is performed to gradually advance the ignition timing retarded in step ST203 (see FIG. 8), and the actual ignition timing is changed to the calculated value (normal control value) of the ignition timing. Thereafter, this control routine is temporarily terminated (RETURN).

  The load factor kl can be calculated, for example, as a value indicating the current load ratio with respect to the maximum engine load with reference to a map or the like based on the engine speed Ne and the intake pressure.

  On the other hand, when the determination result of step ST201 is negative (NO), that is, when the oil-tight leak assumption condition of the injector 2 is not satisfied or the misfire state is not determined (when normal starting). Advances to step ST210. In step ST210, any one of the conditions "the engine speed Ne calculated from the output signal of the crank position sensor 31 is equal to or higher than the start determination speed (see FIG. 8, for example, 500 rpm)" or "the starter signal is OFF" It is determined whether or not is established. If the determination result is negative, the process proceeds to step ST220. In step ST220, after setting the ignition timing A (for example, 5 ° BTDC), this control routine is temporarily terminated.

  If the determination result in step ST210 is affirmative (YES), the process proceeds to step ST211. In step ST211, ignition timing B (for example, 2 ° BTDC) is set and ignition timing control (retarding control) of the spark plug 3 is performed.

  Next, in step ST212, any one of the conditions “reach the rotation increase end determination time tb (see FIG. 8)”, “a predetermined time has elapsed after the engine starts”, or “shift shift to D range” is set. It is determined whether or not it is established. If the determination result is negative (NO), the ignition timing control in step ST211 is continued.

  The rotation rise end determination time tb is the time from when the engine starts at t3 (or when cranking starts) until the increase in the engine speed Ne ends when the engine is started with the intake air amount at the normal start. Yes, it can be adapted by experiment and calculation. The predetermined time after the engine is started is, for example, the time until the engine speed is stabilized after the engine is started, and is adapted by experiments and calculations.

  Then, when the determination result in step ST212 is affirmative (YES), the process proceeds to step ST213. In step ST213, based on the current engine speed Ne and the engine load factor kl calculated from the output signal of the crank position sensor 31, the ignition timing is calculated with reference to a map adapted in advance through experiments and calculations. Then, a gradual change process for gradually advancing the ignition timing is performed (see FIG. 8), and the actual ignition timing is changed to the calculated value of the ignition timing. Thereafter, this control routine is temporarily terminated.

  Next, the engine start control of this modification will be specifically described with reference to the timing chart of FIG.

  First, a description will be given of a case where an oil tight leak assumption condition of the injector 2 is established and a misfire state is determined.

  As described above, when the oil-tight leak assumption condition is satisfied, if the misfire state is determined at the time of starting the engine, the fuel injection amount by the injector 2 is corrected to decrease, and the throttle opening is adjusted during normal start control. The intake air amount is increased with respect to the normal start control. The increase in the intake air amount facilitates scavenging of the fuel (HC) leaked from the injector 2 into the intake manifold 11b (intake port 11a). Is optimized. Thereby, a combustion state becomes favorable and an engine speed comes to rise rapidly.

  During this increase process, when the engine rotational speed Ne exceeds the start determination rotational speed (for example, 500 rpm) (t1) and then reaches the scavenging completion rotational speed (for example, 1000 rpm), the fuel injection amount is reduced or sucked. End the air volume increase (return the throttle opening during normal control). Further, the ignition timing is retarded by setting the ignition timing to −40 ° BTDC. By such ignition timing retardation control, it is possible to suppress the engine speed Ne from being blown up after reaching the scavenging completion speed.

  This ignition timing retardation control is continued until the above-described rotation rise end determination time ta is reached. Then, when the rotation rise end determination time ta is reached, a gradual change process for gradually advancing the ignition timing retarded at the time t2 is performed, and the actual ignition timing is set to the normal control value after the engine start (current Ignition timing calculated based on the engine speed Ne and the load factor kl).

  Here, the control in this example is a case where the shift range is shifted from the N range to the D range by operating the shift lever 50 of the driver at the time t4, for example, while the ignition timing retarding control is continued. Even if there is, the ignition timing retard control is continued. By doing in this way, the deterioration of the drivability at the time of the shift change from N range and the rotation increase of the engine 1 (rotation increase shown with a broken line in FIG. 8) can be suppressed.

  Next, a description will be given of at least one of cases where the oil-tight leak assumption condition of the injector 2 is not satisfied or the misfire state is not determined (normal start control).

  If the oil-tight leak assumption is not satisfied or the misfire state is not determined, the fuel injection amount reduction correction is not performed, and the throttle opening is set to the opening at the normal start control, The start control is performed with the intake air amount at the normal start. After the cranking is started, the ignition timing is set to the retard side at time t3 when the engine speed Ne reaches the start determination rotational speed (for example, 500 rpm). This state is continued until the above-described rotation rise end determination time tb is reached. Then, when the engine speed Ne reaches the rotation rise end determination time tb, a gradual change process for gradually advancing the ignition timing is performed, and the actual ignition timing is changed to the ignition timing (in normal control after engine startup) ( The current engine speed Ne and the load factor kl are calculated).

  Since the increase in engine speed (torque up) is smaller at the normal start time than at the time when the intake air amount is increased, for example, at the timing t4 until the rotation increase end determination time tb is reached. Even if the shift range is shifted from the N range to the D range by operating the shift lever 50, the influence on the drivability at the time of the shift change from the N range is small. Therefore, in this example, a gradual change process is performed in which the ignition timing is gradually advanced at time t4 when the shift operation is performed, so that the actual ignition timing is changed to the ignition timing at the normal control after the engine is started (FIG. (See broken line 8).

-Other embodiments-
In the above-described embodiment, when the oil-tight leak assumption condition is satisfied at the time of starting the engine and the misfire state is determined, the fuel injection amount is decreased and the intake air amount is increased. The invention is not limited to this. That is, as shown in an example in the flowchart of FIG. 9, the fuel injection amount may be reduced while the intake air amount may not be increased.

  In the illustrated flow, in steps ST301 to 303 and 310, processing similar to that in steps ST101 to 103 and 110 in the flow shown in FIG. 3 is performed. That is, in step ST301, it is determined that an oil-tight leak assumption condition is satisfied, and in step ST302, start control is started with the fuel injection amount and the intake air amount for normal start. In step ST303, it is determined whether or not a misfire state occurs.

  If a misfire state is determined (YES), the process proceeds to step ST304, and the fuel injection amount is corrected to decrease in the same manner as in step ST105 in the flow shown in FIG. 3, and in step ST305, the engine speed Ne is set in the same manner as in step ST106. It is determined whether or not a determination value has been reached, and the fuel injection amount reduction correction is continued until this determination value is reached. On the other hand, if the determination value is reached, the process proceeds to step ST306 to end the fuel reduction correction. When the air amount is not increased in this way, there is no fear that the engine speed will rise when the start is completed without performing the retard control of the ignition timing.

  Further, in the above-described embodiment, the timing at which the increase of the intake air amount (scavenging control) is terminated is the time when the engine speed reaches the determination value. However, the present invention is not limited to this, for example, the engine The engine speed change rate dNe / dt (see FIG. 5) at the start reaches a predetermined determination value (for example, the speed increase rate at which HC can sufficiently scavenge a high-concentration mixture). At this point, the increase in the intake air amount may be terminated. Further, the increase in the intake air amount may be terminated when the engine speed becomes equal to or higher than a determination value when the engine is started and the change rate of the engine speed becomes equal to or higher than a predetermined value.

  In addition, the correction control for decreasing the fuel injection amount or increasing the intake air amount when starting the engine may be terminated when the number of rotations of the crankshaft 15 exceeds a predetermined value. In this case, every time the crankshaft 15 rotates 360 °, the count value is incremented by one, and the count value is a predetermined value (for example, a count value that enables HC to sufficiently scavenge a high-concentration mixture (engine rotation If the number of times)) or more, the correction control is terminated.

  Further, in the above-described embodiment, the example in which the present invention is applied to the start control of the port injection type engine (internal combustion engine) has been described. However, the present invention is not limited to this, and the start control of the in-cylinder direct injection type engine. It is also applicable to.

  In the above-described embodiment, the case where the present invention is applied to a four-cylinder engine has been described. However, the present invention is not limited to this, and start control of an engine having any other number of cylinders, such as a six-cylinder engine, for example. It is also applicable to. In addition to the in-line multi-cylinder engine, the present invention can be applied to start control of a V-type multi-cylinder engine.

  INDUSTRIAL APPLICABILITY The present invention can be used for a start control device for an internal combustion engine (engine) mounted on a vehicle or the like, and more specifically, can be used for a start control device for an internal combustion engine intended to ensure good startability. Can do.

1 Engine 2 Injector (fuel injection valve)
5 Throttle valve 31 Crank position sensor 200 ECU

Claims (7)

An internal combustion engine start control device for obtaining power by burning an air-fuel mixture of intake air and fuel injected from a fuel injection valve in a combustion chamber,
If a predetermined oil-tight leak assumption condition is assumed in which the oil-injection leak of the fuel injection valve is satisfied, if the misfire state is determined at the time of engine start, the fuel injection amount by the fuel injection valve is reduced and corrected. An internal combustion engine start control device. The start control device for an internal combustion engine according to claim 1,
The internal combustion engine has a plurality of cylinders, and the fuel injection valve is disposed for each cylinder;
The start control device for an internal combustion engine, wherein the determination of the misfire state is performed at least after the first ignition for each cylinder is completed. The start control device for an internal combustion engine according to claim 2,
The internal combustion engine is provided with a crank position sensor for detecting a crank angle,
An internal combustion engine start control apparatus, wherein after the second ignition for each cylinder is completed, a misfire state is determined from an output signal of the crank position sensor. The start control device for an internal combustion engine according to any one of claims 1 to 3,
A start control device for an internal combustion engine, wherein the fuel injection amount reduction correction amount is set based on at least an engine water temperature. The start control device for an internal combustion engine according to any one of claims 1 to 4,
The scavenging control is executed to increase the intake air amount and promote the scavenging of the air-fuel mixture if the misfire state is determined at the time of starting the engine when the oil tight leak assumption condition is satisfied. Start control device. In the internal combustion engine start control device according to claim 5,
When increasing the intake air amount, the opening degree of the throttle valve provided in the intake passage leading to the combustion chamber is controlled to an opening degree at which the intake passage downstream from the throttle valve does not become negative pressure. An internal combustion engine start control device. The start control device for an internal combustion engine according to claim 6,
An opening control device for an internal combustion engine, wherein the opening of the throttle valve when increasing the intake air amount is set based on an engine water temperature and an engine speed.

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