JP4793181B2 - Engine crank angle detector - Google Patents

Description

  The present invention relates to an engine crank angle detection device.

For example, in Patent Document 1, an ion current generated in a combustion chamber is detected by an ion current detection circuit, and based on the difference between the maximum value in the detected ion current waveform and the compression top dead center, MBT (Minimum advance for the Best Torque) is disclosed.
JP-A-6-34490

  By the way, in a mass production engine, the compression top dead center based on the detected value of the crank angle sensor may deviate from the actual compression top dead center due to, for example, tolerance variation or some factor during use. When such a deviation occurs, even if the MBT is detected based on the difference between the maximum value in the ion current waveform and the compression top dead center as described in the above-mentioned patent document, the detected MBT is displaced. In addition, the valve timing of the intake and / or exhaust valves, ignition timing, and fuel injection timing, etc., which are controlled based on the crank angle, are controlled by a phase variable mechanism (hereinafter referred to as VVT). Misalignment will occur.

  The present invention has been made in view of such a point, and an object thereof is to make it possible to determine the displacement of the compression top dead center.

  The inventor of the present application has studied to solve the above problem, and as a result, the ion current detected by the ion current detection means has a waveform characteristic including a first peak and a second peak, and the ignition timing is advanced. As a result, it was found that the crank angle position of the peak of the mountain in the latter half converges near the compression top dead center, and the present invention has been completed.

  That is, in the waveform of the ion current detected by the ion current detection means, for example, two peaks in the first half and the second half appear as shown in FIG. Here, the first half of the mountain is considered to represent changes in the ion current mainly using ions generated on the flame surface after ignition, while the second half of the peak represents the ionic current indicated by the combustion process. As the temperature rises, it is considered that NOx present in the burned gas uses ions generated by thermal ionization as a medium. The peak of the mountain in the latter half shows the maximum combustion temperature position.

  Here, as shown in FIG. 4, according to the relationship between the ignition timing, the maximum combustion temperature position, and the maximum combustion pressure position based on the result obtained by the simulation, the maximum combustion temperature is increased by advancing the ignition timing. It can be seen that both the position and the maximum combustion pressure position converge to a predetermined value.

  Therefore, if the ignition timing is changed to the advance side and the crank angle position of the peak of the latter half converges to a predetermined position, the maximum is determined based on the crank angle position (in other words, the detected maximum combustion temperature position). The combustion pressure position (in other words, compression top dead center) can be detected.

  That is, according to one aspect of the present invention, an engine crank angle detection device is disposed facing a combustion chamber of an engine and performs ignition discharge at a predetermined timing, and the ignition plug after the ignition discharge of the ignition plug. An ion current detecting means for detecting an ion current generated in the combustion chamber and having a waveform characteristic including a first peak and a second peak with respect to the progress of the crank angle; and a peak of the second peak of the ion current waveform The ignition timing changing means for changing the ignition timing of the spark plug to the advance side so as to be near the compression top dead center, and when the ignition timing is changed to the advance side by the ignition timing changing means, The peak of the latter half of the ion current is detected by the ion current detection means, and the compression top dead center is determined based on the crank angle position where the peak occurs. Comprising a determining means.

  According to this configuration, the ignition timing is changed to the advance side by the ignition timing changing means so that the peak of the latter half of the ion current waveform detected by the ion current detecting means is near the compression top dead center. That is, the peak of the latter half of the ionic current waveform is made to be substantially constant (converge) even if the ignition timing is changed to the advance side.

  In this state, the determination unit detects the peak of the latter half of the ion current, and as described above, it is possible to determine the compression top dead center based on the crank angle position where the peak occurs. .

  Preferably, the ignition timing changing means changes the ignition timing to an advance side when the operating state of the engine is in a low rotation range.

  In this way, when the engine is operating in the middle or high speed range, the combustion period (time) becomes relatively short, so that the initial combustion cannot catch up with the combustion period, and the peak of the latter half of the peak When the engine operating state is in the low rotation range, the peak of the latter half of the peak converges near the compression top dead center by changing the ignition timing to the advance side. As a result, the compression top dead center can be accurately determined.

  Preferably, the crank angle detection device further includes a filling amount correction unit that corrects the intake filling amount according to the change amount when the ignition timing is changed to the advance side by the ignition timing changing unit. .

  By doing so, there is a risk that the torque may change as the ignition timing is changed, but the change in torque is caused by the charging amount correction means correcting the suction filling amount according to the amount of change in the ignition timing. This cancels out and torque fluctuation is suppressed in advance.

  The crank angle detection device may further include timing correction means for correcting the control timing of various parameters controlled based on the crank angle in accordance with the compression top dead center determined by the determination means.

  In this way, for example, when the sensor value of the compression top dead center detected by the crank angle sensor is deviated from the actual compression top dead center, it is based on the compression top dead center determined by the determination means. By correcting the control timing of various parameters (for example, ignition timing, valve timing, fuel injection timing, etc.), the control timing is optimized.

  As described above, according to the present invention, the compression top dead center can be accurately determined based on the ion current detected by the ion current detection means. Thereby, for example, when the compression top dead center detected by the crank angle sensor is deviated from the actual one, the control timing of various parameters controlled based on the crank angle can be optimized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

(Schematic configuration of the engine)
FIG. 1 schematically shows an engine 1 of an embodiment provided with a detection device according to the present invention. In this example, the engine 1 includes a plurality of cylinders 2, 2,... (Only one is shown in the figure) in series. Is a spark ignition type engine. As shown in the figure, the upper end of the cylinder 2 opens at the upper end surface of the cylinder block 3 and is closed by the lower surface of the cylinder head 4 mounted thereon. A piston 5 is fitted in the cylinder 2 so as to be able to reciprocate. A combustion chamber 6 is defined between the upper surface of the piston 5 and the lower surface of the cylinder head 4. On the other hand, a crankshaft (not shown) is disposed in the crankcase below the piston 5 and is connected to the piston 5 by a connecting rod.

  The cylinder head 4 is provided with an ignition plug 7 for each cylinder 2 and is arranged so that the electrode at the tip thereof faces the combustion chamber 6, while the base end portion of the ignition plug 7 is connected to the ignition circuit 8. Has been. Although only shown in FIG. 2, the ignition circuit 8 includes an igniter 8a composed of a power transistor and an ignition coil 8b. The ignition circuit 8 receives a control signal from a PCM 30 described later and receives a predetermined timing (for each cylinder 2). The ignition plug 7 is energized at the ignition timing. In this example, an ion current detection circuit 33 is connected to each ignition circuit 8 so that the ion current can be detected for each cylinder 2 as shown in FIG. 3 or FIG. To do.

  The cylinder head 4 is formed with an intake port 9 and an exhaust port 10 so as to open toward the combustion chamber 6 for each cylinder 2, and each port opening is opened and closed by a cam shaft. In addition, an intake valve 11 and an exhaust valve 12 are arranged. Although not shown in the figure, one camshaft is provided on each of the intake side and the exhaust side, and is connected to the crankshaft by a common cam chain. The intake shaft is synchronized with the rotation of the crankshaft. The intake and exhaust valves 11 and 12 are opened and closed at predetermined timings by rotating the side and exhaust side camshafts, respectively.

  Further, in this example, the intake side camshaft is provided with a phase variable mechanism 13 capable of continuously changing the phase with respect to the rotation of the crankshaft within a predetermined angle range (for example, 40 to 60 ° CA). By this VVT 13, the lift curve of the intake valve 11 is changed to the advance side and the retard side. As a result, the charging efficiency of the intake air can be increased, and the amount of burnt gas (internal EGR) remaining in the combustion chamber 6 can be changed by adjusting the overlap period with the lift curve of the exhaust valve 12. You can also.

  Further, an intake passage 15 is disposed on one side of the cylinder head 4 (left side in FIG. 1) so that the downstream end communicates with the intake port 9. The upstream end of the intake passage 15 is connected to an air cleaner 16 for filtering fresh air introduced from the outside. From there, an air flow sensor 17 for detecting the intake air flow rate in order toward the downstream side, and an electric motor 18a. Are provided with throttle valves 18 that throttle the intake passage 15 and four injectors 19, 19,... (Only one is shown in the drawing) for injecting fuel into each cylinder 2.

  On the other hand, on the opposite side of the cylinder head 4 (the right side in FIG. 1), an exhaust passage 20 communicates with the exhaust port 10 and exhausts burnt gas (exhaust gas) from the combustion chamber 6 in each cylinder 2. It is arranged. In this exhaust passage 20, in order from the upstream side, an oxygen concentration sensor (hereinafter referred to as O2 sensor) 21 for detecting the air-fuel ratio of the air-fuel mixture based on the oxygen concentration in the exhaust gas, and a catalyst for purifying the exhaust gas A converter 22 is provided.

  Further, an exhaust gas recirculation passage 24 (hereinafter referred to as an EGR passage) for recirculating a part of the exhaust gas to the intake air passage 15 is branched and connected to the exhaust passage 20 upstream of the O2 sensor 21. The downstream end of the passage 24 communicates with the intake passage 15 on the downstream side of the throttle valve 18. An electric flow control valve 25 (hereinafter referred to as an EGR valve) whose opening degree can be adjusted is disposed near the downstream end of the EGR passage 24, and the flow rate of the exhaust gas (external EGR) recirculated through the EGR passage 24. Is to adjust.

  Furthermore, a crank angle sensor 26 comprising an electromagnetic pickup or the like for detecting the rotation angle (crank angle) of the crankshaft is provided in the crankcase below the cylinder block 3 of the engine 1. The crank angle sensor 26 is an electromagnetic pickup that outputs a signal corresponding to the passage of a convex portion provided on the outer peripheral portion thereof as the rotor 27 attached so as to rotate integrally with the end portion of the crankshaft is rotated. It consists of a coil 26. Further, a water temperature sensor 28 for detecting the temperature state of the cooling water is provided on the water jacket (not shown) of the cylinder block 3.

  Output signals from the airflow sensor 17, the O2 sensor 21, the crank angle sensor 26, the water temperature sensor 28, etc. are input to a PCM (Power-train Control Module) 30, respectively. As is well known, the PCM 30 includes a CPU, ROM, RAM, an I / O interface circuit, etc. In addition to the sensors, a cam angle sensor 31 that detects at least the rotation angle (rotation position) of the intake camshaft. And an accelerator opening sensor 32 that detects the amount of operation of the accelerator pedal, respectively, to receive signals output from the accelerator pedal.

  The PCM 30 determines the operating state of the engine 1 based on the signals input from the sensors and controls the operation of the engine 1 accordingly. That is, the PCM 30 outputs an ignition timing control signal for each cylinder 2 to the ignition circuit 8, outputs a signal for controlling the operation timing of the intake valve 11 to the VVT 13, and intakes the throttle valve 18. A signal for controlling the flow rate is output, and a pulse signal for controlling the fuel injection amount and the injection timing is output to the injectors 19, 19,... For each cylinder 2. Further, the PCM 30 outputs a control signal to the EGR valve 25 in order to control the amount of exhaust gas (external EGR) that circulates to the intake system through the EGR passage 24.

  In the engine 1 of this embodiment, the ion current detection circuit 33 connected to the ignition circuit 8 as described above detects the ion current generated in the combustion chamber 6 after ignition for each cylinder 2, thereby compressing top dead center. And the control for correcting the ignition timing and the valve timing by the VVT 13 is performed according to the determination result.

(Relationship between ignition timing and maximum combustion pressure position)
First, the ion current waveform detected by the ion current detection circuit 33 will be described. Conventionally, the ion current is considered to be generated using ions generated by combustion as a medium. In this embodiment, as shown in FIG. 2, the ion current is detected in the ignition circuit 8 of the engine 1. A circuit 33 is connected.

  In the illustrated example, the ion current detection circuit 33 includes a power supply capacitor 33a connected in series to the end opposite to the ignition plug 7 on which the secondary side of the ignition coil 8b is grounded, and a detection circuit 33b. When the spark plug 7 is energized by the operation of 8a (ignition), a circuit is constituted by the electric charge stored in the power supply capacitor 33a and the ions generated in the combustion chamber 6, and a current flows, and this current is detected. The circuit 33b detects it. A signal from the detection circuit 33b is output to the PCM 30.

  The ion current value thus detected changes with the progress of the crank angle after ignition as schematically shown in FIG. 3, and two peaks in the first half and the latter half usually appear in the waveform. The ionic current represented in the first half of the mountain is thought to be based on ions (radicals) present on the flame surface that expand as the flame nuclei grow after the mixture has ignited. It is strongly influenced by the speed of the combustion chamber and the flow strength of the combustion chamber. That is, the first half of the mountain becomes steeper as the initial combustion becomes active, and its peak advances.

  On the other hand, the ion current expressed in the latter half of the mountain is not only ions (radicals) generated by the combustion reaction itself as described above, but also NOx present in the burned gas is thermally ionized as the temperature of the combustion chamber rises. It is considered that the generated ions are also used as a medium, and the peak appears at the crank angle position (maximum combustion temperature position) at which the temperature of the combustion chamber becomes maximum, and becomes higher as the combustion is active as a whole. The slower it is, the lower it becomes.

  Next, the relationship between the ignition timing, the maximum combustion temperature position, and the maximum combustion pressure position will be described with reference to FIG. FIG. 4 shows the result of a simulation for determining the relationship between the maximum combustion temperature position and the maximum combustion pressure position with respect to the ignition timing. When the ignition timing is advanced, the maximum combustion temperature position and the maximum combustion pressure position are set to a predetermined crank. It can be seen that it converges to the angular position. Therefore, in the actual engine 1, the ignition timing is advanced to a predetermined angle or more so that the maximum combustion temperature position and the maximum combustion pressure position converge to predetermined values, and the peak of the latter half of the ion current waveform at that time is If the generated crank angle position (maximum combustion temperature position) is detected, the maximum combustion pressure position, that is, the compression top dead center can be determined based on the crank angle position.

  Next, a procedure for determining the compression top dead center will be specifically described with reference to FIGS.

(Embodiment 1)
First, FIG. 5 is a flowchart of a procedure for determining the compression top dead center according to the first embodiment. In step SA1 after the start of illustration, if execution of monitoring of compression top dead center is instructed, it is determined in subsequent step SA2 whether or not the monitor execution condition is satisfied. The execution conditions here include whether or not the engine water temperature, the engine speed, and the charging efficiency are within a predetermined range. In particular, the condition of the engine speed includes a low speed range, which takes into account the balance between the initial combustion speed and the combustion period. In other words, when the engine speed is in the middle or high speed range, the combustion period (time) becomes relatively short, so the initial combustion cannot catch up with the combustion period, and the peak of the latter half of the peak is compressed top dead. It will not be near the point. If YES in step SA2, the process proceeds to step SA3. If NO in step SA2, step SA2 is repeated.

  In step SA3, the ignition timing Igt is set to Igttdc = pre-change Igt + ΔIgttdc to a predetermined value, and the intake charge amount is corrected according to the advance correction of the ignition timing. That is, the charging efficiency ce is set to ce + Δcetdc before correction. In this way, by correcting the intake charge amount, the torque fluctuation due to the change in the ignition timing is offset.

  Here, ΔIgttdc may be set as a function of the engine speed ne and the charging efficiency ce based on the experimental value. Similarly, Δcetdc is also set based on the experimental value of the engine speed ne, the charging efficiency ce before correction, and It may be set as a function of ΔIgttdc.

  Then, ignition discharge is performed at the changed ignition timing, and in step SA4, an ion signal is detected, and a crank angle position (CA2ndp) at which the peak of the latter half (2nd Peak) occurs is calculated. The calculation of the crank angle position (CA2ndp) in step SA4 is performed according to the flow shown in FIG.

  In step SB1 in the flow of FIG. 6, after completion of ignition discharge by the spark plug 7, the ion current is measured for each crank angle by the ion current detection circuit 33, and in the subsequent step SB2, as shown in FIG. The crank angle position (CA2ndp) of the maximum value of the ion current value within the range of ± ΔCAtdc with respect to the TDC set as the value is obtained. Here, ΔCAtdc may be set to about 10 ° CA, for example.

  If the crank angle position (CA2ndp) at which the peak of the latter half of the mountain occurs is detected, the process returns to step SA5 in the flow of FIG. 5 to determine whether the crank angle position (CA2ndp) has been determined a predetermined number of times. When the predetermined number of times has been performed, the process proceeds to step SA6. When the predetermined number of times has not been performed, the process returns to step SA2, and the above steps SA2 to SA4 are performed. Repeatedly detect the crank angle position (CA2ndp) where the peak of the peak occurs.

  In step SA6, the average (CA2ndpave) of the calculated crank angle position (CA2ndpave) is calculated, and the compression top dead center (CAtdc) is calculated based on the calculated average value (CA2ndpave). Here, it is assumed that there is a predetermined deviation between the maximum combustion temperature position (that is, CA2ndpave) and the maximum combustion pressure position (that is, compression top dead center (CAtdc)) as shown in FIG. The compression top dead center (CAtdc) is calculated based on the value (CAtdcofs) obtained by the above (CAtdc = CA2ndpave + CAtdcofs, where CAtdcofs is a function of the engine speed ne and the charging efficiency ce).

  In step SA7, the CAtdc calculated in step SA6 is stored in the PCM 30 as a monitor value for compression top dead center.

  When the monitoring of the compression top dead center in this flow is finished, the ignition timing is returned to the ignition timing corresponding to the engine operating state.

  Accordingly, the ignition timing changing means 41 for changing the ignition timing of the spark plug 7 to the advance side so that the peak of the latter half of the ion current waveform is in the vicinity of the compression top dead center according to the flow of FIGS. When the ignition timing is changed to the advance side by the ignition timing changing means 41, the peak of the latter half of the ion current is detected by the ion current detecting means 33, and the crank angle position where the peak occurs is detected. The determination means 42 which determines compression top dead center based on it is comprised.

  Further, according to the flow of FIG. 5, when the ignition timing is changed to the advance side by the ignition timing changing means 41, the filling amount correcting means 43 for correcting the intake filling amount according to the changed amount is configured. Yes.

(Embodiment 2)
FIG. 8 is a flowchart of a procedure for determining a compression top dead center according to the second embodiment. In step SC1 after the start of illustration, if execution of monitoring of compression top dead center is instructed, it is determined in subsequent step SC2 whether or not the monitor execution condition is satisfied. The execution conditions here are the same as those in step SA2 in FIG. When the condition is satisfied, the process proceeds to step SC3. When the condition is not satisfied, the process repeats step SC2.

  In step SC3, the ignition timing Igt is set to Igttdc = previous cycle Igt + ΔIgtadd, and is advanced by ΔIgtadd, and the intake charge amount is corrected in accordance with the advance correction of the ignition timing. That is, the filling efficiency ce is set to ce + Δceadd before correction. In this way, by correcting the intake charge amount, the torque fluctuation due to the change in the ignition timing is offset.

  Here, ΔIgtadd may be set as a function of the engine speed ne and the charging efficiency ce based on the experimental value. Similarly, Δceadd is also determined based on the experimental value of the engine speed ne, the charging efficiency ce before correction, and It may be set as a function of ΔIgtadd.

  Then, ignition discharge is performed at the changed ignition timing, and in step SC4, an ion signal is detected, and a crank angle position (CA2ndp) at which the peak of the latter half (2nd Peak) occurs is calculated. The calculation of the crank angle position (CA2ndp) in step SC4 is performed according to the flow shown in FIG. In step SC4, the difference ΔCA2ndp (n) (= CA2ndp (n) between the crank angle position (CA2ndp (n-1)) calculated in the previous cycle and the crank angle position calculated this time (CA2ndp (n)). -CA2ndp (n-1)) is calculated.

  In the following step SC5, it is determined whether or not the value of the crank angle position (CA2ndp) at which the peak of the latter half of the mountain has converged. As the convergence determination here, for example, determination may be made according to the following expression based on the deviations ΔCA2ndp (n) to ΔCA2ndp (n−3) of the past four crank angle positions including the current value.

ABS (ΔCA2ndp (n) + ΔCA2ndp (n-1) + ΔCA2ndp (n-2) + ΔCA2ndp (n-3)) / 4 <ΔCA2ndpcnv
ΔCA2ndpcnv is a predetermined determination value. Here, it is determined that CA2ndp has converged when the amount of change between cycles is smaller than a predetermined determination value. The convergence determination is not limited to the one based on the previous formula, and various methods can be adopted.

  In step SC5, when the convergence is YES, the process proceeds to step SC6. When the convergence is NO, the process returns to step SC2. Accordingly, when the process returns to step SC2 because it has not converged, the ignition timing is further advanced by ΔIgtadd, and the above steps SC3 to SC5 are executed.

  In step SC6, the convergence value (CA2ndpcnv) of the crank angle position is calculated by the following equation. Here, the average value of the crank angle positions CA2ndp (n) to CA2ndp (n-4) for the past five times including the current value is adopted as the convergence value.

CA2ndpcnv = (CA2ndp (n) + CA2ndp (n-1) + CA2ndp (n-2) + CA2ndp (n-3) + CA2ndp (n-4)) / 5
Further, the compression top dead center (CAtdc) is calculated based on the calculated convergence value (CA2ndpcnv) (CAtdc = CA2ndpcnv + CAtdcofs, where CAtdcofs is a function of the engine speed ne and the charging efficiency ce).

  In step SC7, the CAtdc calculated in step SC6 is stored in the PCM 30 as a monitor value for compression top dead center.

  In the control procedure according to the second embodiment, when the compression top dead center is monitored, the ignition timing is advanced by a predetermined value. For example, when the ignition timing is greatly advanced at once, drivability is reduced. There is an advantage that such a possibility can be eliminated.

  Therefore, according to the flow of FIG. 8, the ignition timing changing means 41 and the determining means 42 are configured, and the filling amount correcting means 43 is configured.

(Correction of ignition timing and valve timing)
Next, the procedure for correcting the ignition timing and the valve timing by VVT using the result of monitoring the compression top dead center as described above will be described with reference to the flowchart shown in FIG.

  If the execution of correction of the ignition timing and the valve timing is instructed in step SD1 after the start shown in the figure, the monitor value (CAtdc) of the compression top dead center is stored in the PCM 30 in one of the aforementioned flows in the subsequent step SD2. It is determined whether or not it has been done. When YES is stored, the process proceeds to step SD3. When NO is stored, the process proceeds to step SD6 and the compression top dead center is monitored by the flow of FIG. 5 or FIG. Return to step SD2.

  In step SD3, the compression top dead center monitor value (CAtdc) stored in the PCM 30 is read, and the compression top dead center TDC (the compression top dead center recognized in the PCM 30) obtained by the detected value of the crank angle sensor 26 is read. From the crank angle, a correction amount Δtdc is calculated (Δtdc = TDC−CAtdc).

  In the subsequent step SD4, the ignition timing Igt and the valve timing avtt are each corrected by a correction amount Δtdc (Igt = Igtrom−Δtdc, avtt = avttrom−Δtdc, where Igtrom and avttrom are control values in the PCM 30, respectively). Then, in step SD5, it is determined whether or not to continue the present control. If YES in step SD5, the process returns to step SD3. If NO in step SD5, the process ends as it is.

  In this way, by correcting the ignition timing and the valve timing based on the compression top dead center determined by the detection of the ion current, the crank angle sensor 26 detects, for example, a tolerance variation or some factor during use. Even if there is a shift in the compression top dead center, ignition timing control and valve timing control can be performed in a state in which the deviation is corrected, and the respective control timings can be optimized.

  Here, the ignition timing and the valve timing are corrected. However, the correction of the control timing of other parameters executed based on the crank angle, such as the combustion injection timing, is also determined by detecting the ion current. Can be performed based on the compression top dead center.

  Accordingly, the flow of FIG. 9 constitutes timing correction means 44 for correcting the control timing of various parameters related to combustion, which are controlled based on the crank angle, in accordance with the compression top dead center determined by the determination means 42. Yes.

  As described above, the present invention can determine the compression top dead center based on the ionic current, and thus is useful as an apparatus for detecting the crank angle of an engine mounted on, for example, an automobile.

1 is a schematic structural diagram of an engine including an engine crank angle detection device according to an embodiment of the present invention. It is explanatory drawing which shows the structure of an ion current detection circuit typically. It is explanatory drawing which shows typically the waveform of the ion current detected by the ion current detection circuit. It is a graph of the simulation result which shows the relationship between an ignition timing, the maximum combustion temperature position, and the maximum combustion pressure position. It is a flowchart which shows the monitoring procedure of a compression top dead center. It is a flowchart which shows the procedure which detects the crank angle which the peak of the peak of the latter half of ion current generate | occur | produces. FIG. 7 is an explanatory diagram for explaining a target range when detecting a crank angle at which the peak of the latter half of the ion current occurs in the flowchart of FIG. 6. It is a flowchart which shows the monitoring procedure of a compression top dead center different from the flow shown in FIG. It is a flowchart which shows the correction | amendment procedure of an ignition timing and a valve timing.

Explanation of symbols

1 Engine 33 Ion current detection circuit (ion current detection means)
41 ignition timing changing means 42 determining means 43 filling amount correcting means 44 timing correcting means

Claims (3)

An ignition plug that is disposed facing the combustion chamber of the engine and performs ignition discharge at a predetermined timing;
An ion current detection means for detecting an ion current generated in the combustion chamber after the ignition discharge of the spark plug and having a waveform characteristic including a first peak and a second peak with respect to a crank angle;
Ignition timing changing means for changing the ignition timing of the ignition plug to the advance side so that the peak of the latter half of the ion current waveform is near the compression top dead center;
When the ignition timing is changed to the advance side by the ignition timing changing means, the peak of the latter half of the ion current is detected by the ion current detecting means, and based on the crank angle position where the peak occurs. Determining means for determining compression top dead center ,
The ignition timing changing means is an engine crank angle detection device that changes the ignition timing to an advance side when the operating state of the engine is in a low rotation range . The crank angle detection device according to claim 1,
A crank angle detection device further comprising a filling amount correcting means for correcting the intake filling amount according to the change amount when the ignition timing is changed to the advance side by the ignition timing changing means. The crank angle detection device according to claim 1,
A crank angle detection device further comprising timing correction means for correcting the control timing of various parameters controlled based on the crank angle in accordance with the compression top dead center determined by the determination means.

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