JP2011085026A - Internal combustion engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine control device capable of easily reducing vibration and improving startability of an internal combustion engine when starting the internal combustion engine. <P>SOLUTION: This internal combustion engine control device, in the case wherein engine starting conditions are satisfied (S400: Yes) and the rotation stop position of an engine is stored (S402: Yes), computes the timing of a rise of the common rail pressure to a predetermined pressure based on the rotation stop position of the engine (S404), and specifies an injection starting cylinder, which injects the fuel first, based on the computed timing of a rise, and computes the timing of switching a throttle device from a full closing position to a full opening position (S406). The internal combustion engine control device starts cranking (S408), and opens the throttle valve device full before injecting the fuel in the injection starting cylinder (S410). In the case wherein the internal combustion engine control device dose not store the rotation stop position of the engine (S402: No), the internal combustion engine control device sets a cylinder, which executes compressing strokes in a preset order, as an injection starting cylinder. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is an internal combustion engine that is applied to a fuel injection system in which the amount of intake air drawn into a cylinder of the internal combustion engine is adjusted by a throttle device, and fuel supplied from a fuel supply pump and accumulated in a common rail is injected from a fuel injection valve into the cylinder. The present invention relates to a control device.

  In order to start the internal combustion engine quickly in an internal combustion engine in which the fuel accumulated in the common rail is injected into the cylinder from the fuel injection valve and compressed and ignited, the cylinder that can compress and ignite the fuel at the earliest time when the internal combustion engine is started is specified. It is conceivable to start the first first injection from the identified cylinder. In particular, in the idle stop system, it is desirable that the internal combustion engine is quickly started when the driver performs an operation to resume running from the idle stop state, so that the driver does not feel uncomfortable.

  In such a compression ignition type internal combustion engine, the fuel injection pressure, that is, the common rail pressure is increased to a predetermined pressure required for the compression ignition in order to enable the compression ignition by executing the first injection at the start of the internal combustion engine. At the same time, it is necessary for each cylinder to perform which of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke, that is, the cylinder discrimination is completed.

  By the way, after starting the internal combustion engine, the common rail pressure is increased to a predetermined pressure and a predetermined cranking time by the starter motor is required until the cylinder discrimination is completed. At this time, if the intake air drawn into the cylinder is compressed by cranking in a cylinder other than the cylinder that executes the first injection before the first injection, vibration is generated in the internal combustion engine.

  In addition, if the intake air sucked in the cylinders other than the cylinder that performs the first injection is compressed by cranking before the first injection, an extra starter motor is required before the compression stroke is performed in the cylinder that performs the first injection. Since the work is performed, the rate of increase in the compression pressure in the cylinder that performs the first injection decreases. As a result, the ignitability in the cylinder that performs the first injection is reduced, and the startability of the internal combustion engine is reduced.

  Therefore, in Patent Document 1, at the time of cranking, the compression pressure is reduced by retarding the closing timing of the intake valve to near the top dead center for the cylinder before the first injection is performed. Thus, the vibration of the internal combustion engine at the time of starting is to be suppressed.

  Further, in Patent Document 1, when the cooling water temperature is lower than a predetermined value or when the required torque is higher than a predetermined value, the closing timing of the intake valve of the cylinder in which the first injection is performed is set near the bottom dead center. By changing, the intake air amount is increased to improve the startability.

JP 2007-239461 A

  However, in order to suppress the vibration of the internal combustion engine at the time of starting and improve the startability by adjusting the closing timing of the intake valve to control the compression pressure and the intake air amount, the closing timing of the intake valve A variable valve mechanism for controlling the motor is required. However, it is difficult to control the closing timing of the intake valve with a large operating angle between the vicinity of the top dead center and the bottom dead center with a mechanical variable valve mechanism.

  Therefore, in Patent Document 1, in order to control the closing timing of the intake valve with a large operating angle between the vicinity of the top dead center and the vicinity of the bottom dead center, the camshaft is directly driven by a motor regardless of the crankshaft. A variable valve mechanism is provided.

  However, although the camshaft can be controlled regardless of the crankshaft by driving the motor, it is necessary to control the driving speed of the motor relative to the camshaft based on the rotational speed of the crankshaft, so the control of the variable valve mechanism is complicated. is there.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an internal combustion engine control apparatus that can easily realize vibration reduction and startability improvement of an internal combustion engine when the internal combustion engine is started. .

  According to the first to fifth aspects of the present invention, the cylinder specifying means specifies an injection start cylinder capable of compression ignition by first injecting fuel from the fuel injection valve after the internal combustion engine starts to start, and an intake amount When the start of the internal combustion engine is commanded, the control means controls the throttle device to limit the amount of intake air taken into the cylinder, and limits the amount of intake before the first fuel injection is started in the injection start cylinder. To release.

  In this way, when the start of the internal combustion engine is commanded, the throttle device is controlled to limit the amount of intake air taken into the cylinder. Therefore, before compression ignition is performed in the injection start cylinder, The amount of work to compress the inhaled intake air by cranking can be reduced as much as possible. By reducing the amount of compression work, vibrations at the time of starting the internal combustion engine can be reduced.

  Further, the compression work performed by the starter motor before compression ignition is performed in the injection start cylinder is reduced, so that the increase rate of the compression pressure in the injection start cylinder is improved. As a result, compression ignition is easily performed in the injection start cylinder, so that the startability of the internal combustion engine is improved.

  Further, the opening degree of the throttle device can be easily adjusted by energization control to the motor. Therefore, when the start of the internal combustion engine is commanded, the vibration reduction and the startability improvement of the internal combustion engine can be easily realized by controlling the throttle device to limit the amount of intake air taken into the cylinder.

  According to the second aspect of the present invention, the cylinder specifying means, when the stop rotation position when the internal combustion engine stops when the start of the internal combustion engine is commanded is known, based on the stop rotation position, A pressure increase timing at which the pressure is increased from a fuel injection valve to a predetermined pressure required for compression ignition is predicted, and an injection start cylinder is specified based on the pressure increase timing.

  As described above, when the stop rotational position when the internal combustion engine is stopped is known, the cylinder discrimination is already completed when the internal combustion engine starts starting, and the start rotational position is known. Thereby, since it is not necessary to perform cylinder discrimination after the start of the internal combustion engine is instructed, it is possible to quickly and accurately predict the pressure increase timing at which the common rail pressure is increased to a predetermined pressure based on the stop rotation position. As a result, after the internal combustion engine has started, compression ignition can be performed in the injection start cylinder as early as possible based on the pressure increase timing.

According to a third aspect of the present invention, the cylinder specifying means sets the cylinder that first becomes the compression top dead center after the pressure increase timing as the injection start cylinder.
As a result, the pressure of the common rail is increased from the fuel injection valve to a predetermined pressure necessary for compression ignition, and fuel is injected into the injection start cylinder at the earliest time to execute compression ignition. Can start.

  According to the fourth aspect of the present invention, the cylinder specifying means is configured to start the engine when the internal combustion engine starts when the stop rotational position when the internal combustion engine stops when the start of the internal combustion engine is commanded is not known. A cylinder that executes a compression stroke in a preset order is defined as an injection start cylinder.

  As described above, when the stop rotational position when the internal combustion engine is stopped is not known, it is obvious that the start rotational position when the start of the internal combustion engine is instructed is unknown. However, it is possible to specify the number of the compression strokes at which the compression ignition is possible at the latest after the internal combustion engine starts the cranking start.

  Therefore, by setting in advance the number of compression strokes that will be executed after the internal combustion engine has started, the fuel is first injected and compression ignition is set in advance, so that the compression ignition start timing is actually compressed. Even if there is a possibility of being delayed from the time when ignition is possible, compression ignition can be reliably performed in the injection start cylinder.

  By the way, if the stop rotation position when the internal combustion engine is stopped is not known, the cylinder from which the internal combustion engine starts to start and the cylinder discrimination is completed and the common rail pressure is increased to a predetermined pressure, the injection start cylinder can be specified. . However, since the stop rotation position of the internal combustion engine is not known, it is impossible to predict when the cylinder discrimination is completed and when the common rail pressure is increased to a predetermined pressure.

  Therefore, according to the fifth aspect of the present invention, the order in which the compression stroke that is executed after the internal combustion engine starts is set as the injection start cylinder is determined after the internal combustion engine starts. The completion timing of cylinder determination of the internal combustion engine is set in advance based on the completion time when the cylinder discrimination is completed latest and the timing when the common rail pressure is increased to the predetermined pressure latest.

  In this way, after the internal combustion engine has started in a state where the stop rotational position when the internal combustion engine has stopped is unknown, the completion timing of the cylinder determination of the internal combustion engine is completed most recently, and the pressure on the common rail is the latest. Based on the timing when the pressure is increased to a predetermined pressure, compression is performed in the injection start cylinder by setting in advance the number of compression strokes to be executed from the start of the internal combustion engine as the injection start cylinder. Ignition can be performed reliably.

  The functions of the plurality of means provided in the present invention are realized by hardware resources whose functions are specified by the configuration itself, hardware resources whose functions are specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources that are physically independent of each other.

The block diagram which shows the fuel-injection system by this embodiment. The schematic diagram which shows a crank angle sensor and a cam angle sensor. The time chart which shows a crank angle signal and a cam angle signal. The time chart which shows the common rail pressure after starting an engine, throttle opening, and a cylinder discrimination completion flag. The flowchart which shows an engine starting routine.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A fuel injection system according to an embodiment of the present invention is shown in FIG.
(Fuel injection system 20)
The pressure accumulation type fuel injection system 20 of this embodiment includes a throttle device 22, a fuel supply pump 32, a common rail 34, a fuel injection valve 40, an electronic control unit (ECU) 60, and the like.

  A diesel engine (hereinafter also simply referred to as an engine) 12 to which the fuel injection system 20 supplies fuel is a four-cylinder internal combustion engine. The engine may be a multi-cylinder engine having a number of cylinders other than four cylinders.

An EGR (Exhaust Gas Recirculation) valve 14 adjusts the flow rate of circulating the exhaust of the engine 12 cooled by the EGR cooler 16 to the intake side.
The turbocharger compressor 2 is rotationally driven by a turbine 4 arranged coaxially. The intake air compressed by the compressor 2 passes through the intercooler 6, is adjusted in flow rate by the throttle device 22, and is sucked into each cylinder of the engine 12.

  The throttle device 22 is installed in the intake passage on the downstream side of the intercooler 6, and the opening degree is adjusted by energization control with respect to a motor (not shown) to adjust the intake air amount sucked into each cylinder of the engine 12. The throttle device 22 is throttled in order to put more EGR in the light load region, but is kept almost fully open in the high load region in order to increase the intake amount and reduce the pumping loss. The pressure of the intake air taken into the engine 12 is detected by the intake pressure sensor 10.

  The fuel supply pump 32 is a known pump that pressurizes the fuel sucked into the pressurizing chamber from the fuel tank 30 when the plunger reciprocates as the cam rotates. The fuel supply pump 32 incorporates a feed pump that sucks fuel from the fuel tank 30.

  By controlling the current value supplied to the metering valve (not shown) of the fuel supply pump 32 by the ECU 60, the fuel suction amount that the fuel supply pump 32 sucks in the suction stroke is metered. Then, by adjusting the fuel intake amount, the fuel discharge amount of the fuel supply pump 32 is adjusted.

  The common rail 34 accumulates the fuel pumped by the fuel supply pump 32 and maintains the fuel pressure at a predetermined high pressure according to the engine operating state. The pressure of the common rail 34 (hereinafter also referred to as “common rail pressure”) is controlled by the discharge amount of the fuel supply pump 32 and a pressure reducing valve (not shown) installed on the common rail 34.

  The fuel injection valve 40 is installed in each cylinder of the engine 12 and injects fuel stored in the common rail 34 into the cylinder. The fuel injection valve 40 performs multistage injection including pilot injection, main injection, post injection, and the like in one combustion cycle of the engine 12. The fuel injection valve 40 is a known electromagnetically driven valve that controls the fuel injection amount by controlling the pressure of a control chamber that applies fuel pressure to the nozzle needle in the valve closing direction.

  As shown in FIG. 2, the crank angle sensor 44 is an electromagnetic pickup type sensor provided facing the outer periphery of the crank rotor 46 fixed to the crankshaft of the engine 12. Teeth 47 are formed on the outer periphery of the crank rotor 46 at intervals of a predetermined angle (for example, 10 °), and one missing tooth portion 48 having missing teeth (for example, two) is provided in the middle of the dentition. It has been.

  The interval between the teeth 47 formed on the outer periphery of the crank rotor 46 is not limited to 10 °, and may be smaller or larger than 10 °. If the rotational position of the crankshaft is detected with high accuracy, it is desirable to make the interval between the teeth 47 smaller than 10 °.

  The crank angle sensor 44 outputs a pulsed crank angle signal (also referred to as an NE signal) every time the crankshaft rotates 10 ° (every 10 ° crank angle (CA)). When the rotation position of the crankshaft (hereinafter also referred to as the crank angle position) reaches the reference position where the missing tooth portion 48 of the crank rotor 46 faces the crank angle sensor 44, the crank angle is set for the missing tooth portion 48. The rising edge interval of the signal becomes longer. As a result, a rising edge as an effective edge occurs every 10 ° CA in the crank angle signal, and when the crank angle position reaches the reference position, a portion where the rising edge is missing appears.

The ECU 60 detects the engine position by detecting the crank position based on the crank angle signal and calculating the number of pulses of the crank angle signal per unit time.
The cam angle sensor 50 is an electromagnetic pickup type sensor provided facing the outer periphery of the cam rotor 52 fixed to the camshaft of the engine 12 that rotates at a ratio of 1/2 with respect to the rotation of the crankshaft.

  One tooth 53 is formed on the outer periphery of the cam rotor 52. The position of the tooth 53 is set within a range corresponding to the missing tooth portion 48 of the crank rotor 46. The cam angle sensor 50 has a pulsed cam angle signal (also referred to as a G signal) when the tooth 53 reaches a position facing the cam angle sensor 50, that is, a reference position corresponding to the missing tooth portion 48 of the crank rotor 46. Is output.

  With the configuration of the crank angle sensor 44, the crank rotor 46, the cam angle sensor 50, and the cam rotor 52, as shown in FIG. 3, the crank angle signal corresponds to the tooth 53 of the cam rotor 52 at the reference position corresponding to the missing tooth portion. When the cam angle signal is detected, it can be determined that the crank angle position is near the bottom dead center of the compression stroke of the # 1 cylinder. Further, when the cam angle signal corresponding to the tooth 53 of the cam rotor 52 is not detected at the portion corresponding to the missing tooth portion of the crank angle signal, it can be determined that the crank angle position is near the bottom dead center of the compression stroke of the # 4 cylinder. . Thereby, it is possible to execute cylinder discrimination for determining which cylinder is executing which stroke in one combustion cycle of the engine 12 including the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke. Then, by determining the cylinder, the crank angle position of the engine 12 is detected.

  As shown in FIG. 1, the ECU 60 is mainly configured by a microcomputer having a rewritable storage device such as a CPU 62, a RAM 64, a ROM 66, and a flash memory 68. The ECU 60 is acquired from various sensors such as the intake pressure sensor 10, the crank angle sensor 44, and the cam angle sensor 50 by the CPU 62 executing a control program stored in a storage device such as the ROM 66 and the flash memory 68 of the ECU 60. Based on the engine operating state, energization to the EGR valve 14, the metering valve of the fuel supply pump 32, and the fuel injection valve 40 is controlled.

  The ECU 60 controls the injection timing and the injection amount of the fuel injection valve 40 based on the engine operating state obtained from various sensors. The ECU 60 outputs an injection pulse signal as an injection command signal for controlling the injection timing and the injection amount of the fuel injection valve 40. When the pulse width of the injection pulse signal is increased, the time during which the control chamber of the fuel injection valve 40 is opened to the low pressure side is increased, so that the injection amount is increased. The ECU 60 stores an injection amount characteristic representing the relationship between the pulse width of the injection pulse signal and the injection amount in a storage device such as the ROM 66 or the flash memory 68 as a map for each common rail pressure that is an injection pressure.

(Stop rotation position when engine 12 stops)
When the idle stop condition is satisfied or when the engine start switch is turned off, the ECU 60 stops the fuel injection from the fuel injection valve 40 and stops the engine 12. Here, the engine 12 includes a case where the piston of the cylinder is reversely stopped without exceeding the compression top dead center (compression TDC) and a case where the cylinder 12 is rotated forward and stopped beyond the compression TDC.

  When the crank angle sensor 44 is a pulse type, the reverse rotation crank angle in the direction opposite to the rotation direction during normal operation cannot be counted down, so the piston of which cylinder is compression dead on the basis of the change rate information of the pulse interval time of the NE signal. It is determined whether the point (compression TDC) has not been exceeded and the rotation has been reversed and stopped, or the compression TDC has been reversed and the rotation has been stopped. A cylinder that has been reversed and stopped without exceeding the compression TDC is a cylinder that is stopped in the compression stroke (also referred to as a compression stop cylinder). Further, the cylinder that is in the compression stroke next to the cylinder that has been rotated forward and stopped beyond the compression TDC is the compression stopped cylinder.

  Then, when the engine 12 is stopped, the crank angle position can be calculated as the stop rotation position where the compression stop cylinder is stopped together with the compression stop cylinder based on the forward rotation crank angle or the reverse rotation crank angle from the compression TDC.

  When the crank angle sensor 44 is an incremental type, the reverse crank angle can be counted down, so that the compression stop cylinder and the crank angle position at which the compression stop cylinder stops can be easily calculated.

In this way, the ECU 60 functions as a stop rotation position detection unit that detects a stop rotation position when the engine 12 is stopped.
When the engine 12 is stopped by turning off the engine start switch, the ECU 60 stores the compression stop cylinder and the crank angle position at which the compression stop cylinder stops in the flash memory 68 or a backup RAM (not shown). The ECU 60 may store the compression stop cylinder and the crank angle position at which the compression stop cylinder is stopped in the RAM 64 when the engine 12 is stopped due to idle stop.

(Control at engine start)
(1) When the crank angle position when the engine is stopped is known The ECU 60 stores the compression stop cylinder when the engine 12 is stopped and the crank angle position where the compression stop cylinder is stopped. When the engine stop switch is turned on when an idle stop restart request due to brake-off or the like is satisfied or the engine start switch is turned on in the idle stop state, the stored compression stop cylinder and compression Based on the crank angle position where the stopped cylinder is stopped, the common rail pressure is increased to a predetermined pressure required to inject fuel from the fuel injection valve 40 to cause compression ignition.

  Thus, when the crank angle position when the engine is stopped is known, the cylinder discrimination is completed when the start of the engine 12 is commanded. Therefore, in FIG. 4, when the engine 12 is instructed to start, the cylinder discrimination completion flag is on.

  The fuel supply pump 32 pumps fuel pressurized by the plunger being reciprocated by a drive shaft that rotates in synchronization with the crankshaft. Therefore, the degree of increase in the amount of fuel pumped by the fuel supply pump 32 after the engine 12 starts is different depending on the crank angle position when the engine 12 is stopped, that is, the reciprocating position of the plunger of the fuel supply pump 32. The rate of increase in the common rail pressure varies depending on the increase in the amount of fuel pumped by the fuel supply pump 32.

  In other words, when the start of the engine 12 is instructed, the rate of increase of the common rail pressure after the engine 12 starts can be calculated based on the crank angle position when the engine 12 is stopped. As a result, it is possible to predict the pressure increase timing at which the common rail pressure is increased from the fuel injection valve 40 to a predetermined pressure required for compression ignition after the engine 12 starts to be started by cranking. FIG. 4 shows a case where the rise of the common rail pressure is fast and a case where it is slow.

  When the common rail pressure is increased to a predetermined pressure, the fuel injected from the fuel injection valve 40 can be compressed and ignited in the cylinder executing the compression stroke. Then, the ECU 60 identifies the cylinder that first becomes the compression TDC after the pressure increase timing when the common rail pressure is increased to a predetermined pressure as the injection start cylinder that can inject the fuel from the fuel injection valve 40 and can perform compression ignition. In FIG. 4, * indicates the first injection timing after the engine 12 is started.

  In FIG. 4, the injection start cylinder is a cylinder that executes the compression stroke second after the engine 12 starts starting when the common rail pressure rises quickly, and when the common rail pressure rises slowly, This is the third cylinder that performs the compression stroke after the engine 12 starts to start.

  When the start of the engine 12 is commanded, the ECU 60 fully closes the opening of the throttle device 22 in order to limit the amount of intake air drawn into the cylinders of the engine 12 during cranking. Since the throttle device 22 is fully closed when the motor is turned off, the throttle device 22 is fully closed if the motor of the throttle device 22 is kept off when the engine 12 is instructed to start. The state remains.

  Then, before the fuel is injected into the injection start cylinder, the intake air is sucked in the intake stroke of the injection start cylinder, and the intake air is compressed in the compression stroke in the injection start cylinder so that the cylinder before the injection start cylinder is compressed. By energizing the motor of the throttle device 22 at a predetermined crank angle advance side with respect to the compression TDC, the fully closed state of the throttle device 22 is released and fully opened. While the throttle device 22 is being cranked in the fully closed state, the in-cylinder pressure is decreased, and therefore, slightly advanced from the compression TDC of the cylinder before the injection start cylinder, that is, the intake stroke of the injection start cylinder. Even when the throttle device 22 is fully opened on the advance side slightly from the bottom dead center (BDC), the intake air can be sufficiently sucked into the cylinder in the intake stroke of the injection start cylinder.

  Further, when the throttle device 22 is fully closed to fully opened, the injection start cylinder performs the intake stroke so that intake air is sucked at the initial stage of the compression stroke and compression work by cranking is not performed in cylinders other than the injection start cylinder. It is desirable that it is as slow as possible within the range where inhalation can be inhaled.

In this manner, the ECU 60 functions as a throttle device control unit that controls the throttle device 22 from the fully closed state to the fully opened state in the intake stroke before the compression stroke in the injection start cylinder.
(2) When the crank angle position when the engine is stopped is not known The ECU 12 or the battery replacement may cause the compression stop cylinder when the engine 12 is stopped and the crank angle position where the compression stop cylinder is stopped to be indefinite. .

In this case, the cylinder discrimination completion flag is OFF because the cylinder discrimination is not completed when the start of the engine 12 is commanded.
Therefore, when the start of the engine 12 is commanded, the ECU 60 needs to execute cylinder discrimination based on the NE signal and the G signal. As described above, the cylinder discrimination is performed by determining whether or not the G signal corresponding to the tooth 53 is detected at a portion corresponding to the missing tooth portion of the NE signal.

  As shown in FIG. 4, when the cylinder discrimination is early, it is completed before the compression TDC of the cylinder that becomes the compression stroke for the second time after the engine 12 starts to start. This is completed before the compression TDC of the cylinder which is the third compression stroke after starting.

  When the common rail pressure rises the fastest, the common rail pressure is increased to a predetermined pressure before the compression TDC of the cylinder that performs the second compression stroke after the engine 12 starts to start. Therefore, if the crank angle position when the engine is stopped is not known, or in the earliest case, compression ignition can be performed with the cylinder that performs the second compression stroke after the engine 12 starts starting as the injection start cylinder.

  However, if the crank angle position when the engine is stopped is not known, the ECU 60 cannot predict whether the cylinder discrimination will be completed early or late after the engine 12 starts starting, and the common rail pressure is increased to a predetermined pressure early. I can't predict whether to boost or slow.

  Therefore, based on the cylinder discrimination completion timing at which the cylinder discrimination is completed latest and the boost timing at which the common rail pressure is increased to the predetermined pressure latest, the preset order is set after the engine 12 starts to be started later. In the present embodiment, the cylinder that performs the third compression stroke is the injection start cylinder, and fuel is injected from the fuel injection valve 40 to cause compression ignition.

  Further, when the start of the engine 12 is instructed, the ECU 60 fully closes the opening degree of the throttle device 22. Then, at the time when the start of the engine 12 is instructed, the ECU 60 is able to suck in the intake stroke of the cylinder that performs the third compression stroke from the start start position of the engine 12, for example, 180 °. It is set that the throttle device 22 is changed from fully closed to fully opened after CA. As a result, the compression work of the starter motor due to cranking can be reduced in the cylinders that execute the first and second compression strokes.

  Here, as described above, the cylinder discrimination is completed before the compression TDC of the cylinder that becomes the compression stroke for the second time after the engine 12 starts to be started at the early stage. Then, the cylinder discrimination completion timing is advanced from the start start position of the engine 12 after 180 ° CA, that is, the time when the throttle device 22 is set from fully closed to fully open when the engine 12 is instructed to start. If it is on the more advanced side, the ECU 60 resets the timing for fully opening the throttle device 22 slightly on the more advanced side than the compression TDC of the cylinder that is in the second compression stroke.

As a result, it is possible to prevent the intake work from being sucked in the initial stage of the compression stroke in the cylinders other than the injection start cylinder and performing the compression work by the cranking.
(Engine start routine)
FIG. 5 shows an engine start routine. The routine of FIG. 5 is always executed. In FIG. 5, “S” represents a step.

In S400, the ECU 60 determines whether or not an engine start condition is satisfied. In the following cases, the ECU 60 determines that the engine start condition is satisfied.
(1) When the engine 12 is stopped due to an idle stop. In the case of an AT vehicle, for example, the brake pedal is released.
・ In the case of MT cars, for example, the clutch pedal was depressed.
(2) When the engine start switch is off and the engine 12 is stopped-The engine start switch is turned on.

When the engine start condition is not satisfied (S400: No), the ECU 60 ends this routine.
When the engine start condition is satisfied (S400: Yes), in S402, the ECU 60 stores the compression stop cylinder which is the cylinder discrimination information when the engine 12 is stopped, and the crank angle position information where the compression stop cylinder is stopped. It is determined whether or not. In the state where the start of the engine 12 is commanded, the energization of the motor of the throttle device 22 is cut off, and the throttle opening is fully closed.

  When the cylinder determination information when the engine 12 is stopped and the stopped crank angle position information are stored (S402: Yes), in S404, the ECU 60 determines the cylinder determination information when the engine 12 is stopped, and the stopped crank Based on the angular position information, the common rail pressure calculates and predicts the pressure increase timing at which the common rail pressure is increased to the minimum injection pressure as a predetermined pressure necessary for injecting fuel from the fuel injection valve 40 to cause compression ignition.

  Then, the ECU 60 calculates the time when the throttle device 22 is fully opened from the fully closed state after the engine 12 starts to start based on the calculated pressure increase timing, and first injects fuel from the fuel injection valve 40. The injection start cylinder to be ignited by compression is specified (S406), the engine 12 is cranked by the starter, and the start is started (S408).

  When the fully open timing calculated in S406 is reached, the ECU 60 fully opens the throttle device 22 (S410), injects fuel from the fuel injection valve 40 installed in the injection start cylinder (S410), and ends this routine.

  When the cylinder discrimination information when the engine 12 is stopped and the stopped crank angle position information are not stored (S402: No), in S414, the ECU 60 sets the start start position as the time when the throttle device 22 is fully closed to fully open. And 180 ° CA retarded angle side is set. In S416, the ECU 60 starts the engine 12 by cranking the engine 12 with a starter.

  Note that, as described above, the ECU 60 starts the engine 12 in accordance with the later timing based on the cylinder discrimination completion timing at which the cylinder discrimination is completed latest and the common rail pressure is increased to the predetermined pressure latest. The cylinder that executes the compression stroke third after the start is set as the injection start cylinder.

  In S418, the ECU 60 determines whether or not the cylinder discrimination is completed on the advance side from the fully opened timing of the throttle device 22 after the engine 12 is cranked by the starter. If the cylinder discrimination is not completed on the advance side of the fully opened timing of the throttle device 22 that has been set (S418: No), the ECU 60 proceeds to S422.

  When the cylinder discrimination is completed on the advance side with respect to the set full opening timing of the throttle device 22 (S418: Yes), in S420, the ECU 60 sets the timing at which the throttle device 22 is fully opened to the second compression stroke. It is reset slightly ahead of the compression TDC.

  In S422, the ECU 60 opens the throttle device 22 from fully closed to fully open based on the set time. Then, the process proceeds to S412 to inject fuel from the fuel injection valve 40 installed in the injection start cylinder, and this routine is finished.

  In the present embodiment, the ECU 60 corresponds to the internal combustion engine control device of the present invention. 5 corresponds to the function executed by the cylinder specifying means of the present invention, and the process of S410 corresponds to the function executed by the intake air amount control means of the present invention.

  In the above-described embodiment, when the engine 12 is instructed to start, the throttle device 22 is fully closed, and before the fuel is first injected from the fuel injection valve 40 installed in the injection start cylinder, the throttle device 22 is turned on. Fully open. Thereby, before fuel is injected in the injection start cylinder, the work amount for compressing the intake air sucked into the cylinder can be reduced as much as possible in the cylinders other than the injection start cylinder. By reducing the amount of compression work, it is possible to reduce vibrations when the engine 12 is started.

  Further, since the compression work performed by the starter motor before injecting fuel in the injection start cylinder is reduced, the rate of increase in the compression pressure in the injection start cylinder is improved. As a result, compression ignition is easily performed in the injection start cylinder, so that the startability of the engine 12 is improved.

  Further, since the opening degree of the throttle device 22 can be easily adjusted by energization control to the motor, when the start of the engine 12 is instructed, the throttle device 22 is controlled to limit the amount of intake air taken into the cylinder. Vibration reduction and startability improvement when starting the engine 12 can be easily realized.

[Other Embodiments]
In the above embodiment, when the start of the engine 12 is commanded, the throttle device 22 is fully closed, and before the fuel is injected in the injection start cylinder, the amount of intake air sucked into the cylinders other than the injection start cylinder Restricted. Instead of fully closing the throttle device 22, the amount of intake air drawn into the cylinder may be limited by reducing the opening of the throttle device 22.

  In the above embodiment, the functions of the cylinder specifying means and the intake air amount limiting means are realized by the ECU 60 whose functions are specified by the control program. On the other hand, at least a part of the functions of the above means may be realized by hardware whose function is specified by the circuit configuration itself.

  As described above, the present invention is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

12: Diesel engine (internal combustion engine), 20: Fuel injection system, 22: Throttle device, 32: Fuel supply pump, 34: Common rail, 40: Fuel injection valve, 60: ECU (Internal combustion engine control device, Cylinder specifying means, Intake air) Amount limiting means)

Claims (5)

In an internal combustion engine control apparatus applied to a fuel injection system that adjusts an intake air amount sucked into a cylinder of an internal combustion engine with a throttle device and injects fuel supplied from a fuel supply pump and accumulated in a common rail into the cylinder from a fuel injection valve ,
Cylinder specifying means for specifying an injection start cylinder capable of compression ignition by injecting fuel from the fuel injection valve first after the internal combustion engine starts starting;
When the start of the internal combustion engine is commanded, the throttle device is controlled to limit the amount of intake air taken into the cylinder, and the first fuel injection is started in the injection start cylinder specified by the cylinder specifying means. An intake air amount control means for releasing the restriction of the intake air amount before;
An internal combustion engine control device comprising:   If the stop rotation position when the internal combustion engine is stopped when the start of the internal combustion engine is commanded is known, the cylinder specifying means determines the pressure of the common rail based on the stop rotation position as the fuel injection 2. The internal combustion engine control according to claim 1, wherein a boosting timing at which the pressure is increased to a predetermined pressure required for injection from the valve to perform compression ignition is predicted, and the injection start cylinder is specified based on the boosting timing. apparatus.   The internal combustion engine control device according to claim 2, wherein the cylinder specifying means sets the cylinder that first becomes a compression top dead center after the boosting timing as the injection start cylinder.   The cylinder specifying means, when the start rotational position of the internal combustion engine is instructed and when the stop rotational position when the internal combustion engine stops is not known, The internal combustion engine control device according to claim 1, wherein a cylinder that executes a compression stroke is the injection start cylinder.   The order is that the cylinder discrimination completion timing when the cylinder discrimination of the internal combustion engine is completed after the start of the internal combustion engine and the pressure of the common rail are injected from the fuel injection valve to perform compression ignition. 5. The internal combustion engine control device according to claim 4, wherein the internal combustion engine control device is preset based on a boosting timing at which the pressure is boosted latest to the required predetermined pressure.

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