JP2007138758A - Combustion discriminating device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect with high accuracy the effective peak position of an ion current detection signal by a simple method, in a system detecting ions generated by burning an air-fuel mixture. <P>SOLUTION: In this combustion discriminating device, a combustion state detecting zone for discriminating combustion state such as misfire is set per ignition, and also a peak position detecting zone is set in the combustion state detecting zone. The peak position detecting zone is a zone including a peak position at the time of combustion of the optimal ignition timing (for example, near ATDC15°CA), and set to a zone, for example, from TDC to ATDC40°CA. An effective peak value and an effective peak position are updated and memorized in an RAM at every time the peak value and the peak position are detected in the peak position detecting zone, thereby, the final peak value and the final peak position in the peak position detecting zone are updated and memorized in the RAM as the effective peak value and the effective peak position. Also, when the peak value detected in the combustion state detecting zone is a predetermined value or below, it is determined that the combustion state is unstable, and combustion control is prohibited. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to combustion information detection means for outputting a signal corresponding to ions or in-cylinder pressure generated by combustion of an air-fuel mixture in an internal combustion engine, and peak position detection means for detecting a peak position of an output signal of the combustion information detection means. It is invention regarding the combustion determination apparatus of the internal combustion engine provided with.

  Generally, it is known that when the ignition timing is controlled to the optimum ignition timing (MBT: Minimum Spark Advance for Best Toruque), the peak position of the in-cylinder pressure (combustion pressure) falls within a specific crank angle range (for example, near ATDC 15 ° C). ing. Also, at the peak position of the in-cylinder pressure, the combustion temperature also peaks, and the amount of ions generated in the combustion gas reaches a peak. Therefore, the ion current collected through the ignition plug or the like is used as combustion information. In the detection system, it is known that the peak position of the ion current detection signal substantially coincides with the peak position of the in-cylinder pressure (see FIG. 3).

  In consideration of such characteristics, as shown in Patent Document 1 (Japanese Patent No. 3313882), a technique for detecting the peak position of an ion current detection signal and controlling the ignition timing to MBT is known. However, as shown in FIG. 2, since the waveform of the ion current detection signal is a complex waveform having a plurality of peaks, it is necessary to specify an effective peak position from the plurality of peak positions.

  Therefore, in Patent Document 1, in consideration of the generation of an unnecessary peak for a while after the ion current starts to flow, the ion current detection gain is set so that an unnecessary peak is not detected for a while from the start of the ion current detection. After that, the effective peak position is detected by gradually increasing the ion current detection gain.

In Patent Document 2 (Japanese Patent Laid-Open No. 10-252632), the first peak generated after the ion current starts to flow is determined as an unnecessary peak, and the second peak position generated thereafter is regarded as an effective peak position. I try to detect it.
Japanese Patent No. 3313882 (first page to second page, etc.) JP 10-252632 A (Claim 1 etc.)

  In Patent Document 1, it is necessary to variably set the ion current detection gain so that the effective peak generated near the peak position of the in-cylinder pressure is always higher than the other peaks, but the number of peaks depends on the combustion state. Because the peak position fluctuates in a complicated manner, it is difficult to realize a circuit that always detects the effective peak higher than the other peaks, and there is a possibility that the effective peak position may be erroneously detected, improving the detection accuracy. Has the disadvantage of being difficult.

  Further, depending on the combustion state, an effective peak that occurs near the peak position of the in-cylinder pressure may occur after the third position. Therefore, as in Patent Document 2, the second peak position is always the effective peak position. In such a configuration, there is a possibility that an effective peak position may be erroneously detected, and it is difficult to improve detection accuracy.

  The present invention has been made in view of these circumstances. Therefore, the object of the present invention is to determine an effective peak position of a detection signal by a simple method in a system for detecting ions or in-cylinder pressure generated by combustion of an air-fuel mixture. An object of the present invention is to provide a combustion determination device for an internal combustion engine that can detect with high accuracy and can satisfy the demand for improvement in detection accuracy at low cost.

  In order to achieve the above object, the invention according to claim 1 is directed to a combustion information detecting means for outputting a signal corresponding to an ion generated by combustion of an air-fuel mixture of an internal combustion engine or a cylinder pressure, and an output of the combustion information detecting means. An internal combustion engine combustion determination apparatus including a peak position detection means for detecting a peak position of a signal, wherein the peak position detection means detects a plurality of peak positions within a detection section set for each combustion (for each ignition). In this case, the final peak position is set as an effective peak position.

  The inventor operates the internal combustion engine under various combustion conditions, analyzes the waveform of the output signal of the combustion information detection means that outputs a signal corresponding to ions or in-cylinder pressure, and generates it near the peak position of the in-cylinder pressure. As a result of examining the positional relationship between the effective peak and other peaks, it was found that the final peak position is an effective peak position. Therefore, in the first aspect of the invention, the final peak position among the plurality of peak positions detected in the detection section set for each combustion is set as an effective peak position. Thereby, an effective peak position of the detection signal can be detected with a simple method with high accuracy, and the demand for improvement in detection accuracy can be satisfied at a low cost.

  In the above-mentioned Patent Document 2, the A / D conversion value (ion current detection value) of the ion current detection signal is sampled at a predetermined cycle and stored in the memory in time series in the detection section set for each combustion. Since the second peak position is calculated by searching the time-series sampling data stored in the memory after the end of the detection section, a huge memory for storing all the sampling data in the detection section Capacity is required, and it is difficult to meet the demand for cost reduction.

  In this respect, the present invention sets the final peak position as an effective peak position, and stores the peak position every time the peak position is detected within the detection section set for each combustion as in claim 2. In this case, the final peak position can be updated and stored in the storage means as an effective peak position. In this configuration, since it is not necessary to store all the sampling data in the detection section, it is possible to detect an effective peak position with a considerably small memory capacity as compared with Patent Document 2, and satisfy the demand for cost reduction. be able to.

  Further, as in claim 3, an effective peak position is detected from positions where a peak of a change amount of the output signal of the combustion information detecting means is ignored and a peak having a larger change amount is ignored. You may make it do. In this way, erroneous detection of the peak position due to noise can be prevented.

  In this case, as in claim 4, the peak value and the bottom value of the output signal of the combustion information detecting means are detected, and a peak whose difference or ratio between the peak value and the bottom value is less than a predetermined value is ignored. Alternatively, an effective peak position may be detected from positions where large peaks occur. In this way, it is possible to more accurately determine whether it is a peak or noise.

  In the inventions according to claims 3 and 4, as in claim 5, the final peak position among the plurality of peak positions may be set as an effective peak position, or a conventional peak position detection technique ( For example, you may implement in combination with patent document 1,2.

  The combustion state of the internal combustion engine is determined by the combustion state determining unit based on the effective peak position detected by the peak position detecting unit and the signal peak value at the effective peak position. Also good. Here, since the effective peak position and the signal peak value are information correlated with the peak position and the peak temperature of the combustion temperature, the combustion state can be accurately determined.

  Further, as in claim 7, the peak position detection means detects the peak value and / or peak position of the output signal of the combustion information detection means within the combustion state detection section set for each combustion, The peak value and / or the peak position of the output signal of the combustion information detecting means within the peak position detection section including the peak position at the time of combustion at the optimum ignition timing (MBT) (for example, near ATDC 15 ° C. A) within the combustion state detection section. Means for detecting and comparing the peak value and / or peak position detected in the combustion state detection section with the peak value and / or peak position detected in the peak position detection section, and within the peak position detection section It is good also as a structure provided with the means to determine whether the detected peak value and / or peak position are effective. In this way, it is possible to confirm whether or not the peak value and / or peak position detected in the peak position detection section is correct, and the detection accuracy can be improved.

  Further, the peak value and / or peak position of the output signal of the combustion information detecting means is detected by the peak position detecting means within the detection section including the peak position at the time of combustion at the optimum ignition timing, and the detection is performed. When the value is in a preset effective range, the combustion control means corrects the control value of the internal combustion engine and / or the feedback control range of the control value based on the detected value to optimize the combustion state. May be. In short, when the peak value or peak position of the output signal of the combustion information detecting means is within the preset effective range, it is determined that the combustion state is relatively stable, and the internal combustion engine is determined according to the peak value or peak position. The control value is corrected, and the feedback control range of the control value is corrected. This enables stable combustion control according to the peak value and peak position of the output signal of the combustion information detection means, and also includes knock control for feedback control of the ignition timing near the knock limit, feedback control for variable valve timing, etc. The feedback control range can be expanded.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment embodying the best mode for carrying out the invention will be described with reference to the drawings. First, the circuit configuration of the ignition control system will be described with reference to FIG. One end of the primary coil 22 of the ignition coil 21 is connected to the battery 23, and the other end of the primary coil 22 is connected to the collector of the power transistor 25 built in the igniter 24. One end of the secondary coil 26 is connected to a spark plug 27, and the other end of the secondary coil 26 is connected to the ground via two Zener diodes 28 and 29.

  The two Zener diodes 28 and 29 are connected in series in opposite directions, a capacitor 30 is connected in parallel to one Zener diode 28, and an ion current detection resistor 31 is connected in parallel to the other Zener diode 29. A potential Vin between the capacitor 30 and the ionic current detection resistor 31 is input to the inverting input terminal (−) of the inverting amplifier circuit 33 via the resistor 32 and is inverted and amplified. The output voltage V of the inverting amplifier circuit 33 is ionized. The current detection signal is input to the engine control circuit 34. The ion current detection circuit 35 (combustion information detection means) includes Zener diodes 28 and 29, a capacitor 30, an ion current detection resistor 31, an inverting amplification circuit 33, and the like.

  During engine operation, the power transistor 25 is turned on / off at the rise / fall of the ignition signal transmitted from the engine control circuit 34 to the igniter 24. When the power transistor 25 is turned on, a primary current flows from the battery 23 to the primary coil 22. After that, when the power transistor 25 is turned off, the primary current of the primary coil 22 is cut off and a high voltage is electromagnetically induced in the secondary coil 26. This high voltage causes spark discharge between the electrodes 36 and 37 of the spark plug 27. This spark discharge current flows from the ground electrode 37 of the spark plug 27 to the center electrode 36, is charged to the capacitor 30 via the secondary coil 26, and flows to the ground side via the Zener diodes 28 and 29. After the capacitor 30 is charged, the ion current detection circuit 35 is driven using the charging voltage of the capacitor 30 regulated by the Zener voltage of the Zener diode 28 as a power source, and the ion current is detected as described later.

  On the other hand, the ion current flows in the opposite direction to the spark discharge current. In other words, after ignition is finished, a voltage is applied between the electrodes 36 and 37 of the spark plug 27 by the charging voltage of the capacitor 30, so that ions generated when the air-fuel mixture burns in the cylinder are connected between the electrodes 36 and 37. Although an ionic current flows, the ionic current flows from the center electrode 36 to the ground electrode 37, and further flows from the ground side through the ion current detection resistor 31 to the capacitor 30. At this time, the input potential Vin of the inverting amplifier circuit 33 changes according to the change of the ionic current flowing through the ionic current detection resistor 31, and the voltage V corresponding to the ionic current is output to the engine control circuit 34 from the output terminal of the inverting amplifier circuit 33. The ionic current is detected.

  The engine control circuit 34 is mainly composed of a microcomputer, and executes fuel injection control and ignition timing control by executing various engine control routines stored in the ROM. Further, the engine control circuit 34 executes an ion current detection routine of FIG. 3 to be described later, thereby permitting combustion control permission / permission based on the peak value and peak position of the ion current detection signal output from the ion current detection circuit 35. Determine prohibition.

  In this embodiment, as shown in FIG. 2, a combustion state detection section for determining a combustion state such as misfire is set for each ignition, and a peak position detection section is set in the combustion state detection section. The combustion state detection section is set to a section from immediately after the ignition timing to ATDC 180 ° C., and the peak position detection section is a section including a peak position (for example, near ATDC 15 ° C. A) at the time of combustion at the optimal ignition timing (MBT). For example, it is set in a section from TDC to ATDC 40 ° C.

  The engine control circuit 34 detects the peak value APH of the ion current detection signal within the combustion state detection section, and detects the effective peak value PMBT of the ion current detection signal and the effective peak position WMBT within the peak position detection section.

  At this time, as shown in FIG. 2, a plurality of peaks are detected in the peak position detection section, but the positional relationship between the effective peak generated near the peak position of the in-cylinder pressure and other peaks under various combustion conditions. As a result, it was found that the final peak position becomes the effective peak position WMBT.

  Therefore, in this embodiment, every time the peak value / peak position is detected within the peak position detection section, the effective peak value PMBT / effective peak position WMBT is updated and stored in the RAM (storage means) of the engine control circuit 34. The final peak / peak position in the peak position detection section is updated and stored in the RAM as the effective peak value PMBT / effective peak position WMBT.

  Further, in this embodiment, in order to distinguish a peak detected in the peak position detection section from noise, a peak value and a bottom value are detected, and a peak whose difference or ratio between the peak value and the bottom value is a predetermined value or less is detected. Is judged to be noise and ignored, and an effective peak is detected from peaks larger than that.

  The engine control circuit 34 determines whether or not the combustion state is stable based on whether or not the peak value APH detected within the combustion state detection section is greater than or equal to a predetermined value. If the combustion state is not stable, Prohibit combustion control.

  On the other hand, when the peak value APH detected in the combustion state detection section is equal to or greater than a predetermined value and it is determined that the combustion state is stable, the effective peak value PMBT detected in the peak position detection section and the combustion state detection section The effective peak value PMBT detected in the peak position detection section is confirmed to be really effective based on whether or not the two are substantially the same.

  Furthermore, the effective peak position WMBT detected in the peak position detection section is detected in the peak position detection section depending on whether or not the peak position at the time of combustion at the optimum ignition timing (MBT) is near (for example, ATDC 5 to 30 ° C.). It is confirmed whether or not the effective peak position WMBT is really effective. Alternatively, the effective peak position WMBT detected in the peak position detection section is compared with the peak position detected in the combustion state detection section, and it is detected in the peak position detection section depending on whether or not they are substantially the same. It is also possible to confirm whether or not the effective peak position WMBT is really effective.

  The engine control circuit 34 permits the combustion control when it is confirmed that the effective peak value PMBT / effective peak position WMBT detected within the peak position detection section is really effective. Ban.

  The effective peak position WMBT detected in the peak position detection section substantially coincides with the peak position of the in-cylinder pressure (see FIG. 3). When the effective peak position WMBT is at the optimal ignition timing (MBT), the combustion state becomes the state of optimal combustion efficiency. Therefore, if the effective peak position WMBT is behind the optimal ignition timing (MBT), the ignition timing is advanced. If the effective peak position WMBT is too early than the optimum ignition timing (MBT), combustion control is performed by retarding the ignition timing and delaying combustion.

  Further, since the effective peak value PMBT has a correlation with the in-cylinder pressure peak value and thus the combustion temperature peak value, if the effective peak value PMBT is too low, the valve is set so as to reduce the internal EGR by shortening the combustion period, for example. Combustion control is performed so that the overlap amount is reduced or the air-fuel ratio is enriched. If the effective peak value PMBT is too high, the valve overlap amount is increased to slow down the combustion and increase the internal EGR, for example. Combustion control is performed by enlarging or reducing the air-fuel ratio.

  The detection processing and combustion control of the effective peak value PMBT / effective peak position WMBT described above and the combustion control are executed by the engine control circuit 34 according to the routines shown in FIGS. The processing contents of these routines will be described below.

[Ion current detection routine]
The ion current detection routine of FIG. 4 is executed in the sampling period (for example, 10 μs period) of the ion current detection signal, and plays a role as a peak position detection means in the claims. When this routine is started, first, in step 101, it is determined whether or not it is within a combustion state detection section for determining a combustion state such as misfire (within a section from immediately after the ignition timing to ATDC 180 ° C.), If it is not within the combustion state detection section, the routine proceeds to step 105, where it is determined whether it is the combustion state detection section end timing, and if it is not the combustion state detection section end timing, this routine is ended as it is.

  On the other hand, if it is determined in step 101 that the current state is within the combustion state detection section, the process proceeds to step 102, where the peak value APH and the current ion current detection signal A in the combustion state detection section stored in the RAM are measured. / D conversion value (hereinafter referred to as “ion current detection value”) ADi, and if the current ion current detection value ADi is larger than the previous peak value APH, the process proceeds to step 103 and the current ion current detection value. ADi is updated and stored in the RAM as the peak value APH. On the other hand, if it is determined in step 102 that the current ion current detection value ADi is smaller than the previous peak value APH, the update processing of the peak value APH in step 103 is not performed.

  Thereafter, the process proceeds to step 104, where an effective peak detection routine of FIG. 5 described later is executed to detect the effective peak value PMBT and the effective peak position WMBT within the peak position detection section. Thereafter, the routine proceeds to step 105, where it is determined whether or not it is the end timing of the combustion state detection section.

  Thereafter, when the combustion state detection section end timing is reached, it is determined as “Yes” in step 105, and the process proceeds to step 106 where the peak value APH detected in the combustion state detection section is larger than the predetermined value C1. No, it is determined whether the combustion state is stable. If the peak value APH is equal to or less than the predetermined value C1, it is determined that the combustion state is unstable, and the routine proceeds to step 110 to prohibit combustion control. To do.

  On the other hand, if it is determined in step 106 that the peak value APH detected in the combustion state detection section is larger than the predetermined value C1, it is determined that the combustion state is stable, and the routine proceeds to step 107, where the peak position is determined. The effective peak value PMBT detected in the detection section is compared with the peak value APH detected in the combustion state detection section, and the effective value detected in the peak position detection section is determined by whether or not the ratio between the two is approximately 1. It is confirmed whether or not the peak value PMBT is an original effective peak value. As a result, if it is determined that the ratio between the two is not approximately 1, it is determined that the effective peak value PMBT detected in the peak position detection section is not the original effective peak value, the process proceeds to step 110, and combustion control is performed. Is prohibited.

  On the other hand, if it is determined in step 107 that the ratio between the effective peak value PMBT detected in the peak position detection section and the peak value APH detected in the combustion state detection section is approximately 1, the peak position The effective peak value PMBT detected in the detection section is determined to be the original effective peak value, and the process proceeds to step 108 where the effective peak position WMBT detected in the peak position detection section is within the range of ATDC 5 to 30 ° C. Whether or not the effective peak position WMBT detected in the peak position detection section is the original effective peak position is confirmed based on whether or not (near MBT).

  If it is determined in this step 108 that the effective peak position WMBT detected in the peak position detection section is within the range of ATDC 5 to 30 ° C., the effective peak position WMBT detected in the peak position detection section is originally effective. If it is determined that the peak position is correct, the routine proceeds to step 109, where combustion control is permitted. On the other hand, if it is determined in step 108 that the effective peak position WMBT detected in the peak position detection section is out of the range of ATDC 5 to 30 ° C., the detected effective peak position WMBT is the original effective. If it is determined that the peak position is not correct, the routine proceeds to step 110 where combustion control is prohibited.

[Effective peak detection routine]
The effective peak detection routine of FIG. 5 is a subroutine executed in step 104 of the ion current detection routine of FIG. 4 and plays a role as a peak position detection means in the claims. When this routine is started, first, in step 201, it is determined whether or not an effective peak detection condition is satisfied. Here, the effective peak detection condition is an operation condition capable of detecting MBT.

  If it is determined in step 201 that the effective peak detection condition is not satisfied, this routine is terminated without performing the subsequent processing. On the other hand, if it is determined that the effective peak detection condition is satisfied, the routine proceeds to step 202, where it is determined whether or not it is within the peak position detection section (within the section from TDC to ATDC 40 ° C. A). As a result, if it is determined that it is not within the peak position detection section, the process proceeds to step 211 to determine whether or not it is the peak position detection section end timing. finish.

  On the other hand, if it is determined in step 202 that the current position is within the peak position detection section, the process proceeds to step 203, where the number of samplings of the ion current detection value ADi after the start of the peak position detection section is counted, and in the next step 204, It is determined whether or not the second and subsequent samplings are based on whether or not the number of samplings is greater than one. As a result, if it is determined that it is the first sampling after the start of the peak position detection section, the process proceeds to step 207, where the peak value HPH and the bottom value LBH in the peak position detection section stored in the RAM are set as initial values. Is set as the initial value of the peak position counter NPH, and this routine is terminated.

  On the other hand, if it is determined in the above step 204 that the sampling is the second or later, the process proceeds to step 205, where the peak value HPH up to the previous time in the peak position detection section stored in the RAM and the current ion current detection are detected. If the current ion current detection value ADi is larger than the previous peak value HPH, the process proceeds to step 206, where the current sampling count is updated and stored as the peak position counter NPH, and the current ion current The detected value ADi is updated and stored in the RAM as the peak value HPH.

  On the other hand, if it is determined in step 205 that the current ion current detection value ADi is smaller than the peak value HPH up to the previous time, the process proceeds to step 208 and the peak value HPH in the peak position detection section stored in the RAM. It is determined whether the ratio of the bottom value LBH is greater than a predetermined value C2. As a result, if it is determined that the ratio between the peak value HPH and the bottom value LBH is greater than the predetermined value C2, it is determined that the peak value HPH is not noise, and the process proceeds to step 209, where the peak value HPH is converted to the effective peak value. Update and store in the RAM as PMBT. If the ratio between the peak value HPH and the bottom value LBH is equal to or less than the predetermined value C2, it is determined that the peak value HPH may be noise, and the update processing of the effective peak value PMBT in step 209 is not performed. . Thereafter, the process proceeds to step 210, and the current ion current detection value ADi is updated and stored in the RAM as the bottom value LBH.

  Thereafter, the process proceeds to step 211, where it is determined whether it is the end timing of the peak position detection section. If it is not the end timing of the peak position detection section, this routine is ended as it is.

Thereafter, when the peak position detection section end timing is reached, it is determined as “Yes” in step 211, and the process proceeds to step 212 where the number of samplings from the start to the end of the peak position detection section is stored as ADE. The effective peak position WMBT is calculated by the following equation.
WMBT = (NPH / ADE) × 40 ° C.
Here, NPH is the value of the peak position counter set in step 206. 40 ° C. is the crank angle of the entire peak position detection section.

[Combustion control routine]
The combustion control routine of FIG. 6 is executed at an engine control cycle. When this routine is started, it is first determined in step 300 whether or not combustion control is permitted based on the processing result of the ion current detection routine of FIG. 4, and if combustion control is prohibited, the subsequent steps are performed. This routine is terminated without performing any processing.

  On the other hand, if it is determined in step 300 that the combustion control is permitted, the process proceeds to step 301 where the current engine operating conditions (for example, engine speed, load, ignition timing, valve timing, etc.) are read, In the next step 302, the target peak position Θp, the ignition timing control value Θig, and the valve timing control value V corresponding to the current engine operating conditions are calculated using a map or the like.

Thereafter, the process proceeds to step 303, and a deviation ΔΘp between the target peak position Θp and the effective peak position WMBT is calculated.
ΔΘp = Θp -WMBT
Here, the effective peak position WMBT is an effective peak position detected in the peak position detection section by the effective peak detection routine of FIG.

Then, in the next step 304, it is determined whether or not feedback control of the engine control value (for example, knock feedback control, valve timing feedback control) is stopped, and if any feedback control is executed, Proceeding to step 305, using the deviation ΔΘp between the target peak position Θp and the effective peak position WMBT, the knock advance guard value Θg and the valve timing control guard value Vg are corrected by the following equations.
Θg = Θg + ΔΘp / K2
Vg = Vg + ΔΘp / K3
Here, K2 and K3 are coefficients.

  For example, when the effective peak position WMBT is behind the MBT, the ignition timing guard value Θg is advanced by ΔΘp / K2 to accelerate combustion, and conversely, when the effective peak position WMBT is too early than the MBT, The ignition timing guard value Θg is retarded by ΔΘp / K2 to retard combustion. Similarly, when the effective peak position WMBT is behind the MBT, the valve timing control guard value Vg is advanced by ΔΘp / K3 to reduce the valve overlap amount (internal EGR amount). When the position WMBT is too early than the MBT, the valve timing control guard value Vg is retarded by ΔΘp / K2 to increase the valve overlap amount (internal EGR amount). In addition, the air-fuel ratio may be corrected according to the deviation ΔΘp between the target peak position Θp and the effective peak position WMBT.

  On the other hand, if it is determined in step 304 that all feedback control of the engine control value is stopped, the process proceeds to step 306, where the deviation ΔΘp between the target peak position Θp and the effective peak position WMBT is larger than the predetermined value Co. It is determined whether or not. As a result, if it is determined that the deviation ΔΘp is larger than the predetermined value Co, the routine proceeds to step 307, where the ignition timing control value Θig is retarded by ΔΘp / K1 (where K1 is a coefficient), and the effective peak position The WMBT is brought close to the target peak position Θp.

  If it is determined in step 306 that the deviation ΔΘp between the target peak position Θp and the effective peak position WMBT is equal to or less than the predetermined value Co, it is determined that the ignition timing is controlled near the MBT, and the process proceeds to step 308. Whether or not the combustion state is a slow combustion state with a low combustion temperature is determined based on whether or not the effective peak value PMBT detected in the peak position detection section by the effective peak detection routine of FIG. 5 is smaller than the predetermined value Po. As a result, if it is determined that the effective peak value PMBT is smaller than the predetermined value Po, it is determined that the combustion temperature is low and the combustion state is low, and the routine proceeds to step 309, where the valve timing control value V is increased by the predetermined amount ΔV. Correction is made to reduce the valve overlap amount (internal EGR amount), thereby speeding up combustion.

  On the other hand, if it is determined in step 308 that the effective peak value PMBT is greater than or equal to the predetermined value Po, it is determined that the combustion temperature is high and combustion is being performed at an appropriate speed, and the valve timing control value V is set to This routine is terminated without correction.

  According to the present embodiment described above, the final peak position among the plurality of peak positions detected in the peak position detection section set to include the peak position (MBT) of the in-cylinder pressure is the effective peak position. Since the final peak position is detected as the effective peak position WMBT among a plurality of peak positions detected within the peak position detection section, the effective peak of the ion current detection signal can be detected with a simple method. The position WMBT can be detected with high accuracy, and the demand for improved detection accuracy can be satisfied at a low cost.

  Moreover, in this embodiment, every time the peak value / peak position is detected within the peak position detection section, the effective peak value PMBT / effective peak position WMBT is updated and stored in the RAM of the engine control circuit 34, so that the peak position detection section In the RAM, the last peak / peak position is updated and stored in the RAM as the effective peak value PMBT / effective peak position WMBT, so it is not necessary to store all the sampling data in the peak position detection section. The effective peak value PMBT / effective peak position WMBT can be detected with a considerably smaller memory capacity than in the case of 2, and the demand for cost reduction can be satisfied.

  The present embodiment is an embodiment in which the present invention is applied to a system that detects ion current as combustion information using an ion current detection circuit 35 as combustion information detection means. The present invention may be applied to a system that detects in-cylinder pressure as combustion information using

It is a circuit diagram which shows the structure of the ignition control system and ion current detection circuit in one Example of this invention. It is a time chart which shows an example of an ignition signal, a combustion state detection area, a peak position detection area, and an ion current detection waveform. It is a time chart explaining the relationship between an ion current detection waveform and an in-cylinder pressure detection waveform. It is a flowchart which shows the flow of a process of an ion current detection routine. It is a flowchart which shows the flow of a process of an effective peak detection routine. It is a flowchart which shows the flow of a process of a combustion control routine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 21 ... Ignition coil, 22 ... Primary coil, 23 ... Battery, 24 ... Igniter, 25 ... Power transistor, 26 ... Secondary coil, 27 ... Spark plug, 31 ... Ion current detection resistor, 33 ... Inversion amplification circuit, 34 ... Engine Control circuit (peak position detection means), 35 ... ion current detection circuit (combustion information detection means), 36 ... center electrode, 37 ... ground electrode

Claims (8)

An internal combustion engine comprising combustion information detection means for outputting a signal corresponding to ions or in-cylinder pressure generated by combustion of an air-fuel mixture of an internal combustion engine, and peak position detection means for detecting a peak position of an output signal of the combustion information detection means In the engine combustion determination device,
The internal combustion engine combustion determination device, wherein the peak position detection means sets the final peak position as an effective peak position when a plurality of peak positions are detected within a detection section set for each combustion.   The peak position detection means updates and stores the peak position in the storage means every time the peak position is detected within the detection section set for each combustion, whereby the final peak position is stored in the storage means as an effective peak position. The combustion determination device for an internal combustion engine according to claim 1, wherein the combustion determination device is updated and stored. An internal combustion engine comprising combustion information detection means for outputting a signal corresponding to ions or in-cylinder pressure generated by combustion of an air-fuel mixture of an internal combustion engine, and peak position detection means for detecting a peak position of an output signal of the combustion information detection means In the engine combustion determination device,
The peak position detecting means ignores a peak whose change amount of the output signal of the combustion information detecting means is a predetermined value or less, and detects an effective peak position from positions where a peak of a larger change amount occurs. A combustion determination apparatus for an internal combustion engine characterized by the above.   The peak position detecting means has means for detecting a peak value and a bottom value of an output signal of the combustion information detecting means, ignoring a peak whose difference or ratio between the peak value and the bottom value is a predetermined value or less, The combustion determination device for an internal combustion engine according to claim 3, wherein an effective peak position is detected from positions where a larger peak is generated.   5. The combustion determination device for an internal combustion engine according to claim 3, wherein the peak position detection unit sets a final peak position as an effective peak position among a plurality of peak positions. 6.   2. A combustion state determination unit for determining a combustion state of an internal combustion engine based on an effective peak position detected by the peak position detection unit and a signal peak value at the effective peak position. The combustion determination device for an internal combustion engine according to any one of claims 1 to 5. An internal combustion engine comprising combustion information detection means for outputting a signal corresponding to ions or in-cylinder pressure generated by combustion of an air-fuel mixture of an internal combustion engine, and peak position detection means for detecting a peak position of an output signal of the combustion information detection means In the engine combustion determination device,
The peak position detecting means includes means for detecting a peak value and / or peak position of an output signal of the combustion information detecting means within a combustion state detecting section set for each combustion, and optimum ignition within the combustion state detecting section. Means for detecting a peak value and / or peak position of the output signal of the combustion information detecting means within a peak position detecting section including a peak position at the time of combustion, and a peak value detected within the combustion state detecting section and / or Or means for comparing the peak position and the peak value and / or peak position detected in the peak position detection section to determine whether the peak value and / or peak position detected in the peak position detection section is valid. A combustion determination apparatus for an internal combustion engine, comprising: Combustion information detection means for outputting a signal corresponding to ions or in-cylinder pressure generated by combustion of an air-fuel mixture of an internal combustion engine;
A peak position detecting means for detecting a peak value and / or a peak position of an output signal of the combustion information detecting means within a detection section including a peak position at the time of combustion at an optimal ignition timing;
When the peak value and / or peak position detected by the peak position detection means is within a preset effective range, the control value of the internal combustion engine and / or feedback of the control value based on the peak value and / or peak position Combustion control means that corrects the control range and optimizes the combustion state. A combustion determination device for an internal combustion engine, comprising:

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