JPH0826839B2 - Ignition timing control method for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control method for an internal combustion engine, and more particularly to an ignition timing control method for an internal combustion engine equipped with a knocking control system.

[Conventional technology]

BACKGROUND ART Conventionally, there is known an ignition timing control device including a knocking control system that detects whether or not knocking, which is a column vibration generated due to self-ignition of end gas in a cylinder, occurs and controls the knocking. . In this ignition timing control device, a peak value a of the engine vibration in a predetermined crank angle range (for example, 10 ° CA ATDC to 50 ° CA ATDC) after ignition of each cylinder and a level of engine vibration that is not due to knocking, that is, a background Constant K for level b
The determination level K · b obtained by multiplying by is compared to determine whether knocking has occurred. Here, the peak value a is obtained by attaching a knocking sensor composed of a piezoelectric element, a magnetostrictive element, or the like for converting engine vibration to an electric signal to the cylinder block to determine the frequency band (6
It is obtained by inputting an electric signal into a peak hold circuit through a Pand Pass Filter that can pass a signal of ~ 8 KHz) and holding a peak value in a predetermined crank angle range. Further, the determination level K · b is obtained by multiplying a value (back ground level) obtained by integrating the electric signal corresponding to the engine vibration not depending on the knocking by the integrating circuit by the constant K. When the occurrence of knocking is detected, the ignition timing is retarded by a predetermined amount each time the occurrence of knocking is detected, and when the occurrence of knocking is not detected for a predetermined number of ignitions, the ignition timing is advanced by a correction delay. By calculating the angle amount and correcting the ignition timing using this correction retard amount, the ignition timing is controlled to the maximum advance angle (knocking limit) at which knocking does not occur (for example, actual opening 57- 92074, JP-A-60-26172
Issue).

However, in the ignition timing control device having the conventional knocking control system, it is erroneously determined that the knocking has occurred due to the manufacturing error of the engine and the knocking sensor, the knocking is likely to occur due to the change of the weather condition, or the wireless When it is erroneously determined that the peak value is increased due to electrical noise such as the occurrence of knocking, the correction retard amount is increased accordingly, and the ignition timing is controlled to the retard side from the required ignition timing. Become. When the ignition timing is controlled to the retard side as described above, not only the exhaust gas temperature rises and the exhaust gas purification rate deteriorates, but also the engine output decreases.
The problem occurs.

Therefore, conventionally, as shown in Japanese Utility Model Application Laid-Open No. 57-92074, a maximum retardation amount that changes according to the engine speed is set, and the correction retardation amount is restricted so as not to exceed this maximum retardation amount. Therefore, the ignition timing is not retarded excessively, and the exhaust temperature is prevented from rising and the engine output is prevented from decreasing.

On the other hand, if it is determined that the knocking is occurring despite the fact that the knocking is not occurring due to a malfunction of the knocking sensor or the like, the above-mentioned correction retard amount becomes large and the ignition timing is exceeded in the same manner as above. A retard angle occurs, the exhaust temperature rises, and the engine output decreases. Therefore, conventionally, as disclosed in Japanese Patent Laid-Open No. 54-155322, when the failure of the knocking sensor is detected, the correction retard amount is limited to the maximum retard amount to increase the exhaust temperature and the engine output. We are trying to prevent the decline of. In this method, the correction retard amount is limited by the constant maximum retard amount even in the region where knocking is likely to occur and in the region where knocking is unlikely to occur. It is necessary to set the angle amount, which may cause the ignition timing to be excessively retarded in the region where knocking is unlikely to occur.
Therefore, it has been proposed that the maximum retardation amount is set according to the engine speed corresponding to the frequency of occurrence of knocking, and the correction retardation amount at the time of failure of the notking sensor is limited according to this maximum retardation amount. .

[Problems to be solved by the invention]

However, in the method of setting the maximum retardation amount according to the engine rotation speed as described above, when the actual engine rotation speed is constant but varies depending on the measurement error of the engine rotation speed, etc. The maximum retardation amount also changes according to the change in the measured value. For this reason, when controlling the knocking in the vicinity of the operating region where the ignition timing retard amount becomes the maximum retard amount, the correction retard amount also changes as the maximum retard amount changes, and in reality, the knocking occurs. However, the correction retard amount is limited by the maximum retard amount reduced due to the measurement error, which causes a problem that the occurrence of knocking cannot be suppressed.
In addition, when operating in the vicinity of the boundary between the region where knocking is likely to occur and the region where knocking is unlikely to occur when the knocking sensor fails, the measurement error causes the knocking to occur even though the region is prone to knocking. If the ignition timing is controlled with the maximum retardation amount in the area that is difficult to occur,
Since the maximum retardation amount in the region where knocking is unlikely to occur is smaller than the maximum retardation amount in the region where knocking is likely to occur, there is a problem in that the occurrence of knocking cannot be suppressed in the same manner as described above.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an ignition timing control method for an internal combustion engine in which it is possible to prevent the knocking from being unable to be suppressed due to a variation in the maximum retardation amount due to a measurement error. .

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention calculates a correction retard amount for retarding the ignition timing when the occurrence of knocking is detected and advancing the ignition timing when the occurrence of knocking is not detected, and the operating state The maximum retard angle amount is set in accordance with the detected driving state by detecting the above, and the corrected retard angle amount is restricted so as not to exceed the maximum retard angle amount, and the corrected retard angle amount and the operating state are limited. In the ignition timing control method of the internal combustion engine for controlling the ignition timing based on the basic ignition advance determined according to the above, the maximum retard amount was used to limit the previously corrected retard amount according to the detected operating state. If it is smaller than the maximum retardation amount, it is used as the maximum retardation amount for limiting the correction retardation amount and the maximum retardation amount according to the detected driving condition and the previous correction retardation amount. Using the average value with the maximum retardation amount And butterflies.

[Action]

According to the present invention, a correction retard amount for retarding the ignition timing when the occurrence of knocking is detected and advancing the ignition timing when the occurrence of knocking is not detected is calculated, and the detected operation state is set. The maximum retard amount is set accordingly. This correction retard amount is limited so as not to exceed the maximum retard amount, but the maximum retard amount according to the detected operating condition is less than the maximum retard amount used to limit the previous correction retard amount. When it is small, that is, when the ignition timing may be controlled to the advance side, it is used to limit the maximum retardation amount and the previously corrected retardation amount according to the detected operating state. The average value with the maximum retard amount is calculated, and the calculated average value is used as the maximum retard amount for limiting the correction retard amount, and the correction retard amount is limited so as not to exceed this average value. It

As described above, when the maximum retardation amount according to the detected driving state is smaller than the maximum retardation amount used for limiting the previous correction retardation amount, the maximum retardation angle for limiting the correction retardation amount As the amount, since the average value of the maximum retardation amount according to the detected driving condition and the maximum retardation amount used for limiting the previous correction retardation amount is used, for example, the maximum retardation amount in the driving condition is As long as the changed driving state continues for a while, the maximum retardation amount according to the detected driving state is smaller than the maximum retardation amount used to limit the previously corrected retardation amount, The corrected retard amount is limited by using the average value of the detected maximum retard amount according to the operating condition and the maximum retard amount used for limiting the previously corrected retard amount.

〔The invention's effect〕

As described above, according to the present invention, when the maximum retardation amount according to the detected driving state is smaller than the maximum retardation amount used for limiting the previous correction retardation amount, the detected driving The correction retard amount is limited so that it does not exceed the average value of the maximum retard amount according to the condition and the maximum retard amount used to limit the previous corrected retard amount, so the detection error of the operating state Even if it occurs, it is possible to prevent the maximum retardation amount from largely fluctuating, and even when the correction retardation amount is limited by the maximum retardation amount, the ignition timing may be controlled to the advance side from the knotting limit. Therefore, even if there is a measurement error, it is possible to suppress the occurrence of knocking.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 shows an example of an internal combustion engine (engine) provided with an ignition timing control device to which the present invention can be applied.
4 cycle 6 cylinder gasoline engine 10 distributor
A cylinder discriminating sensor 16 and a rotation angle sensor 18, each of which is composed of a signal rotor fixed to the distributor controller and a pick-up fixed to the distributor housing, are attached to the unit 14. Cylinder discrimination sensor
The pulse generator 16 generates one pulse every one rotation of the distributor shaft, that is, every two rotations of the crankshaft (every 720 ° CA). The position where this pulse is generated is, for example, the top dead center (TDC) of the first cylinder. The rotation angle sensor 18 generates, for example, 24 pulses for each revolution of the distributor system, and thus one pulse for every 30 ° CA.
The cylinder discrimination sensor 16 and the rotation angle sensor 18 are connected to a control circuit 20 composed of a microcomputer or the like, and an electric signal generated by each sensor is input to the control circuit 20. The control circuit 20 has a throttle valve in the intake passage 22.
An intake air amount signal from an air flow sensor 24 mounted on the upstream side of 25 is input. A cylinder block of the engine 10 is provided with a knocking sensor 12 including a magnetostrictive element for detecting engine vibration, and an electric signal output from the knocking sensor 12 is input to the control circuit 20. . On the other hand, an ignition signal is output from the control circuit 20 to the igniter 26, and the high voltage generated by the ignition coil provided in the igniter 26 is generated by the distributor 14.
Spark plugs distributed by each cylinder and mounted on each cylinder
28 in sequence.

Note that various sensors such as an intake air temperature sensor that detects an operating state parameter are attached to a normal internal combustion engine, and the control circuit 20 also controls the fuel injection valve 29 and the like, but these are not directly related to the present invention. , Illustration is omitted.

Control circuit 20 including a microcomputer
As shown in FIG. 3, a random access memory (RA
M) 58, read-only memory (ROM) 60, microprocessing unit (MPU) 62, first input / output port 64,
A second input / output port 66, a first output port 68, a second output port 70, and a bus 72 such as a data bus and a control bus for connecting these are provided. First input / output port
64 is connected to the air flow meter 24 via an analog-digital (A / D) converter 74, a multiplexer 76 and a buffer 78A, and is also connected to an intake air temperature sensor, an engine cooling water temperature sensor, etc. not shown via the buffer not shown. It is connected. The first input / output port 64 is also connected to supply a control signal to the A / D converter 74 and the multiplexer 76. A waveform shaping circuit is provided at the second input / output port 66.
The cylinder discrimination sensor 16 and the rotation angle sensor 18 are connected via 80, and the knocking sensor 12 is connected via the input circuit 82.
Is connected.

As shown in FIG. 4, the input circuit 82 has a series circuit including a knock gate circuit 82A and a peak hold circuit 82B, one end of which is connected to the knocking sensor 12, and is connected in parallel to the series circuit. An integrating circuit 82E, a multiplexer 82C connected to the series circuit and the integrating circuit 82E,
And an A / D converter 82D connected to the multiplexer 82C. The knock gate circuit 82A, the multiplexer 82C and the A / D converter 82D are connected to the second input / output port 66.
Connected so as to be controlled by a control signal from

The first output port 68 is connected to the igniter 26 via a drive circuit 86, and the second output port 70 is connected to the fuel injection valve 29 via a drive circuit 88. Incidentally, 90 is a clock, and 92 is a timer. A program for a control routine described below is stored in the ROM 60 in advance.

Next, the operation of the embodiment of the present invention will be described in detail while describing the control routine. FIG. 5 shows the main routine of this embodiment. In step 100, the engine speed N calculated from the pulse every 30 ° CA and stored in RAM and A / D converted and stored in RAM. Taking the intake air amount Q, the basic fuel injection time TP (= k · Q / N, where k is a constant) is calculated from the engine speed N and the intake air amount Q in the step 102, and the intake step Q is performed in the next step 104. Basic fuel injection time according to temperature and engine cooling water temperature
The fuel injection time TAU is calculated by correcting the basic fuel injection time TP using the air-fuel ratio feedback back correction coefficient FAF obtained from the O ₂ sensor (not shown). At the next step 106, it is determined whether the current piston position is the compression top dead center (TDC) based on the cylinder discrimination signal and the rotation angle signal. In the case of TCD, the multiplexer 82C is controlled in step 114 to output the knocking sensor 12 to the integrating circuit 8
It is input to the A / D converter 82D via 2E and the multiplexer 82C, and the A / D conversion of the output of the integrating circuit 82E, that is, the background level b is started. As a result, a digital value of the engine vibration level that does not depend on knocking, that is, the back ground level b is obtained, and this digital value is stored in a predetermined area of the RAM at the end of A / D conversion. On the other hand, if step 106 determines that the TDC is not set, step 10
In step 8, it is judged whether or not the current piston position is, for example, 15 ° CA ATDC, and when the judgment in step 108 is affirmative, in step 110, a control signal is output from the second input / output port 66 to the knock gate circuit 82A to output the knock gate. Open the circuit 82A and start the knock gate circuit from the knocking sensor 12.
The output of the knocking sensor 12 is input to the A / D converter 82D via the 82A, the peak hold circuit 82B, and the multiplexer 82C. At the next step 112, the time t (corresponding to 90 ° CA ATDC) at which the knock gate circuit 82A is closed is calculated from the present time and the time corresponding to the predetermined crank angle range, and is set in the compare register.

FIG. 6 shows a time coincidence interrupt routine which is interrupted when the time set in step 112 is reached. When the current time coincides with the time set in the compare register, the second input / output port 66 is set in step 116.
Outputs a control signal to the A / D converter 82D, starts A / D conversion of the output of the peak hold circuit 82B, and returns to the main routine.

FIG. 7 shows an interrupt routine interrupted by the A / D conversion end signal from the A / D converter 82D when the A / D conversion of the output of the peak hold circuit 82B is completed.
At 118, the A / D converted value is stored as a peak value a in a predetermined area of the RAM, and at step 120, a control signal is output from the second input / output port 66 to the knock gate circuit 82A to close the knock gate circuit 82A.

FIG. 1 shows the routine of the first embodiment of the present invention for calculating the ignition timing when the knocking control device is abnormal. In step 124, the engine load Q / N is a predetermined value (for example, 0.7 /
rev) It is judged whether or not it is in the knocking control region by judging whether or not it is above, and when it is not in the knocking control region, the interpolation method is performed from the map determined by the engine load Q / N and the engine speed N in step 126. The basic ignition advance angle θ _BASE calculated by the above is set as the execution ignition advance angle θi and the process returns to the main routine. On the other hand, when it is determined in step 124 that the control range is the knocking control region, the peak value a and the back ground level b are taken in and the peak value a is acquired in step 128.
And the judgment level K · b. When the peak value a is larger than the judgment level K · b, it is judged that knocking has occurred, and the correction retard angle θ _K is increased in step 130 by a predetermined value (for example, 1 ° CA). On the other hand, when it is determined that the peak value a is equal to or lower than the determination level K · b, it is determined that knocking does not occur, and it is determined in step 132 whether a predetermined number of ignitions (for example, 100 ignitions) has elapsed, and the predetermined number of ignitions is determined. If the time has elapsed, the correction retard angle amount θ _K is reduced by a predetermined value (for example, 1 ° CA) in step 134.

In the next step 136, it is determined whether or not the knocking control device including the knocking sensor 12 and the input circuit 82 is abnormal. Whether or not the knotting control device is abnormal can be determined by determining whether or not the signal input from the input circuit 82 to the input / output port 66 has a value other than the value within the predetermined range. For example, when the signal is no longer output from the knocking sensor due to the disconnection of the knocking sensor, the signal input to the input / output port 66 becomes a value less than the lower limit value of the above predetermined range, and the wiring connecting the knocking sensor When a battery voltage or the like is applied to this wiring due to a short circuit or the like, the signal input to the input / output port 66 exceeds the upper limit value of the above predetermined range. Therefore,
As described above, it is possible to determine the abnormality of the knocking control device by determining whether or not the signal input to the input / output port 66 is within the predetermined range. If the knocking control device is determined to be normal in step 136, the process proceeds directly to step 148, and if it is determined to be abnormal in the knocking control device in step 136, it is determined in step 138 according to the engine speed and stored in the ROM. The maximum retardation amount θ _Kmaxi corresponding to the current engine speed is calculated from the table of the maximum retardation amount that is present.

In this table, the maximum retardation amount is determined according to the engine speed. For example, the maximum retardation amount is 5 ° CA in the range of 1000 rpm or less, and the maximum retardation amount is 10 ° CA in the range of 1000 to 2000 rpm. The maximum retardation amount is 7 ° CA in the range of 3000 rpm or more. In this way, the reason why the maximum retardation amount is changed according to the engine speed is that there is a region where knocking is likely to occur and a region where knocking is unlikely to occur depending on the operating state, and knocking is likely to occur. It is set such that the maximum retardation amount becomes large in the region and the maximum retardation amount becomes small in the region where knocking is hard to occur.

At the next step 140, the maximum retardation amount θ _Kmax calculated last time
And the current maximum retardation amount θ _Kmaxi calculated in step 138 are compared.When θ _Kmax ≧ θ _Kmaxi , the current maximum retardation amount changes in the direction of becoming smaller than the previously calculated maximum retardation amount. Therefore, in step 142, the weighted average value of the maximum retardation amount is calculated according to the following equation.

However, K is a coefficient related to weight, and K = 4 in this embodiment.

On the other hand, when it is determined in step 140 that θ _Kmax <θ _Kmaxi , the current maximum value angle amount is larger than the previously calculated maximum value angle amount, and therefore, in step 144 the current maximum value angle amount θ _Kmaxi
Is stored in the RAM as θ _Kmax , and the process proceeds to step 146. Calculating a running spark advance theta _i by subtracting the correction retard amount theta _K from the basic ignition angle theta _BASE In step 148 a step 146 the maximum retardation amount theta _Kmax as the value of the delay correction amount theta _K. Then, the igniter is turned on a predetermined time before the execution ignition advance angle θ _i calculated in step 126 or step 148, and when the execution ignition advance angle θ _i is reached, the igniter is turned off to execute the execution ignition advance angle. The ignition timing is controlled so as to ignite at.

As a result of the above, when an abnormality occurs in the knocking control device, the ignition timing is controlled with an ignition advance that is a crank angle retarded by a crank angle that is equivalent to the maximum retard amount from the basic ignition advance. If it becomes smaller accordingly, the ignition timing is retarded by the crank angle corresponding to the weighted average value of the previously calculated maximum retard amount and the present maximum retard amount. Therefore, even when the maximum retardation amount suddenly decreases due to the measurement error of the engine rotation speed, the above-mentioned weighted average value changes gently, so that as shown in FIG. Rapid changes in quantity are prevented. The broken line in FIG. 8 shows the change in the maximum retardation amount according to the detected engine speed.

Next, a second embodiment of the present invention will be described. FIG. 9 shows the ignition timing calculation routine of the present embodiment. In FIG. 9, the parts corresponding to those in FIG.

In the present embodiment, the present invention is applied to the setting of the maximum retardation amount for limiting the ignition timing so as not to be overretarded when the correction retardation amount becomes large due to noise or the like.

After calculating the correction retardation amount θ _K in the same manner as above, the maximum retardation amount is calculated from the table in the same manner as above, and if the maximum retardation amount changes in the same direction as above, weighting is applied. The maximum retardation amount θ _Kmax is calculated by calculating the average value.

At the next step 150, the corrected retard amount θ _K and the maximum retard amount θ
Compare with _Kmax . If θ _K <θ _Kmax , proceed to step 148. If θ _K ≧ θ _Kmax , set the maximum retard angle amount θ _Kmax at step 152 to the corrected retard amount θ _K value. Thus, the corrected retard amount θ _K is restricted so as not to exceed the maximum retard amount θ _Kmax , and the routine proceeds to step 148. Then, the ignition timing is controlled in the same manner as above.

Although an example in which the maximum retardation amount is determined according to the engine rotation speed has been described above, the present invention is not limited to this and the maximum retardation amount is determined according to the engine rotation speed N and the engine load Q / N. The angular amount may be set. Also, in the above, an example in which the maximum retardation amount is used as it is when the maximum retardation amount changes is explained, but the weighted average value is also set when the maximum retardation amount changes. You may ask. In this case, the coefficient K relating to the weight in the above equation (1) is made smaller than that in the above case.

[Brief description of drawings]

1 is a flow chart showing an ignition timing calculation routine of a first embodiment of the present invention, FIG. 2 is a schematic diagram of an internal combustion engine equipped with a knocking control device applicable to the present invention, and FIG. 3 is a diagram of FIG. A block diagram showing details of the control circuit, FIG. 4 is a block diagram showing details of the input circuit of FIG. 3, FIG. 5 is a flow chart showing a main routine of the embodiment of the present invention, and FIG. 6 is a time coincidence interrupt routine. 7 is a flowchart showing the A / D conversion end interrupt routine, FIG. 8 is a diagram showing changes in the maximum retardation amount and the detected engine rotation speed, and FIG. 9 is a second embodiment of the present invention. It is a flowchart which shows the ignition timing calculation routine of an example. 12 …… notching sensor, 16 …… cylinder discrimination sensor, 18 …… rotation angle sensor, 20 …… control circuit, 24 …… air flow meter.

Claims (1)

[Claims] 1. A correction retard amount for retarding the ignition timing when the occurrence of knocking is detected, and advancing the ignition timing when the occurrence of knocking is not detected is calculated, and is detected by detecting an operating state. The maximum amount of retard angle is set according to the operating condition, and the corrected amount of retard angle is limited so as not to exceed the maximum amount of retard angle. In the ignition timing control method for an internal combustion engine that controls the ignition timing based on the angle, the maximum retard amount is smaller than the maximum retard amount used to limit the previously corrected retard amount according to the detected operating state. In this case, as the maximum retard amount to limit the correction retard amount,
An ignition timing control method for an internal combustion engine, comprising using an average value of a maximum retardation amount according to a detected operating condition and a maximum retardation amount used for limiting a previous correction retardation amount.