JP2007278074A - Engine control method and engine controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine control method capable of preventing idle hunching from occurring when a load is applied to an auxiliary device while a torque by the start of an engine is instable. <P>SOLUTION: This engine control method comprises the step of retarding an ignition timing from a timing for starting to a timing for promoting the warmup of the catalyst when the engine rotational speed reaches the target one during idling, the step of so starting to open a throttle valve at a predetermined time period before the rotational speed reaches the target rotational speed during idling that an intake air amount required to hold the rotational speed at the target one during idling when the rotational speed reaches the target one, the step of temporarily increasing the injection amount of fuel from the time when the throttle valve is started to open and the time when a variation in intake pressure or intake flow velocity is settled after the rotational speed reaches the target one during idling, and the step of prohibiting the application of an auxiliary device load to the engine until an engine torque is stabilized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine (internal combustion engine) control method and control device, and more particularly to control at a cold start.

After the complete explosion due to the cranking in the cold state, the ignition timing is set as the starting ignition timing until the engine speed increases, and after the engine speed increases, the activation of the catalyst is promoted. There is one that retards the ignition timing stepwise to a predetermined crank angle position after compression top dead center (see Patent Document 1).
Japanese Patent Laid-Open No. 8-232645

  By the way, in the technique of Patent Document 1, before the ignition timing is retarded stepwise to a predetermined crank angle position after compression top dead center, the intake air amount is increased by increasing the ISC opening, etc. It is proposed that it is preferable to further increase the intake air amount after the timing of retarding the timing stepwise, and this makes smoothing or speeding up of the engine.

  However, although it is intended to smooth or speed up the engine blow-up, it is wasteful to increase the engine rotation speed beyond the target rotation speed during idling in terms of fuel consumption. It will be consumed. Therefore, from the viewpoint of improving fuel efficiency, it is preferable that the engine speed is converged to the target speed at idling without overshooting after the complete explosion, even during cold start.

  Therefore, at the timing when the engine speed from cranking reaches the target speed at idling, the ignition timing is retarded in steps from the ignition timing for starting to the ignition timing for promoting catalyst warm-up, and fuel efficiency is improved. In view of the above, the throttle valve is set so that the intake air amount required to maintain the engine speed at the target speed at idling is supplied to the combustion chamber at the timing when the engine speed reaches the target speed at idling. Considering the response delay of the intake air amount from the position to the combustion chamber, a configuration is considered in which the throttle valve starts to open at a timing before a predetermined period before the timing at which the engine rotation speed reaches the target rotation speed during idling.

  And when I experimented with this configuration, after the engine rotation speed reached the target rotation speed during idling as expected, the engine rotation speed did not blow up beyond the target rotation speed during idling. However, it has been newly found that the actual air-fuel ratio leans beyond the combustion stability limit, resulting in a drop in rotation from the target rotation speed during idling or an increase in HC.

  Therefore, when the engine speed from cranking reaches the target speed at idling, the ignition timing is retarded stepwise from the ignition timing for starting to the ignition timing for promoting catalyst warm-up. The target engine speed when the engine is idling so that the intake air amount required to maintain the engine speed at the target engine speed during idling is supplied to the combustion chamber when the target engine speed during idling is reached. The throttle valve starts to open a predetermined time before the timing at which the intake valve reaches, and the timing at which the throttle valve starts to open is used as a starting point, and the intake pressure or intake port intake flow velocity after the engine rotational speed reaches the target rotational speed at idle Cold start by temporarily increasing the fuel injection amount from the fuel injection valve until the change settles The engine speed after the complete explosion is quickly converged toward the target speed during idling while promoting warm-up of the catalyst, and the actual speed is also reduced after the engine speed reaches the target speed during idling. It is conceivable to use an engine control method and control device in which the fuel ratio does not exceed the combustion stability limit and does not become lean.

  On the other hand, an alternator is provided for charging a battery that is a power supply device, and this alternator is driven by an engine to generate electricity. In the current control, since the engine rotation is unstable within a predetermined period from the start of cranking, even if there is a power generation request for the alternator, power generation by the alternator is not performed. Therefore, the alternator starts power generation after a lapse of a predetermined period from the start of cranking. However, the fact that the alternator starts power generation means that a load (auxiliary load) is applied to the engine. To do.

  In this case, according to the current control, the engine rotational speed blows up exceeding the target rotational speed at the time of idling, so even if the alternator load is turned on after a predetermined period has elapsed since the cranking start, Although the rotational speed does not become unstable, as described above, when it is configured so that the engine rotational speed does not exceed the target rotational speed at the time of idling for further fuel efficiency improvement, When the alternator load is applied to the engine at the timing when the engine speed from cranking reaches the target speed during idling, so-called idle hunting (or rotation) occurs where the engine speed fluctuates and fluctuates. It is possible that the engine stalls when the fall is large.

  Therefore, the present invention provides an engine control method and an engine control device that can prevent idle hunting and engine stall caused by the introduction of an auxiliary load to the engine when the engine torque from the start of the engine is unstable. The purpose is to provide.

  The present invention relates to an engine having an exhaust passage with a catalyst that functions only after being activated, and a fuel injection valve for injecting fuel into an intake passage (for example, an intake port). When the target rotational speed is reached, the ignition timing is retarded stepwise from the ignition timing for starting to the ignition timing for promoting catalyst warm-up, and the engine rotational speed reaches the target rotational speed during idling. The throttle valve is set a predetermined time before the timing at which the engine speed reaches the target rotational speed during idling so that the intake air amount required to maintain the rotational speed at the target rotational speed during idling is supplied to the combustion chamber. Starting from the timing at which the throttle valve begins to open, and the target engine speed when the engine speed is idle After reaching the target, the fuel injection amount from the fuel injection valve is temporarily increased until the change in the intake pressure or the intake air flow velocity at the intake port settles, and the engine speed reaches the target rotation speed during idling. The construction is such that the auxiliary load on the engine is prohibited until the timing when the torque is stabilized, and the auxiliary load is allowed on the engine when the engine torque is stable.

  According to the present invention, the ignition timing is retarded stepwise from the ignition timing for starting to the ignition timing for promoting catalyst warm-up at the timing when the engine rotational speed from the start reaches the target rotational speed at the time of idling, When the engine speed is at idle, the intake air amount necessary to maintain the engine speed at the target speed at idling is supplied to the combustion chamber when the engine speed reaches the target speed at idling. Since the throttle valve starts to open a predetermined time before the timing of reaching the target rotational speed of the engine, the exhaust temperature is raised early while suppressing the blow-up after the engine rotational speed reaches the target rotational speed during idling. Thus, the catalyst activation time can be shortened while suppressing wasteful fuel consumption.

  In this case, the intake pressure and / or the intake port intake flow velocity may continue to change for a while after the engine rotation speed reaches the target rotation speed during idling. As the air pressure and the intake air flow velocity of the intake port change, the fuel wall flow rate at the intake port wall decreases, and the amount of fuel supplied to the combustion chamber is reduced accordingly, and the air-fuel ratio of the air-fuel mixture in the combustion chamber reaches the combustion stability limit. However, according to the present invention, the engine rotational speed reaches the target rotational speed at the time of idling, starting from the timing at which the throttle valve starts to open. After that, the fuel injection amount from the fuel injection valve is temporarily increased until the change in the intake pressure or intake flow velocity of the intake port settles, so the engine speed is the target when idling Even if the intake pressure or the intake air flow velocity at the intake port continues to change after reaching the rotation speed, the air-fuel ratio of the air-fuel mixture in the combustion chamber exceeds the combustion stability limit and becomes lean. Can be prevented. As a result, it is possible to suppress an increase in HC after the engine rotation speed reaches the target rotation speed during idling and a drop in rotation from the target rotation speed during idling.

  In addition, according to the present invention, it is prohibited to apply an auxiliary load to the engine until the engine torque stabilizes after the engine rotational speed reaches the target rotational speed during idling. Since the auxiliary load is permitted, idle hunting and engine stall caused by the negative load on the engine when the engine torque is unstable can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of an engine control apparatus used directly for carrying out an engine control method.

  The air metered by the throttle valve 23 is stored in the intake collector 2 and then introduced into the combustion chamber 5 of each cylinder via the intake manifold 3. Fuel is intermittently injected and supplied into the intake port at a predetermined timing from a fuel injection valve 21 disposed in the intake port 4 of each cylinder. The fuel injected into the intake port 4 is mixed with air to form an air-fuel mixture. The air-fuel mixture is confined in the combustion chamber 5 by closing the intake valve 15, compressed by the ascending piston 6, and the spark plug 14 It is ignited and burns. The gas pressure due to the combustion works to push down the piston 6, and the reciprocating motion of the piston 6 is converted into the rotational motion of the crankshaft 7. The combusted gas (exhaust gas) is discharged into the exhaust passage 8 when the exhaust valve 16 is opened.

A first catalyst 9 (start-up catalyst) is provided in the manifold passage portion of the exhaust passage 8, and a second catalyst 10 is provided at a position below the floor of the vehicle. These two catalysts 9, 10 are, for example, all three-way catalysts, and when the air-fuel ratio of the exhaust is in a narrow range centered on the stoichiometric air-fuel ratio, the three-way catalyst simultaneously converts HC, CO, and NOx contained in the exhaust. It can be removed efficiently. For this reason, the engine controller 31 to which the intake air amount signal from the air flow meter 32 and the signal from the crank angle sensor (the position sensor 33 and the phase sensor 34) are input is based on these signals and the basic from the fuel injection valve 21. The fuel injection amount is determined, and the air-fuel ratio is feedback-controlled based on a signal from an O ₂ sensor 35 provided upstream of the first catalyst 9.

On the other hand, at the time of cold start, the catalyst is activated early, and the O ₂ sensor 35 is also activated early to execute air-fuel ratio feedback control. Therefore, the O ₂ sensor 35 is immediately started by a heater (not shown). heating, looking at signals from the O ₂ sensor 35, O ₂ sensor 35 is started feedback control of the air-fuel ratio at the timing of activation.

  In addition, the structure of the catalysts 9 and 10 is not restricted to this. For example, in order to improve fuel efficiency after completion of engine warm-up, when operating at a leaner air / fuel ratio than the stoichiometric air / fuel ratio in the low-load side operation region, NOx generated frequently during lean operation is absorbed. For this reason, the second catalyst 10 is constituted by a NOx trap catalyst, and this NOx trap catalyst is provided with a three-way catalyst function, but such a constitution may also be used.

  The throttle valve 23 is driven by a throttle motor 24. Since the torque required by the driver appears in the amount of depression of the accelerator pedal 41 (accelerator opening), the engine controller 31 determines a target torque based on a signal from the accelerator sensor 42, and a target air for realizing this target torque. The throttle valve drive device (not shown) controls the opening degree of the throttle valve 23 via the throttle motor 24 so that the target air amount is obtained.

  Further, the rotational phase difference between the variable valve lift mechanism 26 constituted by a multi-joint link mechanism that continuously and variably controls the valve lift amount of the intake valve 15, the crankshaft 7, and the intake valve camshaft 25. A variable valve timing mechanism 27 is provided for continuously varying and controlling the opening / closing timing of the intake valve 15 to advance or retard.

  Now, the engine speed from the cranking in the cold state is blown up well, and the ignition timing is retarded in order to warm up the first catalyst 9 provided in the exhaust passage 8 at an early stage. Yes. This situation will be specifically described in the case of a four-cylinder engine with reference to FIG.

  First, the current control will be described. At present, as indicated by the one-dot chain line at the top of FIG. 2, the engine speed corresponds to the first explosion in three cylinders from the timing t0 when the starter switch is switched from OFF to ON for starting. It fluctuates, and the engine speed rapidly increases due to the explosion of the fourth cylinder, and blows up across the target speed NSET during idling at the timing of t2 (see the one-dot chain line). From the timing of t2 when the engine speed reaches the target engine speed NSET during idling, the intake air that can maintain the target engine speed NSET during idling is shown in FIG. The throttle valve opening is stepwise opened to a predetermined opening TVO1 so as to be introduced into the combustion chamber 5.

  In addition, the fuel injection amount is that not all of the injected fuel is sucked into the combustion chamber 5 at the beginning of the cold start, but a part of the injected fuel amount adheres to the intake port 4 wall or the back of the intake valve 15 umbrella, Since it is used to form a so-called fuel wall flow that flows in a liquid state on the intake port wall, a fuel supply delay to the combustion chamber 5 occurs. For this reason, as shown by the alternate long and short dash line in the fourth stage of FIG. 2, while much of the fuel wall flow on the intake port wall is deprived at the beginning of the start, extra fuel is injected and supplied, and the fuel wall flow is formed. The fuel injection amount is gradually decreased from the timing when many are not lost.

  On the other hand, the ignition timing is currently set to the first ignition timing ADV1, which is the ignition timing for starting from the timing of t0, as shown by the one-dot chain line in the second stage of FIG. 2, and from the timing of t2, The 1st catalyst 9 is gradually switched to the second ignition timing ADV2 that is greatly retarded in order to promote warm-up.

  Here, if the engine rotation speed from cranking is divided into the front and the rear at the timing t2 when the engine rotation speed reaches the target rotation speed during idling, the engine rotation speed Ne is blown after t2 from the viewpoint of improving fuel efficiency. It is desirable to quickly settle down to the target rotational speed NSET during idling without increasing. This is because fuel consumption increases as the engine speed increases beyond the target rotational speed NSET during idling.

  It is desirable that the actual air-fuel ratio settles to the stoichiometric air-fuel ratio after t2. This is because the first catalyst 9 after completion of warm-up can simultaneously purify the harmful three components (HC, CO, NOx) only when it is in a narrow range centered on the stoichiometric air-fuel ratio.

  Therefore, at the timing t2 when the engine rotational speed Ne from the cranking reaches the target rotational speed NSET during idling, the ignition timing is changed from the first ignition timing ADV1 to the first ignition timing ADV1 as shown by the solid line in the second stage of FIG. 2 From the viewpoint of improving the fuel efficiency, the ignition timing ADV2 is retarded stepwise, and the engine rotational speed Ne is set to the idling target rotational speed at the timing t2 when the engine rotational speed Ne reaches the idling target rotational speed NSET. In consideration of the response delay of the intake air amount from the throttle valve position to the combustion chamber 5 so that the intake air amount required to be held in NSET is supplied to the combustion chamber 5, a solid line in the fifth stage of FIG. As shown in Fig. 5, the throttle speed is slower than the timing t1 a predetermined period before the timing t2 when the engine speed Ne reaches the target rotational speed NSET during idling. Considering the configuration to start to open the torque valve 23.

  As a result of experiments with this configuration, after the engine rotational speed Ne has reached the target rotational speed NSET during idling, the engine rotational speed increases beyond the target rotational speed NSET during idling. As shown by the one-dot chain line in the sixth stage of FIG. 2, the actual air-fuel ratio is the theoretical air-fuel ratio at the timing t2 when the engine rotational speed Ne reaches the target rotational speed NSET during idling. Although it is (Stoichiki), after that, it becomes leaner beyond the combustion stability limit line, and this excessive leaning newly increases HC as shown by the one-dot chain line in the seventh stage of FIG. Turned out to.

  The experiment was conducted by assuming that this is mainly due to the fuel wall flow in the intake port 4 wall. As shown in the third stage of FIG. 2, the engine speed Ne is the target rotation when idling. The intake pressure continued to decrease after the timing t2 when the speed NSET was reached. That is, the fuel wall flow rate of the intake port wall depends on the pressure of the portion where the fuel wall flow flows (that is, the intake pressure) and the intake flow velocity of the portion where the fuel wall flow flows (the intake flow velocity of the intake port 4). The characteristic becomes smaller (this is because the vaporization characteristic of the fuel becomes better as the intake pressure becomes smaller), and becomes smaller as the intake flow velocity of the intake port 4 becomes larger (this means that the vaporization of the fuel becomes larger as the intake flow velocity of the intake port 4 becomes larger). Characteristics (because the characteristics are improved), the intake pressure and the intake port flow velocity at the intake port and the intake port flow velocity at the timing t2 in the middle of the change in the intake pressure and intake port flow velocity are the predetermined values. The fuel wall flow rate at the timing of t3 when it settles down becomes smaller. Since the amount of fuel flowing into the combustion chamber 5 includes this fuel wall flow rate, the reduction in the fuel wall flow rate during the period from t2 to t3 means that the amount of fuel flowing into the combustion chamber 5 also decreases this fuel wall flow rate. Therefore, even if the air-fuel ratio of the air-fuel mixture becomes the stoichiometric air-fuel ratio at the timing of t2, the actual air-fuel ratio goes to the lean side as the fuel wall flow rate decreases, It seems to have become leaner than the combustion stability limit.

  Therefore, the present invention performs the following three operations.

  [1] From the timing t2 when the engine rotational speed Ne reaches the target rotational speed NSET at the time of idling, the engine rotational speed Ne exceeds the target rotational speed NSET at the time of idling while promoting warm-up of the first catalyst 9 in particular. 2, as indicated by a solid line in the second stage of FIG. 2, the ignition timing is t2, and the first ignition timing (ignition timing for starting) ADV1 to the second ignition timing (catalyst warm-up). The ignition timing for acceleration) is retarded stepwise to ADV2. Such ignition timing control is executed for each cylinder. Here, idling means a state in which the driver does not depress the accelerator pedal 41. The target rotational speed NSET at the time of idling is a conforming value.

  [2] In order to maintain the engine rotational speed Ne at the idling target rotational speed NSET from the timing t2, the intake air amount necessary to maintain the idling target rotational speed NSET is supplied to the combustion chamber 5. Yes, the air supply to the combustion chamber 5 needs to be completed at the timing of t2. In this case, it is the throttle valve 23 provided in the intake passage upstream of the intake collector 2 that controls the intake air amount in the current engine, and therefore, the response of the intake air amount from the throttle valve position to the combustion chamber 5. In consideration of the delay, as indicated by the solid line in the fifth stage of FIG. 2, the throttle valve 23 starts to open toward the predetermined value TVO1 at the timing t1 before the predetermined period before t2, and is predetermined at the timing t2. Try to settle to the value TVO1.

  [3] Although the engine rotational speed Ne settles to the target rotational speed NSET during idling due to the step delay of the ignition timing at t2, the fuel wall flow rate decreases due to a change in the intake pressure immediately after that and the intake port intake air flow velocity. Since the air-fuel ratio becomes excessively lean and HC increases (or the engine speed Ne decreases from the target rotational speed NSET during idling), in order to prevent this increase in HC, As shown by the solid line in the fourth stage, the fuel wall flow rate to the combustion chamber 5 starts from the timing t1 when the throttle valve 23 starts to open until t3 when the change in the intake air pressure and the intake air flow velocity of the intake port is settled. The fuel injection amount is temporarily increased to compensate for the decrease.

  Here, on the premise of the current fuel injection control, the post-startup increase correction coefficient KAS is used to execute the operation [3]. This will be described in detail with reference to FIG. 3. The uppermost stage in FIG. 3 is the same as the uppermost stage in FIG. The second stage of FIG. 3 shows the movement of the ignition timing by the operation [1], and the fourth stage shows the movement of the throttle valve opening by the operation [2].

  First, at present, as indicated by a one-dot chain line in the third stage of FIG. 3, the initial value KAS0 (0.3 in the figure) is set as the post-startup increase correction coefficient KAS from the timing t0 when the starter switch 36 is switched from OFF to ON. After that, the engine speed Ne is decreased toward zero at a predetermined speed from the timing t5 when the engine speed Ne reaches the complete explosion speed N0. On the other hand, in the present embodiment, as indicated by a solid line in the third stage of FIG. 3, the initial value KAS0 is held until the timing t2, and is decreased toward zero at a predetermined speed from the timing t2. That is, the timing for decreasing the post-startup increase correction coefficient KAS from the initial value KAS0 is delayed from t5 to t2. As a result, the area indicated by hatching in the third stage of FIG. 3 is the amount of fuel increase, and excessive leaning exceeding the combustion stability limit of the air-fuel ratio can be prevented.

  As described above, the actual air-fuel ratio obtained when the timing for decreasing the post-startup increase correction coefficient KAS from the initial value KAS0 is delayed from t5 to t2 (the fuel injection amount from the fuel injection valve is temporarily increased). The theoretical air-fuel ratio has been confirmed. That is, the post-startup increase correction coefficient KAS (fuel injection from the fuel injection valve 21) so that the actual air-fuel ratio obtained when the fuel injection amount from the fuel injection valve 21 is temporarily increased becomes the stoichiometric air-fuel ratio. The amount of increase) is set.

  Here, the post-startup amount increase correction coefficient KAS is constant (initial value KAS0) between t5 and t2, and thereafter linearly decreases. However, the present invention is not limited to this. In short, starting from the timing t5 when the throttle valve 23 starts to open, the timing until the timing t3 when the change in the intake pressure and the intake flow velocity at the intake port settles after the timing when the engine rotation speed Ne reaches the target rotation speed NSET during idling. In this case, the post-startup increase correction coefficient KAS may be changed so that the fuel injection amount from the fuel injection valve 21 is temporarily increased.

  In addition, the fuel injection amount from the fuel injection valve is temporarily increased by delaying the timing at which the post-startup increase correction coefficient KAS is decreased from the initial value KAS0 from t5 to t2. However, the present invention is not limited to this. For example, a new increase correction coefficient is introduced separately from the post-startup increase correction coefficient KAS, and the timing of t5 at which the throttle valve 23 starts to be opened by this increase correction coefficient is the starting point. The fuel injection amount from the fuel injection valve 21 may be temporarily increased until t3 when the change in the intake pressure and the intake air flow velocity at the intake port settles after the timing when NSET is reached.

  In FIG. 3, the timing at t5 when the engine rotational speed Ne reaches the complete explosion rotational speed N0 is set as the timing at which the throttle valve 23 starts to be opened, but is not limited to this.

Also, as described above, the air-fuel ratio feedback control is started at the timing when the O ₂ sensor 35 is activated. The timing at which the air-fuel ratio feedback control is started is the target rotation when the engine speed Ne is idle. If the change in the intake pressure or the intake flow velocity at the intake port comes before the timing t3 after the timing when the speed NSET is reached, the operation of [3] above may be canceled and returned to the current operation. preferable. This is because the actual air-fuel ratio is kept within a predetermined window width centered on the stoichiometric air-fuel ratio by the air-fuel ratio feedback control, thereby preventing excessive leaning.

  This control executed by the engine controller 31 will be described in detail with reference to the following flowchart.

  FIG. 4 is for setting a complete explosion flag and a target rotation arrival flag, and is executed at regular time intervals (for example, every 100 ms).

  In FIG. 4, in step 1, the engine speed Ne is read. The engine speed Ne is calculated based on signals from the crank angle sensors (33, 34).

  Step 2 looks at the complete explosion flag. This complete explosion flag is a flag that is initially set to zero when an ignition switch (not shown) is switched from OFF to ON. For this reason, since the complete explosion flag = 0 at the beginning, the process proceeds from step 2 to step 3 to compare the engine rotation speed Ne with the complete explosion rotation speed N0 (for example, 1000 rpm). The complete explosion speed N0 is a conforming value. If the engine rotational speed Ne has not reached the complete explosion rotational speed N0, the current process is terminated.

  When the engine speed Ne reaches the complete explosion speed N0 in Step 3 (Ne ≧ N0), the process proceeds to Step 4 to set the complete explosion flag = 1 to indicate that the engine speed Ne has reached the complete explosion speed N0.

  In step 5, a timer is started (timer value TIME = 0). This timer is for measuring the elapsed time from when the engine speed Ne reaches the complete explosion speed N0.

  Since the complete explosion flag = 1, the process proceeds from step 2 to step 6 from the next time. In step 6, the timer value TIME is compared with the predetermined value DT. The predetermined value DT is preliminarily adapted at a time interval from the timing when the engine rotational speed Ne reaches the complete explosion rotational speed N0 to the timing when the engine rotational speed Ne reaches the target rotational speed NSET during idling (see FIG. 3). Since the timer value TIME is initially less than the predetermined value DT when the timer is started, the process proceeds to step 7 and the timer value TIME is incremented by the control period (100 ms).

  If the increment of the timer value TIME in step 7 is repeated several times, the timer value TIME eventually becomes equal to or greater than the predetermined value DT. At this time, the process proceeds from step 6 to step 8 to set the target rotation arrival flag (initially set to zero when the ignition switch is switched from OFF to ON) = 1 to indicate that the target rotation speed NSET during idling has been reached.

  FIG. 5 is for calculating the ignition timing command value and the throttle valve target opening, and is executed at regular intervals (for example, every 100 ms) following the flow of FIG.

  In FIG. 5, in step 21, it is determined whether or not the ignition switch is switched from OFF to ON. When the ignition switch is switched from OFF to ON, the routine proceeds to step 22 where the cooling water temperature TW detected by the water temperature sensor 37 is taken in as the starting water temperature TWINT, and the first ignition timing ADV1 is set according to the starting water temperature TWINT. In step 23, the calculated first ignition timing ADV1 is transferred to the ignition timing command value ADV. The first ignition timing ADV1 is the optimal ignition timing for starting and is largely on the advance side.

  In step 24, an initial value (for example, zero) is input to the throttle valve target opening tTVO.

  After the ignition switch is switched from OFF to ON, that is, when the ignition switch is turned ON, the process proceeds from step 21 to steps 25 and 26. In steps 25 and 26, the complete explosion flag and the target rotation arrival flag (both flags are set according to FIG. 4) are observed. When the complete explosion flag = 0, the routine proceeds to step 27, where the first ignition timing ADV1 calculated when the ignition switch is switched from OFF to ON is maintained. Also at this time, the operation of step 24 is executed.

  When the complete explosion flag = 1 and the target rotation arrival flag = 0, the routine proceeds from step 26 to step 28, where the first ignition timing ADV1 calculated when the ignition switch is switched from OFF to ON is maintained.

  In step 29, the throttle valve target opening tTVO is calculated by the following equation.

tTVO = tTVO (previous) + ΔTVO (1)
Where ΔTVO: constant value,
tTVO (previous): previous value of tTVO,
Here, the predetermined value ΔTVO in the equation (1) is a value that determines an increment of the throttle valve target opening per predetermined time, and this value is a timing at which the engine rotational speed Ne reaches the target rotational speed NSET during idling. Thus, the throttle valve target opening tTVO is determined in advance so as to reach a predetermined value TVO1 described later. The initial value of “tTVO (previous)”, which is the previous value of the throttle valve target opening, is set to zero.

  In step 30, the throttle valve target opening tTVO is compared with a predetermined value TVO1. The predetermined value TVO1 is the throttle valve opening when the minimum intake air amount necessary to generate the torque for maintaining the target rotational speed NSET flows. The predetermined value TVO1 is obtained in advance by adaptation.

  After experiencing step 29 for the first time during the engine operation this time, the throttle valve target opening tTVO is less than the predetermined value TVO1, and thus the current process is terminated. Until the target rotation arrival flag = 1, the operation in step 29 is repeated, and the throttle valve target opening tTVO gradually increases. Immediately before the target rotation arrival flag = 1, the throttle valve target opening tTVO becomes equal to or greater than the predetermined value TVO1. At this time, the routine proceeds from step 30 to step 31 to maintain the throttle valve target opening tTVO at the same value as the previous time.

  When the target rotation arrival flag = 1, the routine proceeds from step 26 to step 32, where the second ignition timing ADV2 is calculated according to the cooling water temperature TW detected by the water temperature sensor 37, and this is calculated at step 33. Move to command value ADV.

  The second ignition timing ADV2 is an ignition timing for promoting warm-up of the first catalyst 9 at the time of cold start, and is set on the retard side with respect to the ignition timing after completion of warm-up of the first catalyst 9. Therefore, the ignition timing is stepwise from the first ignition timing ADV1 to the second ignition timing ADV2 at the timing t2 when the engine rotational speed Ne reaches the target rotational speed NSET as shown in the second stage of FIG. It will be switched.

  The ignition timing command value ADV calculated in this way is transferred to the output register, and the primary current of the ignition coil is cut off at a timing when the actual crank angle coincides with the ignition timing command value ADV.

  Further, in the slot valve drive device that receives the throttle valve target opening tTVO, the throttle motor 24 is driven so that the actual throttle valve opening coincides with the throttle valve target opening tTVO.

  FIG. 6 is for calculating the target equivalent ratio TFBYA, and is executed at regular intervals (for example, every 100 ms).

  In FIG. 6, in step 41, it is determined whether or not the ignition switch is switched from OFF to ON. When the ignition switch is switched from OFF to ON, the routine proceeds to step 42, where the initial value KAS0 of the post-startup increase correction coefficient is calculated according to the starting water temperature TWINT detected by the water temperature sensor 37, and this is calculated at step 43. To shift to the increase correction coefficient KAS after starting. The initial value KAS0 of the post-startup increase correction coefficient is a value that increases as the starting water temperature TWINT decreases.

  After the ignition switch is switched from OFF to ON, that is, when the ignition switch is turned on, the routine proceeds from step 41 to step 44. In step 44, the target rotation arrival flag is checked (set according to FIG. 4). When the target rotation arrival flag = 0, the routine proceeds to step 45, where the post-startup increase correction coefficient KAS is maintained at the same value as before (that is, the initial value KAS0).

  When the target rotation arrival flag = 1, the routine proceeds from step 44 to step 46, where the post-startup increase correction coefficient KAS is compared with zero. Since the post-startup increase correction coefficient KAS is greater than zero at the timing when the target rotation arrival flag = 1 (because the initial value KAS0 is entered), the routine proceeds to step 47, where the post-startup increase correction coefficient KAS is calculated by the following equation. .

KAS = KAS (previous) −Δt × KAS (previous) (2)
Where Δt is a constant value,
KAS (previous): previous value of KAS,
Here, the predetermined value Δt in the equation (2) is a value that determines the decrease per predetermined time of the post-startup increase correction coefficient KAS, and this value becomes zero at the timing of t3 when the intake pressure settles to a constant value. , Determined in advance by conformity. The initial value of “KAS (previous)”, which is the previous value of the increase correction coefficient after starting, is KAS0.

  When the target rotation arrival flag = 1, when the operation in step 47 is repeated, the post-startup increase correction coefficient KAS gradually decreases. Accordingly, the post-startup increase correction coefficient KAS is compared with zero at step 48, and when the post-startup increase correction coefficient KAS becomes a negative value, the routine proceeds to step 49 where the post-startup increase correction coefficient KAS = 0.

  In this way, the post-startup increase correction coefficient KAS is a value that gradually decreases to zero from the timing when the engine rotational speed Ne coincides with the target rotational speed NSET during idling.

  At present, the post-start-up increase correction coefficient KAS is gradually smaller than the timing when the engine rotational speed Ne reaches the complete explosion rotational speed N0. However, in the present invention, the engine rotational speed Ne is equal to the target rotational speed NSET during idling. The initial value is maintained until the coincidence timing, and the engine rotation speed Ne becomes gradually smaller than the coincidence with the target rotation speed NSET during idling.

  Steps 50 and 51 are the same as the current situation. That is, in step 50, the water temperature increase correction coefficient KTW is calculated according to the cooling water temperature Tw detected by the water temperature sensor 37 at that time. The water temperature increase correction coefficient KTW is a value that increases as the cooling water temperature Tw decreases.

  In step 51, the target equivalent ratio TFBYA is calculated by the following equation using the water temperature increase correction coefficient KTW and the post-startup increase correction coefficient KAS.

TFBYA = 1 + KTW + KAS (3)
The target equivalent ratio TFBYA is a value centering on 1.0, and after the engine warm-up is completed, TFBYA = 1 (KTW = 0, KAS = 0), thereby obtaining a stoichiometric air-fuel mixture. . At the cold start, the post-startup increase correction coefficient KAS is added, so the target equivalent ratio TFBYA exceeds 1.0, because the fuel wall flow rate is taken into consideration. That is, at the time of cold start, the target equivalence ratio TFBYA exceeds 1.0, but the stoichiometric air-fuel mixture is obtained at the timing when the engine speed reaches the target speed NSET during idling. .

  FIG. 7 is for calculating the fuel injection pulse width Ti. The float of FIG. 6 is executed independently at regular time intervals (for example, every 100 ms). This flow is the same as the current situation.

  In FIG. 7, in step 61, the starting fuel injection pulse width Ti1 is calculated by the following equation.

Ti1 = TST × KNST × KTST (4)
Where TST: basic injection pulse width at start,
KNST: rotational speed correction coefficient,
KTST: Time correction coefficient,
Since the method of obtaining the basic injection pulse width TST, the rotational speed correction coefficient KNST, and the time correction coefficient KTST at the start is well known, detailed description thereof is omitted.

  In step 62, it is determined whether or not the output of the air flow meter 32 has been input. If the output of the air flow meter 32 is not input, the steps 63 and 64 are skipped and the routine proceeds to a step 65, where the starting fuel injection pulse width Ti1 is moved to the final fuel injection pulse width Ti.

  On the other hand, when the output of the air flow meter 32 is input, the process proceeds from step 62 to step 63, and the normal fuel injection pulse width Ti2 is calculated by the following equation using the target equivalent ratio TFBYA obtained from FIG.

Ti2 = (Tp × TFBYA + Kathos) × (α + αm−1) × 2 + Ts
... (5)
Where Tp: basic injection pulse width,
TFBYA: target equivalent ratio,
Kathos: Transient correction amount,
α: Air-fuel ratio feedback correction coefficient,
αm: air-fuel ratio learning value,
Ts: Invalid injection pulse width,
The basic injection pulse width Tp, transient correction amount Kathos, air-fuel ratio feedback correction coefficient α, air-fuel ratio learning value αm, and invalid injection pulse width Ts in equation (5) are well known. For example, the basic injection pulse width Tp is calculated by the following equation.

Tp = K × Qa / Ne (6)
Where Qa: the intake air amount calculated from the air flow meter 32,
The air / fuel ratio of the air-fuel mixture is set to the stoichiometric air / fuel ratio by the constant K in the equation (6). Therefore, while the post-startup increase correction coefficient KAS is a positive value exceeding zero, the fuel injection amount (fuel injection pulse width Ti) from the fuel injection valve 21 is corrected to be increased.

  The transient correction amount Kathos in the equation (5) is a value that is basically calculated based on the engine load, the rotational speed, and the temperature of the fuel adhering portion in consideration of the fuel wall flow rate of the intake port wall. It is considered that sometimes this transient correction amount Kathos works to increase the fuel injection amount by the amount deprived as the fuel wall flow of the intake port wall from the fuel injection amount. As a result, the air-fuel ratio is excessively leaned. This is because the calculation of the transient correction amount Kathos does not take into account changes in the intake pressure or the intake port flow velocity.

  In steps 64 to 66, the starting fuel injection pulse width Ti1 and the normal fuel injection pulse width Ti2 are compared, and the larger one is selected as the final fuel injection pulse width Ti.

  The post-startup increase correction coefficient KAS is used for fuel injection when the normal fuel injection pulse width Ti2 is adopted as the final fuel injection pulse width Ti. That is, in the present embodiment, it is assumed that the normal fuel injection pulse width Ti2 is larger than the starting fuel injection pulse width Ti1 immediately before the timing t5 in FIG.

  The fuel injection pulse width Ti calculated in this way is transferred to the output register, and when the predetermined fuel injection timing is reached, the fuel injection valves 21 of the respective cylinders are opened sequentially only during the pulse width Ti.

  Here, the effect of this embodiment is demonstrated.

  According to the present embodiment (the invention described in claims 1 and 7), the ignition timing is set to the first ignition timing ADV1 (starting timing) at the timing when the engine rotation speed Ne from the cranking reaches the target rotation speed NSET during idling. Ignition timing) to the second ignition timing ADV2 (ignition timing for promoting catalyst warm-up) (see steps 26 and 32 in FIG. 5), and the engine rotational speed Ne is the target rotational speed when idling. The intake air amount from the throttle valve position to the combustion chamber 5 is supplied to the combustion chamber 5 so that the intake air amount necessary to maintain the engine rotation speed Ne at the target rotation speed NSET during idling is reached at the timing when it reaches NSET. In consideration of the response delay, the timing t1 before the predetermined period DT from the timing when the engine rotational speed Ne reaches the target rotational speed NSET during idling. The throttle valve 23 starts to open (see Steps 25, 26, 29, 30, and 31 in FIG. 5), so that the engine speed Ne reaches the target rotational speed NSET at the time of idling and suppresses the blow-up early. The exhaust temperature can be raised (see the solid line at the bottom of FIG. 2), and the catalyst activation time can be shortened while suppressing wasteful fuel consumption.

  In this case, the intake pressure and the intake air flow velocity of the intake port 4 may continue to change for a while after the engine rotation speed Ne reaches the target rotation speed NSET during idling. The fuel wall flow rate at the intake port wall decreases with changes in the intake pressure and the intake air flow velocity of the intake port 4, and the amount of fuel supplied to the combustion chamber 5 is insufficient accordingly, and the air-fuel ratio of the air-fuel mixture in the combustion chamber However, according to the present embodiment (the inventions described in claims 1 and 7), the engine becomes lean beyond the combustion stability limit, leading to an increase in HC and a drop in rotation from the target rotation speed NSET during idling. For example, starting from the timing at which the throttle valve 23 starts to open, after the engine speed Ne reaches the target speed NSET during idling, the change in the intake pressure or the intake air flow rate at the intake port 4 is settled. During this period, the fuel injection amount from the fuel injection valve 21 is temporarily increased by using the post-startup increase correction coefficient KAS (see steps 44, 45 and 51 in FIG. 6), so that the engine speed Ne is at the idling time. Even after the target rotational speed NSET has been reached, the intake air pressure or the intake air flow velocity of the intake port 4 may continue to change to a smaller value, the air-fuel ratio of the air-fuel mixture in the combustion chamber will exceed the combustion stability limit and become leaner. Can be prevented. As a result, it is possible to suppress an increase in HC after the engine rotational speed Ne reaches the target rotational speed NSET during idling and a decrease in rotation from the target rotational speed NSET during idling (see the solid line in the seventh stage in FIG. 2).

  In the first embodiment, fuel injection is performed using the post-startup increase correction coefficient KAS so that the actual air-fuel ratio obtained when the fuel injection amount from the fuel injection valve 21 is temporarily increased becomes the stoichiometric air-fuel ratio. As described above in the case where the amount of increase is set, the actual air-fuel ratio obtained when the fuel injection amount from the fuel injection valve 21 is temporarily increased becomes the lean-side air-fuel ratio that does not exceed the combustion stability limit. As described above, the increase amount of the fuel injection amount can be set using the post-startup increase correction coefficient KAS. When the actual air-fuel ratio obtained when the fuel injection amount from the fuel injection valve 21 is temporarily increased becomes the lean air-fuel ratio that does not exceed the combustion stability limit, the fuel injection from the fuel injection valve 21 is performed. The CO and HC at the engine outlet can be reduced rather than the actual air-fuel ratio obtained when the amount is temporarily increased to be the stoichiometric air-fuel ratio.

  In addition to the first embodiment, after the engine rotational speed Ne reaches the target rotational speed NSET during idling, the throttle valve opening degree is set so that the actual engine rotational speed Ne matches the target rotational speed NSET during idling. Alternatively, feedback control may be performed using any one of the fuel injection amount and the ignition timing. According to such a configuration, even if the actual rotational speed Ne may hunt after the engine rotational speed Ne reaches the idle target rotational speed NSET, the engine rotational speed Ne can settle to the idle target rotational speed NSET. Can do.

  FIG. 8 shows a schematic configuration diagram of an engine power supply apparatus according to the second embodiment.

  As shown in FIG. 8, the engine 1 is provided with an alternator 51 as a generator that is operated by power through a belt 53 (or chain). The alternator 51 is operated by an IC regulator 52 that receives a command signal from the engine controller 31, and generates electric power according to the command signal. The battery 55 can be charged and discharged, and stores the electric power generated by the alternator 51. The generated power of the alternator 51 and the discharged power of the battery 53 are supplied to the starter 56 and other electrical components 57, 58 and 59. The electrical components include headlights, air conditioner blowers, defoggers, and the like.

  The engine controller 31 receives a signal of the charge / discharge current Ic of the battery 55 from the current sensor 61, a signal from the ignition switch 62, and a signal from the start switch 63. The engine controller 31 receives an alternator based on these signals. It is determined whether or not the condition for permitting the power generation by 51 is satisfied. If the condition for permitting the power generation by the alternator 51 is not satisfied, the power generation by the alternator 51 is prohibited and the condition for allowing the power generation by the alternator 51 is permitted. When it is, the actual charge state rSOC of the battery 55 is detected, and the generated power of the alternator 51 is variably controlled (variable generation voltage control) according to the detected actual charge state rSOC.

  Here, the variable power generation voltage control means that, in the past, 14 V, which is the maximum power generation voltage of the alternator 51, is given to the IC regulator 52 as a voltage command value, but only when a predetermined permission condition is satisfied, for example, charging of the battery 55 In this control, the voltage command value is reduced from 14 V to 13 V when there is no need to perform the power generation, or the power generation is cut during acceleration (that is, the voltage command value = 0).

  In the current control, since engine rotation is unstable within a predetermined period from the start of cranking, even if there is a power generation request to the alternator 51, power generation by the alternator 51 is not performed. Therefore, when there is a power generation request to the alternator 51, the alternator 51 starts power generation after a predetermined period from the start of cranking. However, the fact that the alternator 51 starts power generation means that a load ( Auxiliary load) is input.

  In this case, according to the current control, the engine rotational speed Ne exceeds the target rotational speed NSET during idling, so that the alternator load is applied after the timing t2 in FIG. However, the engine rotational speed Ne does not become unstable. However, in the present invention, as described in the above-described embodiment (first embodiment), the engine rotational speed Ne is set to further improve fuel efficiency. Since it is configured not to blow over the target rotational speed NSET during idling, as shown in FIG. 9, the alternator load on the engine 1 is after the timing t2 (for example, at the timing t2). When the engine is turned on, so-called idle hunting occurs in which the engine speed Ne fluctuates and fluctuates as shown by the solid line at the top of FIG. (Or rotation drop there is a possibility to reach the engine stall when large) it is considered.

  This is because, as shown in the lowermost part of FIG. 9, the introduction of the alternator load acts as a disturbance with respect to the engine speed, so that it settles until the target speed NSET at the time of idling until the timing of t6. End up. Note that the one-dot chain line in the lowermost part of FIG. 9 indicates a change in the engine friction load, and a certain amount of alternator load is added to the timing at the timing t2.

  Thus, according to the first embodiment, the ignition timing is changed from the first ignition timing ADV1 (starting ignition timing) to the first ignition timing ADV1 at the timing when the engine rotation speed Ne from the cranking reaches the target rotation speed NSET during idling. 2 Ignition timing ADV2 (ignition timing for catalyst warm-up promotion) is stepwise retarded, and the engine rotation speed Ne is set to the target rotation at idling when the engine rotation speed Ne reaches the target rotation speed NSET at idling. Considering the response delay of the intake air amount from the throttle valve position to the combustion chamber 5 so that the intake air amount necessary for maintaining the speed NSET is supplied to the combustion chamber 5, the engine rotation speed Ne is By starting to open the throttle valve 23 at a timing before the predetermined period DT from the timing at which the target rotational speed NSET is reached, the engine speed Although the exhaust temperature is raised at an early stage while suppressing the blow-up after the degree Ne reaches the target rotational speed NSET during idling, the alternator load is input to the engine as a disturbance during such control. Therefore, idle hunting and engine stall can occur.

  Accordingly, in the second embodiment, power generation by the alternator 51 (input of auxiliary machinery load to the engine) is prohibited until the engine torque stabilizes after the engine rotational speed reaches the target rotational speed during idling, so that the engine torque is stable. Then, power generation by the alternator 51 is permitted.

  In the following, an explanation will be given on the case where the auxiliary load that is input to the engine is an alternator, but the auxiliary load is not limited to the alternator 51. For example, idle hunting and engine stall can occur even when an engine-driven air conditioner compressor or power window hydraulic pump (both auxiliary load) is input to the engine at timing t2 in FIG. The engine torque is stabilized by prohibiting the operation of the air conditioner compressor and power window hydraulic pump (input of auxiliary machinery load to the engine) until the engine torque stabilizes after the rotational speed reaches the target rotational speed during idling. By the way, the operation of the compressor for the air conditioner and the hydraulic pump for the power window is permitted.

  Here, the timing at which the engine torque is stabilized is one of the following three timings.

[4] Timing at which changes in intake pressure or intake air flow velocity at the intake port settle after the engine rotation speed Ne reaches the target rotation speed NSET during idling [5] Air-fuel ratio feedback control start timing [6] Idle rotation speed feedback Control start timing Here, the timing of [4] is the actual air-fuel ratio if the change in the intake pressure or the intake air flow velocity of the intake port settles after the engine rotational speed Ne reaches the target rotational speed NSET during idling. This is because the engine speed does not become unstable even if the stoichiometric air-fuel ratio is settled and the alternator load is applied in the stoichiometric air-fuel ratio state. The timing of [5] is that the actual air-fuel ratio is maintained in the vicinity of the theoretical air-fuel ratio with the best combustion efficiency according to the air-fuel ratio feedback control. This is because the rotational speed does not become unstable. The timing of [6] is that, according to the feedback control of the idle rotational speed, when the actual rotational speed Ne falls outside a predetermined width (± ε) centered on the target rotational speed NSET during idling, This is because the engine speed does not become unstable even if an alternator load is applied during the feedback control of the idling speed because the fuel is increased.

  Of these, FIG. 9 shows the case [4]. That is, the timing of t3 in FIG. 9 is the timing when the change in the intake pressure or the intake flow velocity of the intake port settles. As a result, in the second embodiment, power generation by the alternator 51 is prohibited until a timing t3 that is a predetermined period DT2 delayed from the timing t2 by which the power generation is started by the alternator 51. Then, since the power generation by the alternator 51 is started at the timing of t3 and the battery 55 is charged, the battery voltage VB is changed from the timing of t3 as shown by the one-dot chain line in the fourth stage of FIG. It further rises above the required holding voltage VB1. Here, the required holding voltage VB1 is a battery voltage to be maintained at a minimum in order to keep ignition by the spark plug 14 appropriately.

  This control executed by the engine controller 31 will be described in detail with reference to the following flowchart.

  10 and 11 are for setting the power generation permission flag, and are executed at regular intervals (for example, every 100 msec). Of these, FIG. 10 corresponds to [4] above, and FIG. 11 corresponds to [5] and [6] above.

  First, referring to FIG. 10, this flow is basically the same as the flow of FIG. The difference is that the flow of FIG. 10 is used only for power generation voltage control.

  In FIG. 10, at step 71, the engine speed Ne is read. Step 2 looks at the second complete explosion flag. The second complete explosion flag is a flag that is initially set to zero when the ignition switch 62 is switched from OFF to ON. For this reason, since the second complete explosion flag = 0 is initially set, the process proceeds from step 72 to step 73, where the engine rotational speed Ne and the complete explosion rotational speed N0 (for example, 1000 rpm) are compared. The complete explosion speed N0 is a conforming value. If the engine rotational speed Ne has not reached the complete explosion rotational speed N0, the current process is terminated.

  When the engine speed Ne reaches the complete explosion speed N0 (Ne ≧ N0) in step 73, the process proceeds to step 74, and the second complete explosion flag = 1 is set to indicate that the engine speed Ne has reached the complete explosion speed N0. .

  In step 75, the second timer is started (second timer value TIME2 = 0). The second timer is for measuring an elapsed time from when the engine rotational speed Ne reaches the complete explosion rotational speed N0.

  Since the second complete explosion flag = 1, the process proceeds from step 72 to step 76 from the next time. In step 76, the second timer value TIME2 and the sum of the first predetermined value DT and the second predetermined value DT2 are obtained. Compare. As described above with reference to FIG. 4, the first predetermined value DT is preliminarily adapted at a time interval from the timing when the engine rotational speed Ne reaches the complete explosion rotational speed N0 to the timing when the engine rotational speed Ne reaches the target rotational speed NSET during idling. (See FIG. 3). The second predetermined value DT2 is from the timing (t2 in FIG. 9) when the engine rotational speed Ne reaches the target rotational speed NSET during idling to the timing (t3 in FIG. 9) at which the change in the intake pressure or the intake air flow velocity at the intake port settles. This time interval is also adapted in advance (see FIG. 3). Since the second timer value TIME2 is initially less than the sum of two predetermined values (DT + DT2) when the second timer is started, the process proceeds to step 77, and the second timer value TIME2 is incremented by the control period (100 ms).

  When the increment of the second timer value TIME2 in step 77 is repeated several times, the second timer value TIME2 eventually becomes equal to or greater than the sum of two predetermined values (DT + DT2). At this time, the routine proceeds from step 76 to step 78, where the first power generation permission flag (initially set to zero when the ignition switch 62 is switched from OFF to ON) = 1 is set to indicate that power generation is permitted.

  Next, in FIG. 11, in steps 81 and 82, the ignition switch 62 and the starter switch 63 are viewed. When the ignition switch 62 is OFF, or when the ignition switch is ON and the starter switch 63 is ON (during cranking), the current process is terminated.

When the ignition switch 62 is ON and the starter switch 63 is OFF, it is determined that cranking has ended, and the routine proceeds to step 83 where it is determined whether air-fuel ratio feedback control is being executed. In the air-fuel ratio feedback control, the fuel injection amount is feedback-corrected so that the actual air-fuel ratio falls within a predetermined range centered on the stoichiometric air-fuel ratio. Since the exhaust gas purification efficiency by the catalysts 9 and 10 is improved by starting this control earlier at the time of cold start, the O ₂ sensor 35 is heated by a heater (not shown), and at the timing when the O ₂ sensor 35 is activated. Air-fuel ratio feedback control is started. Accordingly, if the O ₂ sensor 35 is activated, it is determined that the air-fuel ratio feedback control is being executed, and the routine proceeds to step 84 where the second power generation permission flag (ignition switch 62 is turned off) to indicate that power generation is permitted. Is set to zero at the time of switching to ON) = 1.

When the O ₂ sensor 35 is not activated, the routine proceeds from step 83 to step 85, where it is determined whether or not the feedback control of the idle speed is being executed. The idle speed feedback control is started at a timing when the idle switch is ON (accelerator opening is zero) and a predetermined time has elapsed since the engine is started. If a predetermined time has elapsed since the engine was started, it is determined that the feedback control of the idle rotation speed is being executed, and also at this time, the routine proceeds to step 84 and the second power generation permission flag = 1 is set.

  FIG. 12 is for setting the generated voltage, and is executed at regular intervals (for example, every 100 msec) following the flow of FIGS. 10 and 11. In step 91, the first power generation permission flag (set by FIG. 10) is checked, and in step 92, the second power generation permission flag (set by FIG. 11) is viewed. When the first power generation permission flag = 0 and the second power generation permission flag = 0, the routine proceeds to step 93 where the power generation voltage = 0 (that is, the power generation by the alternator 51 is prohibited).

  When the first power generation permission flag = 1 or the second power generation permission flag = 1, the power generation voltage is set in steps 94 to 98. That is, in step 94, the target level tSOC of the charged state of the battery 55 is set to a predetermined value tSOCi. In step 95, the actual state of charge rSOC of the battery 55 is detected. The actual state of charge rSOC is approximated by the calculated integrated value ΣIc by integrating the charging / discharging current Ic of the battery 55 (a positive value during charging and a negative value during discharging).

  In step 96, the detected actual state of charge rSOC is compared with the target level tSOC. When the actual charging state rSOC of the battery 55 does not reach the target level tSOC, it is necessary to charge the battery 55. Therefore, the routine proceeds to step 97, where the power generation voltage Vg of the alternator 51 is set to a relatively large first predetermined value tVgh. To do. On the other hand, when the actual state of charge rSOC of the battery 55 has reached the target level tSOC, the routine proceeds from step 96 to step 98, where the power generation voltage Vg of the alternator 51 is set to a second predetermined value tVgl smaller than the first predetermined value tVgh. To do. Note that the first predetermined value tVgh and the second predetermined value tVgl both increase or decrease in accordance with the operating state of the electrical component, that is, the magnitude of the electrical load.

  The power generation voltage Vg set in this way is output to the IC regulator 52 by the engine controller 31 as a voltage command value.

  Here, the effect of 2nd Embodiment is demonstrated.

  This will be described again with reference to FIG. 9. Under the current control, an alternator load may be input to the engine for power generation at the timing t2, which cannot be said to be a state where the engine torque is stable in FIG. Along with this, idle hunting (or engine stall) may occur (see the solid line from t2 in the uppermost stage in FIG. 9), but the second embodiment (in claims 1 and 7) According to the described invention), the alternator load is not applied (the auxiliary load is applied to the engine) until the timing t3 when the engine torque is stabilized after the engine rotational speed Ne reaches the idle target rotational speed NSET. (Refer to steps 91, 92, and 93 in FIG. 12) Since the alternator load is allowed to be input when the engine torque is stable (see FIG. 10). 76, 78, steps 83 and 84 in FIG. 11 or steps 85 and 84), as indicated by the one-dot chain line in the uppermost part of FIG. 9, the target rotation speed at the idling time after the timing at which the engine rotation speed Ne is t3. NSET is maintained, thereby preventing idle hunting and engine stall due to the loading of an auxiliary machine load on the engine when the engine torque is unstable.

  By the way, when the state of charge of the battery 55 is poor at the time of starting the engine (for example, when the battery voltage VB is less than the required holding voltage VB1 with the ignition switch 62 turned on), the battery voltage VB is insufficient and the ignition coil Sufficient charge is not accumulated and appropriate ignition is not performed, and the engine rotational speed Ne may fluctuate in an unstable manner or engine stall may occur. In such a case, that is, when the state of charge of the battery 55 is poor at the time of starting the engine, as shown in FIG. 9, at the timing t2 when the engine rotational speed Ne from the cranking reaches the target rotational speed NSET during idling. Instead of retarding stepwise from the first ignition timing ADV1 (ignition timing for starting) to the second ignition timing ADV2 (ignition timing for promoting catalyst warm-up), as shown in FIG. The ignition timing ADV1 (ignition timing for start-up) is gradually retarded from the second point to timing ADV2 (ignition timing for promoting catalyst warm-up) (see the two-dot chain line in FIG. 13). It is preferable to generate power by the alternator 51 at a timing when the engine rotation speed Ne from the ranking reaches the target rotation speed NSET during idling (third embodiment). In the first and second embodiments, the reason why the ignition timing is retarded stepwise from the first ignition timing ADV1 to the second ignition timing ADV2 is to cause afterburning and raise the exhaust gas temperature. In the third embodiment, the ignition timing is gradually retarded from the first ignition timing ADV1 to the second ignition timing ADV2 in the third embodiment, so that the ignition timing is the same as that of the first and second embodiments. If the advance angle side is kept from the case, the engine torque increases accordingly, and the increase in the engine torque can counter the introduction of the alternator load. That is, according to the third embodiment (the inventions described in claims 6 and 12), even when the charging state of the battery 55 is poor at the time of starting the engine, improper ignition due to power shortage of the battery 55 immediately after starting or its failure. It can prevent engine stall due to proper ignition.

  The ignition timing retardation processing procedure according to claim 1 is performed by steps 26, 32, and 33 in FIG. 5, and the intake air amount supply processing procedure is performed by steps 25, 26, 29, 30, and 31 in FIG. The increase processing procedure is based on steps 44, 45 and 51 in FIG. 6, and the auxiliary load input prohibition / permission processing procedure is steps 91, 92 and 93 in FIG. 12, steps 76 and 78 in FIG. 10, and steps 83 and 84 in FIG. Or it is performed by steps 85 and 84, respectively.

  The function of the ignition timing retarding means according to claim 5 is performed by steps 26, 32, 33 in FIG. 5, and the function of the intake air amount supplying means is performed by steps 25, 26, 29, 30, 31 of FIG. The functions of the injection amount increasing means are shown in steps 44, 45 and 51 in FIG. 6, and the auxiliary load input prohibiting / permitting means are functions in steps 91, 92 and 93 in FIG. 12, steps 76 and 78 in FIG. This is accomplished by steps 83 and 84 or steps 85 and 84, respectively.

The schematic block diagram of the control apparatus of the engine of 1st Embodiment of this invention. The wave form diagram for demonstrating the effect | action of 1st Embodiment compared with the present control. The wave form diagram for demonstrating the control method of 1st Embodiment. The flowchart for demonstrating the setting of two flags. The flowchart for demonstrating calculation of an ignition timing command value and a throttle valve target opening. The flowchart for demonstrating calculation of target equivalence ratio. The flowchart for demonstrating calculation of a fuel injection pulse width. The schematic block diagram of the power supply device of the engine of 2nd Embodiment. The wave form diagram for demonstrating the effect | action of 2nd Embodiment. The flowchart for demonstrating the setting of the 1st electric power generation permission flag of 2nd Embodiment. The flowchart for demonstrating the setting of the 2nd electric power generation permission flag of 2nd Embodiment. The flowchart for demonstrating the setting of the power generation voltage of 2nd Embodiment. The wave form diagram for demonstrating the effect | action of 3rd Embodiment.

Explanation of symbols

5 Combustion chamber 9 First catalyst 14 Spark plug 21 Fuel injection valve 23 Throttle valve 31 Engine controller 33, 34 Crank angle sensor 36 Starter switch 37 Water temperature sensor 51 Alternator (auxiliary load)
55 battery

Claims (12)

In an engine provided with a catalyst that functions only after being activated in the exhaust passage and a fuel injection valve for injecting fuel in the intake passage,
Ignition timing retarding procedure that retards the ignition timing step by step from the ignition timing for starting to the ignition timing for promoting catalyst warm-up when the engine speed from cranking reaches the target rotational speed at idle When,
When the engine speed is at idle, the intake air amount necessary to maintain the engine speed at the target speed at idling is supplied to the combustion chamber when the engine speed reaches the target speed at idling. Intake air amount supply processing procedure for starting to open the throttle valve a predetermined period before the timing of reaching the target rotational speed of
The fuel injection amount from the fuel injection valve from the timing when the throttle valve starts to open until the change in the intake pressure or the intake air flow velocity at the intake port settles after the engine rotation speed reaches the target rotation speed during idling A fuel injection amount increase processing procedure for temporarily increasing
After the engine speed reaches the target speed during idling, the engine load is prohibited until the engine torque stabilizes, and the engine load is allowed when the engine torque is stable. A method for controlling an engine, comprising: an auxiliary machine load input prohibition / permission processing procedure. An alternator driven by an engine;
The engine control method according to claim 1, further comprising: a battery for storing electric power generated by the alternator, wherein the auxiliary load on the engine is generated by the alternator.   The timing at which the engine torque stabilizes after the engine rotational speed reaches the target rotational speed during idling is such that the change in the intake pressure or the intake air flow velocity at the intake port settles after the engine rotational speed reaches the target rotational speed during idle. The engine control method according to claim 1, wherein the timing is timing. Including a processing procedure for performing air-fuel ratio feedback control,
2. The engine control method according to claim 1, wherein the timing at which the engine torque stabilizes after the engine rotation speed reaches the target rotation speed during idling is at the start of the air-fuel ratio feedback control. Including a processing procedure for performing feedback control of the idle rotation speed,
2. The engine control method according to claim 1, wherein the timing at which the engine torque stabilizes after the engine rotation speed reaches the target rotation speed during idling is at the start of feedback control of the idle rotation speed. .   If the battery charge state is poor at the time of engine start, the engine ignition speed from cranking to the ignition timing for promoting catalyst warm-up from the timing at which the engine speed from cranking reaches the target rotation speed during idling. Instead of stepwise retarding, the engine timing is gradually retarded from the starting ignition timing to the catalyst warming acceleration ignition timing, and the timing at which the engine rotational speed from cranking reaches the target rotational speed during idling. The engine control method according to claim 2, wherein power is generated by the alternator. In an engine provided with a catalyst that functions only after being activated in the exhaust passage and a fuel injection valve for injecting fuel in the intake passage,
Ignition timing retarding means for retarding the ignition timing step by step from the ignition timing for starting to the ignition timing for promoting catalyst warm-up when the engine speed from cranking reaches the target rotational speed at idle ,
When the engine speed is at idle, the intake air amount necessary to maintain the engine speed at the target speed at idling is supplied to the combustion chamber when the engine speed reaches the target speed at idling. Intake air amount supply means for starting to open the throttle valve a predetermined period before the timing to reach the target rotational speed of
The fuel injection amount from the fuel injection valve from the timing when the throttle valve starts to open until the change in the intake pressure or the intake air flow velocity at the intake port settles after the engine rotation speed reaches the target rotation speed during idling A fuel injection amount increasing means for temporarily increasing
After the engine speed reaches the target speed during idling, the engine load is prohibited until the engine torque stabilizes, and the engine load is allowed when the engine torque is stable. An engine control apparatus comprising: auxiliary load input prohibition / permission means. An alternator driven by an engine;
The engine control device according to claim 7, further comprising: a battery that stores electric power generated by the alternator, wherein the auxiliary load on the engine is generated by the alternator.   The timing at which the engine torque stabilizes after the engine rotational speed reaches the target rotational speed during idling is such that the change in the intake pressure or the intake air flow velocity at the intake port settles after the engine rotational speed reaches the target rotational speed during idle. The engine control device according to claim 7, wherein the timing is a timing. Including a processing procedure for performing air-fuel ratio feedback control,
8. The engine control device according to claim 7, wherein the timing at which the engine torque stabilizes after the engine rotation speed reaches the target rotation speed during idling is at the start of the air-fuel ratio feedback control. Including a processing procedure for performing feedback control of the idle rotation speed,
8. The engine control device according to claim 7, wherein the timing at which the engine torque stabilizes after the engine rotation speed reaches the target rotation speed during idling is the start of feedback control of the idle rotation speed. .   If the battery charge state is poor at the time of engine start, the engine ignition speed from cranking to the ignition timing for promoting catalyst warm-up from the timing at which the engine speed from cranking reaches the target rotation speed during idling. Instead of stepwise retarding, the engine timing is gradually retarded from the starting ignition timing to the catalyst warming acceleration ignition timing, and the timing at which the engine rotational speed from cranking reaches the target rotational speed during idling. The engine control device according to claim 8, wherein power generation by the alternator is performed.

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