DE102010040843A1 - Control device for internal combustion engine, comprises pressure acquisition unit for acquisition of interior cylinder pressure in each cylinder of internal combustion engine - Google Patents

Abstract

The control device comprises a pressure acquisition unit for acquisition of an interior cylinder pressure in each cylinder of the internal combustion engine. A peak pressure collection unit for collecting a last cylinder with an interior cylinder pressure, which forms a last peak, if the internal combustion engine stops corresponding to the interior cylinder pressure. An independent claim is also included for a method for controlling an internal combustion engine.

Description

BACKGROUND OF THE INVENTION

(Field of the Invention)

The present invention relates to a control apparatus for an internal combustion engine. More particularly, the present invention relates to a control apparatus for an internal combustion engine that identifies a cylinder that stops in a compression stroke when an internal combustion engine stops.

(Description of the Related Art)

As one of various control devices for an internal combustion engine, a technique is known in which, in order to start an internal combustion engine quickly, a cylinder most likely to quickly ignite a fuel when the internal combustion engine starts is identified. Fuel injection is started from the identified cylinder. In an idling stop system, in particular, it is desirable to prevent a driver from experiencing an uncomfortable feeling by starting the engine quickly when the driver performs an operation to resume driving from an idling stop state.

For example, the Japanese Patent Application Laid-Open Publication No. 2005-120905 a technology for detecting the cylinder with the last peak in-cylinder pressure (tip-in-cylinder pressure) when the internal combustion engine stops, and for determining that the cylinder has been stopped in the compression stroke. A cylinder stopped in the compression stroke starts from the compression stroke when the internal combustion engine is started. Therefore, in the Japanese Patent Application Laid-Open Publication No. 2005-120905 Starting a fuel injection from the cylinder, which starts in the compression stroke when the internal combustion engine is started, and the internal combustion engine is started quickly.

In the Japanese Patent Application Laid-Open Publication No. 2005-120905 A crankshaft leads to an upper compression dead center (TDC) of a particular cylinder when the engine stops. However, the crankshaft is turning backwards because the crankshaft can not move beyond the compression TDC. The last peak in the in-cylinder pressure is determined to occur in the particular cylinder at that time. It should be noted that the particular cylinder is the cylinder with the last peak inner cylinder pressure as a result of the crankshaft being backward rotated since it is unable to move beyond the compression TDC, even though it is toward the compression TDC is advanced when the internal combustion engine stops.

However, when the crankshaft advances to the compression TDC of the specific cylinder when the engine stops, and moves beyond the compression TDC of the specific cylinder and the cylinder crankshaft in the expansion stroke, the cylinder in which the crankshaft in the Expansion stroke stops being the cylinder with the last peak inside cylinder pressure. Therefore, by merely detecting the cylinder with the last peak inner cylinder pressure, it is not possible to determine whether the detected cylinder was stopped in the compression stroke or a cylinder that is in the compression stroke following the cylinder with the last peak inner cylinder pressure was stopped in the compression stroke.

SUMMARY OF THE INVENTION

The present invention is provided to solve the problem described above. It is an object of the present invention to provide a control apparatus for an internal combustion engine that identifies with high accuracy a cylinder that stops in a compression stroke when an internal combustion engine stops.

The inventors of the present invention have focused on the in-cylinder pressure which constitutes the last peak in a final cylinder with the in-cylinder pressure forming the last peak when the engine stops, regardless of whether the piston of the cylinder is rotating backwards without being able to move beyond the compression TDC and stop in the compression stroke, or if the piston of the cylinder moves above the compression TDC and stops in an expansion stroke.

The inventors have found that the change state of the in-cylinder pressure forming the last peak is changed depending on whether the piston of the cylinder stops after being moved over the compression TDC or stops without being able to to move over the compression TDC. In other words, when the piston stops without being able to move beyond the compression TDC, the peak in the in-cylinder pressure is steeper than the peak in the in-cylinder pressure when the piston moves above the compression TDC and stops.

Therefore, according to a first aspect of the present invention, an invention comprises: pressure acquiring means for acquiring an in-cylinder pressure in each Cylinder of an internal combustion engine; a pressure peak detecting means for detecting a last cylinder having an in-cylinder pressure forming a last peak when the internal combustion engine stops based on the in-cylinder pressure acquired by the pressure acquiring means; determining means for determining whether a piston of the last cylinder moves above an upper compression dead center when the internal combustion engine stops based on a state of change of the in-cylinder pressure forming the last peak in the last cylinder; an identification means for identifying a cylinder stopped in the compression, which stops in a compression stroke; and storage means for storing the cylinder stopped in the compression identified by the identification means.

As a result, whether the piston of the cylinder has moved beyond the compression TDC and is stopped or the piston has reversed without being able to move beyond the compression TDC and stopped the basis of the state of change of the in-cylinder pressure forming the last peak in the last cylinder can be determined with high accuracy, rather than based on how high the in-cylinder pressure is.

When the piston of the cylinder moves and stops above the compression TDC, a cylinder to be a cylinder following the compression stroke becomes the cylinder stopped in the compression, which stops in the compression stroke when the engine stops. When the piston of the cylinder rotates backward without being able to move beyond the compression TDC, the cylinder of the cylinder stopped in the compression stops, which stops in the compression stroke when the internal combustion engine stops.

As a result of the cylinder stopped in the compression, which stops in the compression stroke when the internal combustion engine stops, and which is identified and stored without being erroneously determined, the internal combustion engine can be started quickly if fuel is ignitable in the stopped in the compression Cylinder is when the engine is started.

Therefore, the duration of operation by a starter forcibly rotating the engine before the fuel is ignited in the cylinder and the engine is started is shortened. As a result, the life of the starter is improved. Further, in an idling stop system, a driver is prevented from experiencing an uncomfortable feeling because the engine starts quickly when the driver performs an operation to resume driving from an idling stop state.

In an invention according to a second aspect in the present embodiment, the determining means determines whether the piston of the last cylinder moves above the top compression dead center when the internal combustion engine stops, based on a rate of change in the in-cylinder pressure that is the last peak in the last cylinder forms.

The peak of the in-cylinder pressure in a cylinder in which the piston stops without being able to move beyond the compression TDC is steeper than the peak of the in-cylinder pressure in a cylinder moving above the compression TDC and stops. Therefore, the rate of change of the in-cylinder pressure differs between the in-cylinder pressure when the cylinder stops without being able to move beyond the compression TDC and the in-cylinder pressure when the cylinder moves and stops above the compression TDC. Based on the rate of change in the in-cylinder pressure forming the last peak in the last cylinder, it may be determined whether the piston of the last cylinder has moved beyond the compression TDC when the engine stops.

In an invention according to a third aspect in the present embodiment, the determining means determines whether the piston of the last cylinder has moved above the top compression dead center when the internal combustion engine stops by comparing a maximum value the rate of change in the in-cylinder pressure forming the last peak in the last cylinder with a predetermined value.

The peak of the in-cylinder pressure in a cylinder in which the piston stops without being able to move beyond the compression TDC is steeper than the peak of the in-cylinder pressure in a cylinder moving above the compression TDC and stops. Therefore, the maximum value of the rate of change of the in-cylinder pressure differs between the in-cylinder pressure when the cylinder stops without being able to move beyond the compression TDC and the in-cylinder pressure when the cylinder moves above the compression TDC and stops. Whether the piston of the last cylinder has been moved beyond the compression TDC when the internal combustion engine stops can be determined with high accuracy by comparing between the maximum value of the rate of change in the in-cylinder pressure forming the last peak in the last cylinder and a predetermined value be determined. The predetermined value, which is compared with the maximum value of the rate of change in the in-cylinder pressure constituting the last peak in the last cylinder, may be a constant value. Alternatively, the predetermined value may be a variable value that varies depending on a rotational speed calculated based on the rotational speed (rotational speed) of the last cylinder as a parameter.

In an invention according to a fourth aspect in the present embodiment, the determining means determines whether the piston of the last cylinder moves above the top compression dead center when the internal combustion engine stops based on a second derivative of the in-cylinder pressure including the last peak in the last cylinder forms.

The peak of the in-cylinder pressure in a cylinder in which the piston stops without being able to move beyond the compression TDC is steeper than the peak of the in-cylinder pressure in a cylinder moving above the compression TDC and stops. Therefore, the waveform differs rather than the amount of in-cylinder pressure between the in-cylinder pressure when the cylinder stops without being able to move beyond the compression TDC and the in-cylinder pressure when the in-cylinder pressure exceeds the compression TDC moves and stops. A second derivative of the in-cylinder pressure expresses a waveform of the in-cylinder pressure. Therefore, based on the second derivative of the in-cylinder pressure forming the last peak in the last cylinder, it may be determined whether the piston of the last cylinder has moved beyond the compression TDC when the engine stops.

Each function provided by the plurality of means included in the present invention is realized by hardware resources whose functions are specified by their constitution, by hardware resources whose functions are specified by programs, or by their combination. The functions provided by the plurality of means are not limited to those realized by hardware resources arranged physically independently of each other.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings show:

1 Fig. 10 is a block diagram showing a fuel injection system according to an embodiment;

2 FIG. 12 is a schematic diagram showing a crank angle sensor and a cam angle sensor; FIG.

3 Fig. 12 is a diagram of a NE signal and a G signal explaining a cylinder in which an injection starts when an engine starts;

4 Fig. 10 is a time chart showing a relationship between the number of revolutions, the in-cylinder pressure and the stroke of each cylinder when the engine stops;

5 Fig. 11 is another time chart showing the relationship between the rotational speed, the in-cylinder pressure and the stroke of each cylinder when the engine stops; and

6 is an identification routine for identifying a cylinder that stops in the compression stroke and a cylinder in which an injection starts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below with reference to the drawings.

1 shows a fuel injection system according to an embodiment of the present invention.

(Fuel injection system 20 )

A fuel injection system 20 The memory type according to the embodiment is by a high-pressure pump 32 , a common rail 34 , a fuel injection valve 40 , a combustion pressure sensor (CPS) 42 , an electronic control unit (ECU) 60 and the like.

A diesel engine (hereinafter also referred to simply as "engine") 12 to which the fuel injection system 20 Fuel is an internal combustion engine with four cylinders. The machine may also be a multi-cylinder machine having more or less than four cylinders.

A compressor 2 a turbocharger is powered by driving a machine 4 rotated, which is arranged on the same axis. Intake air passing through the compressor 2 is compressed, flows through an intercooler 6 , The flow of intake air is through an intake throttle valve 8th regulated. The intake air is then injected into each cylinder of the engine 12 brought in. The intake throttle valve 8th is closed to an exhaust gas recirculation flow (EGR flow) in low load ranges. The intake throttle valve 8th is kept approximately fully open in high load ranges to increase the amount of intake air, reduce pumping losses, and the like. An intake air pressure sensor 10 captures the pressure of the intake air entering the engine 12 is introduced.

An EGR valve 14 regulates the flow of exhaust gas from the engine 12 that by an EGR cooler 16 is cooled and returned to the inlet side.

The high pressure pump 32 is a known pump, which pressurizes a fuel in a pressure chamber from a fuel tank 30 is introduced by reciprocating based on the rotation of a cam on a camshaft. As a result of the ECU 60 controlling a current value supplied to a control valve (not shown) of the high pressure pump 32 is fed, the amount of fuel passing through the high pressure pump 32 is introduced into an intake stroke set. The amount of fuel coming from the high pressure pump 32 is then set as a result of the adjustment of the amount of fuel introduced.

The common rail 34 stores a fuel from the high pressure pump 32 is pumped, and keeps the fuel pressure at a predetermined high pressure in accordance with an operating state of the engine 12 , The pressure in the common rail 34 (hereinafter also referred to as "common rail pressure") is determined by the amount of discharge from the high pressure pump 32 and a pressure reducing valve (not shown) mounted in the common rail 34 is arranged, controlled.

The fuel injector 40 is in every cylinder of the machine 12 arranged and injects the fuel, which is in the common rail 34 is stored in the respective cylinder. The fuel injector 40 performs a multiple injection including a pilot injection, a main injection, a post injection and the like during a single compression cycle of the engine 12 one. The fuel injector 40 is a known electromagnetically operated valve that controls the amount of fuel injection by controlling the pressure within a control chamber in which a fuel pressure is applied to a nozzle needle in a valve closing direction.

The CPS 42 is provided in each cylinder integral with a glow plug (not shown). The CPS 42 is a pressure sensor that measures the internal cylinder pressure in the machine 12 detected. As in 2 is shown is a crank angle sensor 44 an electromagnetic pickup sensor facing the outer periphery of a crank rotor 46 is provided on a crankshaft of the machine 12 is fixed. teeth 47 are at predetermined angular intervals (for example, 10 °) on the outer circumference of the crank rotor 46 educated. A toothless area 48 in which teeth are missing (for example, two teeth) is provided within the row of teeth.

The distance between the teeth 47 located on the outer circumference of the crank rotor 46 are formed is not limited to a 10 ° angle. The angle can be less than or greater than 10 °. To detect the rotational position of the crank angle with high accuracy, the distance between the teeth 47 preferably smaller than the 10 ° angle.

The crank angle sensor 44 outputs a pulsed crank angle signal (hereinafter also referred to as a NE signal) each time the crankshaft rotates 10 ° (every 10 ° CA). The rotational position of the crankshaft (hereinafter also referred to as a crank angle position) reaches a reference position at which the crank angle sensor 44 to the toothless area 48 of the crank rotor 46 facing, being because of the toothless area 48 extends a rising edge interval of the crank angle sensor. Therefore, a rising edge of the crank angle signal serving as an effective edge is generated every 10 ° CA. In addition, a portion having no rising edge occurs when the crank angle position reaches the reference position.

The ECU 60 detects a crank position based on the crank angle signal and detects the engine speed by calculating the number of pulses of the crank angle signal per unit time. A cam angle sensor 50 is an electromagnetic pickup sensor connected to the outer circumference of a cam rotor 52 facing, on a camshaft of the machine 12 is fixed, which rotates at half the speed of the crankshaft. Four teeth 53 are on the outer circumference of the cam rotor 52 formed at a distance of a predetermined angle (90 ° according to the embodiment). An additional tooth 54 , of the four teeth 53 is different, is in front of a tooth 53 from the four teeth 53 provided in the direction of rotation. The four teeth 53 are set such that the rotational position ensures a crank stroke for achieving an in-cylinder pressure required to compress and ignite fuel when a piston approaches the compression TDC, such as a CA of 60 ° before TDC. In addition, the position of the additional tooth 54 set within an area leading to the toothless area 48 of the crank rotor 46 corresponds.

The crank angle sensor 50 gives a pulsed cam angle signal (hereinafter referred to as a G Signal) every time the camshaft rotates 90 ° (180 ° CA). The cam angle sensor 50 Further outputs a pulse signal when the rotational position of the camshaft reaches a reference position at which the cam angle sensor 50 to the extra tooth 54 of the cam rotor 52 is facing.

As a result of the structure of the crank angle sensor 44 with the crank rotor 46 , the cam angle sensor 50 and the cam rotor 52 As described above, as shown in FIG 3 is shown when the cam angle signal equivalent to the additional tooth 54 is detected in a portion of the crank angle signal, which is equivalent to the toothless portion 48 is the crank angle position near the bottom dead center of the compression stroke of a cylinder # 1 determined. If the crank angle signal, equivalent to the additional tooth 54 is, in the portion of the crank angle signal, the equivalent to the toothless portion 48 is not detected, the crank angle position may be determined to be close to the bottom dead center of the compression stroke of a cylinder 44 is. As a result, the cylinder starting in the compression stroke can be determined.

The ECU 60 mainly includes a microcomputer that supports a processor (CPU) 62 , a read-only memory (RAM) 64 , a read-only memory (ROM) 66 and a rewritable storage device such as a flash memory 68 having. The ECU 60 controls an excitation of the control valve of the high-pressure pump 32 and the fuel injection valve 40 based on the operating condition of the machine 12 that of the various sensors such as the intake air pressure sensor 10 the CPS 42 , the crank angle sensor 44 and the cam angle sensor 50 is acquired as a result of the CPU 62 Run control programs in the ROM 66 and in the storage device such as the flash memory 68 the ECU 60 are stored.

The ECU 60 controls the injection timing and the injection amount of the fuel injection valve 40 based on the operating condition of the machine 12 which is acquired by the different sensors. The ECU 60 outputs an injection pulse signal as an injection command signal indicating the injection timing and the injection amount of the fuel injection valve 40 controls. As the pulse width of the injection pulse signal increases, the period of time over which the control chamber of the fuel injection valve increases increases 40 is open to a low pressure side. Therefore, the injection amount increases. The ECU 60 stores the injection amount characteristics indicative of the ratio between the pulse width of the injection pulse signal and the injection amount as a map for each common rail pressure, which is an injection pressure, in the ROM 66 or a storage device such as the flash memory 68 ,

(Change state of the in-cylinder pressure when the engine 12 stops)

4 and 5 show the state of change of an in-cylinder pressure in each cylinder detected by the ECU 60 is acquired on the basis of the output signals from the CPS 42 when the machine stops.

The machine 12 rotates by an inertial force, even after the fuel injection valve 40 the injection of fuel stops. During this rotation, the in-cylinder pressure in each cylinder forms a peak (peak) that is in the middle of the compression TDC. As in 4 is shown when the piston in cylinder # 1 can not move beyond the compression TDC and rotates backwards and the engine 12 as a result of this, the cylinder # 1 stops in the compression stroke, the cylinder pressure of the cylinder # 1 makes the last peak. The cylinder in which the in-cylinder pressure forms the last peak when the engine 12 stops is also referred to as the last cylinder.

On the other hand, as in 5 is shown even when the piston in the cylinder # 1 moves above the compression TDC and stops in the expansion stroke and the engine 12 the cylinder pressure of cylinder # 1 stops the last peak.

In this case, by merely determining the in-cylinder pressure of the # 1 cylinder constituting the last peak, it can not be determined whether the cylinder # 1 was stopped in the compression stroke or stopped in the expansion stroke.

However, as in 4 and 5 8, the state of change of the in-cylinder pressure forming the last peak (hereinafter also referred to as the last in-cylinder pressure) is unambiguously between the states when the piston rotates backward without being able to move beyond the compression TDC , and in the compression stroke stops, and when the piston moves over the compression TDC and stops in the expansion stroke. The change in the in-cylinder pressure (see 4 ), when the piston rotates backward without being able to move beyond the compression TDC and stops in the compression stroke is steeper than that in the in-cylinder pressure (see FIG 5 ) when the piston moves over the compression TDC and stops in the expansion stroke.

Therefore, according to the embodiment, the rate of change in the last in-cylinder pressure is calculated as the state of change of the last in-cylinder pressure when the engine 12 stops. The maximum value of the rate of change in the last in-cylinder pressure and a predetermined value are compared. According to the embodiment, a first derivative is calculated as the rate of change in the last in-cylinder pressure. The predetermined value, which is compared with the maximum value of the rate of change in the in-cylinder pressure forming the last peak in the last cylinder, may be a constant value. Alternatively, the predetermined value may be a variable value that varies depending on a rotational speed calculated by the rotational speed of the last cylinder as a parameter.

The steeper the waveform of the in-cylinder pressure, the greater the maximum value of the first derivative. Therefore, when the predetermined value is suitably set as to whether the last cylinder was stopped in the compression stroke or stopped in the expansion stroke, it can be determined with high accuracy, regardless of whether the last in-cylinder pressure is high or low, by the comparison between FIG maximum value of the first derivative of the last in-cylinder pressure and the predetermined value.

Of course, when the last cylinder was stopped in the compression stroke, the last cylinder is the cylinder that stops in the compression stroke. The cylinder that stops in the compression stroke when the engine 12 stops is also referred to as a cylinder stopped during compression. In 4 Cylinder # 1 is the cylinder stopped during compression.

When the last cylinder has been stopped in the expansion stroke, the cylinder following the compression stroke following the last cylinder becomes a # 3 cylinder 4 , the cylinder stopped during the compression. When the machine 12 as a result, stopping an engine start switch is turned OFF, the ECU stores 60 the cylinder stopped in compression in the flash memory 68 or a backup RAM (not shown). When the machine 12 stopped by the idling stop, the ECU 60 the cylinder stopped in the compression in the RAM 64 to save.

(Control when the machine 12 starts)

The ECU 60 identifies and stores the cylinder stopped during compaction when the engine is stopped 12 stops. When the machine 12 starts, determines the ECU 60 whether the fuel is ignitable in the cylinder stopped in the compression, depending on what occurs first: detection of a G signal by the cam angle sensor 50 or detecting a movement after the compression TDC based on the output signal from the CPS 42 in the cylinder stopped during compression. Movement over the compression TDC is detected by the in-cylinder pressure reaching a peak.

As described above, the four teeth are 53 attached to the outer circumference of the cam rotor 52 are set so that the rotational position is 60 ° CA before the TDC. Therefore, the G signal generated by the cam angle sensor 50 is spent, the teeth 53 detected, detected 60 ° CA before the compression TDC.

The rotational position of the additional tooth 54 that before a tooth 53 from the four teeth 53 is formed in the direction of rotation is set within a range which is to the toothless region 48 of the crank rotor 46 corresponds. Therefore, the G signal generated by the cam angle sensor 50 as a result of the detection of the additional tooth 54 is outputted from the G signals used to determine whether the fuel in the cylinder stopped in the compression is ignitable as a result of the crank angle sensor 44 , the toothless area 48 detected.

Therefore, after a starter motor is driven and the machine 12 is started when the cam angle sensor 50 the G signal picks up that to the teeth 53 before the compression TDC in 3 For example, the cylinder # 1, which is the cylinder stopped in the compression, stops at a stop position in the compression stroke before the compression TDC by 60 ° CA or more (see the solid line with arrow). In 3 is the distance of the NE signals, which is the toothless area 48 exclude, 10 ° CA. At this stop position, when the machine 12 starts and the piston of cylinder # 1 approaches the compression TDC, the internal cylinder pressure required to compress and ignite the fuel is reached. In this case, the fuel may be injected into the cylinder # 1, which is the cylinder stopped in the compression, and may be the engine 12 to be started.

When the fuel is ignitable in the cylinder stopped in the compression, the fuel is injected into the cylinders stopped in the compression and ignited in conjunction with a cranking operation by a starter. The machine 12 can be started quickly. The machine 12 is not on the diesel engine 12 limited. For example, the engine may be started in conjunction with a cranking operation by a starter, even if it is for example A gasoline engine is when the fuel in the cylinder stopped during compression is ignitable when the engine is started.

On the other hand, when the compression TDC is detected, before the cam angle sensor 50 the G signal picks up that to the teeth 53 corresponds, the cylinder # 1, which is the cylinder stopped in the compression, is stopped at a stop position (see dotted line with arrow) in the compression stroke, which is closer to the compression TDC than 60 ° CA. In this stop position can, even if the machine 12 starts and the piston of the cylinder # 1 approaches the compression TDC, the in-cylinder pressure required to compress and ignite the fuel can not be achieved. In this case, the fuel is injected into the cylinder # 3, which is in the compression stroke after the cylinder # 1, which is the cylinder stopped in the compression. The machine 12 is started.

In this way, it can be determined whether the fuel is injectible and ignitable in the cylinder stopped in the compression when the engine 12 is started when it is determined whether the last cylinder was stopped in the compression stroke or the expansion stroke, and the cylinder stopped in the compression is accurately identified.

On the other hand, when the last cylinder having the in-cylinder pressure forming the last peak is identified as the cylinder stopped in the compression, without considering the cylinder which is stopped after being moved over the compression TDC when the engine becomes 12 stops, the # 1 cylinder with the in-cylinder pressure constituting the last peak as the cylinder stopped in the compression identifies whether the cylinder # 3 stops in the compression stroke when the cylinder # 1 moves over the compression TDC and the machine 12 stops.

Therefore, it is determined when the machine 12 starts with respect to the cylinder # 1 which has been erroneously determined as the cylinder stopped in the compression, whether the fuel is injected into the cylinder # 1 and the engine 12 is started, on the basis of what comes first: a detection of the G signal, that to the teeth 53 corresponds, by the cam angle sensor or detecting the movement over the compression TDC based on the output signal of the CPS 42 ,

However, since the cylinder # 3 is actually the cylinder stopped in the compression, the fuel is not ignited even if the fuel is injected into the cylinder # 1 that has gone into the expansion stroke. The machine 12 cant be started. The ECU 60 determines that the cylinder stopped in the compression has been erroneously determined as the cylinder # 1 instead of the cylinder # 3 when the NE signal is the portion leading to the toothless portion 48 corresponds, and the cylinder determination is carried out. When the cylinder determination is performed, the machine can 12 be started by the fuel injected and ignited in the cylinder, which is in the compression stroke. If the cylinder # 1 is erroneously determined as the cylinder stopped in the compression instead of the cylinder # 3, the engine may 12 be started by the fuel injected and ignited in the compression stroke of a cylinder # 4.

Therefore, when the cylinder movement over the compression TDC and the stop is not considered when the engine 12 stops, the ignition start of the machine 12 delayed up to 180 ° CA compared to the case where, according to the embodiment, when the cylinder stopped in the compression is identified with high accuracy considering that the cylinder is moved over the compression TDC and stops when the engine is stopped 12 stops.

In other words, according to the embodiment, by comparing the maximum value of the first derivative of the last in-cylinder pressure with a predetermined value with high accuracy, it can be determined whether the last cylinder was stopped in the compression stroke or in the expansion stroke. As a result, the cylinder that stops in the compression stroke when the engine 12 stops, be identified with high accuracy. Therefore, when the stop position is a crank angle position enabling fuel injection in the cylinder stopped in the compression, the fuel can be injected and ignited in the cylinder stopped in the compression. The machine 12 can be started quickly.

As a result, the duration of the cranking operation by the starter and the driving time of the starter are shortened. Therefore, the life of the starter is improved. An idling stop system prevents the driver from experiencing an uncomfortable feeling as the engine 12 quickly starts when the driver performs an operation to resume driving from an idling stop state.

This is how the ECU works 60 such that an injection start cylinder in which the first fuel injection is started when the engine 12 starts, is identified on the basis of the stopped in the compression cylinder when the machine 12 stops.

(Cylinder Stopped Cylinder Identification Routine and Injection Cylinder Identification Routine)

6 FIG. 12 shows an identification routine for identifying the cylinder stopped in the compression in which the piston stops in the compression stroke when the engine stops, and an identification routine for identifying the injection start cylinder in which the first fuel injection is started when the engine 12 starts. The routines in 6 are constantly running. "S" in 6 indicates a step.

At S400, the ECU determines 60 Whether a machine stop condition is met. The ECU 60 determines that the machine stop condition is met if:
for example, in a vehicle having an automatic transmission (AT), the speed is zero and the brake pedal is depressed; and
For example, in a manual transmission (MT) vehicle, the speed is zero and the shift lever is set to neutral.

If the engine stop condition is not satisfied (No at S400), the ECU proceeds 60 advance to the flow at S410. When the engine stop condition is satisfied (Yes at S400), the ECU stops at S402 60 the fuel injection from the fuel injection valves 40 in all cylinders. The ECU 60 wait until the inner cylinder pressure forms the last peak. If the in-cylinder pressure constitutes the last peak (Yes at S402), the ECU calculates at S404 60 a first derivative with respect to a time for an in-cylinder pressure P (i: i = 1, 2, 3, 4) that has formed the last peak. The ECU 60 compares a maximum value of the first derivative and a predetermined value.

When the maximum value of the first derivative of P (i) is greater than the predetermined value (Yes at S404), the ECU determines 60 in that the state of change of the in-cylinder pressure P (i) formed as the last peak is steep. The ECU 60 determines that the peak in the in-cylinder pressure is formed by the piston of the last cylinder, which rotates backward before the compression TDC. As a result, the ECU identifies at S406 60 the last cylinder (i) with the in-cylinder pressure having formed the last peak as the cylinder (j) stopped in the compression. The ECU 60 then finish the routine.

When the maximum value of the first derivative of P (i) is the predetermined value or less (No at S404), the ECU determines 60 in that the state of change of the in-cylinder pressure P (i) having formed the last peak is graduated (gradual). The ECU 60 determines that the peak in the in-cylinder pressure is formed by the piston of the last cylinder that has moved over the compression TDC and has moved in the expansion stroke. As a result, the ECU identifies at S408 60 a cylinder, the cylinder following the compression stroke (i), with the inner cylinder pressure having formed the last peak, as the cylinder (j) stopped in the compression. The ECU 60 then finish the routine.

If the machine stop condition is not satisfied at S400 (No at S400), the ECU determines at S410 60 Whether a machine start condition is met. The ECU 60 determines that the engine start condition is satisfied when: in a vehicle having an automatic transmission (AT), for example, the brake pedal is not operated; and in a manual transmission vehicle (MT), for example, the clutch pedal is operated.

If the engine start condition is not satisfied (No at S410), the ECU ends 60 the routine. If the engine start condition is satisfied (Yes at S410), the ECU determines at S412 60 whether the cylinder stopped at the compression (j), which was stopped in the compression stroke when the engine 12 stopped is stored. The cylinder (j) stopped during compression can not be stored if, for example, the CPS 42 is operated abnormally or the stored information regarding the cylinder stopped in the compression (j) has been deleted by replacing a battery while the engine 12 stopped by turning the engine start switch OFF.

If the cylinder (j) stopped in the compression is not stored (No at S410), at S424, the ECU determines 60 the cylinder from the ratio between the portion of the toothless area 48 the crank angle signal and the G signal. The ECU 60 The engine starts by performing an ordinary control in which the fuel is injected into the cylinder in the compression stroke.

When the cylinder (j) stopped in the compression is stored (Yes at S412), the ECU drives at S414 60 the starter motor and crank the machine 12 at. Then, at S416 and S418, after the cranking is started, the ECU judges 60 what comes first: a detection of the G signal corresponding to the teeth 53 through the cam angle sensor 50 or detecting movement over the compression TDC based on the output signal of the CPS 42 ,

When the G signal is detected first (Yes at S416), the ECU determines 60 in that the stop position is stopped in that during compaction Cylinder (j) has not been moved beyond a crank angle position that allows injection and ignition of the fuel. The ECU starts at S420 60 the fuel injection in the compression-stopped cylinder (j) and ends the routine.

When the compression TDC is detected first (No at S416 and Yes at S418), the ECU determines 60 in that the stop position in the cylinder (j) stopped during the compression has been moved above the crank angle position which enables the injection and the ignition of the fuel. At S422 the ECU starts 60 the fuel injection at the cylinder which is the compression-stopped cylinder (j) on the compression stroke and terminates the routine.

According to the embodiment, the ECU 60 equivalent to the control apparatus for an internal combustion engine of the present invention. The RAM 64 or the flash memory 86 is equivalent to a memory device of the present invention. The processes involved in S402 and S404 in 6 are equivalent to functions provided by a pressure acquisition device and a pressure peak detection device of the present invention. The processes executed at S404 to S408 are equivalent to functions provided by a determination device and an identification device of the present invention.

According to the embodiment described above, the first derivative, which is the rate of change of the last in-cylinder pressure, is calculated as the rate of change of the last in-cylinder pressure of the last cylinder with the in-cylinder pressure forming the last peak when the engine 12 stops. The maximum value of the first derivative of the last in-cylinder pressure and a predetermined value are compared. Based on the comparison, it can be determined with high accuracy whether the piston in the last cylinder has rotated backward before the compression TDC and is stopped in the compression stroke, or has been moved over the compression TDC and stopped in the expansion stroke , As a result, the cylinder stopped in the compression stopped in the compression stroke when the engine 12 stops, be identified with high accuracy.

Therefore, when the fuel can be injected and ignited in the cylinder stopped in the compression, when the engine 12 is started, the fuel injection are started at the stopped in the compression cylinder. The machine 12 can be started quickly.

[Other embodiments]

According to the above embodiment, the first derivative of the in-cylinder pressure is calculated as the rate of change of the last in-cylinder pressure of the last cylinder with the in-cylinder pressure forming the last peak. In addition to the first derivative, a second derivative may be calculated as the rate of change of the last in-cylinder pressure. The second derivative indicates the waveform of the last in-cylinder pressure, in particular, the steepness of the peak in the in-cylinder pressure. Therefore, based on the second derivative of the last in-cylinder pressure, it can be determined whether the last cylinder stops in the compression stroke or in the expansion stroke. The cylinder stopped during compaction can be identified.

For example, an absolute value of the second derivative of the in-cylinder pressure in the compression TDC is larger when the peak of the in-cylinder pressure is steeper no matter how high the in-cylinder pressure is. Therefore, as a result of the comparison between the second derivative of the last in-cylinder pressure at the compression TDC and a predetermined value, it can be determined whether the last cylinder stops in the compression stroke or the expansion stroke. The cylinder stopped during compaction can be identified.

Identification of the compression-stopped cylinder, which is executed according to the above-described embodiment, is not limited to the diesel engine described above. The identification can also be carried out in a gasoline engine. As a result, even a gasoline engine can be started quickly when the engine can be started by the fuel injected and ignited in the cylinder stopped in the compression.

According to the above-described embodiment, the functions of the pressure acquisition device, the pressure-drop detection device, the determination device, and the identification device are performed by the ECU 60 whose functions are specified by the control programs. However, at least some of the functions of the above-described devices may be performed by hardware whose functions are specified by a circuit construction itself.

As described above, the present invention is not limited to the above-described embodiment. The present invention can be adapted to various Embodiments are applied without departing from the scope of the invention.

When an engine stops, an in-cylinder pressure constitutes the last peak, and a maximum value of a first derivative of a last in-cylinder pressure forming the last peak is greater than a predetermined value, a control apparatus for an engine determines that the peak in the inner cylinder pressure is formed by a piston of a last cylinder with the inner cylinder pressure, which forms the last peak and rotates backwards before an upper compression dead center (TDC). The controller identifies the last cylinder as a cylinder stopped during compression. When the maximum value of the first derivative is the predetermined value or less, the controller determines that the peak in the in-cylinder pressure is formed by the piston of the last cylinder that moves over the compression dead center TDC to an expansion stroke. The control device identifies a cylinder which is to be following the last cylinder in a compression stroke, as the cylinder stopped during the compression.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2005-120905 [0003, 0003, 0004]

Claims (8)

Control device for an internal combustion engine with: pressure acquisition means for acquiring an in-cylinder pressure in each cylinder of the internal combustion engine; pressure-drop detecting means for detecting a last cylinder having an in-cylinder pressure forming a last peak when the internal combustion engine stops based on the in-cylinder pressures acquired by the pressure-acquiring means; determination means for determining whether a piston of the last cylinder moves above an upper compression dead center when the internal combustion engine stops based on the state of change of the in-cylinder pressure forming the last peak in the last cylinder; identification means for identifying a cylinder stopped in the compression, which stops in a compression stroke; and storage means for storing the cylinder stopped in the compression identified by the identification means. The control apparatus according to claim 1, wherein the determining means is configured to determine whether the piston of the last cylinder moves above the top compression dead center when the internal combustion engine stops based on the rate of change in the in-cylinder pressure that is the last peak in the last cylinder forms. The control apparatus according to claim 2, wherein the determining means is configured to determine whether the piston of the last cylinder is moving above the top compression dead center when the internal combustion engine stops by comparing a maximum value of the rate of change in the in-cylinder pressure representing the last peak in the first cylinder last cylinder forms, with a predetermined value. The control apparatus according to claim 1, wherein the determining means determines whether the piston of the last cylinder moves above the top compression dead center when the internal combustion engine stops based on a second derivative of the in-cylinder pressure forming the last peak in the last cylinder. Method for controlling an internal combustion engine, comprising the steps: Acquiring an in-cylinder pressure in each cylinder of the internal combustion engine; Detecting a last cylinder having an in-cylinder pressure forming a last peak when the internal combustion engine stops based on the in-cylinder pressures by a result of the acquisition; Determining whether a piston of the last cylinder is moving above an upper compression dead center when the internal combustion engine stops based on a state of change of the in-cylinder pressure forming the last peak in the last cylinder; Identifying a cylinder stopped in the compression that stops in a compression stroke; and Storing the cylinder stopped in the compression identified by a result of the identification. The method of claim 5, wherein the step of determining whether the piston of the last cylinder moves above the top compression dead center when the engine stops based on a rate of change in the in-cylinder pressure that is the last peak in the last cylinder. The method of claim 6, wherein the step of determining whether the piston of the last cylinder moves above the top compression dead center when the engine stops by comparing a maximum value of the rate of change in the in-cylinder pressure forming the last peak in the last cylinder , with a predetermined value. The method of claim 5, wherein the step of determining if the piston of the last cylinder is moving above the top compression dead center when the engine stops based on a second derivative of the in-cylinder pressure forming the last peak in the last cylinder.

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