JPS5853677A - Ignition timing control method of multi-cylinder internal-combustion engine - Google Patents

Abstract

PURPOSE:To perform an ignition timing control properly with a small number of knock sensors by varying the ignition timing correction quantity corresponding to the presence of knocking for each cylinder in accordance with the difference of knocking detection S/N ratios for individual cylinders by a knock sensor. CONSTITUTION:A digital electronic control circuit 56 is provided on an ignition timing control circuit and it is connected to an air flow meter 24, intake air temperature sensor 26, cooling water temperature sensor 40, cylinder judging sensor 50, rotating angle sensor 52, knock sensor 18, ignitor 44, and injecter 34. When the knock sensor 18 detects knocking, the control circuit 56 calculates so that the ignition timing correction quantity for the first, sixth, second, and fifth cylinders with a lower knocking detection S/N ratio is made smaller than the correction quantity for the third and fourth cylinders with a higher knocking detection S/N ratio, ant it outputs an ignition direction signal to the ignitor 44 and a fuel injection signal to the injecter 34 respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control method for a multi-cylinder internal combustion engine.
In particular, the basic ignition timing, which is suitable for use in gasoline engines installed in automobiles, is determined according to the operating state of the engine, depending on the presence or absence of knocking in each cylinder of the engine as determined from the knock sensor output. Regarding the improvement of the ignition timing control method for a multi-cylinder combustion engine in which correction is made for each cylinder.In general, internal combustion engines, and in particular, spark-ignited internal combustion engines such as gasoline engines installed in vehicles such as automobiles. It is extremely important to control the ignition timing to an appropriate value according to the engine operating conditions in order to improve the output and fuel efficiency of the internal combustion engine. Various ignition timing control methods are used in practical use, but in recent years, knock sensors have been installed on the cylinder block of an internal combustion engine to detect knocking conditions of the internal combustion engine from vibrations of the cylinder block wall, etc. However, the basic ignition timing determined according to the operating state of the engine is corrected for each cylinder according to the presence or absence of knocking in each cylinder of the engine, which is determined from the output of the knock sensor.
An ignition timing control method for a multi-cylinder internal combustion engine has been proposed in which nine ignition timing controls are performed depending on the state of knocking in each cylinder of the internal combustion engine.

According to such an ignition timing control method, the ignition timing is corrected to the optimum value for each cylinder according to the state of knocking in each cylinder of the engine. There was a problem with the ignition timing control method depending on the presence or absence of.

In other words, in the case of a multi-cylinder internal combustion engine, in order to detect knocking with high accuracy, it is possible to install a knock sensor for each cylinder independently at a position where it can detect the most severe knocking in each cylinder, but this requires cost and space. Because of this, the reality is that one or two knock sensors are usually used to detect knocking in the cylinder.

However, in such a case, there will be a difference in the knocking detection ratio of 8/N between cylinders far from the knock sensor and cylinders close to the knock sensor, and in addition to the distance from the knock sensor, the 8/N Normally, there is a difference in the ratio. For example, when one knock sensor 18 is disposed between the 31i cylinder 13 and the 4th cylinder 14 of a 6-cylinder engine 10, as shown in FIG. The knock sensor output distribution for each cylinder without knocking (lol MA) and with knocking (broken #B) is as shown in Figure 2, and the knock sensor output distribution for each cylinder is as shown in Figure 2.
In the No. 1 and No. 4 cylinders 14, the presence or absence of knocking can be clearly distinguished, whereas in the No. 1 cylinders 11 and 6 cylinders 16, which are far from the knock sensor 18, it is difficult to determine the presence or absence of knocking from the output of the knock sensor 18. 0 becomes very difficult
In addition, in the case of the second cylinder 12 and the fifth cylinder 15 located in the intermediate position, in the case of the third cylinder 13 and the fourth cylinder 14,
Therefore, the 8/N ratio of the knocking detection for each cylinder of the knock sensor 18 is also 0, which is between the cases of the first cylinder 11 and the sixth cylinder 16, as shown in FIG. 8/N for No. 13 cylinder and No. 4 cylinder 14
While the ratio is good, in the first cylinder 11 and the sixth cylinder 16, which are far from the knock sensor 18, the
◇ However, conventionally, regardless of the difference in the 8/N ratio of the knocking detection for each cylinder by the knock sensor 18, if it is determined that there is knocking, a certain angle retard is applied to each cylinder. In addition, if it is determined that there is no knocking, the engine is advanced by a certain angle for each cylinder. For this reason, even in cases such as the left cylinder 11 and the 6th cylinder 16, where the 8/N ratio of the knocking effect is poor and it is mistakenly determined that there is knocking even though no knocking actually occurs, the timing is greatly delayed. Or, conversely, when it is incorrectly determined that there is no knocking even though knocking is occurring, the angle of advance is greatly increased. Therefore, the over-advanced angle may cause engineering/performance deterioration, the over-advanced angle may cause large knocking, and even mechanical/jin troubles. An object of the present invention is to provide an ignition timing control method for a multi-cylinder internal combustion engine that can accurately control the ignition timing of the multi-cylinder internal combustion engine using a small number of knock sensors.

The present invention provides a multi-cylinder internal combustion engine in which the basic ignition timing determined according to the operating state of the engine is corrected for each cylinder according to the presence or absence of non-king in each cylinder of the engine determined from the output of a knock sensor. In the engine ignition timing control method, the ignition timing correction amount depending on the presence or absence of knocking is changed for each cylinder depending on the difference in the 8/N ratio of knocking detection for each cylinder of the knock sensor, The purpose has been achieved. Also, the ignition timing correction amount according to the presence or absence of knocking for the cylinder rC with a low 8/N ratio of knocking detection is changed to the ignition timing correction amount for the cylinder with a high 8/N ratio of knocking detection. 8/N of knocking detection by making the quantity smaller.
For cylinders with a low ratio, knocking is less likely to occur, while for cylinders with a high S/N ratio for knocking detection, quick ignition timing control is performed.

For example, in the case of a 6-cylinder machine/engine 10 as shown in Figures 1 to 3 above, the ignition timing correction amount depending on the presence or absence of knocking for each cylinder is as follows: The amount of retard angle at the time of engine knocking can be selected as shown in FIG. 4, while the amount of advance angle when there is knocking for each cylinder can be selected as shown in FIG. still,
The amount of retardation when knocking occurs for each cylinder is not limited to the above example, and can be experimentally selected for the target engine. For example, if a multi-cylinder internal combustion engine has 4 cylinders, and a knock sensor is installed between the 2nd and 3rd cylinders, the ignition timing for the 1st and 4th cylinders is The correction amount can be made smaller than the ignition timing correction cover for the 2nd and 3rd cylinders. Embodiments of the present invention will be described below in detail with reference to the drawings. and as shown in Figure 7, 6ki f'J
an air flow meter 24 that is provided in the intake passage 22 of the engine 10 and outputs an electrical signal in response to the amount of intake air;
An intake temperature sensor 26 provided in the air 70-meter 24 and outputting an electric signal according to the intake air temperature, an intake throttle valve 28 disposed midway in the intake pipe 27, and the intake throttle valve 28. a surge tank 30 disposed on the downstream side of the intake boat; an injector 34 disposed in the intake manifold 32 for injecting fuel such as gasoline into the intake boat; an ignition plug 38, a cooling water temperature sensor 40 that outputs an electric signal according to the engine cooling water temperature, an exhaust manifold 42, an igniter 44 that generates an ignition primary signal, and an ignition 1 generated by the igniter 44. The ignition coil 46 converts the next signal into a high-voltage ignition secondary 1g signal, and the high-voltage ignition secondary signal is given from the ignition coil 46 in accordance with the rotation of the distributor shaft 48a, which rotates once for every two rotations of the engine crankshaft. is distributed to each cylinder of the engine and applied to the ignition plug 38 of the corresponding cylinder.The cylinder discrimination system detects the rotational state of the distributor shaft 48a and outputs a cylinder discrimination signal every two rotations of the crankshaft. sensor 50 and a predetermined crank angle, e.g.
A distributor 48 with a built-in rotation angle sensor 52 that outputs a rotation angle signal for each 0°C person, and a 6-cylinder engine/engine 1
A knock sensor 18 is installed on the 10m wall of the cylinder block of 0 and detects knocking of the engine, the air flow meter 24 output, the intake air temperature sensor 26 output, the cooling water temperature sensor 40 output, the cylinder discrimination sensor 50 output, and the rotation. Depending on the output of the angle sensor 52, the output of the knock sensor 18, etc., the basic ignition timing determined from the intake air amount corrected by the intake air temperature and the engine speed is adjusted based on the presence or absence of knocking in each cylinder of the engine, the cooling water temperature, etc. A nine ignition command signal is output to the igniter 44 according to the ignition advance amount determined for each cylinder by correcting it for each cylinder accordingly, and the intake air amount and engine are similarly corrected according to the intake air temperature. The injector 3 receives a fuel injection signal obtained by correcting the nine basic fuel injection times calculated from the rotation speed according to the engine condition, etc.
4, the digital electronic control circuit 56 adjusts the ignition timing correction amount according to the presence or absence of knocking to the knocking detection S/S for each cylinder of the knock sensor 18. Depending on the difference in the N ratio, it is changed for each cylinder, and as shown in Figures 4 and 5 above, the number 1 with the lowest 8/N ratio for knocking detection,
9 Ignition timing correction ti-, 8 for knocking detection depending on the presence or absence of knocking for the No. 6 cylinder, No. 2, and No. 5 cylinders.
The ignition timing correction amount is set to be smaller than the ignition timing correction amount for the 3rd and 4th cylinders, which have a high /N ratio.

The digital electronic control circuit 56, as shown in detail in FIG. Cylinder discrimination sensor 50 and rotation angle sensor 52 outputs and inputs are input via a multiplexer 66, an analog-to-digital converter 68, an input/output coupler 0, and a shaping circuit 72 for sequential conversion into digital signals. An input/output board 78 for inputting the output of the knock sensor 18 inputted via the circuit 74 and the analog-to-digital converter 76 at appropriate timing, a random access memory 8o, a read-only memory 82, and a central processing circuit. 84 and crystal oscillator 865
1, and the ignition command signal and the fuel injection signal through the drive circuits 88 and 90, respectively.
It is composed of output ports 92 and 94 for outputting to the igniter 44 and the injector 34.

The action will be explained below.

FIG. 8 shows the flow of the main routine. In this main routine, first, in step 100, WSt- is input to start processing, then in step 101, the input/output boat is initialized to the state necessary for starting the engine.Furthermore, in step 102, random access The memory 80 is cleared and initial values are set. Next, in step 103, a clock for the input/output counter is defined, for example,
Set the cycle for analog-to-digital conversion using the program. Furthermore, in step 104, transparent addresses of programs, counters, registers, etc. at the time when an interrupt occurs are specified. Next, in step 105, interrupt permission is granted, and in step 106, the intake air amount Q1 and the engine rotation speed N are stored in the read-only memory 82 in advance from the air flow meter 24 output and the rotation angle sensor 52 output. The engine rotation speed N and the ignition timing θB8m'i based on the intake air are calculated, and the process returns to step 103.

Also, depending on the output of the rotation angle sensor 52, the crank angle 30
An interrupt routine as shown in FIG. 9 is executed every time ℃A. That is, first, in step 110, this 30°C
From the time when the human interrupt routine was passed and the current time, calculate the rotation time required for the engine to rotate eight times at 30°C. This rotation time is used to calculate the engine rotation speed in the main routine. Then step 11
1, the cylinder discrimination signal of the cylinder discrimination sensor 50 output and 30'
Based on the counter that counts up when a CA interrupt occurs, it is calculated how many BTDO times the current interrupt occurs. Further, in step 112, the first cylinder 11 or 6
It is determined whether the top dead center (TDO) of the arrival cylinder 16 is reached, and if it is the top dead center of the No. 1 or No. 6 aromatic cylinder, the injector 34 is opened at step 113 as shown in FIG.
Turn on and fuel injection is activated. After the fuel injection is started in step 113, the fuel injection time τ is calculated from the intake air amount Q and the engine rotational speed N, and the time Ti at which the injection should be stopped is calculated and set in the conveyor register.

Further, in step 115, ATDO10° to ATDO6
After completing 0 step 115 in which the time t at which the knock detection gate should be opened is calculated from the current time and rotation, and set in the conveyor B register, or in step 112, the time t at which the knock detection gate should be opened is Alternatively, if it is determined that the position is other than the top dead center of the No. 6 cylinder 16, step 11
Proceeding to step 6, it is determined whether the current interrupt is a BTDO30° interrupt. If it is an interrupt of BTD 030°, the process proceeds to step 117, where all the outputs of the knock sensor 18 are taken in, and the presence or absence of knocking is determined based on the magnitude of the output level of the knock sensor, for example. Step 117
After determining the presence or absence of knocking in step 1, or
If it is determined in step 16 that the interrupt is other than the BTDO30' interrupt, the process proceeds to step 118, and the current interrupt is
0BT to determine whether or not it is a TDO60° interrupt
If it is an interrupt of DO600, the knock detection gate is closed at step 119 because the time when the knock detection gate should be closed is ATDO60°. Next, in step 120, the optimum ignition timing is calculated from the basic ignition timing θ11 calculated in the main routine and the state of the knock determination flag.

Specifically, as in the ignition timing calculation interrupt routine shown in FIG. 11, first, in step 130, a knock determination flag is set to determine whether or not there was knocking in the previous ignition of the n-th cylinder. At step 131, a knock judgment is made, and if there was a knock j in the previous ignition, that is, if the knock judgment flag is set, the process proceeds to step 132, where retard control is performed. If there was no knocking in the previous ignition, that is, if the knock determination flag is not set, the process advances to step 138 and advance control is performed.In step 132, the current ignition timing calculation is based on the number 1 cylinder 11. Alternatively, it is determined whether it is for the 6th cylinder 16 or another cylinder. This calculation is
No. 1 cylinder 11 or 6 with poor S/N ratio for knocking detection
If it is cylinder No. 16, proceed to step 133, and retard the knock correction value θ of the cylinder by 1 by a minimum amount of 0°5°C, as shown in the following equation, θ, ←ek, -0,5 ℃people・・・・・・・・・(1)
On the other hand, if the calculation is for a cylinder other than the first cylinder 11 or the sixth cylinder 16, the process proceeds to step 134. In step 134, as in step 132, it is determined whether the current vIt calculation is for the second cylinder 12 or the fifth cylinder 15. If so, the process proceeds to step 135, where the knock correction value θkm'ff of the corresponding cylinder is retarded by 0.75° C. as shown in the following equation.

θkm ← θ to −0,75℃ person ・・・・・・
...(2) Also, if it is determined in step 134 that the 2nd cylinder 12 or IHA 51 is a cylinder other than cylinder 15, the current calculation will be performed on the 3rd cylinder with a better 8/N ratio for knocking detection. Since this is for cylinder 13 or 411f cylinder 14, the process proceeds to step 136, where the knock correction value θkm of the corresponding cylinder is retarded by the maximum amount of 1° C., as shown in the following equation.

To θ, ←θkm -1℃ person ・・・・・・・・・＋3)
Further, in step 137, in order to count the number of ignitions after correcting the ignition timing according to the presence or absence of knocking, 10 is entered into the counter Os for the relevant cylinder. On the other hand, if it is determined in step 131 that there is no knocking, , the process advances to step 138, and the counter O for the corresponding cylinder is
Subtract one from the value of n. In step 139, it is determined whether the value of the counter On is zero, that is, after correcting the ignition timing according to the presence or absence of knocking, it is determined whether there have been 10 consecutive ignitions and no knocking. If 10 consecutive ignitions and no knocking have not occurred, the process proceeds to step 146 without rewriting the knock correction value θ with -. On the other hand, if the counter On is zero, ill,
&j1 when there is no ignition knocking for 10 consecutive days
, the process proceeds to step 140 and the counter On is refilled with lO for the next 10 ignitions. Furthermore, step 141
Then, it is determined whether the current ignition timing calculation is for rounding of 1flr''A, cylinder 11, or cylinder No. 6 16.

If the current ignition timing calculation is for the first cylinder 11 or the sixth cylinder 16 with a poor knocking detection S/N ratio, in step 142, the knock correction for the relevant cylinder is performed as shown in the following equation. The angle is advanced by the value θhmt−minimum amount O15°CA.

To θ, ←θha+0.5℃ person ・・・・・・・・・(4
) If the current ignition timing calculation involves a cylinder other than No. 1 cylinder 11 or No. 6 cylinder 16, the process advances to step 143 and determines whether it is for No. 2 cylinder 12 or No. 5 cylinder 15. to judge. The current ignition timing calculation is based on the number 2 cylinder 12 or 5, which has a medium S/N ratio for knocking detection.
If it is for cylinder number 15, step 14
4, the knock correction value θ of the relevant cylinder is determined by the following formula (as shown in
km (Advance by 1tJ1JulO075℃A during j.

θklI←θkm+o,'ys℃A ・・・・・・・・・
(5) Also, if it is determined in step 143 that the calculation is not for the 2nd cylinder 12 or the 5th cylinder 15, that is, the current calculation is for the 3rd cylinder 13 with a good S/N of knocking detection. Alternatively, when the rounding calculation is for the No. 4 cylinder 14, the process proceeds to step 145, where the knock correction value θ of the cylinder is advanced by the maximum amount 1'CA, as shown in the following equation.

To θ, ← to θ, +1℃ person ・・・・・・・・・(6) As above, step 133.135.136.1
After correcting the knock correction value θhalj according to the presence or absence of knocking at 42.144.145 or maintaining the current value, the process proceeds to step 146, where the basic ignition timing θB8g calculated by the main program is determined as shown in the following equation. By adding the knock correction value θhak to , the optimum ignition timing θt-t for the next ignition is calculated.

θゐ ← θB11K + θkm...Mark...
(7) Based on the ignition timing θ calculated in the ignition timing calculation interrupt routine as shown in FIG. is calculated. Then, in step 121,
First, the time 1/(first
(see figure 0). After calculating the time tl- at which the ignition coil 46 should be turned off, or at step 118, B
If it is determined that the interrupt is not a TDO 60o interrupt, the process proceeds to step 122, where it is determined whether the current interrupt is a BTDO 90° interrupt. If it is a BTDO 90' interrupt, the process proceeds to step 123 and determines the time t'' at which the ignition coil 46 should be turned on (see ffilO diagram).
Calculate. After calculating the time t'', a certain routine ends.

If the current crank angle matches the fuel injection stop time T calculated in step 114 of the 3°tA interrupt routine shown in FIG. (Proceeding to the coincidence interrupt routine), the injector 34 is turned off and fuel injection is stopped.

Furthermore, when the current time is calculated in step 115 of the 30°C person interrupt routine and is the time t at which the nine knock detection gates should be opened, the process shifts to the conveyor B coincidence interrupt routine as shown in FIG. , performs ignition control by opening/closing the knock detection gate and turning on/off the ignition coil.

Specifically, first, in step 150, it is determined whether or not the process is for a knock detection gate. If the process is for a knock detection gate, proceed to step 351 and open the knock detection gate.In this case, the next task is step 15.
As shown by 2, this is a process of turning on the ignition coil 46. On the other hand, if it is determined in step 150 that the process is other than the knock detection gate process, the process proceeds to step 153 and it is determined whether the process is ignition=ignition.

If the process is to turn on the ignition coil, step 154
Go to and turn on the ignition coil. In this case, the next task is to turn on the ignition coil, as shown in step 155. If it is determined in step 153 that the process is other than turning on the ignition coil, the process proceeds to step 156 and the process of turning off the ignition coil is performed.
The next task is to open the knock detection gate, as shown in step 157 ◇ In the above embodiment, the present invention is characterized in that the ignition timing control device and the fuel injection device are controlled by a single digital electronic control circuit. However, the scope of application of the present invention is not limited thereto, and is equally applicable to multi-cylinder internal combustion engines in which an ignition timing control device is used alone. It is clear that it can be done.

According to the present invention, it is possible to accurately control the ignition timing of a multi-cylinder internal combustion engine using a small number of knock sensors. Therefore, by reducing the number of knock sensors, it is possible to reduce costs and simplify the system, and it also has the excellent effect of preventing performance degradation due to over-retardation or large knocking due to over-advancement, and even engine trouble. has.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an example of a 6-cylinder engine in which a knock sensor is arranged, and Fig. 2 shows the output distribution for each cylinder of the knock sensor arranged at the position shown in Fig. 1. FIG. 3 is a diagram showing an example of the 8/N ratio of knocking detection for each cylinder, and FIG. 4 is a diagram showing an ignition timing control method for a multi-cylinder internal combustion engine according to the present invention. , a diagram showing an example of the amount of retardation with and without knocking for each cylinder when applied to a six-cylinder engine as shown in FIG. 1 above, and FIG. FIG. 6 is a diagram showing an example of the amount of advance when there is no advance, and shows a diagram of a six-cylinder engine/engine and its electronic control device in which an embodiment of the ignition timing control method for a multi-cylinder internal combustion engine according to the present invention is adopted. FIG. 7 is a block diagram showing the circuit configuration of the digital electronic control [IEJ path] in the embodiment.
FIG. 8 is a flowchart showing the main routine for calculating the basic ignition timing used in the previous example, and FIG.
FIG. 1O, a flowchart showing the 30°C human interrupt routine also used in the embodiment, shows the relationship between the crank angle, fuel injection timing, knock detection gate opening/closing timing, and ignition coil on/off timing in the embodiment. Pairing diagram, 1st
Fig. 1 is a flowchart showing an interrupt routine for calculating ignition timing used in the above embodiment, and Fig. 12 is a flowchart showing a coincidence interrupt routine to the conveyor for stopping fuel injection, which is also used in the above embodiment. The flowchart shown in Figure 13 is as follows:
It is a flowchart showing a conveyor B coincidence interrupt routine for opening the knock side gate and turning on/off the ignition coil, which is also used in the embodiment. 10...6-cylinder engine, 18...knock sensor,
24... Air flow meter, 38... Spark plug, 44
...Igniter, 46...Ignition coil, 48...
Distributor, 50...Cylinder discrimination sensor, 52...Rotation angle sensor,
58...Digital electronic control circuit. Agent Takaya Ron (and 1 other person)

Claims (2)

[Claims] (1) A nine-cylinder internal combustion engine in which the basic ignition timing determined according to the operating state of the engine is corrected for each cylinder according to the presence or absence of knocking in each cylinder of the engine, which is determined from the knock sensor output. In the ignition timing control method, the ignition timing correction amount depending on the presence or absence of knocking is changed for each cylinder according to the difference in the 8/N ratio of the knocking detection for each cylinder of the knock sensor. Features: Ignition timing control method for multi-cylinder internal combustion engines. (2) The ignition timing correction amount according to the presence or absence of knocking for a cylinder with a low knocking detection S/N ratio is smaller than the ignition timing correction amount for a cylinder with a high knocking detection 8/N ratio. An ignition timing control method for a multi-cylinder internal combustion engine according to claim 1.