JP6167888B2 - Engine control device - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine (hereinafter referred to as “engine”), and more particularly to control at the time of starting a direct injection type spark ignition engine.

  When the engine starts, the engine speed rises sharply, takes a peak, and then settles to the target speed during idling. Until the engine speed reaches this peak from the start timing of the engine, the engine output is suppressed by retarding the ignition timing from the ignition timing during idling, thereby suppressing the engine speed from rising. There is a thing (refer patent document 1).

JP 2005-194902 A

  By the way, there is an engine in which a vehicle resonance band is set in a rotational speed range lower than the idle rotational speed. When the ignition timing control of Patent Document 1 is applied at the start of the engine and the ignition timing is retarded, the degree of increase in the engine rotation speed from the start timing is deteriorated by the amount by which the ignition timing is retarded. . For this reason, it takes a long time for the engine speed to pass through the vehicle resonance band, and vehicle vibration occurs.

  Therefore, an object of the present invention is to provide a device that can prevent the occurrence of vehicle vibration immediately after the engine is started.

  The present invention is based on the premise of an engine control device that includes a catalyst in an exhaust passage and raises the temperature of exhaust gas flowing into the catalyst by retarding the ignition timing at the start of the engine from the ignition timing at the time of idling. To do. When the engine rotation speed passes through a predetermined rotation speed range as a vehicle resonance band at the time of starting the engine, the ignition timing at which the peak of the engine rotation speed is generated in the vehicle resonance band is retarded. Advance ahead of time.

  According to the present invention, due to the advance of the ignition timing when the peak of the engine rotation speed is generated in the vehicle resonance band, the engine rotation speed rapidly increases from the start timing, and quickly passes through the vehicle resonance band. This can suppress vehicle vibration immediately after the engine is started.

It is a schematic block diagram of the drive device of the vehicle carrying the engine of 1st Embodiment of this invention. It is a control system figure of a direct injection type spark ignition engine in a cylinder. It is a timing chart which shows the change of engine rotation speed to the elapsed time from engine starting. It is a timing chart which shows the change of the longitudinal acceleration of a vehicle to the elapsed time from engine starting. It is a timing chart which shows each change of engine speed at the time of engine restart, a starter relay, and ignition timing with a model. It is a characteristic view of the ignition timing with respect to the number of combustions from the engine start of the first embodiment. It is a flowchart for demonstrating calculation of the ignition timing of 1st Embodiment. It is a table | surface figure which shows the content of the ignition timing map at the time of the super retard combustion of 1st Embodiment. 6 is a timing chart showing a change in the engine speed increase rate when the ignition timing at which the rotation speed peak occurs in the vehicle resonance band is constant. It is a flowchart for demonstrating calculation of the ignition timing of 2nd Embodiment. It is a table | surface figure which shows the content of the ignition timing map at the time of the super retard combustion of 2nd Embodiment. It is a characteristic view of the ignition timing with respect to the number of combustion since the engine start of the second embodiment.

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

(First embodiment)
FIG. 1 is a schematic configuration diagram of a drive device for a vehicle 1 equipped with an engine 2 according to a first embodiment of the present invention. In FIG. 1, a vehicle 1 includes an engine 2, a motor generator 21, and an air conditioner compressor 31. In other words, the output shaft 3 of the engine 2, the rotation shaft 22 of the motor generator 21, and the rotation shaft 32 of the air conditioner compressor 31 are arranged in parallel, the crank pulley 3 at one end of the output shaft 3, and the pulleys on the rotation shafts 22 and 32. 23 and 33 are attached. A belt 5 is wound around each of the three pulleys 3, 23, 33, and power is transmitted (conducted) between the output shaft 3 and the rotary shafts 23, 33 of the engine 2 by the belt 5.

  The engine 2 is also provided with a starter 6 used for starting the engine. A torque converter 8 and a belt type automatic transmission 9 are connected to the other end of the output shaft 3 of the engine 2. The torque converter 8 has a pump impeller and a turbine runner (not shown). The belt-type automatic transmission 9 includes a primary pulley and a secondary pulley (not shown) and a steel belt that is wound around these pulleys. The rotational driving force of the engine 2 is finally transmitted to vehicle driving wheels (not shown) via the torque converter 8 and the automatic transmission 9.

  As a power source for the vehicle 1, a main battery 41 and a sub battery 42 are provided. Both are 14V batteries. The two batteries 41 and 42 are connected by two relays 43 arranged in parallel.

  The starter 6 and the motor generator 21 are connected between the main battery 41 and the relay 43, and power is supplied from the main battery 41. In addition, since the motor generator 21 is comprised from the alternating current machine, the inverter 24 which converts the direct current from the main battery 41 into alternating current is attached.

  An engine control module 51 is provided to control the engine 2, starter 6 and motor generator 21.

  Here, the configuration of the engine 2 will be outlined with reference to FIG. 2. FIG. 2 is a control system diagram of the in-cylinder direct injection spark ignition engine 2. The crown surface shape of the piston 97 does not represent the actual shape.

  The intake passage 82 is provided with an electronically controlled throttle valve 83, and the throttle motor 88 controls the opening of the throttle valve 83 (hereinafter referred to as “throttle opening”). The actual throttle opening is detected by the throttle sensor 89 and input to the engine control module 51.

  The air metered by the throttle valve 83 provided on the upstream side of the intake passage 82 is stored in the intake collector 84 and then supplied to the combustion chamber 87 of each cylinder via the intake manifold 85. The intake manifold 85 is provided with a normally-open tumble control valve 91 having a notch in a part thereof. When the tumble control valve 91 is closed, the flow rate of the gas flowing into the combustion chamber 87 increases, and the combustion chamber 87 enters the intake manifold 85. A gas flow (mainly a tumble flow) is generated.

  A fuel injector 92 is disposed facing the side of the combustion chamber 87 on the intake manifold 85 side. Fuel in one fuel rail (not shown) is distributed and supplied to the fuel injector 92 of each cylinder. The fuel in the fuel rail is regulated to a predetermined pressure by a high pressure fuel pump and a pressure regulator (not shown). The fuel injector 92 of each cylinder is intermittently opened at a predetermined timing by a control pulse from the engine control module 51, so that an amount of fuel corresponding to the valve opening period and the regulated fuel pressure is in the combustion chamber 87. It is directly injected into the inside (cylinder). The fuel injected into the combustion chamber 87 mixes with air to form an air-fuel mixture.

  A spark plug 94 for igniting the air-fuel mixture is disposed in the center of the ceiling of the combustion chamber 87. By closing the intake valve 93, the air-fuel mixture is trapped in the combustion chamber 87 and compressed by the piston 97 ascending. The engine control module 51 generates a spark in the spark plug 95 by cutting off the primary current of the ignition coil 96 at a predetermined time. As a result, the air-fuel mixture in the combustion chamber 87 is ignited.

  The air-fuel mixture in the combustion chamber 87 is ignited by the spark plug 95 and burned as described above. The gas pressure due to the combustion works to push down the piston 97, and the reciprocating motion of the piston 97 is converted into the rotational motion of the crankshaft 98 (engine output is generated). The combusted gas (exhaust gas) is discharged into the exhaust passage 99 when the exhaust valve 94 is opened. In the exhaust passage 99, three-way catalysts 111 and 112 (catalysts) for purifying harmful gas components in the exhaust gas are arranged, and air-fuel ratio sensors 108 and 109 are provided on the upstream side and the downstream side of the three-way catalyst 111, respectively. Yes.

  The engine control module 51 includes a microcomputer that includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The engine control module 51 receives an accelerator opening signal (amount of depression of the accelerator pedal 106) from the accelerator sensor 105, a crank angle reference position signal and a unit angle signal from the crank angle sensors 103 and 104. Further, an intake air amount signal from the air flow meter 102 and an engine coolant temperature signal from the water temperature sensor 107 are also input. The rotational speed of the engine 2 is calculated from the signals of the crank angle sensors 103 and 104 described above.

  The engine control module 51 determines a combustion method for homogeneous combustion or stratified combustion according to the engine operating conditions detected by the sensors. In accordance with the determined combustion method, the throttle opening, the fuel injection amount from the fuel injector 92, the fuel injection timing when the fuel injector 92 is opened, and the ignition timing when the spark plug 95 performs spark ignition. Control time etc.

  For example, after the activation of the three-way catalyst 111, the engine is operated by stratified combustion in the operating region on the low rotational speed / low load side, and the engine is operated by homogeneous combustion in the operating region on the high rotational speed / high load side. Do. In the operation region where stratified combustion is performed, fuel injection is performed at an appropriate timing in the compression stroke, ignition is performed at a timing before the compression top dead center, and the tumble control valve 91 is closed. As a result, the fuel spray rides on the tumble flow and is gathered in the vicinity of the spark plug 94 to realize extremely lean stratified combustion with an air-fuel ratio of about 30 to 40. On the other hand, in the operation region where homogeneous combustion is performed, fuel injection is performed during the intake stroke, ignition is performed in the MBT before compression top dead center, and the tumble control valve 91 is opened. At this time, a homogeneous air-fuel mixture is formed in the combustion chamber. Homogeneous combustion includes homogeneous stoichiometric combustion in which the air-fuel ratio is the stoichiometric air-fuel ratio and homogeneous lean combustion in which the air-fuel ratio is about 20 to 30 lean depending on the operating conditions.

  On the other hand, when the engine in which the three-way catalyst 111 has not reached the activation temperature is cold started, super retard combustion is performed so that the temperature of the exhaust gas flowing into the three-way catalyst 111 becomes high. The reason for performing super retard combustion is that if the three-way catalyst 111 is below the activation temperature at the time of cold start of the engine, the three-way catalyst 111 below the activation temperature cannot purify harmful gas components in the exhaust gas. This is because the temperature of the catalyst 111 needs to be raised to the activation temperature or higher. In the super retard combustion, the unburned portion of the gas discharged to the exhaust passage 99 is post-burned in the exhaust passage 99, so that the fuel injection timing (at least the last fuel injection timing in the case of multiple injections) and the ignition timing Is the expansion stroke after the compression top dead center, thereby increasing the temperature of the exhaust gas at an early stage.

  Here, the crank angle section from the compression top dead center to the fuel injection timing in the expansion stroke and the crank angle section from the compression top dead center to the ignition timing in the expansion stroke are hereinafter referred to as “retard amount”. The reason why the fuel injection timing and the ignition timing are used as the expansion stroke after the compression top dead center is that the larger the respective retard amounts of the fuel injection timing and the ignition timing, the more the combustion proceeds from the exhaust passage 99 without burning in the combustion chamber 87. This is because the amount of unburned fuel increases, and the exhaust temperature in the exhaust passage increases accordingly.

  However, since the combustion stability of the gas combusted in the combustion chamber 87 deteriorates when the respective retard amounts of the fuel injection timing and the ignition timing are increased, the maximum retard amount is set within a range where the combustion stability is allowed. Become.

  In this case, delaying the fuel injection timing and the ignition timing to the expansion stroke after the compression top dead center affects the engine performance on the other hand. That is, by delaying the fuel injection timing and ignition timing to the expansion stroke after compression top dead center, the combustion speed is lowered and the combustion efficiency is deteriorated by that amount, so the fuel injection timing and ignition when super retard combustion is not performed. Compared to the time, the engine torque obtained from the combustion gas is reduced. However, this torque reduction can be compensated by increasing the amount of intake air flowing into the combustion chamber 87 and increasing the fuel injection amount in accordance with the increased amount of intake air. For this reason, when super retard combustion is performed, the amount of intake air flowing into the combustion chamber 87 is increased by increasing the throttle opening as compared with when super retard combustion is not performed. When the amount of intake air flowing into the combustion chamber 87 increases, the fuel injection amount is increased accordingly, and the generated torque increases. The throttle opening is determined so that the torque after the increase is equal to the engine torque that is generated when super retard combustion is not performed.

  When the permit condition for super retard combustion is satisfied, the actual ignition timing and fuel injection timing are controlled as follows. First, the throttle opening is set to compensate for the torque drop when the fuel injection timing and ignition timing are set to limits where combustion stability is allowed (this limit is referred to as “retard limit”). The throttle opening is an opening that can maintain the engine speed at the target idle speed when the fuel injection timing and the ignition timing are set to the retard limits. The throttle opening is set by a map using engine speed and load as parameters. After the throttle opening is set as described above, the fuel injection timing and the ignition timing are set to the retard limit in consideration of the delay in the response of air due to the change in the throttle opening.

As the fuel injection timing and ignition timing at the time of super retard combustion, the ignition timing is set to 15 ° to 30 ° ATDC (for example, 20 ° ATDC), and the fuel injection timing (specifically, the fuel injection start timing) is set after the compression top dead center. Set in the expansion stroke and before the ignition timing. At this time, the air-fuel ratio is set to the stoichiometric air-fuel ratio or slightly leaner (about 16 to 17). That is, in order to promote the activation of the three-way catalyst 111 and reduce HC generated frequently when the engine is cold. It is effective to delay the ignition timing to the expansion stroke after the compression top dead center. On the other hand, in order to perform stable combustion even in the ignition stroke after the compression top dead center, it is necessary to shorten the combustion period. For that purpose, the combustion chamber 87 is disturbed. Flame propagation must be promoted. In the expansion stroke after the compression top dead center, the turbulence generated in the combustion chamber 87 during the intake stroke and the compression stroke is attenuated, but in this embodiment, the high-pressure fuel in the expansion stroke after the compression top dead center The gas flow is generated by the injection, and thereby the turbulence in the combustion chamber 87 can be generated and strengthened. Thus, flame propagation is promoted even in the expansion stroke after compression top dead center, and stable combustion can be performed.

  As described above, according to the super retard combustion, the turbulence in the cylinder can be generated and strengthened by the fuel spray immediately before ignition, and the flame propagation is promoted, so that the ignition timing reaches the expansion stroke after the compression top dead center. Stable combustion can be performed while suppressing deterioration in combustion stability due to delay. In particular, by retarding the ignition timing from 15 ° to 30 ° ATDC, a sufficient afterburning effect for early activation of the three-way catalyst 111 and HC reduction can be obtained. In other words, even if the ignition timing is greatly delayed until the expansion stroke after the compression top dead center, the fuel injection is delayed until just before that and the generation time of the turbulence is also delayed, thereby achieving an improvement in combustion by improving the flame propagation. It is.

  If the temperature of the three-way catalyst 111 rises to the activation temperature of the three-way catalyst 111 due to the super-retard combustion at the time of cold start, the super-retard combustion is not necessary, so the super-retard combustion is terminated. That is, when the catalyst temperature detected by the catalyst temperature sensor 110 is equal to or higher than the temperature obtained by adding a margin to the activation temperature of the three-way catalyst 111, the super retard combustion is terminated, and the ignition timing and the fuel injection timing are set to normal times. Return to ignition timing and fuel injection timing. For example, if the operation region when the super retard combustion is terminated is an operation region in which stratified combustion is performed, fuel injection is performed at an appropriate time in the compression stroke, and ignition is performed at a time before compression top dead center.

  Returning to FIG. 1, when the engine control module 51 determines that there is an initial start request based on a signal from the starter switch 56, the starter 6 is driven to start the engine 2.

  The engine control module 51 performs idle stop control for the purpose of improving fuel consumption. That is, when the accelerator pedal 106 is not depressed (APO = 0), the brake pedal is depressed (brake switch 58 is ON), and the vehicle 1 is in a stopped state (vehicle speed VSP = 0), the idle stop permission is permitted. The condition is met. At this time, the fuel injection from the fuel injector 92 is shut off and the engine 2 is stopped. This reduces wasteful fuel consumption.

  Thereafter, when the accelerator pedal 106 is depressed or the brake pedal is returned (the brake switch 58 is OFF) in the idle stop state, the idle stop permission condition is not satisfied. At this time, the engine 2 is cranked using the motor generator 21 as a starter, fuel injection from the fuel injector 92 and spark ignition by the spark plug 95 are restarted, and the engine 2 is restarted. Thus, the engine control module 51 has idle stop control means.

  In this way, by using the motor generator 21 exclusively for engine restart from idle stop, the starter 6 is protected by reducing the frequency of use of the starter 6. When the starter 6 and the motor generator 21 are driven, the engine control module 51 cuts off both the two relays 43 to electrically disconnect the main battery 41 and the sub battery 42. This prevents the voltage of the sub-battery 42 from fluctuating with the start operation of the engine 2.

  The vehicle 1 includes an automatic transmission control unit 61. The automatic transmission control unit 61 controls the gear ratio of the automatic transmission 9 steplessly in accordance with the vehicle running conditions determined from the vehicle speed and the throttle opening. The torque converter 8 having a pump impeller and a turbine runner is provided with a mechanical lockup clutch for fastening and releasing the pump impeller and the turbine runner. The travel range of the vehicle that engages the lock-up clutch is predetermined as a lock-up region (vehicle speed and throttle opening are used as parameters). In the automatic transmission control unit 61, when the vehicle driving condition is in the lockup region, the lockup clutch is engaged to directly connect the engine 2 and the transmission 9, and the vehicle driving condition is not in the lockup region. Sometimes the lock-up clutch is released. When the engine 2 and the transmission 9 are in a directly connected state, the torque converter 8 does not absorb the torque, and the fuel efficiency is improved accordingly.

  The vehicle 1 also includes a vehicle dynamics control unit 62 and a vehicle speed-sensitive electric power steering control unit 63. The vehicle dynamic control unit 62 detects a skid state when the vehicle is likely to cause a side slip or a tail swing, and improves vehicle stability during traveling by brake control and engine output control. The vehicle speed sensitive electric power steering control unit 63 outputs an optimum assist torque signal to the EPS motor from the steering torque from the torque sensor and the vehicle speed.

  The automatic transmission control unit 61, the vehicle dynamic control unit 62, and the vehicle speed sensitive power steering control unit 63 are electric loads that cannot tolerate a voltage drop. Therefore, these are supplied with power from the sub-battery 42.

  The engine control module 51 and the three control units 61 to 63 are connected by CAN (Controller Area Network).

  The super retard combustion is performed at the time of cold start of the engine in order to activate the three-way catalyst 111 early. This super retard combustion is combined with the idle stop control, so that there are many opportunities for engine restart. Considering that the vehicle is used even in a cold region, the three-way catalyst 111 may be below the activation temperature even when the engine is restarted due to the idle stop control. That is, even when the engine is restarted due to idle stop control, super retard combustion can be performed. Therefore, in the present embodiment, not only the first cold start of the engine but also the case where super retard combustion is performed at the time of engine restart accompanying the idle stop control is handled. In the following description, “when the engine is started” or “when the engine is started” includes not only the initial cold start of the engine based on the signal from the starter switch 56 but also the restart of the engine accompanying the idle stop control. . However, it is useless to perform super retard combustion even though the three-way catalyst 111 is at the activation temperature or higher when the engine is restarted due to the idle stop control. Therefore, the engine restart associated with the idle stop control is only applicable when the three-way catalyst 111 is below the activation temperature and is substantially equivalent to the engine cold start.

  In this case, when the engine is started, the ignition timing is maintained at the expansion stroke after compression top dead center (for example, 15 ° ATDC), and the fuel injection timing is set slightly before the ignition timing to perform super retard combustion. Is a comparative example. When the comparative example is determined in this way, according to the comparative example, it has been newly found that vehicle vibration occurs when the engine is started as shown in FIGS. Here, FIG. 3 shows the change in the engine speed with respect to the time from the start of the engine. FIG. 4 also shows the change in the longitudinal acceleration of the vehicle with respect to the time from the start of the engine.

  As shown in FIGS. 3 and 4, in order to clarify the cause of vehicle vibration at the time of starting the engine, a change in the engine speed at the time of engine restart accompanying idle stop control is shown as a model in FIG. ing. If the starter relay is switched from OFF to ON at the timing t1 when the idle stop permission condition is not established, the motor generator 21 is driven at the timing t2 when the motor generator 21 is energized. By driving the motor generator 21, the crankshaft 98 of the engine 2 is cranked. When ignition is performed at a predetermined timing in accordance with the ignition sequence, the engine rotational speed rapidly increases and reaches the target rotational speed during idling. Specifically, driving the motor generator 21 causes the engine rotation speed to increase stepwise from the timing t2. The first peak higher than the engine speed increased stepwise by the first combustion from the start is the timing of t4, and the second peak higher than the first peak by the second combustion is t5. It is obtained with timing. When the third peak that is higher than the second peak is obtained at the timing t7 by the third combustion, the target rotational speed at the time of idling is reached.

  In this case, in the engine targeted by the comparative example, there is a vehicle resonance band between zero and the target rotational speed at the time of idling. Here, the vehicle resonance band is an engine rotation speed region in which the vehicle body resonates (the vehicle vibrates) using the engine 2 as an excitation source. In the engine targeted by the comparative example, the vehicle resonance band is set in advance so as to be in the range of 300 to 500 rpm, for example. For this reason, in the comparative example, it is considered that the time when the engine rotation speed passes through the vehicle resonance band is increased from t3 to t6, thereby generating the vehicle vibration. When vehicle vibration occurs, the ride comfort becomes worse. Accordingly, when the ignition timing at the time of super retard combustion is constant at 15 ° ATDC as in the comparative example, the ride comfort is deteriorated when passing through the vehicle resonance band, so the time during which the engine speed passes through the vehicle resonance band. Need to be shorter.

Therefore, in the first embodiment, the same engine targeted by the comparative example is targeted.
And even if super retard combustion is performed at the time of starting the engine for the engine, the ignition timing when the peak of the rotation speed is generated in the vehicle resonance band so that the engine rotation speed rushes through the vehicle resonance band. Is advanced from the ignition timing at the time of super retard combustion.

  For reference, as indicated by adding a broken line in the lower part of FIG. 5, the ignition timing at which the peak of the rotational speed is generated in the vehicle resonance band is advanced from the ignition timing at the time of super retard combustion (for example, 15 degATDC) 4 ° Set to ATDC. In addition, the broken line shown in the lower part of FIG. 5 shows an outline of the ignition timing when the altitude is 0 m (that is, the atmospheric pressure is 1 atm). Details will be described later with reference to FIG. As a reference, the lower part of FIG. 5 shows an outline of the ignition timing when the altitude exceeds 1000 m (that is, the atmospheric pressure is lower than 1 atm) with a thin solid line. The difference in the ignition timing due to the difference in atmospheric pressure will be described later.

  In the engine which is the object of the above comparative example, as described above with reference to FIG. 5, when the number of combustions from the start is the first time and the second time, the rotational speed peak (combustion peak) occurs in the vehicle resonance band. Thus, since it can be known in advance whether or not the number of times of combustion since the start will cause a peak of the rotational speed in the vehicle resonance band, in the present embodiment, the ignition when the peak of the rotational speed occurs in the vehicle resonance band. The ignition timing is advanced from the ignition timing at the time of super retard combustion only at the timing. In the comparative example, the ignition timing when the rotation speed peak occurs in the vehicle resonance band is set to 15 ° ATDC. Therefore, in this embodiment, the ignition timing is set to 4 ° ATDC advanced from 15 ° ATDC.

  In addition, when the ignition timing when the rotational speed peak occurs in the vehicle resonance band is set to the ignition timing advanced from the ignition timing (15 degATDC) at the time of super retard combustion, the fuel injection timing is changed in accordance with this, It should be before the ignited ignition timing. That is, the fuel injection timing is set so that the fuel injection timing comes before the ignition timing (4 ° ATDC) advanced from the ignition timing at the time of super retard combustion. Due to the high-pressure fuel injection at the fuel injection timing, a gas flow is generated, so that the turbulence in the combustion chamber 87 can be generated and strengthened even when the ignition timing is advanced.

  The characteristics of the ignition timing with respect to the number of combustions from the start of the engine will be specifically described with reference to FIG. 6. In FIG. 6, the vertical axis represents the number of combustions from the start and the horizontal axis represents the ignition timing. First, in the comparative example, the ignition timing is 15 ° ATDC irrespective of the number of combustions from the start, so the ignition timings when the number of combustions from the start is 1 and 2 are 15 ° ATDC. On the other hand, in the present embodiment, when the number of combustions from start is 1 and 2 and the engine has a rotational speed peak in the vehicle resonance band when the number is 1, the number of combustions from start is 1 and 2 The ignition timing is advanced from the 15 ° ATDC set in the comparative example. That is, in this embodiment, the ignition timing when the number of combustions from the start is 1 and 2 is set to 4 ° ATDC close to the compression top dead center to increase the engine output, and the engine rotational speed is quickly adjusted to the vehicle resonance. Pass through the belt.

  When the number of combustions from the start is 3 or later, the engine speed is not in the vehicle resonance band, so the ignition timing is returned to 15 ° ATDC, which is the optimum ignition timing for the super retard combustion as in the comparative example. Although not shown, the fuel injection timing is also returned to the same fuel injection timing for super retard combustion as in the comparative example.

  This content executed by the engine control module 51 will be described in detail with reference to the flowchart of FIG. 7. The flow of FIG. 7 is for calculating the ignition timing, and is executed at regular time intervals (for example, every 10 ms). The flow in FIG. 7 may be executed for each predetermined crank angle position. In the super retard combustion, the fuel injection timing is omitted because it is sufficient to inject fuel before the calculated ignition timing.

  First, in step 1, it is checked whether or not the engine is restarting. For example, when the idle stop permission condition is satisfied, it is determined that the engine has not been restarted, and it is determined in step 9 whether or not the idle stop is being performed. If the idle stop is in progress, the current process is terminated. When it is not during idling stop in step 9, the routine proceeds to step 10 where the normal ignition timing and fuel injection timing are calculated. Here, the normal ignition timing and the fuel injection timing are an ignition timing and a fuel injection timing when super retard combustion is not performed. For example, in the operation region where stratified combustion is performed, the ignition timing is a timing before compression top dead center, and the fuel injection timing is before the ignition timing and is an appropriate timing for the compression stroke. In the operation region where homogeneous combustion is performed, the ignition timing is MBT before compression top dead center, and the fuel injection timing is an appropriate timing of the intake stroke.

  When the idle stop permission condition is not satisfied in step 1, it is determined that the engine has been restarted, and the routine proceeds to step 2 where the super retard combustion end flag is checked. This super retard combustion end flag is initially set to zero before the engine restart is started. Here, the process proceeds to step 3 assuming that the super retard combustion end flag = 0.

  In step 3, the super retard combustion permission flag is checked. This super retard combustion permission flag is initially set to zero before the engine restart is started. Here, the routine proceeds to step 4 assuming that the super retard combustion permission flag = 0.

  In step 4, it is determined whether or not the super retard combustion condition is satisfied. Specifically, if the engine coolant temperature detected by the water temperature sensor 107 is lower than the super retard combustion permission temperature, it is determined that the super retard combustion condition is satisfied. Here, the super retard combustion permission temperature is set in advance as the engine coolant temperature when the exhaust temperature is lower than the activation temperature of the three-way catalyst 111. When the engine coolant temperature is equal to or higher than the super retard combustion permission temperature, it is determined that the super retard combustion condition is not satisfied, and the routine proceeds to step 10 where the normal ignition timing and fuel injection timing are calculated.

  When the super retard combustion condition is satisfied in step 4, the process proceeds to step 5 to set the super retard combustion permission flag = 1, and then in step 6, the atmospheric pressure Pb [mb] and the number of combustions n [unknown number] from the start are set. From FIG. 8, the ignition timing [° ATDC] is calculated by referring to the map of FIG. In the map of FIG. 8, the horizontal axis represents the atmospheric pressure from 1013 mb (that is, 1 atmosphere) to 650 mb, and the horizontal axis represents the number of combustions from the start from 1 to 8. As shown in FIG. 8, when the atmospheric pressure Pb is 1013 mb, the ignition timing is 4 ° ATDC when the number of combustions n is 1 and 2 (that is, when a rotational speed peak is generated in the vehicle resonance band), It is advanced from the ignition timing (15 ° ATDC) when the number of combustions n is 3 or later.

  If the super retard combustion permission flag = 1 is set at step 5, super retard combustion is permitted in a flow not shown. At that time, in the state where the atmospheric pressure Pb is 1013 mb, the ignition timing is advanced to 4 ° ATDC in the vehicle resonance band, and fuel is injected before the ignition timing, so that the combustion is performed after exiting the exhaust passage 99. The amount of unburned fuel is reduced and the engine output is increased. As a result, the peak of the rotation speed in the vehicle resonance band becomes high, and the engine rotation speed passes through the vehicle resonance band early.

  Further, in the map of FIG. 8, the ignition timing is corrected to the advance side as the atmospheric pressure Pb falls below 1013 mb.

  Here, the reason why the ignition timing is advanced as the atmospheric pressure falls below 1013 mb will be described with reference to FIG. 9. In FIG. 9, the horizontal axis represents the elapsed time from the start, and the vertical axis represents the engine speed. Is adopted. The cause of the change in the atmospheric pressure is the altitude of the place where the vehicle 1 is driven, and the atmospheric pressure decreases from 1013 mb as the altitude increases from 0 m. FIG. 9 shows that the ignition timing when the rotational speed peak occurs in the vehicle resonance band is constant at 4 ° ATDC, and the fuel passes through the vehicle resonance band due to the difference in altitude when fuel is injected before the ignition timing. It shows how the engine speed increases when the engine speed changes.

  When the ignition timing for generating a peak of the rotational speed in the vehicle resonance band is 4 ° ATDC, when the altitude is 1000 m, the engine rotation is greater when passing the vehicle resonance band than when the altitude is 0 m. The rate of speed increase is decreasing. When the altitude is further increased to a state of 2000 m, the increasing speed of the engine rotation speed when passing through the vehicle resonance band is further lowered than when the altitude is 1000 m, and the vehicle resonance band cannot be escaped. The longer the engine rotational speed when passing through the vehicle resonance band decreases, the longer the time it takes to pass through the vehicle resonance band, and the vibration of the vehicle continues during that time. Therefore, the higher the altitude is from 0 m (the lower the atmospheric pressure is lower than 1013 mb), the ignition timing when the peak of the rotational speed is generated in the vehicle resonance band is advanced, and fuel is injected before the ignition timing. To do. As a result, even if the altitude increases to 1000 m and 2000 m, the increase in the engine rotation speed when passing through the vehicle resonance band is kept the same as when the altitude is 0 m, thereby preventing deterioration of vehicle vibration. It is.

  The atmospheric pressure Pb is detected by an atmospheric pressure sensor 71 (see FIG. 1). The engine control module 51 knows the number of combustions n since the engine start.

  Returning to the flow of FIG. 7, in step 7, it is determined whether or not the super retard combustion end condition is satisfied. Specifically, when the catalyst temperature detected by the catalyst temperature sensor 110 is equal to or higher than a predetermined temperature (a temperature obtained by adding a margin to the activation temperature of the three-way catalyst 111), it is determined that the super retard combustion end condition is satisfied. To do. Alternatively, when a predetermined time has elapsed from the start of super retard combustion, it is determined that the super retard combustion end condition is satisfied. The predetermined time is set in advance. Immediately after the start of the super retard combustion, the catalyst temperature is lower than the predetermined temperature. Therefore, it is determined that the super retard combustion end condition is not satisfied, step 8 is skipped, and the current process is ended.

  Due to the super retard combustion permission flag = 1 in step 5, next time, steps 4 and 5 are skipped from step 3, and the process proceeds to step 6 to calculate the ignition timing. While the super retard combustion permission flag = 1, the operations in steps 3 and 6 are repeated. That is, in the state where the atmospheric pressure is 1013 mb, when the number of combustions from the start is 2, the ignition timing is set to 4 ° ATDC and fuel is injected before the ignition timing. Even when the number of combustions from the start is 2, it is also in the vehicle resonance band, the ignition timing is advanced to 4 ° ATDC in the vehicle resonance band, and fuel is injected before the ignition timing, so that the exhaust passage The amount of unburned fuel that burns after reaching 99 is reduced, and the engine output is increased. As a result, the peak of the rotation speed in the vehicle resonance band becomes high, and the engine rotation speed passes through the vehicle resonance band early.

  On the other hand, when the number of combustions from the start in step 6 becomes 3 or more in step 6, in the state where the atmospheric pressure is 1013 mb, the ignition timing is returned to 15 ° ATDC which is the same as the ignition timing in the super retard combustion of the comparative example, and also during fuel injection. Return to the fuel injection timing at the time of super retard combustion in the comparative example. Due to the significant delay of the ignition timing in this expansion stroke, the amount of unburned fuel that has burned after entering the exhaust passage 99 increases, the temperature of the exhaust gas flowing through the three-way catalyst 111 rises, and the temperature of the three-way catalyst 111 reaches the activation temperature. And rising.

  Eventually, when the catalyst temperature reaches a predetermined temperature in step 7, it is determined that the three-way catalyst 111 is activated, that is, the super retard combustion end condition is satisfied. At this time, the routine proceeds to step 8 to end the super retard combustion, and the super retard combustion end flag = 1 is set. From this super retard combustion end flag = 1, next time, the routine proceeds from step 2 to step 10 to calculate the normal ignition timing and fuel injection timing.

  The ignition timing calculated in this way is output to the ignition register according to a flow not shown. In the output register, when the crank angle detected by the crank angle sensors 103 and 104 coincides with the calculated ignition timing, the primary current of the ignition coil 96 is cut off. As a result, spark ignition is performed at the calculated ignition timing.

  Here, the effect of this embodiment is demonstrated.

  In the present embodiment, the exhaust passage 99 is provided with a three-way catalyst 111 (catalyst). The engine includes a fuel injector 92 that directly injects fuel into the combustion chamber 87 (in-cylinder), and an ignition plug 95 for igniting the air-fuel mixture in the combustion chamber 87 at the ignition timing. This is an in-cylinder direct injection spark ignition engine 2 that performs combustion. In the super retard combustion described above, the ignition timing is set to the expansion stroke after the compression top dead center when the engine is started, and the fuel is injected from the fuel injector 92 before the ignition timing and after the compression top dead center. It is what you want to do. In the present embodiment, when the engine speed passes through the vehicle resonance band when the engine 2 is started, the ignition timing for causing the peak of the engine rotation speed in this vehicle resonance band is advanced from the ignition timing at the time of super retard combustion. (See FIG. 6). According to the present embodiment, even if super retard combustion is performed at the time of engine start, the engine speed rapidly increases from the start timing due to the advance of the ignition timing at the time of engine start, and quickly passes through the vehicle resonance band. This can suppress vehicle vibration immediately after the engine is started.

  More specifically, the case of this embodiment is shown superimposed on FIGS. However, in FIG. 3, the start timing is not the same between the comparative example and the present embodiment. As shown in FIG. 3, according to the present embodiment, the time for passing through the vehicle resonance band is shortened compared to the comparative example. As a result, as shown in FIG. 4, the maximum deflection width B of the vehicle longitudinal acceleration in the case of this embodiment is smaller than the maximum deflection width A of the vehicle longitudinal acceleration in the comparative example.

  In this embodiment, when the ignition timing is advanced in the vehicle resonance band, the fuel is injected before the advanced ignition timing, so that the in-cylinder turbulence is generated and strengthened by the fuel spray just before ignition. Can promote flame propagation. As a result, even if the ignition timing at which the peak occurs in the vehicle resonance band is advanced from the ignition timing at the time of super retard combustion, combustion stability is delayed due to the ignition timing being delayed until the expansion stroke after compression top dead center. It is possible to suppress the deterioration of the property and perform stable combustion.

  The reason for performing the super retard combustion is early activation of the three-way catalyst 111 (catalyst) provided in the exhaust passage 99. For this reason, if the ignition timing is continuously advanced even after the engine rotation speed passes through the vehicle resonance band and fuel is injected before the ignition timing, activation of the three-way catalyst 111 is delayed. In this embodiment, after the engine rotation speed passes through the vehicle resonance band, the ignition timing and the fuel injection timing are returned to the ignition timing and fuel injection timing at the time of super retard combustion, so the engine rotation speed has passed through the vehicle resonance band. Later, the three-way catalyst 111 can be activated quickly.

  Even though the vehicle resonance band is passed quickly, the more the ignition timing is advanced, the less the unburned portion combusted after going out to the exhaust passage 99, and the activation of the three-way catalyst 111 (catalyst) is delayed. In this embodiment, since the ignition timing advanced in the vehicle resonance band is up to the vicinity of the compression top dead center, it is possible to pass the vehicle resonance band early while activating the three-way catalyst 111 (catalyst). .

  In the present embodiment, the engine 2 is automatically stopped when a predetermined idle stop permission condition is satisfied, and when the idle stop permission condition is not satisfied during the engine automatic stop, the engine 2 is controlled so as to restart the engine 2. Have means. And it includes the time of engine restart accompanying the idle stop control at the time of engine start (see step 1 in FIG. 7). For this reason, even when super retard combustion is performed at the time of engine restart due to idle stop control, the engine rotation speed rapidly increases from the start timing due to the advance of the ignition timing at the time of engine restart, and the vehicle resonance band is quickly adjusted. pass. As a result, it is possible to suppress the vehicle vibration immediately after the engine restart accompanying the idle stop control.

  As the atmospheric pressure decreases, the air becomes thinner and the output of the engine decreases, and accordingly, the degree of increase in the engine rotation speed when passing through the vehicle resonance band becomes worse. In the present embodiment, the ignition timing to be advanced in the vehicle resonance band is further advanced as the atmospheric pressure decreases in accordance with the atmospheric pressure, and fuel is injected before the further advanced ignition timing. Even when the atmospheric pressure is lowered, the vehicle resonance band can be passed quickly.

(Second Embodiment)
The flow of FIG. 10 is for calculating the ignition timing of the second embodiment, and is executed at regular time intervals (for example, every 10 ms). The same parts as those in FIG. 7 of the first embodiment are denoted by the same reference numerals. The flow of FIG. 10 may be executed for each predetermined crank angle position.

In the first embodiment, the atmospheric pressure is considered as a factor affecting the increase speed of the engine rotation speed when passing through the vehicle resonance band. However, in the second embodiment, the increase speed of the engine rotation speed when passing through the vehicle resonance band is considered. The engine friction is taken into consideration as an effect factor.
That is, in the first embodiment, 4 ° ATDC is set as the ignition timing to be advanced in the vehicle resonance band when the atmospheric pressure is 1013 mb, and the fuel is injected before the ignition timing. However, the actual engine friction may increase from the engine friction when the 4 ° ATDC is adapted as the ignition timing to be advanced in the vehicle resonance band in the state where the atmospheric pressure is 1013 mb. If the actual engine friction increases from the engine friction when the ignition timing is adapted, the increase speed of the engine rotation speed when passing through the vehicle resonance band is reduced by the increase of the engine friction. Engine friction is a frictional force generated when parts such as pistons and crankshafts move mechanically. Therefore, if engine friction increases from the time of adaptation, the engine output decreases and the engine speed decreases. The rate of ascent will decrease.

  Therefore, in the second embodiment, the engine friction when the ignition timing to be advanced in the vehicle resonance band when the atmospheric pressure is 1013 mb is adapted is defined as “reference friction”. As the actual engine friction increases from the reference friction, the engine output is increased by advancing the ignition timing that is advanced in the vehicle resonance band, and the increased engine output is offset by the increased engine output. So that As a result, even if the actual engine friction increases from the reference friction, the engine rotational speed when passing through the vehicle resonance band is kept the same as when the engine friction is the reference friction, and the vehicle vibration is deteriorated. To prevent.

  More specifically, only the step 21 is different from the flow of FIG. 7 of the first embodiment in the flow of FIG. That is, in step 21, the ignition timing [° ATDC] is calculated by referring to the map of FIG. 11 from the engine friction [N] and the number of combustions n [nameless number] from the start. In the map of FIG. 11, the horizontal axis represents the engine friction from the reference friction a to the maximum engine friction h, and the horizontal axis represents the number of combustions from the start from 1 to 8. As shown in FIG. 11, in the state where the atmospheric pressure Pb is 1013 mb and the reference friction a, the ignition timing when the number of combustions n is 1 and 2 (that is, when a rotational speed peak is generated in the vehicle resonance band). Is 4 ° ATDC, and is advanced from the ignition timing (15 ° ATDC) when the number of combustions n is 3 or later.

  In the map of FIG. 11, the ignition timing when the engine friction increases from the reference friction is adapted in advance as follows. That is, when the number of combustions from the start is 1 and 2, even if the engine friction increases, the increase speed of the engine rotation speed when passing through the vehicle resonance band is the same as that of the reference friction. The ignition timing is adapted in advance. Further, when the number of combustions after the start is 3 or more, the ignition timing is adapted in advance so that the combustion stability at the time of super retard combustion is maintained even if the engine friction increases.

  Further, referring to FIG. 12, what is indicated by a solid line in FIG. 12 is the ignition timing when the atmospheric pressure Pb is 1013 mb and the reference friction state. That is, in the state of the atmospheric pressure Pb of 1013 mb and the standard friction, the ignition timing when the number of combustions from the start is 1 and 2 is 4 ° ATDC, and the ignition timing when the number of combustions from the start is 3 or later is 15 ° Set to ATDC. On the other hand, the broken line shown in FIG. 12 is the ignition timing when the engine friction increases from the reference friction with the same atmospheric pressure Pb of 1013 mb. At this time, the ignition timing is advanced from the reference friction. Further, the fuel is injected before the advanced ignition timing. As a result, even when the engine friction becomes larger than the reference friction, the vehicle resonance band can be passed quickly.

  Factors affecting the engine friction include the engine coolant temperature, the operating state of the air conditioner compressor 31 (air conditioner load) that receives power from the engine 2, and the shift of the automatic transmission 9 that receives power from the engine 2. There are lever positions. In addition, although the power is not directly obtained from the engine 2, the operating state of the electric loads 44 and 45 that are indirectly obtained from the engine 2 via the batteries 41 and 42 also affects the engine friction.

  For example, the engine friction when the engine coolant temperature is at a predetermined reference temperature, the air conditioner compressor 31 and the electric loads 44 and 45 are inactive, and the shift lever position of the automatic transmission 9 is in the N range. Is the standard friction. In this case, the engine friction becomes larger than the reference friction as the engine coolant temperature falls below a predetermined reference temperature. When the air conditioner compressor 31 is in the operating state, the engine friction increases by a certain value from the reference friction than when the air conditioner compressor 31 is in the inactive state. When the shift lever position of the automatic transmission 9 is in the D range, the engine friction is larger than the reference friction than when the shift lever is in the N range. If the electric loads 44 and 45 using the batteries 41 and 42 as power sources are in an operating state, and the SOC (State of Charge) of the batteries 41 and 42 is lowered at this time, a voltage regulator is used to promote charging of the batteries 41 and 42. Increases the target generator voltage of the alternator. Since the alternator also obtains power from the engine 2, when the target power generation voltage of the alternator is increased, the engine friction increases from the reference friction. As described above, the engine friction changes depending on the engine coolant temperature, the operating condition of the load of the air conditioner, the shift lever position of the automatic transmission, and the operating condition of the electric load. Therefore, the actual engine friction may be calculated based on these. .

  The engine output decreases as the engine friction increases from the reference friction, and accordingly, the degree of increase in the engine rotation speed when passing through the vehicle resonance band becomes worse. In the second embodiment, the ignition timing advanced in the vehicle resonance band is further advanced in accordance with the engine friction as the engine friction becomes larger than the reference friction, and fuel is injected before the further advanced ignition timing. To do. As a result, even when the engine friction becomes larger than the reference friction, the vehicle resonance band can be passed quickly.

  In the embodiment, the case where the engine is the in-cylinder direct injection type spark ignition engine 2 has been described as the case where super retard combustion is performed at the start of the engine, but the subject of the present invention is the in-cylinder direct injection type spark ignition engine. It is not limited to the case of 2. For example, there is an engine provided with a spark plug facing a combustion chamber and a fuel injector facing an intake port. In this engine, fuel is always injected in the intake stroke or the exhaust stroke before that. There is an engine ignition timing control device for retarding the ignition timing at the start of the engine from the ignition timing at the time of the engine for early activation of the three-way catalyst provided in the exhaust passage targeting the intake port injection engine. In this case, if the vehicle resonance band is between zero and the target rotation speed during idling, even in this engine control device, the increase speed of the engine rotation speed when passing through the vehicle resonance band decreases and the vehicle resonance The time required to pass the belt becomes longer, and vehicle vibration occurs. Therefore, in this engine control device, when the engine rotation speed passes through the vehicle resonance band when the engine is started, the ignition timing when the engine rotation speed peak occurs in the vehicle resonance band is retarded for early activation of the catalyst. It is conceivable to advance the ignition timing from the ignition timing. Also in this case, due to the advance of the ignition timing at the start of the engine, the engine speed rapidly increases from the start timing and quickly passes through the vehicle resonance band. This can suppress vehicle vibration immediately after the engine is started.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 In-cylinder direct injection type spark ignition engine 51 Engine control module 87 Combustion chamber 92 Fuel injector 95 Spark plug 99 Exhaust passage 111 Three-way catalyst (catalyst)

Claims (8)

Equipped with a catalyst in the exhaust passage,
In an engine ignition timing control device that raises the temperature of the exhaust gas flowing into the catalyst by retarding the ignition timing at the time of engine startup from the ignition timing at the time of idling,
When the engine rotation speed passes through a predetermined rotation speed range as a vehicle resonance band when the engine is started, the ignition timing when the peak of the engine rotation speed is generated in the vehicle resonance band is greater than the retarded ignition timing. An engine control device characterized by being advanced. Equipped with a catalyst in the exhaust passage,
The engine includes a fuel injector that directly injects fuel into the cylinder, and an ignition plug for igniting the air-fuel mixture in the cylinder when the ignition timing is reached, and the ignition timing is compressed and dead at the start of the engine. An in-cylinder direct injection spark ignition engine that performs super retard combustion by injecting fuel from the fuel injector before the ignition timing and after compression top dead center,
When the engine rotation speed passes through the vehicle resonance band at the time of starting the engine, the ignition timing for generating a peak of the engine rotation speed in the vehicle resonance band is advanced from the ignition timing at the time of super retard combustion. The engine control device according to claim 1, wherein   The engine control device according to claim 1 or 2, wherein when the ignition timing is advanced in the vehicle resonance band, fuel is injected before the advanced ignition timing.   The engine control device according to claim 3, wherein after the engine rotation speed passes through the vehicle resonance band, the ignition timing and the fuel injection timing are returned to the ignition timing and the fuel injection timing in the super retard combustion. .   The engine control device according to any one of claims 2 to 4, wherein the ignition timing advanced in the vehicle resonance band is close to the compression top dead center. The engine is automatically stopped when a predetermined idle stop permission condition is satisfied, and when the idle stop permission condition is not satisfied during the automatic engine stop, the engine has an idle stop control means for performing an idle stop control for restarting the engine,
The engine control device according to any one of claims 2 to 5, further including a restart time of the engine accompanying the idle stop control when the engine is started.   The ignition timing advanced in the vehicle resonance band is further advanced as the atmospheric pressure decreases according to atmospheric pressure, and fuel is injected before the further advanced ignition timing. The engine control device according to any one of 2 to 6.   3. The ignition timing to be advanced in the vehicle resonance band is further advanced as the engine friction increases in accordance with engine friction, and fuel is injected before the further advanced ignition timing. 8. The engine control device according to any one of items 1 to 7.