JPS593176A - Ignition timing control for internal-combustion engine - Google Patents

Abstract

PURPOSE:To perform regular and proper ignition timing control constantly in a system in which a fundamental ignition timing is corrected in response to the output from the knocking sensor by a method wherein the ignition timing correction toward spark delay is set to a higher value when the knocking is sensed at the cylinder with low sensitivity of knocking condition. CONSTITUTION:An igniter 4 for multi-cylinder type internal-combustion engine is controlled such that uniform ignition timing control is performed for a plurality of cylinders with the ignition timing instruction signal which is provided by correcting the fundamental ignition timing calculated by the outputs from an air flow meter 24 and a rotary angle sensor 52 in a digital control circuit 56 in response to the condition whether the knocking occurs or not. In this case, when the knocking is sensed at the cylinder with low sensitivity of knocking, e.g. the sixth cylinder of six-cylinder type internal combustion engine in said control circuit 56, the ignition timing correction value toward spark delay is controlled to show a higher value. In ths way, the excessive spark delay or excessive spark advance is eliminated to improve the output of the engine as well as the fuel consumption.

Description

[Detailed description of the invention]

The present invention relates to an ignition timing control method for an internal combustion engine. In particular, the basic ignition timing, which is suitable for use in multi-cylinder gasoline engines installed in automobiles, is determined according to the operating state of the engine, and is corrected according to the presence or absence of knock determined from the knock sensor output. The present invention relates to an improvement in an ignition timing control method for an internal combustion engine in which uniform ignition timing control is performed for a plurality of cylinders. In general, in internal combustion engines, especially in spark ignition internal combustion engines such as gasoline engines installed in vehicles such as automobiles, controlling the ignition timing to an appropriate value that matches the engine's operating conditions is a This is extremely important in improving engine output and fuel efficiency. Various methods have been put into practical use as ignition timing control methods used in such internal combustion engines. The basic ignition timing determined according to the operating state of the engine is corrected according to the presence or absence of knock determined from the way the knock sensor outputs, and the basic ignition timing is adjusted for multiple cylinders. An ignition timing control method for an internal combustion engine has been proposed in which uniform ignition timing control is performed. According to such an ignition timing control method, the ignition timing is corrected to an optimal value according to the state of knock in the internal combustion engine. There was a problem with the ignition timing control method. In other words, in the case of a multi-cylinder internal combustion engine, if you want to detect knock with high accuracy, you can install a knock sensor independently for each cylinder at the best position (where knock can be detected) for each cylinder. Due to the location, the reality is that one or two knock sensors are usually used to detect knock on all cylinders. However, in general, the background noise of the knock sensor output is detected by the knock on all cylinders of the engine. It is dominated by knock and mechanical vibration, and is the same for all cylinders, but the vibration caused by knock depends on the position of the knock sensor, the distance from that cylinder,
The shape of the engine block including the water jacket varies depending on the vibration transmission path, so depending on the engine and knock sensor mounting position, cylinders with a poor S/N ratio can only detect large knocks, and cylinders with poor S/N ratios can detect small knocks. A cylinder with a good S/N ratio is generated. For example, as shown in FIG. 1, when one knock sensor 18 is disposed between the third cylinder 13 and the fourth cylinder 14 of a six-cylinder engine 10 having the first cylinder 11 to the sixth cylinder 16. What is the relationship between the knocking level (sensory evaluation) of the three aroma fiJ13 near the knock sensor 18 and the output of the knock sensor 18? The relationship between the knocking level and the output of the knock sensor 18 in the No. 6 cylinder 16, which is located away from the knock sensor 18, is the same (as the range shown by the symbol B in FIG. 2). In Figure 2, the single-point chain MC
is the maximum value of engine vibration unrelated to knocking, that is, the level of background noise. Therefore, for the No. 3 cylinder 131C, if the knock level is greater than the knock (broken line D) located between minute and small, it can be completely detected, whereas for the No. 6 cylinder 16, the knock is close to a medium knock. [Failure, WE] Otherwise, b = there is a case where knocking cannot be detected even if it occurs. However, conventionally, regardless of the difference in the S/N ratio of knock detection for each cylinder by the knock sensor 18, when it is determined that there is a knock, the timing is uniformly retarded by the same predetermined angle for all cylinders. I was doing it. For this reason,
When a large knock is detected from a cylinder with a poor S/N ratio for knocking detection, such as No. 6 cylinder 16, if the retard amount is insufficient, or conversely, 3. The problem is that when a small knock is detected in a cylinder with a good S/N ratio for knock detection, such as cylinder number 13, the ignition timing is retarded more than necessary, resulting in a decrease in engine output and fuel efficiency. It had In order to solve the above-mentioned problems, multiple groups are created for one engine, and one group includes only cylinders with a good S/N ratio, and another group includes cylinders with a poor S/N ratio. One possibility is to change the control speed of the ignition timing, but if a cylinder with a good S/N ratio in a group that includes a cylinder with a poor S/N ratio knocks, the ignition timing may be delayed more than necessary. It may be controlled by the corner side, or conversely, the S/
There were problems such as insufficient retardation amount at N ratio. In addition, in order to solve the above-mentioned problems, it is possible to perform independent ignition timing control for each cylinder, but this method has the disadvantage of requiring a very large storage capacity and increasing cost. Ta. The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and provides an ignition timing control method for an internal combustion engine that can accurately and uniformly control the ignition timing of a plurality of cylinders using a small number of knock sensors. With the goal. The present invention performs uniform ignition timing control for multiple cylinders by correcting the basic ignition timing determined according to the operating state of one engine according to the presence or absence of knock determined from the knock sensor output. In the ignition timing control method for an internal combustion engine as described in Section 5, when knock is detected from a cylinder with low knock detection sensitivity, the ignition timing correction amount to the retard side is increased to achieve the above object. It is something. Referring to the drawings below, an ignition timing control method for an internal combustion engine according to the present invention was adopted. An embodiment of an ignition timing control device for a six-cylinder automobile engine will be described in detail. As shown in FIG. 3, this embodiment includes an air flow meter 24 installed in an intake passage 22 of a six-cylinder engine 10 and outputting an electric signal in response to the amount of intake air, and a throttle meter 24 installed in a throttle body 26. A valve 28, a surge tank 30 for preventing intake interference, and an intake manifold 32
was placed in. 6 cylinder engine lO fuel such as gasoline
The injector 34 injects into the intake port of the combustion chamber 3.
ignition plug 3 for igniting the air-fuel mixture introduced into 6;
8 and was installed in the cylinder block of a 6-cylinder engine lO. 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 a primary ignition signal, and a high-pressure ignition secondary According to the rotation of the ignition coil 46 and the distributor shaft 48a, which rotates once for every two revolutions of the engine crankshaft, a high-voltage secondary ignition signal given from the ignition coil 46 is sent to each cylinder of the engine. Distribute and ignite the corresponding cylinder 1
a distributor 48 for feeding the lug 38; and the above-mentioned disk built into the distributor 48).
A cylinder discrimination sensor 5 detects the rotational state of the IJ computer shaft 48a and outputs a cylinder discrimination signal every two rotations of the crankshaft.
and a rotation angle sensor 52 that outputs a rotation angle signal every predetermined crank angle 1, for example, 300 CA, and a 6-cylinder engine 1.
A knock sensor 18 disposed on the cylinder block wall 1.0a of No. 0 for detecting the presence or absence of engine knock, the output of the air flow meter 24, the output of the cooling water temperature sensor 40, the output of the cylinder discrimination sensor 5o, and the rotation angle sensor. 52 output, knock sensor 1B output, etc., the basic ignition timing determined from the intake air amount and engine rotation/number is corrected depending on the presence or absence of knock, and uniform ignition timing control is performed for all cylinders. In order to do this, an ignition timing command signal is output to the igniter 44Is, and a valve opening time signal obtained by correcting the basic fuel injection time calculated from the intake air amount and the engine speed according to the engine condition, etc. Injector 3
In the ignition timing control device for the 6-cylinder automobile engine 10, which is equipped with a digital control circuit 56 that outputs an output to the 6-cylinder engine 10, when a knock is detected from the 6th cylinder, which has a low knock detection sensitivity, in the digital control circuit 56, The ignition timing correction amount is increased to the retard side. The digital control circuit 56 is as shown in detail in FIG.
, a central processing unit (hereinafter referred to as MPU) consisting of, for example, a microprocessor, for performing four types of arithmetic processing.
58, a multiplexer 66 for sequentially taking in the output of the air flow meter 24 inputted via the buffer 60, the output of the cooling water temperature sensor 40 inputted via the buffer 62, etc.; An analog-to-digital converter 68 for converting into a digital signal, and a first input/output coupler 0 for inputting the output of the analog-to-digital converter 68 into the MPU 58.
and the cylinder discrimination sensor 5 input via the shaping circuit 72.
0 output, rotation angle sensor 52 output, knock sensor 18 output, etc. inputted via input circuit 74 and analog-to-digital converter 76, etc., to the MPU 58 at appropriate timing. , Previous Me[PU5
Random access memory (hereinafter referred to as RAM) 80 for temporarily storing calculation data etc. in 8;
A read-only memory (hereinafter referred to as ItOM) 82 for storing each rice constant and grogram, a clock generation circuit 86, and a drive circuit 8 that stores the calculation results of the MPU 58.
8 to the igniter 4-4 at a predetermined timing;
A 1:1V2 output port 94 is provided for outputting the calculation result of the P U 58 to the injector 34 at a predetermined timing via a drive circuit 92. The operation will be explained below. This embodiment The entire flow of the main routine is shown in Figure 5. In this main routine, when the power is turned on,
The process is started, and first, in step 101, the input and output ports are set to a state necessary for starting the engine. Next, in step 102, the RAM 80'ff: is cleared and initial data is set. Next, the process proceeds to step 103, where a clock for an input/output counter is defined, and, for example, a cycle for performing analog-to-digital conversion is set using a program. Further, the process proceeds to step 104, where the save address of the program, counter, register, etc. when one interrupt occurs is specified. Next, in step lυ5, 1 interrupt permission is given, and in step 106, the air flow meter 24 is
The intake air amount Q is calculated from the output, the engine rotation speed N is calculated from the rotation angle signal output from the rotation angle sensor 52, and the intake air amount 1 per engine rotation is calculated. Next, the process advances to step 107, where the data is stored in the ROM 82vC in advance. The basic ignition timing θB is determined from a map showing the relationship between the engine rotational speed N&0, the intake air amount per engine rotation, and the basic ignition timing θB. After step 107 is completed, return to step 103 mentioned above, and step 1.03~
Repeat step 107. Further, in accordance with the output of the front rotation angle sensor 52, an interrupt routine as shown in FIG. 6 is executed every 30° CA of the crank angle. That is, first in step 201, the previous DO(7) 30
VC that the engine will rotate by 300 cA from the time when the 0CA interrupt routine was passed and the current time,
Calculate the required rotation time and determine the engine rotation speed N from this. Next, the process proceeds to step 202, in which it is determined whether the cylinder row flag FC, which is set in the interrupt routine every 7200 CA by the cylinder discrimination signal output from the cylinder discrimination sensor 5o, is 1 as shown in FIG. Determine. If the determination result is positive, the process proceeds to step 203, where the cylinder discrimination fract G is reset with zero, and the crank angle counter W, which counts up every time an interrupt of 300CA is generated, is set to zero in step 2 (34-c, 300CA). This!L is for correcting the roundness of cylinder discrimination.On the other hand, if the judgment result in step 202 is negative, proceed to step 205, and change the crank angle. The counter wkl is counted up. After step 204 or 205 is completed, step 206
Then, in step 207, the value 2, i fill, which is the value obtained by dividing the count value W of the crank angle counter by 4, is stored in the register R, and at the same time, in step 207, the remainder of 7 is stored in the pt register R'. Next, the process proceeds to step 208, where it is determined whether the value of register R' is zero. If the determination result is positive, that is, if the top dead center of any cylinder is reached, the process proceeds to step 209, and a knock detection gate (referred to as a knock gate) is activated.
Make sure that they are heard and understood. This is to adjust the on-off timing of the knock gate to a normal value when starting the engine, and to correct malfunctions. Then,
Proceeding to step 210, to set it as the background,
this

[Before the hour, analog-to-digital conversion of the knock sensor length 1B output is started (1), and the process further proceeds to step 211, where the time 11 at which the knock gate should be closed is subtracted and a time coincidence interrupt Ai is set. After step 211 is completed, or (c) if the determination result in step 208 is negative (IJ'), the process proceeds to step 212, where it is determined whether or not the value of register R' is 0.25. If the determination result is positive, that is, if the crank angle is 90° BTDC, the process advances to step 213, where the basic ignition timing θnf calculated in the output main routine (8I) is compensated according to the presence or absence of knock. Calculate the ignition timing by calculating the ignition timing. Specifically, 90° CA for ignition timing calculation shown in No. 8M
As in every interrupt routine, in step 301, a counter n indicating the cylinder number is counted down by one. This cylinder number counter n is determined according to the ignition order, for example, 0 is the 1st aroma cylinder, l is the 5th cylinder, 2 is the 3rd cylinder, and 3 is the 6th cylinder.
The number cylinder 4 corresponds to the second cylinder, and the number 5 corresponds to the fourth cylinder. The reason why the value of the cylinder number counter n is counted down by 1 in step 301 is to use the knock sensor output at the time of ignition of the previous cylinder to '5' in the following ignition timing calculation. Next, the process proceeds to step 302, where it is determined whether the value of the cylinder number counter n is greater than or equal to zero or not. If the determination result is negative, the process proceeds to step 303, where the value of the cylinder number counter n is set to 5 and reset. This is to return to calculating the ignition timing for the No. 4 cylinder after calculating the ignition timing for the 1m)' cylinder. Next, the process proceeds to step 304, where the signals are calculated according to the analog-to-digital conversion completion interrupt routine as shown in FIG. 9, and are stored in six consecutive RAMs 80. The contents of the na-th RAM are a1.
Read bH. Next, the process proceeds to step 305, where the peak hold value an is multiplied by the background value bn'kK (K
It is determined whether or not is equal to or greater than a predetermined constant 9. If the determination result is positive, it is determined that there is a knock, and the process proceeds to step 306, where the ignition timing is operated according to the knock, and then the elapsed time counter mk, which is an argument indicating how many ignitions have elapsed, is cleared. do. Then step 307
Then, it is determined whether the count value of the cylinder number counter n is other than 3 or not. If the determination result is negative, that is, if the cylinder in which knock occurred this time is the 6th cylinder 16, the process proceeds to step 308, and the knock correction advance angle θ is determined as shown in the following equation.
The value obtained by subtracting 0.50 CA from K is the new knock compensation advance angle OK. -0,50CA for θ, ←θ ・・・・・・・・・・・・
...(1) Step 308F: After 7, or if the determination result in step 307 is positive, step 3
Proceeding to step 09, as shown in the linear equation, the knock correction advance angle θK minus 10CA is set as the new knock correction advance angle θ. θ to ← θ to -1°CA ・・・・・・・・・・・・
(2) Therefore, when a knock is detected in a cylinder other than the 6-zone cylinder, the knock correction advance angle θK is retarded by 10 CA. On the other hand, when knock is detected from the six scent cylinders 16 with low knock detection sensitivity, the knock correction advance angle θK is retarded by a total of 1.5° CA. On the other hand, if the determination result in step 305 is negative, that is, if no knock is detected, the process proceeds to step 310, and the count value of the elapsed time counter m reaches 100.
It is determined whether or not the above value has been reached. When the determination result is negative, the process advances to step 311, and the elapsed time counter m't
Count up by l. On the other hand, when the determination result in step 310 is positive, that is, when knocking has not been detected 100 times in a row, the process proceeds to step 312, where the elapsed time counter m is cleared, and at step 313, as shown in the linear equation Thus, the knock compensation advance angle θK is advanced by 1° CA. To θ←+10CA to θ ・・・・・・・・・・・・
(3) After steps 309, 311 or 313 are completed. Proceeding to step 314, the basic ignition timing θB calculated in step 107 of the main routine
By adding the knock correction advance angle θK to , the next ignition time Mi9ig is calculated. θig←θB+θK ・・・・・・・・・・・・(4
) Next, the process proceeds to step 315, where the determined ignition timing 0
1g, the current engine speed and crank angle, the time at which the igniter 34 should be turned on is determined, a 1 time coincidence interrupt B is set, and this routine ends. After the ignition timing is calculated in the 90° CA4σ interrupt routine for ignition timing calculation as shown in FIG. 8, or if the determination result in step 212 of FIG. The process advances to step 214 shown in FIG. 6C1, and it is determined whether the value of the register R' is 0.5. If the determination result is positive, that is, the crank angle is 6
If it is 0° BTDC, the process proceeds to step 2'l5, where the time at which the igniter 44 should be turned off is calculated and set in time coincidence interrupt B. After step 215 -
Alternatively, if the determination result in step 214 is negative, this routine is ended and the process returns to the main routine. Moreover, when the current time reaches the time t1 at which the knock gate should be closed, which is calculated in step 21 of the 30° CA interrupt routine shown in FIG. 6, the time coincidence A shown in FIG. The process moves to an interrupt routine and starts analog-to-digital conversion of the peak hold value a. Further, when the analog-to-digital conversion in step 210 of the 30° CA interrupt routine shown in FIG. 6 or the analog-to-digital conversion of the time match A interrupt routine shown in FIG. 9th
Analog-to-digital conversion completion interrupt/
1. -Move to Chin. In step 401, it is determined whether the knock gate is open. If the judgment result is positive. The process proceeds to step 402, where the analog-to-digital conversion value is set to the total peak hold value an, and then, in step 403, the knock gate is closed. -force, step. If the determination result in step 401 is negative, the process proceeds to step 404, where the analog-to-digital conversion value is set to the background value bn, and the knock gate is opened at Stella 7' 405. Further, the time at which the Eve knife 34 whose current time is calculated at step 215 of the 30° CA interrupt routine shown in FIG. Calculated in step 315 of the Q0CA interrupt routine. The time when the Eve knife 34 should be turned on is 9 o'clock, when the time coincidence B interrupt/L as shown in FIG.
, -chin, and in step 501 it is determined whether or not it is an interrupt of the knife on. If the determination result is positive, the process proceeds to step 502 and the Eve knife 34 is turned on. On the other hand, if the determination result in step 501 is negative, 11cfl proceeds to step 503, and the Eve knife 3
4 is off. Crank angle and cylinder discrimination signals in this embodiment. FIG. 12 shows an example of the relationship among the rotation angle signal, the 720° CA interrupt, the 30° CA interrupt, the open/close state of the knock gate, and the on/off state of the Eve knife. In this way, by increasing the control on the retard side only when knock is detected from a cylinder with a poor S/N ratio, when knock is detected only from a cylinder with a good S/N ratio, The ignition timing of that group is retarded by 1 UI than necessary.
I will no longer be controlled. The knocking levels of cylinders with different knock detection sensitivities are made uniform, making it possible to further increase engine output and improve fuel efficiency. In the above embodiment, the present invention is applied to a 6-cylinder automobile engine in which an electronically controlled fuel injection device for intake air is used, but the scope of application of the present invention is not limited to this. An automobile engine that also uses a tube pressure type electronically controlled fuel injection device. Alternatively, it is clear that the present invention can be similarly applied to general internal combustion engines. As described above, according to the present invention, the ignition timing of the internal combustion engine can be accurately and uniformly controlled using a small number of knock sensors. Therefore, by reducing the number of knock sensors and memory capacity IT, it is possible to reduce costs and simplify the system, and it is possible to reduce the performance due to over-retard angle or to increase the knock sensor level due to over-advance angle, thereby reducing the engine output. It has an excellent effect of being able to increase the amount of energy and MoJi all times.

[Brief explanation of drawings]

Fig. 1 is a plan view showing an example of a 6-cylinder engine in which a knock sensor is disposed, and Fig. 2 is a plan view showing an example of a 6-cylinder engine in which a knock sensor is disposed. A diagram comparing and showing the relationship between knocking level and knock sensor output in numbered cylinders. FIG. 3 is a sectional view including a partial block diagram showing the configuration of an ignition timing control device for a six-cylinder automobile engine in which the ignition timing control method for an internal combustion engine according to the present invention is adopted;
The figure is = iJ * I! @f! A block diagram showing the configuration of the digital control circuit used in the
The basic ignition timing tJIi in the above embodiment, the flow showing the main routine to output [2, FIG.
7 is a flowchart showing the 0CA interrupt routine, and FIG. 8 is a flowchart showing the 720°CA interrupt routine.
Figure 9 is a flowchart showing the analog-to-digital conversion completion interrupt /L,-CH, and Figure 1 is a flowchart showing the CA interrupt routine. FIG. 11 shows the interrupt routine for time coincidence B, and FIG. 12 shows the interrupt routine for the time coincidence B. FIG. Crank angle, cylinder discrimination signal 1
Rotation angle signal, 720°C 8 interrupt routine, 30°C
It is a diagram showing an example of the relationship between the A11jl entry routine, the opening/closing state of the knock gate, and the on/off state of the Eve knife. IO...6 cylinder engine-16...6th cylinder, 18
... Knock sensor 24 ... Air flow meter, 3
4...Injector, 38...Spark plug. 40...Cooling water temperature sensor, 44...Igniter, 4
6... Ignition coil, 48... Distributor,
50...Cylinder discrimination sensor, 52...Rotation angle sensor. 56...Digital control circuit. Agent Takaya Ron (and 1 other person)

Claims (1)

[Claims] (1) The basic ignition timing determined according to the operating state of the engine is corrected according to the presence or absence of knock determined from the knock sensor output to perform uniform ignition timing control for multiple cylinders. In the ignition timing control method for an internal combustion engine according to the present invention, when knock is detected from a cylinder with low knock detection sensitivity, the ignition timing is corrected to the retarded side. Timing control method.