JP4408550B2 - RUNNING STATE DETECTION DEVICE FOR INTERNAL COMBUSTION ENGINE - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In an internal combustion engine that burns a fuel mixture by spark discharge of a spark plug, the present invention detects a combustion state, an operating state, and the like of the fuel mixture based on an ionic current that flows due to ions generated by the combustion of the fuel mixture. The present invention relates to an operating state detection device for an internal combustion engine.
[0002]
[Prior art]
Conventionally, in order to detect the combustion state (misfire, knocking, etc.) of a fuel mixture in an internal combustion engine, an ionic current that flows due to ions generated in the vicinity of the spark plug electrode after the spark discharge of the ignition plug of the internal combustion engine is used. Technology is known. It is also possible to detect various operating states of the internal combustion engine (air-fuel ratio, air-fuel ratio lean limit, exhaust recirculation limit, etc.) in addition to the combustion state of the fuel mixture in the internal-combustion engine by using an ionic current. Is possible.
[0003]
That is, in the cylinder of the internal combustion engine, ions are generated during combustion (flame propagation) after spark discharge by the spark plug, and the resistance value between the electrodes of the spark plug changes according to the amount of the generated ion. The amount of ions generated varies depending on the combustion state of the fuel mixture and the operating state of the internal combustion engine. For this reason, after applying a high voltage for ignition to the spark plug (that is, after spark discharge of the spark plug), a voltage is applied from the outside to the spark plug, and the ionic current flowing thereby is detected, whereby the spark plug is detected. It is possible to detect a change in the resistance value between the electrodes (that is, a change in the combustion state or operating state of the fuel mixture).
[0004]
By the way, as a determination processing device that determines the operating state of the internal combustion engine based on the ionic current as described above, for example, there is a device that uses a voltage signal that changes in accordance with the ionic current. There is an upper voltage limit that can be entered. In other words, the determination processing device determines the magnitude of the input voltage signal, but cannot determine the magnitude of a voltage that is higher than the drive voltage supplied to drive the determination processing device. For example, since the determination processing device provided in the vehicle internal combustion engine operates using the output voltage from the in-vehicle power supply device (battery) as the driving voltage, the determination processing is performed when a voltage larger than the output voltage of the battery is input. The apparatus cannot operate normally, and in some cases, the determination processing apparatus may be destroyed. For this reason, in the determination processing device, a voltage value equal to the drive voltage is a voltage upper limit value that can be input as a voltage signal.
[0005]
Therefore, in order to control the input signal to the determination processing device to be equal to or lower than the voltage upper limit value, for example, an ion current detection device described in JP-A-10-318114 has been proposed. In this ion current detection device, the voltage value of the voltage signal corresponding to the ion current is controlled by dividing the resistance, and the voltage value of the voltage signal is controlled to be equal to or lower than the voltage upper limit value. Is suppressed.
[0006]
[Problems to be solved by the invention]
However, in the ion current detection device described in the above publication, a minute signal component (for example, knocking (knock)) superimposed on the ion current waveform is accompanied by controlling the voltage signal input to the determination processing device to be equal to or lower than the voltage upper limit value. There arises a problem that the signal detection accuracy of the frequency component is lowered.
[0007]
In other words, controlling the voltage value of the voltage signal to be equal to or lower than the voltage upper limit value reduces the ionic current waveform as a whole in the amplitude direction, and as a result, about the minute signal component superimposed on the ionic current waveform. Is also reduced in the amplitude direction. Since the amplitude of such a small signal component becomes small, it becomes difficult to accurately detect a change in the small signal component, the signal detection accuracy is lowered, and the determination of the combustion state of the internal combustion engine and the like is accurate. Difficult to do.
[0008]
The present invention has been made in view of these problems, and in detecting the operating state of the internal combustion engine based on the ion current, it is possible to accurately determine the operating state of the internal combustion engine while suppressing a decrease in the signal detection accuracy of the ion current. An object of the present invention is to provide an operating state detection device for an internal combustion engine.
[0009]
[Means for Solving the Problems]
  In order to achieve the above object, an invention according to claim 1 includes a primary winding and a secondary winding, an ignition coil for generating a high voltage for ignition at both ends of the secondary winding, and a secondary winding. A spark plug that is connected in series to the winding and generates a discharge between the center electrode and the ground electrode when a high voltage for ignition is applied, and is stored after being charged with the high voltage for ignition. A capacitor element that applies a voltage between the center electrode and the ground electrode by discharging the generated charge; a resistor circuit configured by the resistor element and connected in series to the capacitor element; and the capacitor element and the resistor circuit And a zener diode that is connected in parallel to the series circuit and limits the voltage across the capacitive element during charging to a certain value or less, and ions generated between the center electrode and the ground electrode by application of voltage by the capacitive element Current An ionic current detection means that outputs the ionic current, and a determination means that determines the operating state of the internal combustion engine based on the ionic current detected by the ionic current detection means, and detects the operating state of the internal combustion engine based on the ionic current An internal combustion engine operating state detecting device, wherein the ion current detecting means outputs a voltage across the resistor circuit as a first ion current detection signal, and between one end of the resistor circuit and a middle point inside the resistor circuit. Is output as a second ion current detection signal,The resistance value between both ends of the resistance circuit provided in the ion current detection means is such that the maximum voltage value of the voltage output as the first ion current detection signal is larger than the supply voltage value from the constant voltage power supply. Is set,Specific component extraction means for extracting a specific frequency component from the first ion current detection signal and outputting the extracted signal component as a specific ion current detection signal is provided. The determination means includes the second ion current detection signal and the specific ion. The operating state of the internal combustion engine is determined based on the current detection signal.
[0010]
That is, in the operating state detecting device for an internal combustion engine of the present invention (Claim 1), when detecting the operating state of the internal combustion engine based on the ionic current, the ionic current detecting signals (the first ionic current detecting signal and the second ionic current detecting signal having different amplitudes) are detected. Ion current detection signal) is used.
Since the first ion current detection signal is output as a voltage across the entire resistance circuit, it is a signal having a large amplitude of a signal waveform generated when the ion current flows, and is based on a minute signal superimposed on the ion current. The fluctuation easily appears as the waveform of the first ion current detection signal. For this reason, when the specific component extraction unit extracts the specific frequency component from the ion current waveform, the specific frequency component can be accurately extracted by using the first ion current detection signal.
[0011]
Further, since the specific ion current detection signal output from the specific component extraction means is a signal obtained by extracting a specific frequency component in the first ion current detection signal, the voltage range in which the specific ion current detection signal fluctuates is One ion current detection signal is in a narrower range than the voltage range in which it fluctuates.
[0012]
For this reason, even when the maximum voltage value of the first ion current detection signal exceeds the voltage upper limit value that can be input to the determination means, the specific ion current detection signal rarely exceeds the voltage upper limit value that can be input to the determination means.The
  In particular, in the operating state detection apparatus for an internal combustion engine of the present invention, the ion current detection is performed so that the maximum voltage value of the voltage output as the first ion current detection signal is larger than the supply voltage value from the constant voltage power supply. A resistance value between both ends of the resistance circuit provided in the means is set.
  As a result, the first ion current detection signal has at least an amplitude larger than the ion current detection signal set so that the entire waveform of the ion current can be input to the determination means, and a minute signal component is made a more accurate waveform. Can be represented. By using such a first ion current detection signal, a specific ion current detection signal that is a minute signal component included in the ion current detection signal can be detected satisfactorily.
Therefore, according to the internal combustion engine operating state detection device of the present invention, a minute signal component superimposed on the ion current waveform can be detected well, and the operating state detection accuracy of the internal combustion engine can be improved. .
Note that by further increasing the number of midpoints in the resistor circuit, more ion current detection signals in different voltage ranges (voltage ranges) can be generated, and detection accuracy can be further improved.
[0013]
Furthermore, since the second ion current detection signal is output as a voltage between one end and the middle point in the resistor circuit, the waveform amplitude when the ion current is generated is smaller than that of the first ion current detection signal. Become. For this reason, by using the second ion current detection signal, the voltage range required for detecting the entire waveform of the ion current is set to a narrower range than when the first ion current detection signal is used. Can do.
[0014]
From these, the determination means can detect the entire change of the ion current waveform from the second ion current detection signal by using the second ion current detection signal and the specific ion current detection signal, and the specific ion A minute signal change in the ion current waveform can be detected from the current detection signal. That is, the determination means can detect in detail the change in the ion current waveform ranging from the overall change to the minute change by inputting the second ion current detection signal and the specific ion current detection signal. As a result, the determination means can satisfactorily determine the operating state of the internal combustion engine based on the ion current detected with high accuracy.
[0015]
Therefore, according to the operation state detection apparatus for an internal combustion engine of the present invention (claim 1), the ion current waveform can be detected in detail without the ion current detection signal exceeding the voltage upper limit value that can be input to the determination means. This makes it possible to better detect the operating state of the internal combustion engine.
[0016]
When determining the operating state of the internal combustion engine by the determining means, as described in claim 2, the determining means performs misfire determination based on the second ion current detection signal, and based on the specific ion current detection signal. A knocking determination may be performed.
That is, the misfire determination is to determine whether or not the fuel mixture is normally burned, and can be determined based on whether or not ions are generated. In order to determine whether or not ions are generated, it is necessary to detect an overall change in the ion current waveform. Therefore, by using the second ion current detection signal, the overall change in the ion current waveform can be detected satisfactorily, and misfire determination can be performed with high accuracy.
[0017]
The knocking determination is made based on whether or not a vibration component having a specific frequency generated by knocking is superimposed on the ion current detection signal. However, since the vibration component due to knocking is a minute signal, ions having a small amplitude are used. Detection is relatively difficult from the current detection signal. On the other hand, since the first ion current detection signal has a large amplitude, fluctuation due to a minute signal is likely to appear in the waveform, and thus the frequency component corresponding to knocking is likely to appear in the waveform. And if a specific component extraction means extracts the frequency component corresponding to knocking from a 1st ion current detection signal, and outputs it as a specific ion current detection signal, the vibration component by knocking can be detected favorably. Therefore, by using the specific ion current detection signal, the vibration component generated by knocking can be detected well, and knocking determination can be performed with high accuracy.
[0018]
The determination means does not determine the operating state of different types of internal combustion engines based on the second ion current detection signal and the specific ion current detection signal, but rather the second ion current detection signal and the specific ion current detection signal. Both may be used to determine one item in the operating state of the internal combustion engine. In this way, it is possible to more accurately determine the operating state of the internal combustion engine by determining one item in the operating state of the internal combustion engine based on both the overall change and minute change of the ionic current. .
[0019]
By the way, the second ion current detection signal is a signal representing the magnitude of the ion current as a voltage value, and can be taken by the resistance value between one end and the middle point in the resistance circuit. The maximum value is determined. The determination means is generally realized by a microcomputer or an electronic circuit, etc., but these microcomputers or electronic circuits have a voltage upper limit value that can be input as a voltage signal in order to maintain normal operation. Exists.
[0020]
Therefore, in order to reliably detect the entire ion current waveform in the determination means, the maximum voltage value of the voltage output as the second ion current detection signal can be input to the determination means as described in claim 3. Each resistance value from the middle point to both ends in the resistance circuit provided in the ionic current detection means may be set so as to be equal to or less than the upper limit voltage. In other words, the ratio of each resistance value from the middle point to both ends in the resistor circuit is set so that the maximum voltage value generated between one end and the middle point of the resistor circuit is less than or equal to the upper limit voltage that can be input to the judgment means. To do.
[0021]
As a result, the voltage value as the second ion current detection signal does not become larger than the voltage upper limit value that can be input to the determination means, the operation of the determination means can be maintained normally, and the waveform of the ion current can be maintained. It becomes possible to detect the whole.
Therefore, according to the operating state detection device for an internal combustion engine of the present invention (Claim 3), the entire ion current waveform can be reliably detected, and the detection accuracy of the operating state of the internal combustion engine can be improved.
[0022]
  In general, a voltage lower than the drive voltage for driving a microcomputer or an electronic circuit is set as the voltage upper limit value.The
[0025]
By the way, as one of the factors that affect the operating state of the internal combustion engine, there is smoldering pollution caused by carbon or the like adhering to an insulator (insulator portion) around the center electrode of the spark plug. The ionic current waveform is also affected by smoldering contamination, but the ionic current waveform is more affected by the state of ion generation than the presence or absence of smoldering contamination, so there is a risk that the detection accuracy of smoldering contamination will be lowered.
[0026]
  In order to detect smoldering fouling of the spark plug in the above-described internal combustion engine operating state detection device, a claim is provided.4A discharge current detecting means for detecting a current flowing through the Zener diode during a discharge generated between the center electrode and the ground electrode by applying a high voltage for ignition, and a current detected by the discharge current detecting means And smolder determining means for performing smolder determination.
[0027]
In other words, the discharge current (secondary current) that flows between the electrodes of the spark plug at the time of discharge that occurs between the center electrode and the ground electrode due to the application of the high voltage for ignition is spark discharge (hereinafter referred to as the following spark discharge gap). Different waveforms are shown in the case of normal discharge) and in the case of so-called “backward discharge” in which spark discharge occurs through carbon attached to the insulator surface. That is, during normal discharge and during deep discharge, the resistance value of the discharge path varies depending on the presence or absence of carbon, so the discharge current shows a different value.
[0028]
For this reason, by using the current at the time of spark discharge detected by the discharge current detecting means, it is possible to determine whether the discharge is normal discharge or deep discharge, and in turn, it is possible to determine the presence or absence of smoldering contamination. It becomes possible.
As one of the methods for determining smoldering based on current, the current flowing during the spark discharge period is integrated between the electrodes of the spark plug, and the comparison result between the integrated value of the current and a predetermined integration determination reference value is obtained. There is a method for determining the presence or absence of smoldering contamination using the. For example, the discharge current flowing during the spark discharge occurrence period is integrated, and it is determined whether or not this discharge current integrated value is larger than a predetermined integration determination reference value for distinguishing between normal discharge and deepening, and the integrated value Is determined to be smoldering fouling, assuming that a jump occurs when the value is less than or equal to the integral determination reference value.
[0029]
As another method, a current detection time during which the current value of the current during the discharge period is equal to or greater than a predetermined detection reference value is calculated, and a comparison result between the current detection time and a predetermined detection time determination reference value A method for determining the presence or absence of smoldering stain using For example, it calculates a current detection time when the current flowing during discharge is equal to or greater than a detection reference value, and determines whether or not the current detection time is greater than a predetermined detection time determination reference value for distinguishing between normal discharge and skipping. When the current detection time is less than or equal to the detection time determination reference value, it is determined that there is smoldering contamination, assuming that a jump occurs.
[0030]
In addition, the method for performing the smoldering determination by calculating the integrated value of the current flowing at the time of discharge or the integrated value of the current detection time in this way is compared with the method of performing the smoldering determination using the instantaneous value of the current flowing at the time of discharging, The influence of external noise that occurs instantaneously can be suppressed.
[0031]
  Therefore, the claim4According to the internal combustion engine operating state detection device described in 1), it is possible to accurately determine the presence or absence of smoldering contamination, which is one of the factors affecting the operating state of the internal combustion engine.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
First, FIG. 1 is an electric circuit diagram showing the configuration of an internal combustion engine operating state detection device that detects an internal combustion engine operating state based on ion current. Note that the internal combustion engine operating state detection device described in the present embodiment can be applied to an internal combustion engine having a plurality of cylinders. However, in FIG. It is described.
[0033]
As shown in FIG. 1, the internal combustion engine operating state detection device 1 of the present embodiment includes a DC power supply (battery) 11 that generates a DC constant voltage (for example, a voltage of 12 [V]), a primary winding L1, and two An ignition coil 13 having a secondary winding L2, a main control transistor 15 composed of an npn-type power transistor connected in series with the primary winding L1, and a central electrode 17a by forming a closed loop together with the secondary winding L2. An ignition plug 17 that generates a spark discharge with respect to the ground electrode 17b, an ion current that is provided on a closed loop including the secondary winding L2 and the ignition plug 17 and that flows due to ions generated by the combustion of the fuel mixture is detected. An ionic current detection circuit 29 for extracting, a band pass filter (BPF) 41 for extracting and outputting a specific frequency component in the input signal, and the sign of the input signal are inverted An inverting amplifier circuit 43 that outputs a signal, a determination circuit 45 that determines the operating state of the internal combustion engine based on signals from the bandpass filter 41 and the inverting amplifier circuit 43, and an ignition command signal IG to the main control transistor 15 And an electronic control unit (hereinafter referred to as an ECU) 21 to which the knocking detection signal Sk and the misfire detection signal Sm are input from the determination circuit 45.
[0034]
The primary winding L1 of the ignition coil 13 has one end connected to the positive electrode of the DC power supply device 11 and the other end connected to the collector of the main control transistor 15. The secondary winding L <b> 2 has one end connected to the center electrode 17 a of the spark plug 17 and the other end connected to the ion current detection circuit 29. Furthermore, the ground electrode 17 b of the spark plug 17 is grounded to the ground having the same potential as the negative electrode of the DC power supply device 11. The base of the main control transistor 15 is connected to the output terminal of the ignition command signal IG in the ECU 21, and the emitter is grounded to the ground having the same potential as the negative electrode of the DC power supply device 11.
[0035]
Therefore, when the ignition command signal IG input to the base of the main control transistor 15 is at a low level (generally a ground potential), the base current does not flow through the main control transistor 15, and the main control transistor 15 In the off state, no current flows through the primary winding L1 through the main control transistor 15. When the ignition command signal IG is at a high level (for example, the supply voltage 5 [V] from the constant voltage power supply), the main control transistor 15 is turned on, and the ignition coil is connected to the ignition coil from the positive side of the DC power supply 11. An energization path of the primary winding L1 passing through the primary winding L1 of 13 through the main control transistor 15 to the negative electrode side of the DC power supply device 11 is formed, and the primary current i1 flows through the primary winding L1.
[0036]
Here, the on state of the main control transistor 15 represents a state in which the collector and the emitter of the main control transistor 15 are conductive (short-circuited state), and the off state represents the state of the main control transistor 15. This represents a state where the collector and emitter are not conducting (open state).
[0037]
Therefore, when the ignition command signal IG goes low when the ignition command signal IG goes low when the primary current i1 flows through the primary winding L1 due to the ignition command signal IG being high level, the primary winding L1 is turned off. The primary current i1 is stopped (cut off). Then, the magnetic flux density of the ignition coil 13 changes abruptly and a high voltage for ignition is generated in the secondary winding L2. This high voltage for ignition is applied to the spark plug 17, and the electrodes 17a-17b of the spark plug 17 are applied. A spark discharge occurs in the meantime.
[0038]
The ignition coil 13 generates a negative ignition high voltage lower than the ground potential on the center electrode 17a side of the spark plug 17 when the primary current i1 in the primary winding L1 is cut off by the main control transistor 15. It is configured. Thereby, the secondary current i2 flowing through the secondary winding L2 due to the spark discharge at the spark plug 17 passes from the center electrode 17a of the spark plug 17 to the ion current detection circuit 29 through the secondary winding L2. Flowing into.
[0039]
Next, the ion current detection circuit 29 will be described.
As shown in FIG. 1, the ionic current detection circuit 29 includes a resistor 31 having one end grounded to the ground having the same potential as the negative electrode of the DC power supply device 11, a resistor 33 connected in series to the resistor 31, and a resistor in the resistor 33. A capacitor 35 having one end connected to an end opposite to the 31 side, and a Zener diode 37 having an anode connected to the ground and a cathode connected to the end opposite to the connection side of the capacitor 35 to the resistor 33. And a diode 39 whose cathode is grounded and whose anode is connected to the connection point between the resistor 33 and the capacitor 35.
[0040]
In the ion current detection circuit 29, the diode 39 is connected in parallel to the series circuit including the resistor 31 and the resistor 33, and the Zener diode 37 is connected to the resistor 31, the resistor 33, and the capacitor 35. Is connected in parallel to the series circuit.
[0041]
Further, in the ion current detection circuit 29 configured as described above, the connection point between the capacitor 35 and the Zener diode 37 is connected to the secondary winding L2, and the connection point between the resistor 33 and the capacitor 35 is the band pass filter. 41, and a connection point between the resistor 31 and the resistor 33 is connected to the inverting amplifier circuit 43.
[0042]
In the ion current detection circuit 29, immediately after the ignition high voltage is generated in the secondary winding L2 and the spark discharge is generated, the secondary current i2 flowing from the secondary winding L2 is converted into the capacitor 35 and the diode 39. It flows through a route that passes through. When the secondary current i2 flows, the capacitor 35 is charged and the voltage across the capacitor 35 rises. The voltage across the series circuit composed of the capacitor 35 and the diode 39 is equal to the Zener voltage Vz of the Zener diode 37. Then, the secondary current i2 flows through the Zener diode 37. Therefore, the capacitor 35 is charged with a voltage Vc (= Vz−Vf) that is smaller than the Zener voltage Vz of the Zener diode 37 by the forward voltage Vf of the diode 39.
[0043]
After that, when the ignition high voltage in the secondary winding L2 is reduced and the spark discharge is finished, and the secondary current i2 due to the ignition high voltage stops flowing, the voltage charged in the capacitor 35 causes the center of the spark plug 17 to When an ionic current flows between the electrode 17a and the ground electrode 17b, a current Iio flows in the order of the capacitor 35, the secondary winding L2, the spark plug 17, the resistor 31, and the resistor 33. At this time, the voltage between both ends of the resistor 31 and the resistor 33 becomes a value proportional to the magnitude of the current Iio. The potential V2 at the connection point between the resistor 33 and the capacitor 35 is output to the bandpass filter 41 as the first ion current detection signal Si1, and the potential V1 at the connection point between the resistor 31 and the resistor 33 is the second ion current. The detection signal Si2 is output to the inverting amplifier circuit 43.
[0044]
The band-pass filter 41 extracts a predetermined frequency component (for example, 3 [kHz] to 20 [kHz]) corresponding to the knock in the first ion current detection signal Si1 from the ion current detection circuit 29 to extract the third ion. The current detection signal Si3 is output.
[0045]
Note that the resistor 31 and the resistor 33 have a maximum value of the voltage (potential V2) generated at both ends of the series circuit of the resistor 31 and the resistor 33 when the capacitor 35 is discharged. V]) and the maximum voltage of the third ion current detection signal Si3 is less than or equal to the supply voltage from the constant voltage power source, and the maximum value of the voltage (potential V1) generated across the resistor 31 is the constant voltage power source. Each resistance value is set so as to be equal to or lower than the supply voltage from. That is, the first ion current detection signal Si1 is output as a voltage signal whose maximum voltage is higher than the supply voltage from the constant voltage power supply, and the second ion current detection signal Si2 is the supply voltage from the constant voltage power supply. The third ion current detection signal Si3 is output as a voltage signal whose maximum voltage is equal to or lower than the supply voltage from the constant voltage power source.
[0046]
The inverting amplifier circuit 43 outputs a signal obtained by inverting the sign of the second ion current detection signal Si2 from the ion current detection circuit 29 as the fourth ion current detection signal Si4. In the inverting amplifier circuit 43 of this embodiment, the signal is not amplified, and the amplitude of the fourth ion current detection signal Si4 is equal to the amplitude of the second ion current detection signal Si2.
[0047]
Next, the determination circuit 45 will be described.
As shown in FIG. 1, the determination circuit 45 includes a knock determination circuit 47 that performs knock determination based on the third ion current detection signal Si3 output from the bandpass filter 41, and a fourth ion output from the inverting amplifier circuit 43. A misfire determination circuit 49 that performs misfire determination based on the current detection signal Si4. The determination circuit 45 is constituted by a CPU (hereinafter also referred to as a microcomputer) having a CPU, a RAM, a ROM, and an input / output unit as main parts. Further, since the determination circuit 45 operates using the supply voltage (5 [V]) from the constant voltage power supply as a drive voltage, the upper limit voltage value of a signal that can be input to the determination circuit 45 is 5 [V]. .
[0048]
The knock determination circuit 47 receives the first window signal W1 from the ECU 21 in addition to the third ion current detection signal Si3, and the first window signal W1 is at a high level (for example, supplied from a constant voltage power source). The knocking determination process is performed based on the waveform of the third ion current detection signal Si3 input during the period of voltage 5 [V]). In response to the determination result of the knock determination process, knock determination circuit 47 outputs a knock detection signal Sk to ECU 21.
[0049]
Here, the processing content of the knocking determination process executed by the knock determination circuit 47 will be described. The knocking determination process starts when the first window signal W1 changes from the low level to the high level.
When the knocking determination process is started, first, the third ion current detection signal Si3 from the bandpass filter 41 is compared with a preset specified value voltage Vs. Thereafter, during the period until the first window signal W1 changes from the high level to the low level, the time during which the third ion current detection signal Si3 is equal to or higher than the specified value voltage Vs is integrated. Subsequently, it is determined whether or not the accumulated time Ts is larger than a preset determination reference time Tk for knocking determination, and knocking occurs when the accumulated time Ts is larger than the determination reference time Tk. It is determined that Further, when the accumulated time Ts is equal to or shorter than the determination reference time Tk, it is determined that knocking has not occurred. When it is determined that knocking has occurred, the knocking detection signal Sk is output as a high level, and when it is determined that knocking has not occurred, the knocking detection signal Sk is output as a low level.
[0050]
As described above, when the knocking determination (knock determination) is performed based on the third ion current detection signal Si3 and the knocking detection signal Sk corresponding to the determination result is output to the ECU 21, the knocking determination process ends.
Note that the ECU 21 sets a period (start timing and end timing) suitable for knocking determination based on the ignition timing. During this period, the ECU 21 outputs the first window signal W1 as a high level, and during other periods. Outputs the first window signal W1 as a low level.
[0051]
Next, in addition to the fourth ion current detection signal Si4, the misfire determination circuit 49 receives the second window signal W2 from the ECU 21, and the second window signal W2 is at a high level (for example, from a constant voltage power source). The misfire determination is performed based on the waveform of the fourth ion current detection signal Si4 input during the period of the supply voltage 5 [V]). The misfire determination circuit 49 outputs a misfire detection signal Sm to the ECU 21 in accordance with the determination result of the misfire determination process.
[0052]
Here, the processing content of the misfire determination process executed by the misfire determination circuit 49 will be described. Note that the misfire determination process starts when the second window signal W2 changes from the low level to the high level.
When the misfire determination process is started, first, the fourth ion current detection signal Si4 from the inverting amplifier circuit 43 is compared with a preset misfire determination reference voltage Vm for misfire determination. Thereafter, until the second window signal W2 changes from the high level to the low level, it is determined whether or not the fourth ion current detection signal Si4 is equal to or higher than the misfire determination reference voltage Vm, and the second window signal W2 is An integrated time during which the fourth ion current detection signal Si4 is equal to or higher than the misfire determination reference voltage Vm during the high level period is calculated. Subsequently, it is determined whether or not the calculated integration time is equal to or less than a predetermined time set for misfire determination. When the integration time is equal to or less than a predetermined time, it is determined that misfire has occurred. When it is determined that misfire has occurred, the misfire detection signal Sm is output as a high level, and when it is determined that normal combustion is performed, the misfire detection signal Sm is output as a low level.
[0053]
As described above, when the misfire determination is performed based on the fourth ion current detection signal Si4 and the misfire detection signal Sm corresponding to the determination result is output to the ECU 21, the misfire determination process ends.
Note that the ECU 21 sets a period (start timing and end timing) suitable for misfire determination based on the ignition timing, and outputs the second window signal W2 as a high level during this period, and during other periods. Outputs the second window signal W2 as a low level.
[0054]
Here, FIG. 2 shows a time chart representing the states of the ignition command signal IG, the first ion current detection signal Si1, and the third ion current detection signal Si3 in the operating state detection device for the internal combustion engine of the present embodiment.
In FIG. 2, when the current Iio flows in the direction from the resistor 33 toward the capacitor 35 in the circuit diagram shown in FIG. 1, the waveform of the first ion current detection signal Si1 is expressed as a negative value. For this reason, it is shown that the larger the value of the first ion current detection signal Si1 is, the larger the current Iio flows (as it extends downward in FIG. 2). Although not shown in FIG. 2, the second ion current detection signal Si2 is a waveform obtained by reducing the waveform of the first ion current detection signal Si1 in the amplitude direction.
[0055]
When the ignition command signal IG changes from a low level (generally a ground potential) to a high level (for example, supply voltage 5 [V] from a constant voltage power supply) at time t1 shown in FIG. The ON state is entered, and energization of the primary current i1 (not shown in FIG. 2) is started. When the ignition command signal IG changes from the high level to the low level at time t2, the primary current i1 is cut off, a high voltage for ignition is generated in the secondary winding L2, and a spark discharge is generated between the electrodes of the spark plug 17. appear.
[0056]
After the spark discharge occurs at time t2, when the spark discharge ends at time t3 when the duration of the spark discharge has elapsed, the discharge of the capacitor 35 is started. Then, after the first ion current detection signal Si1 fluctuates (oscillates) in the negative region immediately after the start of discharge, the voltage value once approaches 0 [V], and after time t4, the ion current gradually increases. The voltage value changes in an increasing direction. Then, when a little has elapsed from time t5, the first ion current detection signal Si1 shows a peak value, and then gradually approaches 0 [V].
[0057]
Note that the large vibration of the first ion current detection signal Si1 immediately after time t3 is a noise component generated with the stop of the ignition high voltage, and the actual ion current is after the vibration has converged (time t4). The current value gradually increases after that, reaches a peak value at a point slightly after time t5, and then gradually decreases.
[0058]
In addition, the third ion current detection signal Si3 output from the bandpass filter 41 shows a relatively large value during the period from time t5 to time t6. Such a waveform shows knocking. It is because it is doing. Further, even during the period from time t3 to time t4, that is, immediately after the end of the spark discharge, the third ion current detection signal Si3 shows a large value, but as described above, it occurred due to the stop of the ignition high voltage. It is a noise component and not due to knocking.
[0059]
Therefore, in order to perform knocking determination based on the third ion current detection signal Si3, it is desirable to avoid the influence due to the stop of the ignition high voltage. Therefore, in this embodiment, from time t5 to time t6 shown in FIG. The knocking determination is performed using the third ion current detection signal Si3 corresponding to the period up to. In this embodiment, the ECU 21 sets a detection period of the third ion current detection signal Si3 used for knocking determination and notifies the knock determination circuit 47 of this detection period using the first window signal W1. .
[0060]
The knock determination circuit 47 performs the above-described knock determination process based on the third ion current detection signal Si3, and notifies the ECU 21 of the determination result using the knock detection signal Sk.
The fourth ion current detection signal Si4 has a waveform obtained by inverting the sign of the second ion current detection signal Si2 by the inverting amplifier circuit 43. The waveform of the first ion current detection signal Si1 shown in FIG. The waveform is shown by reversing and reversing positive and negative.
[0061]
The fourth ion current detection signal Si4 also includes a noise component generated by the stop of the ignition high voltage during the period from time t3 to time t4. Therefore, in order to perform misfire determination using the fourth ion current detection signal Si4, it is desirable to avoid the influence of this vibration component. Therefore, in this embodiment, from time t4 to time t6 shown in FIG. The misfire determination is performed using the fourth ion current detection signal Si4 corresponding to the period. In this embodiment, the ECU 21 sets a detection period of the fourth ion current detection signal Si4 used for misfire determination, and notifies the misfire determination circuit 49 of this detection period using the second window signal W2.
[0062]
Next, an ignition control process executed by the ECU 21 will be described.
The ECU 21 is provided to comprehensively control the spark discharge generation timing (ignition timing), fuel injection amount, engine speed, etc. of the internal combustion engine based on the operating state of the internal combustion engine. , ROM and a microcomputer (hereinafter, also referred to as a microcomputer) whose main part is an input / output part. In addition to the ignition control process described below, the ECU 21 detects the operating state of each part of the engine, such as the intake air amount (intake pipe pressure), rotation speed, throttle opening, cooling water temperature, intake air temperature, etc. of the internal combustion engine. Operation state detection processing, fuel control processing for supplying fuel into the intake pipe at the fuel injection timing, and the like are performed.
[0063]
The ignition control processing is performed after the internal combustion engine is started, for example, based on a signal from a crank angle sensor that detects the rotation angle (crank angle) of the internal combustion engine, the internal combustion engine performs intake, compression, combustion, and exhaust 1 Run once per combustion cycle.
Then, when the internal combustion engine is started and the ignition control process is started, first, the operation state of the internal combustion engine detected by the operation state detection process that is separately executed is read and set in advance based on the read operation state. The ignition timing suitable for the operating state of the internal combustion engine is set using the map or calculation formula. The operation state read at this time includes the operation state notified from the determination circuit 45 by the knocking detection signal Sk and the misfire detection signal Sm.
[0064]
Note that the map or calculation formula for setting the ignition timing is, for example, to set the ignition timing according to the operating state of the internal combustion engine using the operating state such as the engine speed of the internal combustion engine and the engine load as parameters. It is configured. If knocking has occurred, correct the ignition timing in a direction to suppress the occurrence of knocking. If misfire has occurred, correct the ignition timing in a direction to suppress misfire. Then correct the ignition timing.
[0065]
Then, in the next process in the ignition control process, the ignition command signal IG is set at a time (time t1 in FIG. 2) earlier than the ignition timing by using the set ignition timing (time t2 in FIG. 2) as a reference. Is changed to a high level to turn on the main control transistor 15 to start energization of the primary current i1. The predetermined time here is the primary current energization time before the spark discharge, in order to generate a spark discharge that can reliably ignite the fuel even under operating conditions with poor ignitability, that is, a high ignition high voltage. In order to generate this, a time during which sufficient magnetic flux energy can be accumulated in the ignition coil is set in advance in the primary current energization time.
[0066]
In the next process in the ignition control process, the ignition command signal IG is set to low level at the ignition timing (time t2 in FIG. 2) when the primary current energization time has elapsed since the ignition command signal IG was changed to high level. As a result, the main control transistor 15 is turned off. Thus, by turning off the main control transistor 15, the primary current i1 is sharply cut off, and an ignition high voltage as an induced electromotive force is generated in the secondary winding L2, and a spark discharge is generated in the spark plug 17. Let
[0067]
Therefore, the ignition control process sets the ignition timing according to the operating state of the internal combustion engine, and changes the ignition command signal IG to a high level at an energization start timing that is earlier than the ignition timing by a predetermined primary current energization time. Energization of the primary current i1 is started (time t1 in FIG. 2). Thereafter, the ignition command signal IG is changed to a low level at the time when the primary current energization time has elapsed, that is, at the ignition timing (time t2 in FIG. 2) set according to the operating state of the internal combustion engine, and the spark plug 17 A spark discharge is generated between the electrodes and the fuel mixture is burned.
[0068]
Next, a knock detection period control process for controlling the state of the first window signal W1 will be described.
The knock detection period control processing is performed after the internal combustion engine is started, for example, based on a signal from a crank angle sensor that detects the rotation angle (crank angle) of the internal combustion engine. It is executed at a rate of once per combustion cycle.
[0069]
When the internal combustion engine is started and the knock detection period control process is started, first, the operation state of the internal combustion engine detected in the operation state detection process that is separately executed is read, and based on the read operation state in advance. The high level output period of the first window signal W1 is set using the set map or calculation formula. At this time, the start timing and end timing of the high-level output period are set as relative timings based on the ignition timing.
[0070]
The above map or calculation formula for setting the high level output period of the first window signal W1 has a period suitable for knocking determination using, for example, the operating state such as the engine rotation speed and engine load of the internal combustion engine as a parameter. The high-level output period of the first window signal W1 is set.
[0071]
Then, after the ignition timing set in the ignition control process (time t2 in FIG. 2) has elapsed, the start timing (FIG. 2) of the high-level output period of the first window signal W1 set using a map or a calculation formula. At time t5), the first window signal W1 is changed from the low level to the high level. Thereafter, at the end of the high level output period of the first window signal W1 (time t6 in FIG. 2), the first window signal W1 is changed from the high level to the low level.
[0072]
When the process of changing the first window signal W1 to the low level is finished, the knock detection period control process is finished.
As described above, the knock detection period control process changes the state of the first window signal W1, so that the knock determination circuit 47 executes the knock determination process and performs the knock determination.
[0073]
Next, a misfire detection period control process for controlling the state of the second window signal W2 will be described.
The misfire detection period control process is performed after the start of the internal combustion engine, for example, based on a signal from a crank angle sensor that detects the rotation angle (crank angle) of the internal combustion engine. It is executed at a rate of once per combustion cycle.
[0074]
When the internal combustion engine is started and the misfire detection period control process is started, first, the operation state of the internal combustion engine detected in the operation state detection process that is separately executed is read, and based on the read operation state in advance. The high level output period of the second window signal W2 is set using the set map or calculation formula. At this time, the start timing and end timing of the high-level output period are set as relative timings based on the ignition timing.
[0075]
The above map or calculation formula for setting the high level output period of the second window signal W2 is a period suitable for misfire determination, for example, with the operating state of the internal combustion engine such as the engine speed and engine load as parameters. The high-level output period of the second window signal W2 is set.
[0076]
Then, after the ignition timing set in the ignition control process (time t2 in FIG. 2) has elapsed, the start timing (FIG. 2) of the high-level output period of the second window signal W2 set using a map or a calculation formula. At time t4), the second window signal W2 is changed from the low level to the high level. Thereafter, at the end of the high-level output period of the second window signal W2 (time t6 in FIG. 2), the second window signal W2 is changed from the high level to the low level.
[0077]
When the process of changing the second window signal W2 to the low level is finished, the misfire detection period control process is finished.
As described above, the misfire detection period control process changes the state of the second window signal W2, whereby the misfire determination circuit 49 executes the misfire determination process and performs the misfire determination.
[0078]
In the internal combustion engine operating state detection device according to the present embodiment, the capacitor 35 corresponds to the capacitive element recited in the claims, and the series circuit including the resistor 31 and the resistor 33 corresponds to the resistor circuit. The connection point with the resistor 33 corresponds to the middle point of the resistor circuit, the ion current detection circuit 29 corresponds to the ion current detection means, the determination circuit 45 corresponds to the determination means, and the bandpass filter 41 serves as the specific component extraction means. The third ion current detection signal Si3 corresponds to the specific ion current detection signal.
[0079]
As described above, in the operating state detection apparatus for an internal combustion engine using the ion current of the present embodiment, two ion current detection signals having different amplitudes of the first ion current detection signal Si1 and the second ion current detection signal Si2. Is used to detect the operating state of the internal combustion engine. The first ion current detection signal Si1 is output as a potential V2 that is the sum of the voltages at both ends of the resistor 31 and the resistor 33. The second ion current detection signal Si2 is output as a potential V1 that is the voltage across the resistor 31. Is output.
[0080]
At this time, the first ion current detection signal Si1 is output as a voltage signal whose maximum voltage is higher than the supply voltage (5 [V]) from the constant voltage power supply, and the amplitude thereof is the second ion current detection signal Si2. It becomes larger than the amplitude, and a minute signal component can be detected more accurately. Therefore, when the band-pass filter 41 extracts the predetermined frequency component corresponding to the knock in the first ion current detection signal Si1 and outputs it as the third ion current detection signal Si3, the knock frequency component can be extracted well. it can.
[0081]
Since the third ion current detection signal Si3 is a signal obtained by extracting the knock frequency component in the first ion current detection signal Si1, the voltage upper limit value of the third ion current detection signal Si3 is the first ion current detection signal. It is output as a voltage signal that is lower than Si1 and whose maximum voltage is not more than the supply voltage (5 [V]) from the constant voltage power supply. As a result, the third ion current detection signal Si3 does not become a signal having a higher potential than the drive voltage of the determination circuit 45, and thus malfunction of the determination circuit 45 (specifically, the knock determination circuit 47) can be prevented.
[0082]
Furthermore, since the second ion current detection signal Si2 has a smaller amplitude than the first ion current detection signal Si1, the entire ion current waveform is detected as compared with the case where the first ion current detection signal Si1 is used. The voltage range (voltage range) required for the operation can be set to a narrow range. When misfire determination is made based on whether or not ions are generated, since it is necessary to detect the overall change in the ion current waveform, the overall change in the ion current waveform can be achieved by using the second ion current detection signal. Can be detected satisfactorily, and misfire determination can be performed with high accuracy.
[0083]
In addition, the second ion current detection signal Si2 is output as a voltage signal whose maximum voltage is equal to or lower than the supply voltage (5 [V]) from the constant voltage power supply, so that conversion processing for expanding and contracting the amplitude is not performed. The signal indicating the entire waveform of the ion current can be input to the determination circuit 45. In the present embodiment, since the second ion current detection signal Si2 is output as a negative value, the fourth ion current detection signal Si4 obtained by inverting the positive / negative using the inverting amplifier circuit is determined by the determination circuit 45 (in detail). Is input to the misfire determination circuit 49).
[0084]
Therefore, according to the operating state detection apparatus for an internal combustion engine of the present embodiment, the ion current detection signal input to the determination circuit 45 does not exceed the input voltage upper limit (5 [V]). It is possible to prevent the determination circuit 45 from malfunctioning due to an increase in the voltage value of the current detection signal. In addition, by using the first ion current detection signal (third ion current detection signal) and the second ion current detection signal (fourth ion current detection signal), from the overall change in the ion current waveform to the minute change, The change in waveform can be detected in detail, and the operating state of the internal combustion engine can be accurately determined.
[0085]
Next, as a second embodiment, an internal combustion engine operating state detection device in which a smoldering determination circuit is additionally provided in the above-described embodiment (hereinafter referred to as the first embodiment) will be described.
FIG. 3 is an electric circuit diagram showing the configuration of the internal combustion engine operating state detection apparatus as the second embodiment. As in the first embodiment, the internal combustion engine operating state detection apparatus described in the second embodiment can be applied to an internal combustion engine having a plurality of cylinders. For ease of viewing, only one cylinder is shown.
[0086]
As shown in FIG. 3, the operating state detection device 1 for the internal combustion engine of the second embodiment includes a DC power supply device (battery) 11 that generates a DC constant voltage (for example, a voltage 12 [V]), and a primary winding L1. And the secondary coil L2, the main control transistor 15 comprising an npn-type power transistor connected in series with the primary coil L1, and the secondary coil L2 to form a closed loop to form the center electrode An ionic current flowing by the ions generated by the combustion of the fuel mixture provided on the closed loop composed of the spark plug 17 that generates a spark discharge between 17a and the ground electrode 17b, the secondary winding L2 and the spark plug 17 An ion current detection circuit 29 for detection, a band pass filter (BPF) 41 that extracts and outputs a specific frequency component in the input signal, and the polarity of the input signal is inverted. An inverting amplifier circuit 43 that outputs the detected signal, a determination circuit 45 that determines the operating state of the internal combustion engine based on signals from the bandpass filter 41 and the inverting amplifier circuit 43, and an ignition command signal IG to the main control transistor 15 And an electronic control unit (hereinafter referred to as ECU) 21 to which the knocking detection signal Sk and the misfire detection signal Sm are input from the determination circuit 45.
[0087]
Note that the internal combustion engine operating state detection device 1 of the second embodiment has a configuration in which a resistor 51 and a smoldering determination circuit 55 are added to the internal combustion engine operating state detection device of the first embodiment. Therefore, in the following description, these added portions will be mainly described.
First, the resistor 51 is provided in the ion current detection circuit 29, and one end is connected to the anode of the Zener diode 37 and the other end is connected to the ground having the same potential as the negative electrode of the DC power supply device 11. The potential V3 at the connection point between the resistor 51 and the Zener diode 37 is output to the determination circuit 45 (specifically, the smolder determination circuit 55) as the discharge current detection signal S5.
[0088]
When the ignition high voltage is generated, when the voltage across the series circuit composed of the capacitor 35 and the diode 39 becomes equal to the Zener voltage Vz of the Zener diode 37 and the secondary current i2 flows through the Zener diode 37, the secondary current i2 Flows to the resistor 51, and a voltage across the resistor 51 is generated.
[0089]
In the resistor 51, the maximum value of the both-end voltage (potential V3) generated by the flow of the secondary current i2 when the ignition high voltage is generated is equal to or less than the supply voltage (5 [V]) from the constant voltage power source. Thus, the resistance value is set. That is, the discharge current detection signal S5 is output as a voltage signal whose maximum voltage is equal to or lower than the supply voltage (5 [V]) from the constant voltage power supply.
[0090]
Next, the smoldering determination circuit 55 will be described.
The smolder determination circuit 55 is provided in the determination circuit 45, and performs smolder determination based on the discharge current detection signal S5 from the ion current detection circuit 29. The smolder determination circuit 55 receives the third window signal W3 from the ECU 21 in addition to the discharge current detection signal S5, and the third window signal W3 is at a high level (for example, the supply voltage 5 from the constant voltage power source). The smoldering determination process is performed based on the waveform of the discharge current detection signal S5 input during the period [V]). The smolder determination circuit 55 outputs a smolder detection signal Sc to the ECU 21 according to the determination result of the smolder determination process.
[0091]
Here, the processing content of the smoldering determination process executed by the smoldering determination circuit 55 will be described. Note that the smoldering determination process starts when the third window signal W3 changes from the low level to the high level.
When the smoldering determination process is started, first, the integration process of the voltage value of the discharge current detection signal S5 from the smoldering determination circuit 55 is started, and then the third window signal W3 changes from the high level to the low level. Integration processing is performed until an integral value SS of the discharge current detection signal S5 is calculated. Subsequently, it is determined whether or not the integral value SS is smaller than a preset determination reference value RS for smoldering determination. When the integral value SS is smaller than the determination reference value RS, smoldering contamination occurs. It is determined that Further, when the integral value SS is equal to or greater than the determination reference value RS, it is determined that smoldering contamination has not occurred. When it is determined that smoldering contamination has occurred, the smolder detection signal Sc is output as a high level, and when it is determined that smoldering contamination has not occurred, the smolder detection signal Sc is output as a low level. To do.
[0092]
As described above, when the smolder determination is performed based on the discharge current detection signal S5 and the smolder detection signal Sc corresponding to the determination result is output to the ECU 21, the smolder determination process ends.
The ECU 21 sets a period (start timing and end timing) suitable for smoldering determination based on the ignition timing. During this period, the ECU 21 outputs the third window signal W3 as a high level, and during other periods. Outputs the third window signal W3 as a low level. In this embodiment, the ECU 21 thus sets the detection period of the discharge current detection signal S5 used for the smolder determination, and notifies the smolder determination circuit 55 of this detection period using the third window signal W3.
[0093]
Here, although not shown in FIG. 2, since the secondary current i2 is generated in the period from time t2 to time t3 in FIG. 2, it is necessary to integrate the discharge current detection signal S5 in this period. In this embodiment, the smoldering determination is performed using the integral value SS of the discharge current detection signal S5 from time t2 to time t3 shown in FIG.
[0094]
That is, the smolder determination circuit 55 performs the above-described smolder determination process based on the discharge current detection signal S5 in the detection period notified from the ECU 21, and notifies the ECU 21 of the determination result using the smolder detection signal Sc.
Next, the smoldering detection period control process executed by the ECU 21 will be described. The smoldering detection period control process is executed to control the state of the third window signal W3.
[0095]
The smoldering detection period control process is performed after the internal combustion engine is started, for example, based on a signal from a crank angle sensor that detects a rotation angle (crank angle) of the internal combustion engine. It is executed at a rate of once per combustion cycle.
[0096]
When the internal combustion engine is started and the smoldering detection period control process is started, first, the operation state of the internal combustion engine detected in the operation state detection process that is separately executed is read, and based on the read operation state in advance. The high level output period of the third window signal W3 is set using the set map or calculation formula.
[0097]
Note that the above map or calculation formula for setting the high level output period of the third window signal W3 has a period suitable for smoldering determination using, for example, the operating state such as the engine speed of the internal combustion engine and the engine load as a parameter. The high-level output period of the third window signal W3 is set. At this time, the start timing of the high-level output period is set at the same time as the ignition timing (time t2 in FIG. 2) set in the ignition control process.
[0098]
When the ignition timing set in the ignition control process, that is, the start timing (time t2 in FIG. 2) of the high-level output period of the third window signal W3 set using a map or a calculation formula, The window signal W3 is changed from the low level to the high level. Thereafter, at the end of the high level output period of the third window signal W3 (time t3 in FIG. 2), the third window signal W3 is changed from the high level to the low level.
[0099]
When the process of changing the third window signal W3 to the low level is finished, the smoldering detection period control process is finished.
As described above, the smolder detection period control process changes the state of the third window signal W3, so that the smolder determination circuit 55 executes the smolder determination process, and determines the presence or absence of smolder contamination.
[0100]
In the internal combustion engine operating state detection device of the second embodiment, the resistor 51 corresponds to the discharge current detection means in the claims, and the smolder determination circuit 55 corresponds to the smolder determination means.
As described above, in the internal combustion engine operating state detection apparatus according to the second embodiment, the potential V3 that changes according to the magnitude of the secondary current i2 is input to the smolder determination circuit 55 as the discharge current detection signal S5, and the smoldering is detected. Judgment is being made.
[0101]
Here, the discharge current (secondary current) that flows between the electrodes of the spark plug during application of a high voltage for ignition, that is, during spark discharge, differs in the resistance value of the discharge path depending on the presence or absence of carbon. The value is different from that at the time of jump discharge. For this reason, by using the discharge current at the time of spark discharge detected based on the discharge current detection signal S5, it is possible to determine whether the discharge is normal discharge or deep discharge, and in turn, the presence or absence of smoldering contamination is determined. It becomes possible to do.
[0102]
In the second embodiment, since the integral value SS of the discharge current detection signal S5 is calculated to determine the presence or absence of smoldering contamination, the method for performing smoldering determination using the instantaneous value of the discharge current detection signal S5 is used. In comparison, it is possible to suppress the influence of external noise that occurs instantaneously.
[0103]
Therefore, according to the operating state detection apparatus for an internal combustion engine of the second embodiment, it is possible to accurately determine the presence or absence of smoldering contamination, which is one of the factors affecting the operating state of the internal combustion engine.
As mentioned above, although the Example of this invention was described, this invention is not limited to the said Example, A various aspect can be taken.
[0104]
For example, in the above-described embodiment, the knock detection period control process, the misfire detection period control process, and the smolder detection period control process are executed at a rate of once per combustion cycle, but once every multiple combustion cycles. It may be executed at a rate of. Thereby, an excessive increase in the processing load in the determination circuit can be suppressed. Although it is possible to reduce the processing load by widening the execution interval of each process, on the other hand, there is a possibility that the detection accuracy may be lowered, so that the operation interval of each process may hinder the operation of the internal combustion engine. It is necessary to set within the range.
[0105]
In addition, as another method for determining smoldering in the second embodiment, a current detection time when the discharge current detection signal is equal to or greater than a predetermined detection reference value is calculated, and the current detection time is determined as normal discharge and skipping. It may be determined whether or not it is larger than a predetermined detection time determination reference value for identification. Then, when the current detection time is equal to or less than the detection time determination reference value, it is determined that there is smoldering contamination, assuming that there is a jump.
[0106]
Furthermore, the operating state detection device for the internal combustion engine may be configured so that the determination process in the determination circuit 45 is realized as an internal process in the ECU 21.
Further, as the resistor circuit that generates the second ion current detection signal Si2, a resistor circuit that is configured so that the position of the middle point can be changed and the ratio of each resistance value between the middle point and both ends can be changed is used. May be.
[Brief description of the drawings]
FIG. 1 is an electric circuit diagram showing a configuration of an internal combustion engine operating state detection apparatus according to a first embodiment.
FIG. 2 is a time chart showing the state of each part in the operating state detection device for the internal combustion engine.
FIG. 3 is an electric circuit diagram showing the configuration of an internal combustion engine operating state detection apparatus according to a second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Operating condition detection apparatus, 11 ... DC power supply device, 13 ... Ignition coil, 15 ... Main control transistor, 17 ... Spark plug, 17a ... Center electrode, 17b ... Ground electrode, 21 ... Electronic control unit (ECU), 29 DESCRIPTION OF SYMBOLS ... Ion current detection circuit, 31 ... Resistance, 33 ... Resistance, 35 ... Capacitor, 37 ... Zener diode, 39 ... Diode, 41 ... Band pass filter, 43 ... Inversion amplifier circuit, 45 ... Determination circuit, 47 ... Knock determination circuit, 49 ... Misfire determination circuit, 51 ... Resistance, 55 ... Smoldering determination circuit, L1 ... Primary winding, L2 ... Secondary winding.

Claims (4)

An ignition coil comprising a primary winding and a secondary winding, and generating a high voltage for ignition at both ends of the secondary winding;
A spark plug that is connected in series to the secondary winding and generates a discharge between the center electrode and the ground electrode when the ignition high voltage is applied, and
After being charged with the high voltage for ignition, the accumulated charge is discharged to thereby apply a voltage between the center electrode and the ground electrode, and a resistance element. A resistor circuit connected in series; and a Zener diode connected in parallel to a series circuit composed of the capacitor element and the resistor circuit, and limiting a voltage across the capacitor element during charging to a predetermined value or less. An ion current detecting means for detecting an ion current generated between the center electrode and the ground electrode by application of the voltage by an element;
Determination means for determining the operating state of the internal combustion engine based on the ion current detected by the ion current detection means;
An internal combustion engine operating state detection device for detecting an internal combustion engine operating state based on an ion current,
The ion current detection means outputs a voltage across the resistor circuit as a first ion current detection signal, and outputs a voltage between one end of the resistor circuit and a middle point in the resistor circuit as a second ion current detection signal. Output as
A resistance value between both ends of the resistance circuit provided in the ion current detection means so that a maximum voltage value of the voltage output as the first ion current detection signal is larger than a supply voltage value from a constant voltage power source. Is set,
Specific component extraction means for extracting a specific frequency component from the first ion current detection signal and outputting the extracted signal component as a specific ion current detection signal is provided,
The determination means determines an operating state of the internal combustion engine based on the second ion current detection signal and the specific ion current detection signal;
An operating state detecting device for an internal combustion engine characterized by the above. The determination means performs misfire determination based on the second ion current detection signal, and performs knocking determination based on the specific ion current detection signal;
The operating state detecting device for an internal combustion engine according to claim 1. From the middle point in the resistance circuit provided in the ion current detection means so that the maximum voltage value of the voltage output as the second ion current detection signal is equal to or less than the voltage upper limit value that can be input to the determination means. Each resistance value to both ends is set,
The operating state detecting device for an internal combustion engine according to claim 1 or 2, characterized by the above-mentioned. A discharge current detecting means for detecting a current flowing through the Zener diode at the time of discharge generated between the center electrode and the ground electrode by application of the ignition high voltage;
  Smoldering determining means for performing smoldering determination based on the current detected by the discharge current detecting means;
  The operating state detecting device for an internal combustion engine according to any one of claims 1 to 3, wherein

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