JP2008215192A - Start controller of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a start controller of an internal combustion engine capable of appropriately controlling a fuel amount sucked into a cylinder in starting. <P>SOLUTION: In the start controller of an internal combustion engine which is applied to the internal combustion engine 1 having a plurality of cylinders 2 and with an injector 12 being respectively arranged in an intake port 3a of respective cylinder 2, judges the piston position of respective cylinder 2 during stopping of the internal combustion engine 1, determines a suction stroke cylinder whose piston 5 has been stopping at a suction stroke on the basis of the result of the judgement, and sets the fuel amount to be supplied to the intake port 3a of the suction stroke cylinder before the start of the internal combustion engine 1 on the basis of the piston position of the suction stroke cylinder, when the fuel is supplied to the intake port 3a of the suction stroke cylinder before the start of the internal combustion engine 1, a compensation amount is set on the basis of the piston position of the suction stroke cylinder, and the fuel amount supplied to the suction stroke cylinder before the start of the internal combustion engine 1 is reduced to be less than the fuel amount supplied to other cylinders in accordance with the compensation amount. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine start control device that sets an amount of fuel to be supplied to a cylinder in which a piston is stopped in an intake stroke based on a piston position when the internal combustion engine is stopped.

  The piston position when the internal combustion engine is stopped is determined, the cylinder where the piston is stopped in the intake stroke is specified based on the determination result, and the fuel injection amount at the start for the specified cylinder is determined for other cylinders There is known a start control device that increases the fuel injection amount relative to the fuel injection amount (see Patent Document 1). Further, in a control device that injects fuel immediately before stopping to a cylinder that is at least in an expansion stroke when the internal combustion engine is stopped, power is supplied to a restart motor that drives the output shaft of the internal combustion engine to restart the internal combustion engine. There is known a control device that detects the remaining amount of the battery and sets the injection amount of the fuel injected just before the stop of the internal combustion engine to a larger value when the remaining amount of the battery is small than when the remaining amount of the battery is large. (See Patent Document 2). In addition, Patent Documents 3 to 8 exist as prior art documents related to the present invention.

JP 2006-220141 A JP 2005-30218 A JP 2005-307826 A JP-A-2005-214124 JP 2001-342874 A JP 2003-269222 A Japanese Patent Laid-Open No. 9-42012 JP 2004-686621 A

  In the case of a so-called port injection type internal combustion engine that injects fuel into the intake port, when the amount of intake air is small, such as when the internal combustion engine is started, part of the injected fuel adheres to the intake port, and the intake port It is known to be sucked into a cylinder together with fuel injected into the cylinder. In such an internal combustion engine, as described in Patent Document 1 or 2, when the amount of fuel to be injected at the start is increased, the fuel adhering to the intake port also increases. Therefore, if the fuel adhering to the intake port is sucked into the cylinder together with the fuel injected after the next time, the amount of fuel supplied into the cylinder may be excessive.

  Therefore, an object of the present invention is to provide a start control device for an internal combustion engine that can appropriately control the amount of fuel sucked into a cylinder at the time of start.

The start control device for an internal combustion engine according to the present invention is applied to an internal combustion engine having a plurality of cylinders and provided with a fuel injection valve in an intake port of each cylinder, and the piston stop of each cylinder when the internal combustion engine is stopped Based on the piston stop position of the intake stroke cylinder determined by the cylinder specifying means for determining the position and specifying the intake stroke cylinder in which the piston is stopped in the intake stroke based on the determination result And a fuel injection amount setting means for setting a fuel amount to be supplied to the intake port of the intake stroke cylinder before starting the internal combustion engine, and a fuel injection amount to be supplied to each cylinder when the internal combustion engine is started. in starting control apparatus for an internal combustion engine having a basic fuel injection amount calculating means, and the case where fuel is supplied to the intake port of the intake stroke cylinder before the start of the internal combustion engine, said internal combustion engine By has a decreasing correction means for reducing than the fuel injection amount calculated by the fuel injection amount supplied to the intake stroke cylinder, which is determined by the cylinder identifying means when starting the basic fuel injection amount calculating means The problem described above is solved (claim 1).

According to the start control device of the present invention, since the fuel injection amount supplied to the intake stroke cylinder at the start of the internal combustion engine is reduced, the fuel is attached to the intake port by the fuel injection performed before the start, and this fuel evaporates. Thus, even if the intake stroke cylinder is inhaled at the start, it is possible to prevent the fuel supplied to the intake stroke cylinder from becoming excessive. Therefore, the amount of fuel sucked into the cylinder at the start can be appropriately controlled. Thereby, since discharge | emission of unburned fuel etc. can be suppressed, exhaust emission can be improved. Moreover, since the torque fluctuation of the internal combustion engine can be suppressed, vibration and noise of the internal combustion engine can be suppressed. The reduction correction means sets a correction amount based on the piston stop position of the intake stroke cylinder determined by the cylinder specifying means, and the basic fuel injection amount calculation means sets the correction amount according to the set correction amount. The calculated fuel injection amount may be decreased (claim 2).

In one form of the start control device of the present invention, the internal combustion engine further includes a starter motor for starting the internal combustion engine, and a battery for supplying electric power to the starter motor, and the pre-startup fuel injection amount setting The means corrects the amount of fuel to be supplied to the intake port of the intake stroke cylinder before starting the internal combustion engine based on the voltage of the battery when the internal combustion engine is stopped, and the reduction correction means It may be set the correction amount based on both the voltage of the battery at the time of stopping the determined piston stop position and the internal combustion engine of the intake stroke cylinder in means (claim 3). As described above, when the fuel amount to be supplied to the intake port of the intake stroke cylinder before the start is corrected based on the battery voltage, the fuel injection amount supplied to the intake stroke cylinder at the start is also corrected based on the battery voltage. . As a result, the amount of fuel drawn into the intake stroke cylinder when the internal combustion engine is started can be controlled more appropriately.

In one form of the start control device of the present invention, the reduction correction means, when the fuel is supplied to the intake port of the intake stroke cylinder before starting the internal combustion engine, the intake air determined by the cylinder specifying means. Reduction correction for reducing the fuel injection amount supplied to the intake stroke cylinder determined by the cylinder specifying means based on the piston stop position of the stroke cylinder, from the fuel injection amount calculated by the basic fuel injection amount calculating means It is provided with a number of corrections setting means for setting the number of good (claim 4). The greater the amount of fuel adhering to the intake port, the longer it takes to evaporate the adhering fuel amount. Therefore, the fuel adhering to the intake port also has an effect on the multiple fuel injections performed on the intake stroke cylinder at the start. Since the amount of fuel supplied to the intake port of the intake stroke cylinder before starting is set based on the piston stop position of the intake stroke cylinder at the time of stop , the number of reduction corrections is set based on the piston stop position in this way By doing so, the number of reduction corrections can be appropriately set in consideration of the fuel adhering to the intake port by the first fuel injection. This makes it possible to appropriately correct the fuel injection amount supplied to the intake stroke cylinder at the start-up corresponding to the period when the fuel adhering to the intake port affects the combustion state of the intake stroke cylinder. The amount of fuel sucked can be controlled more appropriately.

In this embodiment, the reduction correction unit may further include a correction amount changing unit that reduces the correction amount in later cycles when the correction number setting unit sets a plurality of reduction corrections. ( Claim 5 ). Further, the correction amount changing means may be progressively reduced the amount of correction (claim 6). Since the amount of fuel that evaporates from the intake port gradually decreases, the amount of fuel that is drawn into the intake stroke cylinder in accordance with the amount of fuel that evaporates from the intake port is reduced by reducing the correction amount in this way. Can be controlled.

In one form of the start control device of the present invention, the decrease correction means is a fuel injection amount supplied to the intake stroke cylinder even when the start of the internal combustion engine is completed in the middle of the number of times set by the correction number setting means. the may be done to continue decreasing correction to reduce than the fuel injection amount supplied to the other cylinders (claim 7). Thus, even after the completion of the start of the internal combustion engine, the fuel injection amount supplied to the intake stroke cylinder is reduced during a period in which it is estimated that the fuel evaporated from the intake port is sucked into the intake stroke cylinder. Even after completion, the amount of fuel drawn into the intake stroke cylinder can be appropriately controlled.

In this embodiment, the decrease correction means, the correction amount after completion of starting of the internal combustion engine may be smaller than the correction amount during starting of the internal combustion engine (claim 8). In general, the injection amount is adjusted so that the air-fuel ratio becomes richer than the stoichiometric air-fuel ratio during start-up of the internal combustion engine, and after the start-up is completed, the air-fuel ratio becomes leaner than during start-up, for example, the stoichiometric air-fuel ratio. The injection amount is adjusted. For this reason, if the same reduction correction is performed after the start is completed, the air-fuel ratio may be excessively controlled to the lean side. In this embodiment, since the correction amount is reduced after the start of the internal combustion engine, the air-fuel ratio of the intake stroke cylinder can be appropriately controlled.

In one form of the start control device of the present invention, the internal combustion engine is an application target of idle stop control that stops the internal combustion engine when a predetermined stop condition is satisfied and restarts the internal combustion engine when a predetermined restart condition is satisfied. And when the fuel is supplied to the intake port of the intake stroke cylinder before restarting from the stop state by the idle stop control, the decrease correction means is configured to determine a fuel injection amount to be supplied to the intake stroke cylinder at the time of restart. The fuel injection amount supplied to the other cylinders may be decreased according to the correction amount ( claim 9 ). In such an internal combustion engine, the number of times of stopping and starting the internal combustion engine is larger than that of an internal combustion engine that is not subject to idling stop control. Therefore, by applying the present invention, it is possible to appropriately improve the exhaust emission at start-up and appropriately suppress vibration and noise.

As described above, according to the start control device of the present invention, when fuel is supplied to the intake port of the intake stroke cylinder before starting, the fuel adhering to the intake port at this time is taken into consideration at the time of starting. Since the fuel injection amount supplied to the intake stroke cylinder is reduced and corrected, the amount of fuel drawn into the intake stroke cylinder when the internal combustion engine is started can be appropriately controlled.

(First form)
FIG. 1 shows an internal combustion engine in which a start control device according to a first embodiment of the present invention is incorporated. An internal combustion engine (hereinafter sometimes referred to as an engine) 1 in FIG. 1 is mounted on a vehicle as a driving power source, and includes four cylinders 2, an intake passage 3 connected to each cylinder 2, and And an exhaust passage 4. In addition, as shown in FIG. 1, the cylinder numbers # 1 to # 4 are assigned to the cylinders from one end to the other end in the arrangement direction to distinguish them from each other. FIG. 2 shows a schematic view of a cross section of the cylinder 2 of # 1. The other cylinders 2 have the same structure as the cylinder 2 of # 1. As shown in FIG. 2, a piston 5 is inserted into each cylinder 2 so as to be able to reciprocate, and a combustion chamber 6 is formed in each cylinder 2 by the piston 5 and the wall surface of the cylinder 2. Each piston 5 is connected to a crankshaft 9 by a connecting rod 7 and a crank arm 8. The phase of the piston 5 in each cylinder 2 is shifted by 180 ° as a crank angle. Thus, the piston 5 of any one of the four cylinders 2 is always in the intake stroke, and the pistons 3 of the other cylinders 2 are positioned in a stroke other than the intake stroke. Each cylinder 2 has an ignition plug 15, an intake valve 10 for opening and closing an intake port 3 a forming part of the intake passage 3, and an exhaust valve for opening and closing an exhaust port 4 a forming part of the exhaust passage 4. 11 are provided. Each intake port 3a is provided with an injector 12 as a fuel injection valve. Therefore, the engine 1 is configured as a port injection type engine. Further, the engine 1 is provided with a starter motor 13 for starting the engine 1 by rotating the crankshaft 9 and a battery 14 for supplying electric power to the starter motor 13. In addition, these structures may be the same as a well-known engine.

  The operating state of the engine 1 is controlled by an engine control unit (ECU) 20. The ECU 20 is configured as a computer including a microprocessor and peripheral devices such as RAM and ROM necessary for its operation, and executes various processes necessary for controlling the operating state of the engine 1 according to a program recorded in the ROM. To do. For example, the ECU 20 detects the number of revolutions of the engine 1 and the intake air amount from the output signal of a predetermined sensor, and controls the amount of fuel injected from the injector 12 so that a predetermined air-fuel ratio is obtained. As sensors referred to by the ECU 20, a crank angle sensor 21 that outputs a signal corresponding to the phase (crank angle) of the crankshaft 9, an air flow meter 22 (see FIG. 1) that outputs a signal corresponding to the intake air amount, and a battery 14. A voltage sensor 23 that outputs a signal corresponding to the voltage of the accelerator pedal, an accelerator opening sensor 24 that outputs a signal corresponding to the opening of the accelerator pedal, a brake sensor 25 that detects the operation of the brake pedal, and the like are provided.

  The ECU 20 performs so-called idle stop control in which when the predetermined stop condition is satisfied, the fuel injection to the engine 1 is stopped and its operation is stopped, and when the predetermined restart condition is satisfied, the engine 1 is restarted. Run against. The stop condition is satisfied, for example, when the brake pedal is operated and the vehicle speed is zero. For example, in the case of a vehicle equipped with an automatic transmission, the restart condition is satisfied when the brake pedal is released. In the case of a vehicle equipped with a manual transmission, the restart condition is established by performing a shift operation from the neutral position of the shift lever to the first speed, a depression operation of the clutch pedal, or the like. In addition, the stop condition and the restart condition may be set in the same manner as a known technique related to idle stop control.

  FIG. 3 shows a restart control routine executed by the ECU 20 to restart the engine 1 when the stop condition is satisfied and the engine 1 is stopped. The control routine of FIG. 3 is repeatedly executed at a predetermined cycle regardless of whether or not the engine 1 is in operation.

  In the control routine of FIG. 3, the ECU 20 first determines in step S11 whether or not the engine 1 is stopped. When it is determined that the engine 1 is stopped, the process proceeds to step S12, and the ECU 20 determines whether or not the predetermined restart condition described above is satisfied. If it is determined that the restart condition is not satisfied, the current control routine is terminated. On the other hand, if it is determined that the restart condition is satisfied, the process proceeds to step S13, where the ECU 20 stops the piston 5 of any cylinder # 1 to # 4 in the intake stroke based on the output signal of the crank angle sensor 21. Determine if it is. Hereinafter, the cylinder 2 in which the piston 5 is stopped in the intake stroke while the engine 1 is stopped may be referred to as an intake stroke cylinder. Further, the position of the piston 5 of the cylinder 2 determined based on the output signal of the crank angle sensor 21 is acquired. As is well known, the crank angle is based on a state in which the piston 5 of any cylinder # 1 to # 4 is in a predetermined position (for example, the piston 5 of the cylinder 2 # 1 is at the top dead center of the intake stroke). Therefore, the position of the piston 5 of each cylinder 2 can be determined by acquiring the crank angle at the time of stopping. By discriminating the intake stroke cylinder in this way, the ECU 20 functions as the cylinder specifying means of the present invention.

  In the next step S14, the ECU 20 determines whether the position of the piston 5 of the intake stroke cylinder is 0 ° after top dead center (ATDC), that is, within the range of top dead center (TDC) to after top dead center (ATDC) θ °. To do. When the piston 5 is close to the bottom dead center (BDC) of the intake stroke, a large amount of air stays in the cylinder 2 in a heated state, and therefore there is a possibility that self-ignition may occur if fuel is supplied here. Therefore, as θ °, an angle capable of preventing this self-ignition, for example, 90 ° is set.

When it is determined that the piston 5 of the cylinder 2 in the intake stroke is stopped within the range of ATDC 0 ° to θ °, the process proceeds to step S15, and the ECU 20 supplies the intake port 3a of the intake stroke cylinder while the engine 1 is stopped. A pre-startup injection amount that is a fuel amount is calculated. The pre-startup injection amount is calculated based on, for example, the stop position of the piston 5 of the intake stroke cylinder and the battery voltage. The closer the stop position of the piston 5 is to the bottom dead center, the smaller the amount of air sucked into the cylinder 2 when the piston 5 is lowered, and the inflow speed thereof decreases, so that the fuel is less likely to be sucked into the cylinder 2. Further, as the voltage of the battery 14 is lower, the rotational speed of the crankshaft 9 at the time of start-up decreases, so the air inflow speed into the cylinder 2 decreases. Therefore, in this case as well, the fuel is hardly sucked into the cylinder 2. Therefore, the closer the stop position of the piston 5 is to the bottom dead center, and the lower the voltage of the battery 14, the greater the injection amount before start, and the fuel is reliably supplied into the intake stroke cylinder. Specifically, for example, first, the basic injection amount before start is calculated based on the relationship between the piston stop position shown in FIG. 4 and the basic injection amount before start, and then the battery voltage shown in FIG. A corrected injection amount is calculated based on the relationship with the corrected injection amount. Thereafter, the pre-startup injection amount is calculated by adding the pre-startup basic injection amount and the corrected injection amount. The relationship shown in FIGS. 4 and 5 is obtained in advance by experiment or numerical calculation and stored in the ROM of the ECU 20. By executing this processing, the ECU 20 functions as the pre-startup fuel injection amount setting means of the present invention.

  In the next step S16, the ECU 20 controls the operation of the injector 12 so that the pre-startup injection amount of fuel calculated from the injector 12 corresponding to the intake stroke cylinder is injected. Hereinafter, supplying fuel to the intake port 3a of the intake stroke cylinder before the engine 1 is started may be referred to as pre-start injection. In the subsequent step S17, the ECU 20 switches the correction flag indicating that the fuel has been supplied to the intake port 3a of the intake stroke cylinder before the engine 1 is started to an on state. In the next step S18, the ECU 20 starts the starter motor 13. Thereby, restart of the engine 1 is started. Thereafter, the current control routine is terminated.

  When a negative determination is made in step S11, the process proceeds to step S19, and the ECU 20 determines whether or not the engine 1 is being started. Whether or not the engine 1 is being started is determined based on, for example, the rotational speed of the engine 1. When the rotational speed of the engine 1 is a complete explosion rotational speed, that is, when a complete explosion state in which the engine 1 can continue combustion is obtained. It is determined that the engine 1 is being started when the rotational speed is less than. If it is determined that the engine 1 is in operation, the current control routine is terminated.

  On the other hand, when it is determined that the engine 1 is being started, or when step S14 is negatively determined, the process proceeds to step S20, and the ECU 20 calculates the fuel injection amount to be supplied to each cylinder 2 when the engine 1 is started. The calculation of the fuel injection amount is performed by the ECU 20 executing a fuel injection amount calculation routine shown in FIG. The fuel injection amount calculation routine of FIG. 6 will be described.

In the routine of FIG. 6, the ECU 20 first calculates the basic fuel amount to be supplied to each cylinder 2 when the engine 1 is started in step S101. The calculation method of the basic fuel amount may be a known calculation method for calculating based on the coolant temperature of the engine 1, the battery voltage, the rotation speed, and the like. Therefore, detailed description is omitted. By executing this process, the ECU 20 functions as a basic fuel injection amount calculating means of the present invention. In subsequent step S102, the ECU 20 determines whether or not the correction flag is on. If it is determined that the correction flag is off, the current routine is terminated. In this case, the basic injection amount calculated in step S101 is set as the fuel injection amount. On the other hand, if it is determined that the correction flag is on, the process proceeds to step S103, where the ECU 20 determines whether or not the fuel injection amount calculated this time is the amount of fuel supplied to the intake stroke cylinder. If it is determined that the fuel injection amount calculated this time is the amount of fuel supplied to cylinders other than the intake stroke cylinder, the current routine is terminated. Also in this case, the basic injection amount calculated in step S101 is set as the fuel injection amount.

  On the other hand, if it is determined that the fuel injection amount calculated this time is the amount of fuel supplied to the intake stroke cylinder, the routine proceeds to step S104, where the ECU 20 calculates a decrease correction amount. As the decrease correction amount, for example, first the first correction amount is calculated based on the relationship between the piston stop position shown in FIG. 7 and the first correction amount, and then the battery voltage shown in FIG. The second correction amount is calculated based on the relationship with the correction amount, and then calculated by adding the first correction amount and the second correction amount. Since the first correction amount and the second correction amount are set to negative values as shown in FIGS. 7 and 8, the decrease correction amount is also a negative value. In the next step S105, the ECU 20 corrects the basic injection amount by adding the basic injection amount and the decrease correction amount. Thereby, the basic injection amount is corrected to decrease. In this case, the corrected basic injection amount is set as the fuel injection amount. By executing this process, the ECU 20 functions as a weight reduction correction unit of the present invention. In subsequent step S106, the ECU 20 switches the correction flag to an off state. Thereafter, the current routine is terminated.

  Returning to FIG. 3, the description will be continued. After calculating the fuel injection amount in step S20, the process proceeds to step S21, and the ECU 20 controls the operation of each injector 12 based on the calculated fuel injection amount. In other words, the operation of each injector 12 is controlled so that the fuel of the injection amount corrected by the decrease correction amount is supplied to the intake stroke cylinder and the fuel of the basic injection amount is supplied to the other cylinders 2. In subsequent step S22, the ECU 20 activates the starter motor 13. If the starter motor 13 is already operating, this state is maintained. Thereafter, the current control routine is terminated.

  When injection before start is performed, the fuel adheres to the intake port 3a of the intake stroke cylinder. Therefore, the fuel gradually evaporates and is sucked into the cylinder 2 together with the fuel injected for the second time into the intake port 3a. It is. According to the first aspect, when the pre-startup injection is performed, the amount of fuel supplied to the intake stroke cylinder for the second time is reduced, so that excessive intake of fuel into the intake stroke cylinder can be prevented. Thereby, since discharge | emission of unburned fuel etc. can be suppressed, deterioration of exhaust emission can be prevented. Moreover, since the torque fluctuation of the engine 1 can be suppressed, vibration and noise of the engine 1 can be suppressed. Note that the timing for calculating the injection amount supplied to the intake stroke cylinder for the second time is not limited to the timing when the routine of FIG. 6 is executed. This injection amount may be calculated, for example, when the pre-startup injection amount is calculated, and stored in the RAM of the ECU 20 or the like.

(Second form)
A second embodiment of the present invention will be described with reference to FIGS. Also in this form, FIG.1 and FIG.2 is referred about the engine 1. FIG. FIG. 9 shows a restart control routine in the second embodiment. In FIG. 9, the same processes as those of FIG. In the second embodiment, when fuel is supplied to the intake port 3a of the intake stroke cylinder before the engine 1 is started, the number of times that the fuel injection amount to the intake stroke cylinder is corrected to be reduced (hereinafter referred to as the number of corrections). Is different from the first embodiment in that the amount of fuel injection into the intake stroke cylinder is corrected by decreasing the number of times.

  In the control routine of FIG. 9, the process proceeds to step S17 as in the control routine of FIG. In the next step S31, the ECU 20 sets the number of corrections. What is necessary is just to set the frequency | count of correction | amendment based on the relationship between the piston stop position which showed an example in FIG. 10, and the frequency | count of correction | amendment, for example. As described above, the amount of fuel initially supplied to the cylinder 2 in the intake stroke is set to be larger as the piston stop position is closer to the bottom dead center. Therefore, it is considered that the closer the piston stop position is to the bottom dead center, the larger the amount of fuel that adheres to the intake port 3a when the fuel is supplied for the first time, and the longer the period in which the attached fuel amount affects the air-fuel ratio. Therefore, as shown in FIG. 10, the correction number is set to a larger value as the piston stop position is closer to the bottom dead center. By executing this process, the ECU 20 functions as the correction number setting means of the present invention. In the following step S32, the ECU 20 substitutes 1 for a counter C for counting the number of times of performing the reduction correction for the intake stroke cylinder. In the next step S18, the ECU 20 starts the starter motor 13, and then ends the current control routine.

  If step S11 is negatively determined and then step S19 is positively determined, the process proceeds to step S33, and the ECU 20 calculates the fuel injection amount. In this embodiment, the fuel injection amount is calculated by the fuel injection amount calculation routine of FIG. In FIG. 11, the same processes as those in FIG.

  In the routine of FIG. 11, the process proceeds in the same manner as in FIG. 6 until step S103. When it is determined in step S103 that the fuel injection amount calculated this time is the amount of fuel supplied to the intake stroke cylinder, the process proceeds to step S111, and the ECU 20 determines whether or not the counter C is equal to or smaller than the correction count. If it is determined that the counter C is greater than the correction count, the current routine is terminated. On the other hand, if it is determined that the counter C is equal to or less than the correction count, the process proceeds to step S112, where the ECU 20 calculates a decrease correction amount corresponding to the counter C. Since the amount of fuel evaporated from the intake port 3a of the intake stroke cylinder gradually decreases, the decrease correction amount decreases as the value of the counter C increases.

  With reference to FIGS. 12 and 13, the calculation method of the decrease correction amount in the second embodiment will be specifically described. FIG. 12 shows an example of the relationship between the piston stop position and the first correction amount. Lines L1 to L3 in FIG. 12 indicate the relationship between the piston stop position and the first correction amount during the first, second, and third fuel supply during startup, respectively. Therefore, for example, when the second fuel supply is performed to the intake stroke cylinder when the engine 1 is started, that is, when the first correction amount is calculated when the counter C is 2, the line L2 in FIG. 12 is used. As shown in FIG. 12, the first correction amount is gradually decreased as the value of the counter C increases, that is, as time elapses from the pre-start injection. FIG. 13 shows an example of the relationship between the battery voltage and the second correction amount. Lines L11 to L13 in FIG. 13 indicate the relationship between the battery voltage and the second correction amount during the first, second, and third fuel supply during startup, respectively. Therefore, for example, when the second fuel supply is performed to the intake stroke cylinder when the engine 1 is started, that is, when calculating the second correction amount when the counter C is 2, the line L12 in FIG. 13 is used. Similarly to the first correction amount, the second correction amount is calculated to gradually decrease as the value of the counter C increases, that is, as time elapses from the pre-start injection. The decrease correction amount is calculated by adding the first correction amount and the second correction amount. Thus, the ECU 20 functions as the correction amount changing means of the present invention by gradually reducing the decrease correction amount. The relationship shown in FIGS. 12 and 13 is obtained in advance by experiment or numerical calculation and stored in the ROM of the ECU 20 as a map. In FIG. 12, the relationship up to the fourth time is shown as an example, but the relationship between the piston stop position and the first correction amount is the upper limit value of the number of corrections, that is, the number of corrections up to the number of corrections in ATDCθ ° is the ROM of the ECU 20. Is stored as a map. Similarly in FIG. 13, the number of relationships up to the upper limit set as the number of corrections is stored as a map in the ROM of the ECU 20.

  In the next step S113, the ECU 20 increments the value of the counter C by one. In the subsequent step S105, the ECU 20 corrects the basic injection amount by decreasing the amount by adding the calculated decrease correction amount and the basic injection amount. Thereafter, the current routine is terminated.

  Returning to the description of the control routine of FIG. After calculating the fuel injection amount in step S33, the process proceeds to step S21, and the ECU 20 controls the operation of each injector 12 based on the calculated fuel injection amount. In subsequent step S22, the ECU 20 activates the starter motor 13. Thereafter, the current control routine is terminated.

  In the second mode, when the injection before start is performed, the number of corrections for performing the reduction correction for the intake stroke cylinder is set in accordance with the piston stop position of the intake stroke cylinder. Supply can be prevented more appropriately. In addition, the decrease correction amount used for the decrease correction is set to be gradually smaller in later times in consideration of the gradual decrease in the amount of fuel evaporated from the intake port 3a, thereby preventing excessive fuel supply. The air-fuel ratio of the intake stroke cylinder can be appropriately controlled. Therefore, deterioration of exhaust emission can be prevented more appropriately, and vibration and noise of the engine 1 can be appropriately suppressed. Note that the timing for calculating the amount of fuel supplied to the intake stroke cylinder during the start of the engine 1 is not limited to the timing described above. For example, it may be calculated when the number of corrections is set and stored in the RAM of the ECU 20 or the like.

(Third form)
A third embodiment of the present invention will be described with reference to FIGS. Also in this form, FIG.1 and FIG.2 is referred about the engine 1. FIG. 14 and 15 show a restart control routine in the third embodiment. FIG. 15 is a flowchart following FIG. 14 and 15, the same processes as those in FIGS. 3 and 9 are denoted by the same reference numerals, and the description thereof is omitted. In the third mode, when the pre-start injection is performed on the intake stroke cylinder, the start of the engine 1 is completed during a period in which the fuel adhering to the intake port 3a due to the pre-start injection affects the air-fuel ratio of the intake stroke cylinder. After that, it is different from the other embodiments in that the fuel injection amount to the intake stroke cylinder is corrected to decrease.

  In the restart control control routine in the third embodiment, the part shown in FIG. 14 is the same as FIG. 9, and the part shown in FIG. 15 is different from FIG. Therefore, the description of the part shown in FIG. 14 is omitted, and only the part shown in FIG. 15 will be described. If the determination in step S11 is negative and the determination in step S19 is negative in the control routine of FIG. 14, the process proceeds to step S41 of FIG. 15, and the ECU 20 calculates the operating basic injection amount. The calculation of the basic injection amount during operation is performed by a known calculation method that calculates based on, for example, the rotation speed of the engine 1 and the intake air amount. In the next step S42, the ECU 20 determines whether or not the correction flag is on. If it is determined that the correction flag is off, steps S43 to S47 are skipped and the process proceeds to step S48. On the other hand, if it is determined that the correction flag is on, the process proceeds to step S43, and the ECU 20 determines whether or not the fuel injection amount calculated this time is the fuel injection amount to the intake stroke cylinder. If it is determined that the fuel injection amount calculated this time is the fuel injection amount to cylinders other than the intake stroke cylinder, steps S44 to S47 are skipped and the process proceeds to step S48. On the other hand, when it is determined that the fuel injection amount calculated this time is the fuel injection amount to the intake stroke cylinder, the process proceeds to step S44, and the ECU 20 determines whether or not the counter C is equal to or less than the correction count. If it is determined that the counter C is larger than the number of corrections, steps S45 to S47 are skipped and the process proceeds to step S48.

  On the other hand, if it is determined that the counter C is equal to or less than the correction count, the process proceeds to step S45, where the ECU 20 calculates a decrease correction amount corresponding to the value of the counter C. The decrease correction amount is calculated based on the piston stop position and the battery voltage. FIG. 16 shows an example of the relationship between the piston stop position and the first correction amount, and FIG. 17 shows an example of the relationship between the battery voltage and the second correction amount. Lines L21 to L23 in FIG. 16 indicate the relationship between the piston stop position and the first correction amount during the first, second, and third fuel supply during startup, respectively. In FIG. 16, as a comparative example, the relationship during the start of the engine 1 shown in FIG. 12 is indicated by broken lines L1 to L3. As is clear from the comparison with these comparative examples, after the start of the engine 1 is completed, a value closer to 0 is set as the first correction amount than during the start of the engine 1, that is, a smaller value is set as the correction amount. Lines L31 to L33 in FIG. 17 indicate the relationship between the battery voltage and the second correction amount during the first, second, and third fuel supply during startup, respectively. In FIG. 17, the relationship during the start of the engine 1 shown in FIG. 13 as a comparative example is indicated by broken lines L11 to L13. As is clear from the comparison with these comparative examples, like the first correction amount, after the start of the engine 1 is completed, the second correction amount is closer to 0 than during the start of the engine 1, that is, the correction amount is a small value. Is set. The decrease correction amount is calculated by adding the first correction amount and the second correction amount. 16 and 17 are obtained in advance by experiments or numerical calculations and stored in the ROM of the ECU 20 as maps. In FIG. 16, the relationship up to the fourth time is shown as an example, but the number of these relationships up to the upper limit set as the number of corrections is stored as a map in the ROM of the ECU 20. In FIG. 17 as well, the relationship of the number up to the upper limit set as the number of corrections is stored as a map in the ROM of the ECU 20.

  In the next step S46, the ECU 20 increments the counter C by one. In the following step S47, the ECU 20 corrects the driving basic injection amount by decreasing the driving basic injection amount by adding the decreasing correction amount. In the next step S48, the ECU 20 controls the operation of each injector 12 so that the basic fuel injection amount during operation is supplied to the cylinder 2 to which that amount of fuel is to be supplied. Thereby, fuel injection to each cylinder 2 is performed. Thereafter, the current control routine is terminated.

  In the third mode, when the pre-startup injection is performed, the amount of fuel supplied to the intake stroke cylinder is reduced until the counter C becomes greater than the number of corrections even after the start of the engine 1 is completed. An excessive supply of fuel to the stroke cylinder can be further prevented. Therefore, deterioration of exhaust emission can be prevented, and vibration and noise of the engine 1 can be suppressed. In general, the air-fuel ratio of each cylinder 2 is controlled to be richer than the stoichiometric air-fuel ratio during the start of the engine 1, and the air-fuel ratio of each cylinder 2 is controlled to the stoichiometric air-fuel ratio after the start of the engine 1 is completed. Therefore, if the same reduction correction is performed after the engine 1 is started, the air-fuel ratio of the intake stroke cylinder is controlled to be leaner than the stoichiometric air-fuel ratio. In this embodiment, since the decrease correction amount is changed between when the engine 1 is started and after the start is completed, the air-fuel ratio of the intake stroke cylinder can be appropriately controlled according to the state of the engine 1. If the ECU 20 calculates the fuel injection amount during operation of the engine 1 even in a routine different from that shown in FIG. 14, a priority is set in advance as to which routine the fuel injection amount calculated in which routine is used. The fuel injection amount to be used may be determined according to the priority.

  This invention is not limited to each form mentioned above, It can implement with a various form. For example, the present invention can be applied not only at the time of restart from the stop state by the idle stop control but also at the time of start by turning on the ignition switch. Therefore, the present invention can be applied not only to the engine to which the idle stop control is applied, but also to an engine in which the idle stop control is not performed. The present invention may also be applied to an engine mounted on a vehicle so-called hybrid vehicle that includes a motor generator and an engine that function as an electric motor and a generator as a driving power source. In such a vehicle, since the engine is started by the motor generator, the motor generator functions as a starter motor. Therefore, the decrease correction amount may be calculated based on the voltage of the battery that supplies power to the starter motor. In each embodiment described above, the piston position is determined by the crank angle. However, the piston position is not limited to such means, and various means may be used. In each embodiment described above, the reduction correction amount is calculated using a map, but may be calculated using a physical model or a mathematical expression in addition to the map.

The figure which shows the internal combustion engine in which the starting control apparatus which concerns on the 1st form of this invention was integrated. The figure which shows the cross section of the cylinder 2 of # 1 of FIG. The flowchart which shows the restart control routine which ECU performs. The figure which shows an example of the relationship between a piston stop position and the first time basic injection amount. The figure which shows an example of the relationship between a battery voltage and correction | amendment injection quantity. The flowchart which shows the fuel injection amount calculation routine which ECU performs. The figure which shows an example of the relationship between a piston stop position and the 1st correction amount. The figure which shows an example of the relationship between a battery voltage and the 2nd correction amount. The flowchart which shows the restart control routine which concerns on a 2nd form. The figure which shows an example of the relationship between a piston stop position and the frequency | count of correction | amendment. 10 is a flowchart showing a fuel injection amount calculation routine executed in the restart control routine of FIG. The figure which shows an example of the relationship between the piston stop position and 1st correction amount which concern on a 2nd form. The figure which shows an example of the relationship between the battery voltage which concerns on a 2nd form, and 2nd correction amount. The flowchart which shows the restart control routine which concerns on a 3rd form. The flowchart following FIG. The figure which shows an example of the relationship between the piston stop position and 1st correction amount which concern on a 3rd form. The figure which shows an example of the relationship between the battery voltage which concerns on a 3rd form, and 2nd correction amount.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3a Intake port 12 Injector (fuel injection valve)
13 starter motor 14 battery 20 engine control unit (cylinder specifying means, pre-starting fuel injection amount setting means , reduction correction means, correction number setting means, correction amount changing means, basic fuel injection amount calculation means )

Claims (8)

Applied to an internal combustion engine having a plurality of cylinders, each provided with a fuel injection valve in the intake port of each cylinder,
Cylinder specifying means for determining the piston position of each cylinder when the internal combustion engine is stopped and determining the intake stroke cylinder in which the piston is stopped in the intake stroke based on the determination result, and the cylinder specifying means And a fuel amount setting means for setting a fuel amount to be supplied to an intake port of the intake stroke cylinder before starting the internal combustion engine based on a piston position of the intake stroke cylinder. ,
When fuel is supplied to the intake port of the intake stroke cylinder before starting the internal combustion engine, a correction amount is set based on the piston position of the intake stroke cylinder determined by the cylinder specifying means, and the internal combustion engine A start control device for an internal combustion engine, comprising: a reduction correction means for reducing the amount of fuel supplied to the intake stroke cylinder at the time of start of the engine in accordance with the correction amount than the amount of fuel supplied to the other cylinders. The internal combustion engine further includes a starter motor for starting the internal combustion engine, and a battery for supplying electric power to the starter motor,
The fuel amount setting means corrects the amount of fuel to be supplied to the intake port of the intake stroke cylinder before starting the internal combustion engine based on the voltage of the battery when the internal combustion engine is stopped.
The reduction amount correction means sets the correction amount based on both the piston position of the intake stroke cylinder determined by the cylinder specifying means and the voltage of the battery when the internal combustion engine is stopped. The start control device for an internal combustion engine according to claim 1.   When the fuel is supplied to the intake port of the intake stroke cylinder before the internal combustion engine is started, the reduction correction means is configured to perform the intake stroke based on the piston position of the intake stroke cylinder determined by the cylinder specifying means. 3. The internal combustion engine according to claim 1, further comprising a correction number setting unit that sets a number of times of reduction correction for reducing the amount of fuel supplied to the cylinders less than the amount of fuel supplied to the other cylinders. Start control device.   The said reduction | decrease correction means is further provided with the correction amount change means which makes the said correction amount small later, when multiple times are set as the frequency | count of reduction correction by the said correction frequency setting means. The start control device for an internal combustion engine according to claim 3.   The start control apparatus for an internal combustion engine according to claim 4, wherein the correction amount changing means gradually decreases the correction amount.   The reduction amount correction means reduces the amount of fuel supplied to the intake stroke cylinder below the amount of fuel supplied to other cylinders even if the start of the internal combustion engine is completed in the middle of the number of times set by the correction number setting means. The start control device for an internal combustion engine according to any one of claims 3 to 5, wherein the reduction correction is continuously performed.   7. The start control device for an internal combustion engine according to claim 6, wherein the reduction amount correction means makes a correction amount after completion of starting of the internal combustion engine smaller than a correction amount during startup of the internal combustion engine. The internal combustion engine is an application subject of idle stop control that stops the internal combustion engine when a predetermined stop condition is satisfied, and restarts the internal combustion engine when a predetermined restart condition is satisfied,
When the fuel is supplied to the intake port of the intake stroke cylinder before restarting from the stop state by the idle stop control, the reduction amount correction means supplies the amount of fuel supplied to the intake stroke cylinder at the time of restart to another cylinder. The start control device for an internal combustion engine according to any one of claims 1 to 7, wherein the amount of fuel supplied to the engine is decreased in accordance with a decrease correction.

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