JP3911855B2 - Control device for direct-injection spark ignition engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a direct-injection spark ignition engine that performs torque correction based on engine operating conditions.
[0002]
[Prior art]
Conventionally, when a desired target torque is achieved, for example, when shifting an automatic transmission, the intake air amount is feedback controlled so that the engine torque converges to the target torque, while the engine torque and the target torque at that time are In some cases, the target torque is achieved by correcting the ignition timing in accordance with the deviation, that is, the torque control (torque correction) faster than the response of the intake air amount control is performed by the ignition timing correction. (See JP-A-5-163996).
[0003]
On the other hand, in recent years, a direct-injection spark-ignition engine has attracted attention. In this engine, the combustion system is switched in accordance with the operating conditions of the engine, that is, by injecting fuel in the intake stroke, so Switching control between homogeneous combustion, which is performed by diffusing fuel to form a homogeneous mixture, and stratified combustion, where fuel is injected in the compression stroke to form a stratified mixture intensively around the spark plug This is generally done (see Japanese Patent Application Laid-Open No. 59-37236).
[0004]
[Problems to be solved by the invention]
However, in such a direct-injection spark-ignition engine, if torque correction is performed using the ignition timing during stratified combustion, the mixture must be ignited at the timing when the air-fuel mixture comes near the spark plug during stratified combustion. Since the operation fee for the ignition timing is small, it is difficult to perform sufficient torque correction. If forced, the combustion may deteriorate, and in a severe case, misfire may occur.
[0005]
The present invention has been made in view of such a problem, and an object of the present invention is to provide a control device for a direct-injection spark ignition engine capable of performing an optimal torque correction when switching between homogeneous combustion and stratified combustion is possible. .
[0006]
[Means for Solving the Problems]
  Therefore, in the invention according to claim 1, as shown in FIG. 1A, it is possible to switch between homogeneous combustion performed by injecting fuel in the intake stroke and stratified combustion performed by injecting fuel in the compression stroke. A direct-injection spark-ignition engine having a combustion mode switching means, comprising torque correction request means for generating a torque correction request based on the operating conditions of the engine, in response to the torque correction request in the same combustion system During homogeneous combustionOf the ignition timing and air-fuel ratio,Homogeneous combustion torque correction means that corrects at least ignition timing and torque correction, and stratified combustionOf the ignition timing and air-fuel ratio, only the air-fuel ratioAnd stratified combustion torque correction means for correcting torque by correcting the above.
[0007]
  In the invention according to claim 2, as shown in FIG. 1 (B), a combustion system capable of switching between homogeneous combustion performed by injecting fuel in an intake stroke and stratified combustion performed by injecting fuel in a compression stroke A direct-injection spark-ignition engine including switching means, comprising torque correction request means for generating a torque correction request based on the operating conditions of the engine,In the same combustion systemIn response to the torque correction request, torque control means for controlling the intake air amount of the engine to control the torque is provided, and at the same time, at least the ignition timing in the homogeneous combustion so as to perform a highly responsive torque correction for the delay of the intake air amount control. And a stratified combustion torque correcting means for correcting torque by correcting at least the air-fuel ratio at the time of stratified combustion.
[0008]
  In the invention according to claim 3, as shown in FIG. 1 (B), combustion capable of switching between homogeneous combustion performed by injecting fuel in the intake stroke and stratified combustion performed by injecting fuel in the compression stroke A direct-injection spark-ignition engine equipped with system switching means, at least at the accelerator openingIncluding torque correction requirements for the same combustion methodIn the apparatus including target torque calculation means for calculating the target torque of the engine, torque control means for controlling the intake air amount of the engine to perform torque control is provided so as to achieve the target torque. Homogeneous combustion torque correction means that corrects torque by correcting at least the ignition timing during homogeneous combustion, and stratified combustion that corrects torque by correcting at least the air-fuel ratio during stratified combustion so as to perform torque correction with high response to delay A time torque correcting means is provided separately.
[0009]
In the invention according to claim 4, the torque control means includes a required basic fuel amount calculating means for calculating a required basic fuel amount so as to realize the target torque, and a target intake air amount from the required basic fuel amount and the target air-fuel ratio. Target intake air amount calculating means for calculating the target intake air amount, target throttle opening degree calculating means for calculating the target throttle opening amount based on the target intake air amount, and throttle valve drive control for driving the throttle valve to achieve the target throttle opening degree (Refer to FIG. 7).
[0010]
In the invention according to claim 5, the homogeneous combustion torque correction means divides the torque correction amount into an ignition timing correction amount and an air-fuel ratio correction amount, and corrects the ignition timing and air-fuel ratio to perform torque correction. In addition, the stratified combustion torque correction means is characterized in that the torque correction amount is set only for the air-fuel ratio correction, and the torque correction is performed by correcting the air-fuel ratio.
[0011]
  In the invention according to claim 6, in the homogeneous combustion torque correction means and stratified combustion torque correction means, the torque correction amount is calculated in synchronization with the engine rotation, and the reflection of the torque correction amount in the fuel injection amount is calculated in time synchronization. It is characterized by doing.
  In the invention according to claim 7, in the homogeneous combustion torque correction means and stratified combustion torque correction means, the calculation of the torque correction amount and the reflection of the torque correction amount on the fuel injection amount are calculated in synchronization with the engine rotation. Features.
  The invention according to claim 8 is characterized in that the torque correction request is caused by a shift, an air conditioner ON, or a fuel cut recovery.
[0012]
【The invention's effect】
  According to the first aspect of the invention, at least the ignition timing is operated during homogeneous combustion, and during stratified combustion.Air-fuel ratioBy performing the torque correction by operating, a desired torque correction can be performed regardless of the combustion method.
  According to the second aspect of the present invention, high-speed torque correction that cannot be followed by intake air amount control in response to the torque correction request can be realized regardless of the combustion method, and the torque correction request can be met. .
[0013]
According to the third aspect of the present invention, in torque control to the target torque, high-speed torque correction that cannot be followed by intake air amount control can be realized regardless of the combustion method, and the target torque can be achieved.
According to the fourth aspect of the invention, when the throttle opening is controlled by so-called torque demand control (control as shown in FIG. 7 is referred to as torque demand control), a high speed that cannot be followed by the intake air amount control by this control. Torque correction can be realized regardless of the combustion method, and the target torque can be achieved.
[0014]
According to the invention which concerns on Claim 5, the possible range (dynamic range) of the torque control at the time of homogeneous combustion can be expanded.
According to the sixth aspect of the invention, good responsiveness can be realized even in the case of stratified combustion, as in the case of homogeneous combustion, without increasing the calculation load at high revolutions.
According to the seventh aspect of the invention, in the case of stratified combustion and homogeneous combustion, exactly the same responsiveness can be realized at all rotational speeds.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
FIG. 2 is a system diagram of a direct injection spark ignition engine showing an embodiment. First, this will be described.
Air is sucked into the combustion chamber of each cylinder of the engine 1 mounted on the vehicle under the control of the electric throttle valve 4 from the air cleaner 2 through the intake passage 3.
[0016]
The opening degree of the electric throttle valve 4 is controlled by a step motor or the like that is operated by a signal from the control unit 20.
An electromagnetic fuel injection valve (injector) 5 is provided to inject fuel (gasoline) directly into the combustion chamber.
The fuel injection valve 5 is opened by energizing the solenoid by an injection pulse signal output in the intake stroke or compression stroke in synchronization with the engine rotation from the control unit 20, and injects fuel adjusted to a predetermined pressure. It is like that. In the case of intake stroke injection, the injected fuel diffuses into the combustion chamber to form a homogeneous mixture, and in the case of compression stroke injection, a stratified mixture is formed intensively around the spark plug 6. Based on the ignition signal from the control unit 20, the ignition plug 6 ignites and burns (homogeneous combustion or stratified combustion). The combustion method is classified into homogeneous stoichiometric combustion, homogeneous lean combustion (air-fuel ratio 20 to 30), and stratified lean combustion (air-fuel ratio of about 40) in combination with air-fuel ratio control.
[0017]
Exhaust gas from the engine 1 is discharged from an exhaust passage 7, and an exhaust purification catalyst 8 is interposed in the exhaust passage 7.
The control unit 20 includes a microcomputer including a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like, and signals are input from various sensors.
[0018]
As the various sensors, crank angle sensors 21 and 22 for detecting rotation of the crankshaft or camshaft of the engine 1 are provided. These crank angle sensors 21 and 22 have a reference pulse at a predetermined crank angle position (predetermined crank angle position before compression top dead center of each cylinder) every crank angle 720 ° / n, where n is the number of cylinders. In addition to outputting the signal REF, the unit pulse signal POS is output every 1 to 2 °, and the engine speed Ne can be calculated from the cycle of the reference pulse signal REF.
[0019]
In addition, an air flow meter 23 for detecting the intake air flow rate Qa upstream of the throttle valve 4 in the intake passage 3, an accelerator sensor 24 for detecting an accelerator opening (accelerator pedal depression amount) ACC, and an opening TVO of the throttle valve 4 are detected. The throttle sensor 25 (including an idle switch that is turned on when the throttle valve 4 is fully closed), the water temperature sensor 26 that detects the cooling water temperature Tw of the engine 1, and the exhaust passage 7 according to the rich / lean exhaust air / fuel ratio. O to output a signal₂A sensor 27, a vehicle speed sensor 28 for detecting the vehicle speed VSP, and the like are provided.
[0020]
Here, the control unit 20 performs a predetermined calculation process by a built-in microcomputer while inputting signals from the various sensors, so that the throttle opening by the electric throttle valve 4 and the fuel by the fuel injection valve 5 are processed. The injection amount and the ignition timing by the spark plug 6 are controlled.
Among these controls, controls relating to torque control (torque correction) will be described with reference to flowcharts according to first to fifth embodiments.
[0021]
[First embodiment]
The flowchart of the first embodiment is shown in FIGS.
FIG. 3 shows a torque correction amount calculation routine, which is executed in synchronization with the reference pulse signal REF (REF-JOB).
In S1, a torque correction request (increase / decrease request) caused by gear shifting, air conditioner ON, fuel cut recovery, or the like is read. That is, by another routine as a torque correction request means, a torque reduction request is generated at the time of shifting, a torque increase request is generated when the air conditioner is ON, and a torque reduction request is generated at the time of fuel cut recovery. 19 to 21 show flowcharts of a torque correction request (torque correction request calculation) routine, which will be described last.
[0022]
In S2, a torque correction amount PIPER (100 ± α%) is calculated in response to the torque correction request. Specifically, if the basic target torque (driver required torque) excluding the torque correction request is tTe0 (calculated by another routine) and the torque correction request is ΔtTe, PIPER = [(tTe0 + ΔtTe) / tTe0] × It calculates by 100 (%). Here, PIPER = 100% is no correction, PIPER> 100% is a torque increase request, and PIPER <100% is a torque reduction request.
[0023]
In S3, the combustion method is read.
Here, the combustion system is switched by referring to the combustion system switching map based on the engine operating conditions by another routine as a combustion system switching means. That is, a plurality of maps defining the combustion method (and the basic equivalence ratio tφ) using the engine speed Ne and the target torque tTe (= tTe0 + ΔtTe) as parameters are provided according to conditions such as the water temperature Tw and the time after starting. From the map selected from the conditions, the combustion mode (and the basic equivalence ratio tφ) is set to any one of homogeneous stoichiometric combustion, homogeneous lean combustion, and stratified lean combustion according to the parameters of the actual engine operating state. Therefore, this is read. FIG. 22 shows a flowchart of a combustion system switching (and basic equivalence ratio tφ setting) routine, which will be described last.
[0024]
In S4, it is determined whether the combustion is homogeneous combustion (homogeneous stoichiometric combustion or homogeneous lean combustion) or stratified combustion (stratified lean combustion), and branches according to the result.
In the case of homogeneous combustion, the process proceeds to S5, and the torque correction amount PIPER is converted into the ignition timing correction amount TQRET using a table as shown in FIG. The ignition timing correction amount TQRET is a positive value in the case of advance correction, and a negative value in the case of retardation correction. In S6, the torque correction amount PIPER is returned to 100% (no correction), and this routine is terminated.
[0025]
In the case of stratified combustion, the routine proceeds to S7, where the ignition timing correction amount TQRET = 0 is set, and this routine is terminated. In this case, the torque correction amount PIPER is maintained at the calculated value in S2.
FIG. 4 shows an ignition timing calculation routine, which is executed in synchronization with the reference pulse signal REF (REF-JOB).
[0026]
In S11, the basic ignition timing ADVmap calculated by another routine is read. The basic ignition timing ADVmap for homogeneous combustion (homogeneous stoichiometric combustion and homogeneous lean combustion) is calculated according to MBT control, or the engine rotational speed Ne and target torque tTe (or fuel injection amount as shown in FIG. 26 (a)). The basic ignition timing ADVmap is calculated from a map in accordance with Ti). The basic ignition timing ADVmap for stratified combustion is calculated from a map in which the basic ignition timing ADVmap is determined according to the engine speed Ne and the target torque tTe (or the fuel injection amount Ti) as shown in FIG.
[0027]
In S12, the ignition timing correction amount TQRET is read.
In S13, the final ignition timing ADV is calculated by adding the ignition timing correction amount TQRET to the basic ignition timing ADVmap as in the following equation.
ADV = ADVmap + TQRET
Here, since the torque correction amount PIPER is converted into the ignition timing correction amount TQRET at the time of homogeneous combustion, this is reflected in the ignition timing ADV, and torque correction is made by the ignition timing. However, at the time of stratified combustion, the ignition timing correction is performed. Since the amount TQRET = 0, torque correction based on the ignition timing is not performed.
[0028]
In S14, the ignition timing ADV is set in a predetermined register, and ignition is performed at the ignition timing ADV.
FIG. 5 shows a fuel injection amount calculation routine, which is executed every predetermined time, specifically every 10 ms (10 ms-JOB).
In S21, the basic equivalence ratio tφ for air-fuel ratio control set by another routine is read. The basic equivalent ratio tφ is set according to the combustion method. The equivalence ratio here is also called a fuel-air ratio correction coefficient, and is expressed by 14.6 / AFR, where AFR is an AFR.
[0029]
In S22, the torque correction amount PIPER is read.
In S23, the torque correction amount PIPER is converted into an equivalent ratio correction amount (coefficient) Δφ using a table as shown in FIG. Here, since the torque correction amount PIPER = 100% in the homogeneous combustion, the equivalent ratio correction amount Δφ = 1, and in the stratified combustion, the torque correction amount PIPER = 100 ± α%, so the equivalent ratio correction amount Δφ = 1 ± β.
[0030]
In S24, the target equivalent ratio tφd is calculated by multiplying the basic equivalent ratio tφ by the equivalent ratio correction amount Δφ as in the following equation.
tφd = tφ × Δφ
In S25, as shown in the following equation, the basic fuel injection amount Tp is corrected by the target equivalent ratio tφd and the final fuel injection amount Ti is calculated.
[0031]
Ti = Tp × tφd × Kα + Ts
Here, Tp is a basic fuel injection amount corresponding to the stoichiometric air-fuel ratio, and is obtained by Tp = K × Qa / Ne (K is a constant).
Kα is O₂It is an air-fuel ratio feedback correction coefficient based on the sensor signal, and is clamped at Kα = 1 during lean combustion.
[0032]
Ts is an invalid injection time correction depending on the battery voltage.
The fuel injection amount Ti calculated in this way is set in a predetermined register and corresponds to this Ti in the intake stroke of each cylinder in the case of homogeneous combustion and in the compression stroke of each cylinder in the case of stratified combustion. An injection pulse signal having a pulse width to be output is output to each fuel injection valve 5 to perform fuel injection.
[0033]
Here, the portions S1 to S4, S5, S6, S12, and S13 correspond to the homogeneous combustion torque correcting means, and the portions S1 to S4, S7, and S22 to S25 correspond to the stratified combustion torque correcting means.
FIG. 12 shows an example of the response waveform of the first embodiment.
For example, when a torque correction (torque down) request is made due to a shift, in the case of homogeneous combustion, torque correction is performed by correcting the ignition timing, and in the case of stratified combustion, without correcting the ignition timing, Torque correction is performed by correcting the equivalence ratio (air-fuel ratio).
[0034]
In the present embodiment, the electric throttle valve 4 is controlled corresponding to the accelerator opening ACC.
[Second Embodiment]
In the second embodiment, the torque correction amount calculation is performed according to FIG. 6, and the ignition timing calculation and the fuel injection amount calculation are performed according to FIGS. 4 and 5 (explained).
[0035]
FIG. 6 shows a torque correction amount calculation routine, which is executed in synchronization with the reference pulse signal REF (REF-JOB).
In S31, a target torque for torque demand control (including a torque correction request caused by gear shifting, air conditioner ON, fuel cut recovery, etc.) is read.
In S32, as the torque control means, an air correction amount for the target torque is calculated, and thereby the opening degree of the electric throttle valve 4 is controlled.
[0036]
In S33, the output torque at the time of air correction is estimated.
In S34, the estimated torque is subtracted from the target torque based on the torque correction request for torque demand control to calculate the insufficient torque.
In S35, a torque correction amount PIPER (100 ± α%) is calculated in correspondence with the insufficient torque. Here, PIPER = 100% is no correction, PIPER> 100% is a torque increase request, and PIPER <100% is a torque reduction request.
[0037]
In S36, the combustion method is read.
In S37, it is determined whether the combustion is homogeneous combustion (homogeneous stoichiometric combustion or homogeneous lean combustion) or stratified combustion (stratified lean combustion), and branches according to the result.
In the case of homogeneous combustion, the process proceeds to S38, and the torque correction amount PIPER is converted into the ignition timing correction amount TQRET. The ignition timing correction amount TQRET is a positive value in the case of advance correction, and a negative value in the case of retardation correction. In step S39, the torque correction amount PIPER is returned to 100% (no correction), and this routine is terminated.
[0038]
In the case of stratified combustion, the routine proceeds to S40, where the ignition timing correction amount TQRET = 0 is set, and this routine is terminated. In this case, the torque correction amount PIPER is maintained at the calculated value in S35.
The subsequent ignition timing calculation routine is shown in FIG. 4, and the fuel injection amount calculation routine is shown in FIG.
[0039]
Here, S33 to S37, S38, S39, S12, and S13 correspond to the homogeneous combustion torque correction means, and S33 to S37, S40, and S22 to S25 correspond to the stratified combustion torque correction means.
FIG. 7 shows a control block diagram when the torque demand control is performed.
The target torque calculation means 101 inputs the accelerator opening ACC and the engine speed Ne, and sets the basic target torque tTe0 by referring to a map in which the basic target torque (driver required torque) tTe0 is determined in accordance with these inputs. Then, a target torque tTe = tTe0 + ΔtTe is calculated by adding a torque correction required amount ΔtTe caused by gear shifting, air conditioner ON, fuel cut recovery, and the like.
[0040]
The necessary basic fuel amount calculating means 102 inputs the target torque tTe and the engine speed Ne, and outputs a necessary basic fuel amount tQf by referring to a map in which the necessary basic fuel amount tQf is predetermined according to these.
The efficiency correction means 103 corrects the necessary basic fuel amount tQf according to the difference in combustion efficiency when the air-fuel ratio changes greatly, such as in homogeneous combustion and stratified combustion. Specifically, the required basic fuel amount tQf is corrected to be smaller as the air-fuel ratio becomes leaner. This is because the pumping loss becomes smaller and the efficiency becomes higher as leaner.
[0041]
The target air-fuel ratio calculating means 104 inputs the target torque tTe and the engine speed Ne, and outputs a target air-fuel ratio tAFR with reference to a map in which the target air-fuel ratio tAFR is predetermined according to these.
The target intake air amount calculation means 105 includes a multiplier, and calculates a target intake air amount tQcyl = tQf × tAFR by multiplying the required basic fuel amount tQf by the target air-fuel ratio tAFR.
[0042]
The target throttle opening calculation means 106 inputs the target intake air amount tQcyl and the engine speed Ne, and refers to the target throttle opening tTVO according to these (tQcyl × Ne) in advance, with reference to the target throttle opening tTVO. The opening degree tTVO is output.
The throttle valve drive control means 107 controls the throttle valve 4 so as to reach the target throttle opening tTVO by step driving the step motor with a command signal corresponding to the target throttle opening tTVO.
[0043]
FIG. 13 shows an example of the response waveform of the second embodiment.
For example, when a torque correction (torque up) request is made due to the air conditioner being turned on, the air amount is increased, but torque shortage occurs due to a delay in air amount control. Therefore, in order to correct the torque shortage, in the case of homogeneous combustion, torque correction is performed by correcting the ignition timing, and in the case of stratified combustion, by correcting the equivalent ratio (air-fuel ratio) without correcting the ignition timing, Torque correction is made.
[0044]
[Third embodiment]
In the third embodiment, the torque correction amount calculation is performed according to FIG. 8, the ignition timing calculation is performed according to FIG. 4 (explained), and the fuel injection amount calculation is performed according to FIG.
FIG. 8 shows a torque correction amount calculation routine, which is executed in synchronization with the reference pulse signal REF (REF-JOB). 8 differs from FIG. 3 in the portions S1 ', S2', S5 ', and S6'.
[0045]
In S1 ', the torque correction request (increase / decrease request) caused by gear shifting, air conditioner ON, fuel cut recovery, etc. is divided into an ignition timing correction request (ignition) and an air-fuel ratio correction request (equivalent ratio) and read separately. Include.
In S2 ′, the torque correction amount is calculated in response to the torque correction request. Based on the ignition timing correction request (ignition) and the air-fuel ratio correction request (equivalent ratio), the torque correction amount ignition amount PIPERAD A torque correction amount equivalent ratio PIPERMR is calculated. Specifically, if the ignition timing correction requirement is ΔtTeAD and the air-fuel ratio correction requirement is ΔtTeMR, PIPERAD = [(tTe0 + ΔtTeAD) / tTe0] × 100 (%), PIPERMR = [(tTe0 + ΔtTeMR) / tTe0] × 100 ( %). Here, 100% is no correction, 100% or more is a torque increase request, and 100% or less is a torque reduction request.
[0046]
In S3, the combustion method is read.
In S4, it is determined whether the combustion is homogeneous combustion (homogeneous stoichiometric combustion or homogeneous lean combustion) or stratified combustion (stratified lean combustion), and branches according to the result.
In the case of homogeneous combustion, the process proceeds to S5 ', and the torque correction amount ignition amount PIPERAD is converted into the ignition timing correction amount TQRET. The ignition timing correction amount TQRET is a positive value in the case of advance correction, and a negative value in the case of retardation correction. In S6 ', the torque correction amount ignition amount PIPERAD is returned to 100% (no correction), and this routine is terminated.
[0047]
In the case of stratified combustion, the routine proceeds to S7, where the ignition timing correction amount TQRET = 0 is set, and this routine is terminated. In this case, the torque correction amount ignition amount PIPERAD is maintained at the calculated value in S2 '.
The subsequent ignition timing calculation routine is performed according to FIG.
FIG. 9 shows a fuel injection amount calculation routine, which is executed every predetermined time, specifically every 10 ms (10 ms-JOB). FIG. 9 is different from FIG. 5 in S22 '.
[0048]
In S21, the basic equivalence ratio tφ for air-fuel ratio control set by another routine is read.
In S22 ', the torque correction amount PIPERAD and the equivalence ratio PIPERMR are read and added as in the following equation to obtain the total torque correction amount PIPER.
PIPER = PIPERAD + PIPERMR-100 (%)
Here, during homogeneous combustion, torque correction is performed according to the ignition timing and the torque correction amount ignition amount PIPERAD = 100%, so PIPER = PIPERMR.
[0049]
In S23, the torque correction amount PIPER is converted into an equivalent ratio correction amount (coefficient) Δφ.
In S24, the target equivalent ratio tφd is calculated by multiplying the basic equivalent ratio tφ by the equivalent ratio correction amount Δφ as in the following equation.
tφd = tφ × Δφ
In S25, as shown in the following equation, the basic fuel injection amount Tp is corrected by the target equivalent ratio tφd and the final fuel injection amount Ti is calculated.
[0050]
Ti = Tp × tφd × Kα + Ts
The fuel injection amount Ti calculated in this way is set in a predetermined register and corresponds to this Ti in the intake stroke of each cylinder in the case of homogeneous combustion and in the compression stroke of each cylinder in the case of stratified combustion. An injection pulse signal having a pulse width to be output is output to each fuel injection valve 5 to perform fuel injection.
[0051]
FIG. 14 shows an example of the response waveform of the third embodiment.
For example, when a torque correction (torque down) request is made due to fuel cut recovery, in the case of homogeneous combustion, torque correction is made by correcting the ignition timing and correcting the equivalent ratio (air-fuel ratio), and stratified combustion In this case, the torque is corrected by correcting the equivalence ratio (air / fuel ratio) without correcting the ignition timing.
[0052]
[Fourth embodiment]
In the fourth embodiment, the torque correction amount is calculated according to FIG. 10, the ignition timing is calculated according to FIG. 4 (explained), and the fuel injection amount is calculated according to FIG. 9 (explained).
FIG. 10 shows a torque correction amount calculation routine, which is executed in synchronization with the reference pulse signal REF (REF-JOB). FIG. 10 differs from FIG. 6 in the portions of S35 ', S38', and S39 '.
[0053]
In S31, a target torque for torque demand control (including a torque correction request caused by gear shifting, air conditioner ON, fuel cut recovery, etc.) is read.
In S32, an air correction amount for the target torque is calculated, and thereby the opening degree of the electric throttle valve 4 is controlled.
In S33, the output torque at the time of air correction is estimated.
[0054]
In S34, the estimated torque is subtracted from the target torque based on the torque correction request for torque demand control to calculate the insufficient torque.
In S35 ′, the torque correction amount is calculated in correspondence with the insufficient torque amount. The torque correction amount is divided into an ignition timing correction amount (ignition amount) and an air-fuel ratio correction amount (equivalent ratio portion), and the torque correction amount ignition amount is calculated. PIPERAD and torque correction amount equivalent ratio PIPERMR are calculated. Specifically, the insufficient torque is distributed at a predetermined ratio (0: 1 at the time of stratified combustion, x: 1-x at the time of homogeneous combustion; x is a predetermined fixed value or a table value switched according to operating conditions). Thus, the torque correction amount ignition amount PIPERAD and the torque correction amount equivalent ratio amount PIPERMR are calculated. Here, 100% is no correction, 100% or more is a torque increase request, and 100% or less is a torque reduction request.
[0055]
In S36, the combustion method is read.
In S37, it is determined whether the combustion is homogeneous combustion (homogeneous stoichiometric combustion or homogeneous lean combustion) or stratified combustion (stratified lean combustion), and branches according to the result.
In the case of homogeneous combustion, the process proceeds to S38 ', and the torque correction amount ignition amount PIPERAD is converted into the ignition timing correction amount TQRET. The ignition timing correction amount TQRET is a positive value in the case of advance correction, and a negative value in the case of retardation correction. In S39 ', the torque correction amount ignition amount PIPERAD is returned to 100% (no correction), and this routine is terminated.
[0056]
In the case of stratified combustion, the routine proceeds to S40, where the ignition timing correction amount TQRET = 0 is set, and this routine is terminated. In this case, the torque correction amount ignition amount PIPERAD is maintained at the calculated value in S35 '.
The subsequent ignition timing calculation routine is shown in FIG. 4, and the fuel injection amount calculation routine is shown in FIG.
[0057]
FIG. 15 shows a response waveform example of the fourth embodiment.
For example, when a torque correction (torque down) request is made due to a shift, the air amount is reduced, but an excess of torque occurs due to a delay in air amount control. Therefore, in order to correct this, torque correction is performed by correcting the ignition timing and correcting the equivalent ratio (air / fuel ratio), and in the case of stratified combustion, the equivalent ratio (air / fuel ratio) is large without correcting the ignition timing. The torque is corrected by the correction.
[0058]
[Fifth embodiment]
In the fifth embodiment, the torque correction amount calculation and the fuel injection amount calculation are performed according to FIG. 11, and the ignition timing calculation is performed according to FIG. 4 (explained).
In S1, a torque correction request (increase / decrease request) caused by gear shifting, air conditioner ON, fuel cut recovery, or the like is read.
[0059]
In S2, a torque correction amount PIPER (100 ± α%) is calculated in response to the torque correction request. Here, PIPER = 100% is no correction, PIPER> 100% is a torque increase request, and PIPER <100% is a torque reduction request.
In S3, the combustion method is read.
In S4, it is determined whether the combustion is homogeneous combustion (homogeneous stoichiometric combustion or homogeneous lean combustion) or stratified combustion (stratified lean combustion), and branches according to the result.
[0060]
In the case of homogeneous combustion, the routine proceeds to S41, where the torque correction amount PIPER is converted into the ignition timing correction amount TQRET. The ignition timing correction amount TQRET is a positive value in the case of advance correction, and a negative value in the case of retardation correction. In S42, the equivalent ratio correction amount Δφ = 1 (no correction) is set, and the process proceeds to S45 to S47.
In the case of stratified combustion, the process proceeds to S43, and the torque correction amount PIPER is converted into the equivalent ratio correction amount Δφ. In S44, the ignition timing correction amount TQRET = 0 is set, and the process proceeds to S45 to S47.
[0061]
In S45, the basic equivalence ratio tφ for air-fuel ratio control set by another routine is read.
In S46, the target equivalent ratio tφd is calculated by multiplying the basic equivalent ratio tφ by the equivalent ratio correction amount Δφ as in the following equation.
tφd = tφ × Δφ
In S47, as shown in the following equation, the basic fuel injection amount Tp is corrected by the target equivalent ratio tφd and the final fuel injection amount Ti is calculated.
[0062]
Ti = Tp × tφd × Kα + Ts
The fuel injection amount Ti calculated in this way is set in a predetermined register and corresponds to this Ti in the intake stroke of each cylinder in the case of homogeneous combustion and in the compression stroke of each cylinder in the case of stratified combustion. An injection pulse signal having a pulse width to be output is output to each fuel injection valve 5 to perform fuel injection.
[0063]
The subsequent ignition timing calculation routine is performed according to FIG.
The fifth embodiment is different from the first embodiment in that the calculation of the fuel injection amount is performed in rotation synchronization (REF-JOB) similarly to the calculation of the torque correction amount. Also in this embodiment, the calculation of the fuel injection amount can be performed in synchronization with the rotation in the same manner as the calculation of the torque correction amount.
[0064]
Next, the calculation of the fuel injection amount is performed in time synchronization (10 ms-JOB) as in the first to fourth embodiments, and the calculation of the fuel injection amount is rotationally synchronized (REF) as in the fifth embodiment. The difference from the case of -JOB) will be described.
In the calculation of the rotation synchronization (REF-JOB), for example, in the case of four cylinders, the cycle of the reference pulse signal REF for each crank angle of 180 ° is as follows for each engine speed.
[0065]
1000rpm ... 30ms
3000rpm ... 10ms
5000rpm ... 6ms
6000 rpm ... 5 ms
Therefore, at 3000 rpm or higher, the computational load becomes heavier than at 10 ms-JOB, at 6000 rpm, the computational load is twice that of 10 ms-JOB, and becomes more noticeable at 6 and 8 cylinders.
[0066]
For this reason, in the first to fourth embodiments, the calculation of the fuel injection amount is performed in time synchronization (10 ms-JOB) in order to reduce the calculation load.
The reason why the responsiveness at the time of stratified combustion is not impaired by the time-synchronized calculation is as follows.
At low load of stratified combustion (about 1200rpm or less), 10ms-JOB is inserted between calculation of torque correction by rotation synchronization (REF-JOB) and fuel injection, so it is equivalent to ignition timing in homogeneous combustion Responsiveness can be realized.
[0067]
Even when the rotation speed is higher than the above, since the torque correction amount is reflected in the fuel injection amount in time synchronization (10 ms-JOB), the control every 10 ms can be realized, and the torque correction that is usually demanded on a time scale. There is sufficient control over the request.
Further description will be made with reference to FIGS.
Referring to FIG. 16, in the low speed region, for example, the idling speed region, the performance is greatly influenced by whether or not the reflection of the correction amount is delayed by one combustion. Here, when the correction amount (TQRET, PIPER) is calculated by REF-JOB and reflected in the fuel injection amount by 10 ms-JOB, the correction amount (TQRET) is calculated by REF during homogeneous combustion. Since it is immediately reflected in the ignition timing set by REF, the correction amount can be reflected in the combustion immediately after REF. At the time of stratified combustion, the correction amount (PIPER) is calculated by REF. However, in this rotation region, 10 ms-JOB is once inserted between REF and the fuel injection pulse. The correction amount can be reflected in the combustion immediately after.
[0068]
Therefore, in the low rotation region such as the idle rotation region, torque correction can be realized with an equivalent response regardless of whether stratification or homogeneous.
Referring to FIG. 17, in the non-idle engine speed region (high engine speed region), the correction amount (TQRET, PIPER) is calculated by REF-JOB, and the reflection to the fuel injection amount is performed by 10 ms-JOB. At the time of combustion, a correction amount (TQRET) is calculated by REF and immediately reflected in the ignition timing set by the REF. Therefore, the correction amount can be reflected in the combustion immediately after REF.
[0069]
At the time of stratified combustion, the correction amount (PIPER) is calculated by REF. However, in this rotation region, there is a case where 10 ms-JOB never enters between REF and the fuel injection pulse. In this case, the correction amount calculation is performed. This will be reflected in the second combustion.
Therefore, in stratified combustion, the timing at which the correction value is reflected may be delayed compared to the case of homogeneous combustion. However, according to this calculation method, the calculation load in REF-JOB is reduced. It is possible to prevent an increase in the rotation synchronization calculation load when the rotation speed is increased.
[0070]
In addition, the correction request value in the non-idle rotation speed region is sufficient if it can be handled in time synchronization, and the reflection timing request is less severe than the idle rotation speed region, so the correction value is reflected every 10 ms. If it is done, there will be no problem of performance degradation. Therefore, in the non-idle rotation speed region, torque correction can be realized with a sufficient response in both cases of homogeneous and stratified while preventing an increase in calculation load for rotation synchronization.
[0071]
In contrast, the effect of the fifth embodiment will be described with reference to FIG.
When the capability of the calculation means is sufficiently high, both the correction amount TQRET and the fuel injection amount Ti are calculated using REF.
The correction of the fuel amount at the time of stratified combustion can always be reflected in the combustion immediately after the REF similarly to the ignition timing correction value at the time of homogeneous combustion.
[0072]
Therefore, torque correction can be realized with a sufficient response in all the rotational speed regions, whether homogeneous or stratified.
Finally, a torque correction request routine and a combustion system switching routine will be described. FIG. 19 is a flowchart of a torque correction request (torque correction request calculation) routine by shifting.
[0073]
In step S201, it is determined whether or not a shift is being performed. In S203, it is determined whether or not there is a torque correction request. If so, an elapsed time after the torque correction request is calculated in S204, and based on this, a torque correction request is calculated in S205.
FIG. 20 is a flowchart of a torque correction request (torque correction request calculation) routine when the air conditioner is ON.
[0074]
In step S211, it is determined whether or not the air conditioner is ON. If the air conditioner is ON, an elapsed time after ON is calculated in step S212, and a torque correction request is calculated in step S215. If the air conditioner is OFF, the elapsed time after OFF is calculated in S213, and it is determined in S214 whether or not it is within a predetermined time after OFF. If it is within the predetermined time after OFF, based on the predetermined time after OFF in S215. Calculate the torque correction requirement.
[0075]
FIG. 21 is a flowchart of a torque correction request (torque correction request calculation) routine by fuel cut recovery.
In S221, it is determined whether or not the fuel cut is being recovered. In the case of recovery, the elapsed time after recovery is calculated in S222. Then, in S223, it is determined whether or not it is within a predetermined time after recovery. If it is within the predetermined time, a torque correction request is calculated in S224 based on the elapsed time after recovery.
[0076]
FIG. 22 is a flowchart of a combustion system switching (and basic equivalence ratio tφ setting) routine.
In S301, the water temperature, the time after startup, the operating conditions (engine speed, target torque), etc. are read as map switching conditions.
In S302, according to the map switching condition, homogeneous stoichiometric combustion, homogeneous lean combustion, and stratified lean combustion are determined, and a map switching flag (FMAPCH) is calculated.
[0077]
In S303, it is determined whether or not FMAPCH = 0. If YES, the basic equivalence ratio tφ is determined from the engine speed Ne (rpm) and the target torque tTe (kgm) with reference to the homogeneous stoichiometric map in S304. Set.
If FMAPCH ≠ 0, it is determined in S305 whether FMAPCH = 1, and if YES, in S306, referring to the homogeneous lean map, the engine speed Ne (rpm) and the target torque tTe (kgm ) To set the basic equivalent ratio tφ.
[0078]
If FMAPCH ≠ 1, the basic equivalence ratio tφ is set from the engine speed Ne (rpm) and the target torque tTe (kgm) with reference to the stratified lean map in S307.
FIG. 23 shows an example of a general flowchart of overall control.
In step a, it is determined whether or not there is a reservation for 10 ms-JOB, and if there is a reservation, steps b to f are executed. That is, the combustion mode is switched at step b, the torque correction request is detected at step c, the basic ignition timing ADVmap is calculated at step d, the basic equivalence ratio tφ is set at step e, and the fuel injection amount at step d Calculate Ti.
[0079]
On the other hand, if there is no reservation for 10 ms-JOB, it is determined in step g whether or not there is a reservation for REF-JOB. If there is a reservation, steps h and i are executed. That is, the torque correction amount PIPER is calculated in step h, and the ignition timing ADV is calculated in step i.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing the configuration of the present invention.
FIG. 2 is an engine system diagram showing an embodiment of the present invention.
FIG. 3 is a flowchart of a torque correction amount calculation routine of the first embodiment.
FIG. 4 is a flowchart of an ignition timing calculation routine according to the first embodiment.
FIG. 5 is a flowchart of a fuel injection amount calculation routine of the first embodiment.
FIG. 6 is a flowchart of a torque correction amount calculation routine of the second embodiment.
FIG. 7 is a block diagram of torque demand control of the second embodiment.
FIG. 8 is a flowchart of a torque correction amount calculation routine of the third embodiment.
FIG. 9 is a flowchart of a fuel injection amount calculation routine of the third embodiment.
FIG. 10 is a flowchart of a torque correction amount calculation routine of the fourth embodiment.
FIG. 11 is a flowchart of a torque correction amount calculation routine of the fifth embodiment.
FIG. 12 is a diagram showing an example of a response waveform according to the first embodiment.
FIG. 13 is a diagram showing an example of a response waveform according to the second embodiment.
FIG. 14 is a diagram showing an example of a response waveform according to the third embodiment.
FIG. 15 is a diagram showing an example of a response waveform according to the fourth embodiment.
FIG. 16 is a diagram showing the operation of fuel injection amount time synchronization calculation;
FIG. 17 is a diagram showing the operation of fuel injection amount time synchronization calculation;
FIG. 18 is a diagram showing the operation of fuel injection amount rotation synchronization calculation (fifth embodiment).
FIG. 19 is a flowchart of a torque correction request routine using a shift.
FIG. 20 is a flowchart of a torque correction request routine when the air conditioner is ON.
FIG. 21 is a flowchart of a torque correction request routine by fuel cut recovery.
FIG. 22 is a flowchart of a combustion system switching routine.
FIG. 23 is a general flowchart of the entire control.
FIG. 24 is a diagram showing a torque correction amount → ignition timing correction amount conversion table.
FIG. 25 is a diagram showing a torque correction amount → equivalence ratio correction amount conversion table.
FIG. 26 is a diagram showing a basic ignition timing map.
[Explanation of symbols]
1 engine
4 Electric throttle valve
5 Fuel injection valve
6 Spark plug
20 Control unit

Claims (8)

A direct-injection spark-ignition engine having combustion mode switching means capable of switching between homogeneous combustion performed by injecting fuel in an intake stroke and stratified combustion performed by injecting fuel in a compression stroke, and operating conditions of the engine Including torque correction request means for generating a torque correction request based on
With respect to the torque correction request in the same combustion system, at the time of homogeneous combustion, out of the ignition timing and air-fuel ratio, and uniform combustion time torque correcting means for performing torque correction by correcting at least the ignition timing, at the time of stratified charge combustion, the ignition timing A direct-injection spark-ignition engine control apparatus, comprising: a stratified combustion torque correction means that corrects torque by correcting only the air-fuel ratio of the engine and the air-fuel ratio . A direct-injection spark-ignition engine having combustion mode switching means capable of switching between homogeneous combustion performed by injecting fuel in an intake stroke and stratified combustion performed by injecting fuel in a compression stroke, and operating conditions of the engine Including torque correction request means for generating a torque correction request based on
In response to the torque correction request in the same combustion system, while providing a torque control means for controlling the torque by controlling the intake air amount of the engine,
Torque correction means that corrects the torque by correcting at least the ignition timing during homogeneous combustion so as to perform highly responsive torque correction for intake air amount control delay, and torque by correcting at least the air-fuel ratio during stratified combustion A control device for a direct-injection spark-ignition engine, characterized in that stratified combustion torque correction means for performing correction is separately provided. A direct-injection spark-ignition engine having combustion mode switching means capable of switching between homogeneous combustion performed by injecting fuel in an intake stroke and stratified combustion performed by injecting fuel in a compression stroke, and at least an accelerator opening And a target torque calculation means for calculating a target torque of the engine including a torque correction request in the same combustion method ,
While providing torque control means for controlling the intake air amount of the engine so as to achieve the target torque,
Torque correction means that corrects the torque by correcting at least the ignition timing during homogeneous combustion so as to perform highly responsive torque correction for intake air amount control delay, and torque by correcting at least the air-fuel ratio during stratified combustion A control device for a direct-injection spark-ignition engine, characterized in that stratified combustion torque correction means for performing correction is separately provided.   The torque control means includes a required basic fuel amount calculating means for calculating a required basic fuel amount so as to realize a target torque, and a target intake air amount calculation for calculating a target intake air amount from the required basic fuel amount and a target air-fuel ratio. Means, a target throttle opening calculation means for calculating the target throttle opening based on the target intake air amount, and a throttle valve drive control means for driving the throttle valve to achieve the target throttle opening. The direct-injection spark-ignited engine control device according to claim 3.   The homogeneous combustion torque correction means divides the torque correction amount into an ignition timing correction amount and an air-fuel ratio correction amount, corrects the ignition timing and air-fuel ratio, and performs torque correction. The direct-injection spark according to any one of claims 1 to 4, wherein the torque correction amount is set only for an air-fuel ratio correction, and the torque correction is performed by correcting the air-fuel ratio. Control device for ignition engine.   The torque correction amount in the homogeneous combustion torque correction means and the stratified combustion torque correction means is calculated in synchronization with engine rotation, and the reflection of the torque correction amount in the fuel injection amount is calculated in time synchronization. The control device for a direct-injection spark ignition engine according to any one of claims 1 to 5. 2. The homogenous combustion torque correcting means and the stratified combustion torque correcting means, wherein the calculation of the torque correction amount and the reflection of the torque correction amount on the fuel injection amount are calculated in synchronization with the engine rotation. Item 6. The direct-injection spark-ignition engine control device according to any one of Items 5 to 6. 8. The direct-injection spark-ignited engine control device according to claim 1, wherein the torque correction request is caused by shifting, air-conditioner ON, or fuel cut recovery.

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