JP3018740B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control system for an internal combustion engine, and more particularly to an exhaust gas recirculation system for recirculating an appropriately controlled exhaust gas into an intake air mixture to slow down combustion in an engine combustion chamber. The present invention relates to an ignition timing control device for an internal combustion engine having a circulation device.

[0002]

2. Description of the Related Art Conventionally, a part of exhaust gas of an internal combustion engine is recirculated into an intake air-fuel mixture, and heat generated by combustion in an engine combustion chamber is deprived of inert gas in the exhaust gas to lower the maximum combustion temperature. This reduces exhaust gas recirculation (EGR: exhaust gas) to reduce nitrogen oxides (NO _x ).
Recirculation) devices are known.

However, when EGR is performed, the propagation of combustion is slowed with an increase in the amount of exhaust gas to be recirculated (hereinafter, referred to as an EGR amount). Therefore, ignition timing control for advancing the ignition timing with an increase in the EGR amount is performed. An apparatus is known (Japanese Unexamined Patent Publication No.
No. 9-221467). In such an ignition timing control device, as shown in FIG. 11, the base ignition timing I when the EGR is not operating at the same intake pipe pressure PM and the engine speed NE.
In general, the ignition timing is obtained by adding an advance amount by the EGR to the ignition timing. Therefore, the ignition timing is shown in FIG.
It becomes as shown by. In this case, the advance amount by EGR when the EGR amount A in FIG. 11 is ΔSAa. If the EGR amount is changed from this state to a value indicated by B in FIG. In the drawing, ΔSAb is obtained, and the advance amounts ΔSAa and ΔSAb change in proportion to the EGR amount (or the EGR valve control amount).

[0004]

However, fresh air is sucked into the engine combustion chamber together with the exhaust gas recirculated by the EGR, but the high temperature of the exhaust gas causes the fresh air to be heated and expanded. For this reason, the larger the EGR amount, the greater the amount of heat received by the fresh air, the lower the density of the fresh air, and the lower the charging efficiency (mass ratio of the fresh air sucked into the engine).

Therefore, the charging efficiency is not proportional to the change in the EGR amount, and the required ignition timing has a non-linear relationship with the EGR amount as shown by a solid line III in FIG. For this reason,
In the conventional device, B, in which the EGR amount is small, is more advanced than A, in which the EGR amount is large, because the charging efficiency is large,
There is a great possibility that the torque will be reduced (thermal efficiency will be reduced) and knocking will occur.

[0006] The present invention has been made in view of the above points,
An object of the present invention is to provide an ignition timing control device for an internal combustion engine that solves the above-mentioned problem by variably controlling the ignition timing with respect to the EGR amount according to the charging efficiency.

[0007]

FIG. 1 is a block diagram showing the principle of the present invention for achieving the above object. As shown in FIG. 1, in the present invention, a control valve 12 provided in the middle of an exhaust gas recirculation passage 11 that connects the exhaust passage and the intake passage of the internal combustion engine 10 is provided.
The exhaust gas recirculation amount control means 13 controls the exhaust gas recirculation amount to the intake air-fuel mixture by controlling the valve opening degree of the exhaust gas recirculation amount to the intake air-fuel mixture. , the exhaust gas as the exhaust gas recirculation amount is greatly
Advance relative to basic ignition timing when recirculation is not
Lead angle value calculating means 4 for calculating a basic lead angle value on the angle side ;
An ignition timing control apparatus for an internal combustion engine, comprising: an ignition means for igniting the internal combustion engine at a timing according to an input advance value.
7 is provided.

[0008] Here, the first calculating means 16 calculates a correction coefficient of the ignition timing based on the change rate of the exhaust gas recirculation amount. A second calculating means for calculating, based on the correction coefficient and the basic advance value, a corrected advance value that increases in the advance direction in a non-linear manner with respect to the increase in the exhaust gas recirculation amount;
The input advance value is calculated based on the corrected advance value and the basic ignition timing.
And the ignition by the ignition means 15 is performed.

[0009]

According to the present invention, the input advance angle obtained on the basis of the corrected advance value and the basic ignition timing which are nonlinearly increased in the advance direction as the exhaust gas recirculation amount (EGR amount) increases.
Since the ignition by the ignition means 15 is performed according to the value ,
When the GR amount is plotted on the horizontal axis and the ignition timing is plotted on the vertical axis, the EGR amount-ignition timing characteristic is not a straight line as in the conventional case, but as shown by a solid line III in FIG. It is possible to obtain a corrected advance angle value that becomes a curve.

[0010]

FIG. 3 is a block diagram of a main part of an internal combustion engine to which the present invention is applied. In this embodiment, the internal combustion engine 10 has four cylinders 4
This is an example applied to a cycle spark ignition type internal combustion engine (engine), and is controlled by a microcomputer 21 described later. A surge tank 24 is provided downstream of the air cleaner 22 via a throttle valve 23. An intake air temperature sensor 25 for detecting an intake air temperature is attached near the air cleaner 22, and an idle switch 26 that is turned on when the throttle valve 23 is fully closed is attached to the throttle valve 23. A diaphragm type pressure sensor 27 is attached to the surge tank 24.
This pressure sensor 27 detects the intake pipe pressure PM.

A bypass passage 28 is provided to bypass the throttle valve 23 and communicate between the upstream side and the downstream side of the throttle valve 23.
Idle speed control valve (ISCV) 29 whose degree of valve opening is controlled by a solenoid in the middle of
Is installed. The idling rotational speed is controlled to the target rotational speed by controlling the valve opening degree by controlling the duty ratio of the current flowing through the ISCV 29 and thereby adjusting the amount of air flowing through the bypass passage 28. The surge tank 24 is connected to a combustion chamber 33 of an engine 32 (corresponding to the internal combustion engine 10) via an intake manifold 30 and an intake valve 31. Intake manifold 3
A fuel injection valve 34 is provided for each cylinder so as to partially protrude into zero, and the fuel is injected into the airflow passing through the intake manifold 30 by the fuel injection valve 34.

The combustion chamber 33 is connected to a catalyst device 37 via an exhaust valve 35 and an exhaust manifold 36. Reference numeral 38 denotes an ignition plug, which is provided so as to partially project into the combustion chamber 33. Reference numeral 39 denotes a piston which reciprocates vertically in the figure.

The igniter 40 generates a high voltage, and the high voltage is distributed and supplied by the distributor 41 to the spark plug 38 of each cylinder. The igniter 40, the distributor 41 and the ignition plug 38 constitute the ignition means 15. The rotation angle sensor 42 is the distributor 4
The rotation of one shaft is detected and an engine rotation signal indicating the engine speed NE is output to the microcomputer 21 at every 30 ° CA, for example.

A water temperature sensor 43 is provided so as to penetrate the engine block 44 and partially project into the water jacket, and detects the temperature of the engine cooling water to output a water temperature sensor signal. Further, the oxygen concentration detection sensor (O ₂ sensor) 45 is arranged so that a part thereof penetrates and projects through the exhaust manifold 36, and the catalyst device 37.
The oxygen concentration in the exhaust gas before entering is detected.

The exhaust manifold 36 on the upstream side of the O ₂ sensor 45 and the intake manifold 30 on the downstream side of the throttle valve 23 are connected by a recirculation passage 46 corresponding to the exhaust gas recirculation passage 11.
Further, an EGR cooler 47 and an exhaust gas recirculation valve (hereinafter referred to as EGRV) 48 corresponding to the control valve are provided in the recirculation passage 46, respectively.

The EGR cooler 47 is for lowering the temperature of the exhaust gas flowing through the recirculation passage 46. EG
The RV 48 has a structure in which the opening degree of the valve is changed by the valve body 48b being displaced upward in the drawing in accordance with a drive signal input to the step motor 48a from the microcomputer 21 to be described later through the motor drive circuit 49. . By controlling the opening of the EGRV 48, E
The flow rate of the exhaust gas input through the GR cooler 47 is controlled, whereby the amount of exhaust gas recirculated to the intake manifold 30 is controlled.

The microcomputer 21 for controlling the operation of each unit shown in FIG. 3 having such a configuration has a known hardware configuration as shown in FIG. 3, the same components as those of FIG. 3 are denoted by the same reference numerals, and the description thereof will be omitted. FIG.
The microcomputer 21 includes a central processing unit (CPU) 70, a read-only memory (ROM) 71 storing a processing program and a map described later, and a random access memory (RA) used as a work area.
M) 72, a backup RAM 73 that retains data even after the engine is stopped, and a clock generator 74 that supplies the master clock to the CPU 70. These are connected to each other via a bidirectional bus line 75.

The microcomputer 21 includes an input interface circuit 76 having a multiplexer, an A / D
A converter 77 and an input / output interface circuit 78;
The A / D converter 77 and the input / output interface circuit 78 are connected to the bus line 75. The output of the input interface circuit 76 is input to the A / D converter 77.

Intake air temperature sensor 25, pressure sensor 27, O ₂
The respective output detection signals of the sensor 45 and the water temperature sensor 43 are input to the input interface circuit 76, are switched here, are sequentially input to the A / D converter 77, are A / D converted here, and are stored in the RAM 72. Or supplied to the CPU 70. Each output detection signal of the rotation angle sensor 42 and the idle switch 26 is supplied to the input / output interface circuit 7.
8 to the CPU 70 or the like.

Further, the input / output interface circuit 78
The fuel injection valve 34, ISCV2
9, a drive signal is output to the motor drive circuit 49, and an opening control signal of the EGRV 48 is output to the igniter 40. A primary current of the ignition coil is turned on to the igniter 40 from a predetermined crank angle before an ignition timing ABSE described later. A control signal for turning off the primary current is output at the timing of the ignition timing ABSE. Thus, the igniter 40 generates a high voltage at the timing of the ignition timing ABSE, and ignites the ignition plug 38.

The microcomputer 21 having such a hardware configuration is provided with the exhaust gas recirculation amount control means 1 described above.
3. Lead angle calculating means 14, first calculating means 16, second
An EGRV control routine that implements the exhaust gas recirculation amount control unit 13 is described below with reference to FIG.

The CPU 70 first reads the instructed valve opening degree TSTEP from the RAM 72 in step 101 and
In the register inside. The command opening degree TSTEP is a value calculated based on a two-dimensional map of the engine speed NE and the intake pipe pressure PM stored in the ROM 71 as shown in FIG. I have. In FIG. 6, values between cells are calculated by interpolation calculation.

Subsequently, the commanded valve opening degree TSTEP and the EGRV
It is determined whether or not the variable RSTEP corresponding to the actual valve opening degree is equal to 48 (step 102). If it is determined that they are not equal, in the next step 103, TSTEP and RS
The magnitude of each TEP value is compared.

As a result of the comparison, TSTEP <RST
In the case of EP, the value of RSTEP is decremented by 1 (step 104). On the other hand, in the case of TSTEP> RSTEP, the value of RSTEP is incremented by 1 (step 105). To the EGRV 48 through which it is driven (step 106).

On the other hand, at step 102, TSTEP = RS
When the TEP determination is obtained, the process proceeds to step 106, where the EGRV 48 is driven based on the current variable RSTEP, and the process ends.

Therefore, according to the EGRV control routine, the variable RSTEP indicating the actual valve opening is set to the commanded valve opening TST.
When the value is greater than EP, the degree of opening of the EGRV 48 is driven by one step in the closing direction. When the value is smaller than the EP, the degree of opening is driven by one step in the opening direction. become. In this way, the opening of the EGRV 48 is controlled in accordance with the operating state, thereby controlling the amount of exhaust gas recirculation. EGRV4
8 may be controlled in a valve closing direction from TSTEP during acceleration, during warm-up after startup, and depending on operating conditions such as the engine cooling water temperature being equal to or higher than a predetermined value.

Next, the ignition timing calculation routine of the main part of one embodiment of the present invention which realizes the advance angle value calculation means 14, the first calculation means 16 and the second calculation means 17 will be described with reference to FIGS. It is explained together with. When the ignition timing calculation routine shown in FIG. 7 is started, first, a basic advance value AEGR corresponding to an operating state at a predetermined basic opening degree of the EGRV 48.
B is calculated from the map shown in FIG.
1).

The above operation state is determined from the intake pipe pressure PM and the engine speed NE, and as shown in FIG.
M), the value is small at the time of low rotation (NE) and small at the time of high load, but is large at the time of medium load and medium rotation.

Subsequently, the routine proceeds to step 202 in FIG. 7, where the atmospheric pressure correction coefficient KPAEGR is calculated based on the following equation.

[0030]

(Equation 1)

However, in the above formula, PA is atmospheric pressure, and PA-P
M ≧ 0 and 760−PM ≧ 0. “30” is an exhaust pressure correction term. In the above equation, the numerator indicates the estimated EGR amount at the time of the current atmospheric pressure, and the estimated EG amount when the denominator is 760 mmHg.
The R amount is shown.

Subsequently, a correction coefficient KQAEGR for the basic EGR amount when the EGRV 48 is variably controlled is calculated by the following equation (step 203).

KQAEGR = QEEGR / QETEGRB1 (2) In the above equation, QEEGR is the EGR amount at the current number of steps of the EGRV 48, and QETEGRB1 is the EGR amount at the basic target step number ETEGRB1. EGRV
Calculating the correction coefficient KQAEGR for the EGR amount without calculating the correction coefficient for the number of steps corresponding to the opening degree of 48 has a non-linear relationship between the number of steps and the EGR amount, not necessarily linearly. EG
It is converted into an R amount.

The above QETEGRB1 and QEEGR
Is based on the map shown in FIG. 9 and stored in advance in the ROM 71, from the basic target step number ETEGRB1 (corresponding to the instructed valve opening degree TSTEP) to
From the current step number EEGR (corresponding to RSTEP), QEEGR is obtained by interpolation calculation.

Next, the correction coefficient (rate of change) in the basic EGR amount at the standard atmospheric pressure (760 mmHg) is calculated in step 2
02 and the correction coefficient KQA for the basic EGR amount calculated in step 203.
It is determined from the product of the EGR and the EGR (step 204).

Subsequently, the ignition timing correction coefficient (EG) based on the change rate of the EGR amount is referred to from the value of the correction coefficient KPAEGR × KQAEGR calculated in step 204 with reference to a map shown in FIG.
The correction coefficient of the R correction advance angle) KAEGR is calculated (step 205). The ignition timing correction coefficient KAEGR is a correction coefficient calculated by the first calculating means 16 and is shown in FIG.
Is a correction coefficient that gives a downwardly convex characteristic shown in FIG.

Next, the above-mentioned ignition timing correction coefficient KAEGR
And the basic advance value AEGRB calculated in step 201, the EGR corrected advance value AEGR is calculated based on the following equation (step 206).

AEGR = AEGRB × KAEGR (3) Finally, at the basic ignition timing tAST at the time of stoichiometry of the same PM and NE, the above E calculated at step 206 is calculated.
The corrected advanced angle AEGR is calculated by adding the GR corrected advanced value AEGR as shown in the following equation (step 207).

ABSEF = tAST + AEGR (4) Steps 206 and 207 described above correspond to the second calculating unit 17 described above.

As described above, according to this embodiment, the correction coefficient (KP
AEGR × KQAEGR) is not multiplied by the basic advance value AEGRB to calculate a correction advance value, but a correction coefficient (KPAEGR × KQA) in the basic EGR amount at the standard atmospheric pressure.
EGR) with reference to the map shown in FIG. 10 to calculate a correction coefficient KAEGR of the EGR correction advance angle corresponding to the charging efficiency, and multiply the KAEGR by the basic advance value AEGRB to calculate a correction advance value AEGR. Therefore, it is possible to perform ignition timing control in which the charging efficiency is added to the EGR amount, and to prevent an over-advance angle even if the EGR amount decreases.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can also be applied to a device that measures the intake air amount of the engine with an air flow meter to control the fuel injection amount (however, In this case, an atmospheric pressure sensor is required).

[0042]

As described above, according to the present invention, a corrected advance value corresponding to the EGR amount and the charging efficiency can be obtained, so that even if the EGR amount decreases, the over-advance angle can be prevented. In addition, it is possible to prevent a decrease in torque (a decrease in thermal efficiency) and the occurrence of knocking.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a characteristic diagram illustrating the operation of the present invention.

FIG. 3 is a configuration diagram of an example of a main part of an internal combustion engine to which the present invention is applied.

FIG. 4 is a diagram showing a hardware configuration of the microcomputer in FIG. 3;

FIG. 5 is a flowchart illustrating an EGRV control routine;

FIG. 6 is a diagram showing an instruction valve opening degree calculation map used in the routine of FIG. 5;

FIG. 7 is a flowchart showing an ignition timing calculation routine according to an embodiment of the main part of the present invention.

8 is a diagram showing an example of a basic lead angle value calculation map used in the routine of FIG. 7;

9 is a step number conversion EG used in the routine of FIG. 7;
It is a figure showing an example of an R amount calculation map.

FIG. 10 is a diagram showing an example of an EGR correction advance angle value calculation map used in the routine of FIG. 7;

FIG. 11 is a diagram illustrating a relationship between an EGR amount and an ignition timing according to a conventional device.

FIG. 12 is a characteristic diagram for explaining a problem of the conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Internal combustion engine 11 Exhaust gas recirculation passage 12 Control valve 13 Exhaust gas recirculation amount control means 14 Advance value calculation means 15 Ignition means 16 First calculation means 17 Second calculation means 21 Microcomputer 48 Exhaust gas recirculation valve (EGRV) )

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-64-636555 (JP, A) JP-A-1-232150 (JP, A) JP-A-4-1666671 (JP, A) 156973 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 43/00 F02M 25/07 F02P 5/15

Claims (1)

(57) [Claims] An exhaust gas to an intake air-fuel mixture is controlled by controlling a degree of opening of a control valve provided in a middle of an exhaust gas recirculation passage communicating an exhaust passage and an intake passage of an internal combustion engine in accordance with an operation state. an exhaust gas recirculation amount control means for controlling the gas recirculation amount, depending on the operating conditions and the exhaust gas recirculation amount, the exhaust gas recirculation as exhaust gas recirculation amount is greatly
Is advanced with respect to the basic ignition timing when
An ignition timing control apparatus for an internal combustion engine, comprising: an advanced angle value calculating means for calculating a basic advanced angle value; and an ignition means for igniting the internal combustion engine at a timing according to an input advanced value. a first calculation means for calculating a correction coefficient of the ignition timing by the change in ratio of the amount, based on the with the correction factor the basic advance angle value, nonlinearly proceeds with increase of the exhaust gas recirculation amount Second calculating means for calculating a correction advance value that increases in the angular direction, wherein the input advance angle is calculated based on the correction advance value and the basic ignition timing.
An ignition timing control device for an internal combustion engine , wherein a value is obtained and ignition is performed by the ignition means.