JP5956841B2 - Ion current detection device for internal combustion engine and internal combustion engine control system provided with the same - Google Patents

Description

  The present invention relates to an ion current detection device for an internal combustion engine and an internal combustion engine control system, and is particularly suitable for use when setting the gain of an ion current.

  2. Description of the Related Art In recent years, in the technical field of internal combustion engines for transportation typified by automobiles, a technique for suitably controlling an engine based on an analysis result of ion current has been studied under various requests such as improvement of fuel consumption and improvement of drivability. There are a wide variety of considerations such as misfire / combustion determination, turnover determination, knocking determination, ignition timing control, exhaust gas circulation control, and the like.

  Japanese Patent Laid-Open No. 2007-239517 introduces a combustion control device for an internal combustion engine to which such a technique is applied. The internal combustion engine includes an ignition coil and an ion current signal detection unit, and supplies a signal indicating the ion current to a combustion control device (Engine Control Unit). In the combustion control device, the input signal of the ionic current is converted into sample data, and the misfire / combustion state is determined by analyzing (information processing) the sample data.

JP 2007-239517 A

  However, it is known that the ion current significantly changes the detection value when the operating state (condition) of the internal combustion engine changes. Further, even if the control conditions of the internal combustion engine are exactly the same, the ionic current gives a variation of about 10 to 20 times to the detected value. Under such circumstances, in the AD converter circuit, taking into account large fluctuations and variations in sample data, a wide range of data can be set (first countermeasure) or by switching the input gain. It is necessary to take measures such as whether to extend the sample data input range in effect (second measure).

  Here, when the first countermeasure is adopted, since the detection range in which data can be created is expanded, the resolution of the AD conversion circuit is lowered, which is not suitable for a technique for analyzing the behavior of the internal combustion engine. On the other hand, when the second measure is adopted, the problem is how to set the gain so as not to deteriorate the quality of the sample data, while avoiding a decrease in resolution. Further, as described above, the detected value of the ionic current varies in the detected value even if the control conditions of the internal combustion engine are the same due to the property of measuring an object with low reproducibility called combustion gas. For this reason, in the second countermeasure, an advanced analysis technique for determining whether or not the variation of the sample data is caused by variation is required.

  In view of the above problems, it is a first object of the present invention to provide an ion current detection device for an internal combustion engine that optimizes the ion current gain setting. Another object of the present invention is to provide an internal combustion engine control system capable of acquiring high quality sample data.

In order to solve the above problems, the present invention has the following configuration of an ion current detection device for an internal combustion engine. That is, a current detection circuit that detects an ionic current generated according to the ignition operation of the internal combustion engine and outputs a first detection signal proportional to the current value of the ionic current, and a gain to be given to the first detection signal. A gain switching circuit that changes and outputs the signal value of the second detection signal by switching; and a gain setting circuit that outputs a gain switching command signal to the gain switching circuit;
The gain setting circuit includes a threshold setting process for setting each of an upper threshold given as a reference for lowering the gain and a lower threshold given as a reference for raising the gain; and the upper threshold or the lower threshold; And a gain setting process for setting the command signal based on both gains determined by the relationship between the sample data of the ion current and a basic gain determined by a parameter for controlling the internal combustion engine. and, it allowed to function,
The upper threshold and the lower threshold value, the rotational speed or the intake pressure or the internal combustion engine of the information about the charging efficiency, and Rukoto is set based on at least one of information.

A current detection circuit for detecting an ionic current generated in response to an ignition operation of the internal combustion engine and outputting a first detection signal proportional to a current value of the ionic current; and a gain to be given to the first detection signal. A gain switching circuit that changes and outputs the signal value of the second detection signal by switching; and a gain setting circuit that outputs a gain switching command signal to the gain switching circuit;
  The gain setting circuit includes a threshold setting process for setting each of an upper threshold given as a reference for lowering the gain and a lower threshold given as a reference for raising the gain; and the upper threshold or the lower threshold; And a gain setting process for setting the command signal based on both gains determined by the relationship between the sample data of the ion current and a basic gain determined by a parameter for controlling the internal combustion engine. And
  The threshold value setting process sets a small difference between the upper threshold value and the lower threshold value when the distribution range of the sample data is wide, and sets the difference between the upper threshold value and the lower threshold value when the distribution range of the sample data is narrow. The difference is set large.

A current detection circuit for detecting an ionic current generated in response to an ignition operation of the internal combustion engine and outputting a first detection signal proportional to a current value of the ionic current; and a gain to be given to the first detection signal. A gain switching circuit that changes and outputs the signal value of the second detection signal by switching; and a gain setting circuit that outputs a gain switching command signal to the gain switching circuit;
  The gain setting circuit includes a threshold setting process for setting each of an upper threshold given as a reference for lowering the gain and a lower threshold given as a reference for raising the gain; and the upper threshold or the lower threshold; And a gain setting process for setting the command signal based on both gains determined by the relationship between the sample data of the ion current and a basic gain determined by a parameter for controlling the internal combustion engine. And
  The integrated gain is set based on a peak value extracted from the sample data.

A current detection circuit for detecting an ionic current generated in response to an ignition operation of the internal combustion engine and outputting a first detection signal proportional to a current value of the ionic current; and a gain to be given to the first detection signal. A gain switching circuit that changes and outputs the signal value of the second detection signal by switching; and a gain setting circuit that outputs a gain switching command signal to the gain switching circuit;
  The gain setting circuit includes a threshold setting process for setting each of an upper threshold given as a reference for lowering the gain and a lower threshold given as a reference for raising the gain; and the upper threshold or the lower threshold; And a gain setting process for setting the command signal based on both gains determined by the relationship between the sample data of the ion current and a basic gain determined by a parameter for controlling the internal combustion engine. And
  The gain setting process sets the command signal based on an addition value of the integrated gain and the basic gain,
  The gain setting process reduces the rate of change of the integrated gain as the change of the added value proceeds.

Preferably, when the added value is newly calculated after the added value indicates the maximum gain, and the new added value indicates a value exceeding the maximum gain, the gain setting process corrects the integrated gain to zero. I will let you.

Preferably, when the addition value is newly calculated after the addition value indicates the minimum gain, and the new addition value indicates a value lower than the minimum gain, the gain setting process corrects the integrated gain to zero. I will let you.

A current detection circuit for detecting an ionic current generated in response to an ignition operation of the internal combustion engine and outputting a first detection signal proportional to a current value of the ionic current; and a gain to be given to the first detection signal. A gain switching circuit that changes and outputs the signal value of the second detection signal by switching; and a gain setting circuit that outputs a gain switching command signal to the gain switching circuit;
The gain setting circuit includes a threshold setting process for setting each of an upper threshold given as a reference for lowering the gain and a lower threshold given as a reference for raising the gain; and the upper threshold or the lower threshold; And a gain setting process for setting the command signal based on both gains determined by the relationship between the sample data of the ion current and a basic gain determined by a parameter for controlling the internal combustion engine. And
In the gain switching circuit, a resistance value for setting a plurality of gain values is set, and the resistance value increases the amount of change in the resistance value according to the decrease setting of the gain value.

Preferably, the parameter for controlling the internal combustion engine indicates at least one of information on the rotational speed, the intake pressure, or the charging efficiency of the internal combustion engine .

  Preferably, the integrated gain includes sample data of ion current generated in a first combustion cycle, sample data of ion current generated in a second combustion cycle corresponding to a cycle earlier than the first combustion cycle, and It is set based on a plurality of data having different inspection cycles including.

  In the present invention, the following internal combustion engine control system may be configured. That is, an internal combustion engine control device that defines an ignition timing, an ignition coil that generates a high voltage in accordance with the ignition timing, and an ion current detection device for an internal combustion engine according to any one of the above-described inventions. And

  According to the ion current detection apparatus for an internal combustion engine according to the present invention, the gain given to the detection signal of the ion current is set based on both the basic gain and the integrated gain. For this reason, the selected gain reflects information on both the control state and the combustion gas state of the internal combustion engine, and the detected value of the ionic current that is not biased to the occurrence of variation is converted into data. A reasonable gain value is set above.

  Further, according to the internal combustion engine control system according to the present invention, since it is a reasonable gain value in creating data, the internal combustion engine control device does not damage the waveform information of the ion current, and does not damage the high quality data. Is obtained, and a highly accurate analysis result that accurately captures the event is obtained. For this reason, in the internal combustion engine control system, the ignition operation or the like is defined based on a highly reliable analysis result, which can contribute to reduction in fuel consumption or improvement in operability.

The figure which shows the structure of an internal combustion engine control system. The timing chart which shows an ionic current and its sample data. The main routine of the gain setting program according to the present embodiment. A subroutine of a gain setting program according to the present embodiment. The figure which shows the sample data at the time of gain switching. The figure which shows the preferable relationship of two threshold values. The figure which shows the gain control which concerns on a prior art. The figure which shows the gain control which concerns on this Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an internal combustion engine control system according to the present embodiment. As shown in the figure, the internal combustion engine control system 10 includes an internal combustion engine control device 110, an ignition coil 120, and an ion current detection device 100 for the internal combustion engine. Hereinafter, the internal combustion engine control device 110 is referred to as the control unit 110, and the internal combustion engine ion current detection device 100 is simply referred to as the ion current detection device 100.

  The control unit 110 receives various parameters such as the rotational speed, intake pressure, vehicle speed, and the like, and defines the ignition timing of the internal combustion engine based on these information. The control unit 110 is a so-called ECU (Engine Control Unit) and incorporates an information processing circuit and an information communication circuit. The control unit 110 receives engine rotational speed information Ne, intake pressure information Pb, and ion current sample data Dt via a communication line, and stores these pieces of information in a memory circuit one by one. In such data communication, information is transmitted and received using a known communication standard such as CAN (Control Area Network), LIN (Local Area Network), or serial communication standard. Further, the intake pressure information Pb is specified by a detection signal of a pressure sensor arranged in the intake manifold, a detection signal of an air flow meter, control information of a throttle position sensor, or the like. The rotation speed information Ne is information specified by a crank position sensor, a cam position sensor, or the like.

  The control unit 110 generates and outputs an ignition signal SG by performing various analysis processes such as misfire / combustion determination, turnover determination, knocking determination, ignition timing control, and exhaust gas circulation control. Such an analysis process is performed based on ion current information (sample data Dt). When the absolute value information of the sample data Dt is required, the control unit 110 receives the gain setting information Gain from the gain setting circuit 150 and multiplies the sample data Dt by a coefficient corresponding to the selected gain value. By doing this (conversion processing), it becomes possible to recognize (create data) the actual value of the sample data Dt. Further, in the control unit, when using information (frequency information, various dimensionless amounts) that can be calculated without the absolute value information of the data, the above-described conversion process is not necessarily required.

  The ignition coil 120 includes a transformer CL including a primary coil L1 and a secondary coil L2, and a power transistor Tr, and an in-vehicle battery Vb is applied to the primary coil L1. In the ignition coil 120, the power transistor Tr is driven according to the input ignition signal SG, and the secondary coil L2 generates a high voltage. Note that an igniter may be mounted on the ignition coil 120 to correct the waveform of the ignition signal SG. Even in this case, the power transistor Tr is still driven by the ignition signal SG.

  As shown in the figure, the ion current detection device 100 includes a current detection circuit 130, a gain switching circuit 140, and a gain setting circuit 150. The signal line La connects the output terminal of the current detection circuit 130 and the input terminal of the gain switching circuit 140 to transmit the first detection signal Via. The signal line Lg connects the output terminal of the gain switching circuit 140 and the input port of the gain setting circuit 150 to transmit the second detection signal Vig. The signal line Ls connects the output port of the gain setting circuit 150 and the input terminal of the gain switching circuit 140, and transmits a command signal Vsw for selecting a gain. The signal line Ld is interposed between the gain setting circuit 150 and the control unit 110, and transfers the sample data Dt and the gain setting information Gn to the control unit 110.

  The current detection circuit 130 includes a series circuit of a Zener diode Dz and a diode D1, a capacitor C connected in parallel to the Zener diode Dz, a resistor R1 provided between connection terminals A and B, an anode side being a ground potential, and a cathode side being The diode D2 connected to the connection terminal B, the operational amplifier 130a whose connection terminal B is connected to the inverting input terminal and the non-inverting terminal is set to the ground potential, the resistor R2 that defines the output gain of the operational amplifier 130a, and the output signal of the operational amplifier 130a The resistor R3 defines the offset amount.

  When a high voltage is generated on the secondary side of the ignition coil CL, the spark plug PG causes dielectric breakdown at the plug gap, and the discharge current I1 flows from the ground side of the spark plug PG toward the secondary coil L2. The discharge current I1 follows a path of Zener diode Dz → diode D1 → ground (GND), and charges are accumulated in the capacitor C in this scene.

  On the other hand, when dielectric breakdown converges, in the plug gap, radical molecules are distributed around the plug gap, so that a charge transfer path is formed. At this time, the current detection circuit 130 consumes the electric charge stored in the capacitor C, thereby generating an ion current I2 having a path of the capacitor C → secondary coil L2 → ignition plug PG → ground (GND). Therefore, when the ion current I2 is generated, a signal proportional to the current value of the ion current I2 (hereinafter, the first detection signal Via) is output from the output terminal C.

  The gain switching circuit 140 includes a circuit network having a plurality of resistors and a switch function unit Sw driven by a signal Vsw. Among these, the resistance value of each resistor is determined so as to give a predetermined gain, and a desired gain is set by selecting a conduction path between the input end and the output end. Is possible. The switch function unit SW switches the conduction path, and a relay circuit, a transistor, or the like is used. When the first detection signal Via indicating the ionic current I2 is applied to the input terminal, the gain switching circuit 140 gives the gain corresponding to the selected conduction path to the first detection signal Via, that is, the first detection signal Via As a second detection signal Vig obtained by giving a predetermined gain to the detection signal Via, this is output from the output end. When the command signal Vsw is given, the gain switching circuit 140 selects a conduction path corresponding to the command signal Vsw, and the gain of the second detection signal Vig is switched according to this operation, and the signal value is changed. It will be.

  The gain setting circuit 150 is a circuit having an information processing function and an information communication function, and includes a CPU, a memory circuit, an AD conversion circuit, an I / O circuit, a clock circuit, and the like. The memory circuit stores appropriate programs, parameters, and the like, and the gain setting circuit 150 realizes the functional processing defined in the program by causing the hardware resources and software resources described above to function in cooperation. I am letting. In the program, for example, threshold setting processing, gain setting processing, addition gain calculation processing, addition gain correction processing, and the like are defined. In addition to the program, the memory circuit stores map information for selecting a threshold according to the control conditions of the internal combustion engine, peak value information that can refer to past log data of peak values for a certain period, and the like.

  The gain setting circuit 150 is appropriately provided with an input port, an output port, and an I / O port. The second detection signal Vig creates sample data Dt from an analog signal in an AD conversion circuit, and the data Dt is held in a memory circuit or a data register. The sample data Dt and gain setting information are transferred to the control unit 110 via the signal line Ld. Further, a command signal Vsw corresponding to the result value of the gain setting process is output from the output port. It should be noted that specific processing that is performed by the gain setting circuit 150 will be described later.

  FIG. 2 shows an ignition signal SG, a primary current Ic of the coil, a first signal Via proportional to the ion current, a window period Tm in which data sampling is performed, and sample data Dt for the second detection signal Vig, It is a timing chart which shows. In the figure, the representative cylinder is monitored among a plurality of existing cylinders. Further, the interval of the ignition signal SG in a certain cylinder may be referred to as an ignition cycle.

  As illustrated, the primary current Ic starts to increase from the rising time of the ignition signal SG, and rapidly decreases at the falling time of the signal SG. Immediately after this, a high voltage is output from the ignition coil 120 and discharge is performed by the spark plug PG. When the discharge converges, the ion current I2 begins to flow, and the first detection signal Via appears as a mountain-shaped waveform from the current detection circuit 130. The gain setting circuit 150 sets a window period Tm according to the rotational speed Ne of the internal combustion engine, and creates sample data Dt of the second detection signal Vig for the window periods ta to tb. As described above, the sample data Dt is switched to an appropriate offset level by setting the gain (see FIG. 5a).

  FIG. 3 shows a flowchart of a main routine defined by the gain setting program. In the main routine according to the present embodiment, processing S111, processing S112 to S114, and processing S115 to S116 are repeatedly activated for each appropriate event. However, the process S111 is started only when the control information of the internal combustion engine is updated, and the processes S112 to S114 and the processes S115 to S116 are appropriately performed for each ignition cycle. Each is activated at the timing.

  In such a main routine, when the rotational speed information Ne and the intake pressure information Pb of the internal combustion engine are updated, the updated information is stored in a data register of the CPU so that the updated information can be used. (S111). The rotation speed information Ne and the intake pressure information Pb are information given to the control unit 110 via the CAN communication line, and the control unit 110 rewrites (updates) the information Ne and Pb every several μsec, for example. Is implemented. Such information is a parameter indicating the load information of the internal combustion engine, and the numerical information determined based on this parameter reflects the load information of the internal combustion engine. The load information of the internal combustion engine is not limited to the above-described rotation speed information Ne and intake pressure information Pb. For example, information such as the air-fuel mixture charging efficiency ηc may be used. This filling efficiency ηc indicates the actual filling amount of the air-fuel mixture with respect to the cylinder volume, and can also be calculated based on the intake pressure information Pb.

  When the process S111 is completed, the edge detection determination of the ignition signal SG is performed (S112). In the process S112, a threshold value is appropriately set between the detected edge and the next detected edge, and the edge is a rising edge, a falling edge (pulse edge at time te), or Determine whether it is due to noise. In this embodiment, when the falling edge is detected in the process S112, the process S113 (threshold setting process) and the process S114 (gain setting process) are performed, and the falling edge cannot be detected in the process S112. The process proceeds to step S115.

  When the falling edge is detected, in the process S113, the upper threshold th1 and the lower threshold th2 are set. Of these, the upper threshold th1 provides a reference for decreasing the gain, and the lower threshold th2 provides a reference for increasing the gain. These threshold values are given to the sample data Dt. Then, the predetermined point of the sample data Dt is compared with each of the thresholds th1 and th2, and two thresholds having different functions are set, so that an operation for increasing or decreasing the gain value becomes possible.

  Here, the upper threshold th1 and the lower threshold th2 are preferably set based on the rotational speed information Ne and the intake pressure information Pb of the internal combustion engine. Since the distribution of the combustion waveform of the ion current I2 correlates with these parameters, in the present embodiment, the information Ne and Pb are reflected in the threshold values th1 and th2. Thereby, both threshold values th1 and th2 can be set based on the sample data so as to match the tendency of interlocking with the control state of the internal combustion engine.

  With reference to FIG. 5, functions of the upper threshold th1 and the lower threshold th2 will be described. First, the range of broken lines Vp to Vq shown in the figure is determined by the resolution of the AD conversion circuit, and indicates the data creation range in the AD conversion circuit. Among these, Vp is called an upper limit value and Vq is called a lower limit value.

  In the present embodiment, four types of gain values are set, and a relationship of gain value G1> gain value G2> gain value G3> gain value G4 is established. Of these, G1 may be referred to as a maximum gain value, and G4 may be referred to as a minimum gain value. In addition, each gain value is set such that the voltage level of the sample data Dt decreases step by step whenever the gain value decreases by one step (FIGS. 5a to 5c).

  In particular, in the present embodiment, the difference between the gain values (difference in voltage level) is set to increase as the gain value decreases (ΔD1 <ΔD2 <ΔD3). Such setting of the gain value is realized by the gain switching circuit 140. That is, in the gain switching circuit 140, resistance values for setting a plurality of gain values are set, and the resistance values are changed according to the gain value reduction setting (for example, the reduction amount). ) In a stepwise manner.

  The reason for recommending such a gain setting is that the distribution range ΔS1 of the sample data Dt becomes narrower as the gain value decreases, and the range in which data can be created according to the setting of the gain value. This is because Vp to Vq can be effectively used.

  In the strong combustion state, the distribution range ΔS1 of the sample data Dt is widened, so that the gain value is controlled to decrease according to the present embodiment. That is, in a scene where the combustion state is strong, the distribution range ΔS1 can be narrowed and the voltage level thereof can be set low, so that the sample data Dt can be easily stored in the data creation range Vp to Vq. There is an effect.

  FIG. 5A shows a scene where the distribution range ΔS1 of the sample data Dt is relatively narrow, and FIG. 5B shows a scene where the distribution range ΔS2 of the sample data Dt is wide. As described above, the distribution range ΔS of the sample data Dt increases or decreases in the ion current I2 according to the intensity of combustion. When the distribution range ΔS1 is narrow (FIG. 5a), the sample data Dt is likely to be within the range Vp to Vq, so that the degree of freedom in selecting the gain value is high. Therefore, according to FIG. 5A, the sample data Dt is not damaged regardless of which gain value G1 to G4 is selected.

  In the case where the distribution range ΔS2 is wide, according to FIG. 5B, when the gain value G1 is selected, the vicinity of the peak value of the sample data Dt is stuck to the upper limit value Vp, and the data damaged portion K1 is generated. . Further, when the gain value G4 is selected, the vicinity of the end value of the sample data Dt is stuck to the lower limit value Vq, and the data damage portion K2 or K3 is generated. On the other hand, when the gain value G2 and the gain value G3 are selected, the sample data Dt does not intersect with the upper limit value Vp and the lower limit value Vq.

  Therefore, as shown in FIG. 5C, if the upper threshold th1 is set, the sample data Dt is compared with the upper threshold th1, and when a part of the sample data exceeds th1, It is possible to determine that a part is approaching the upper limit value Vp. When the upper threshold value th1 is set in the vicinity of the upper limit value Vp, the gain setting circuit 150 generates a data damage portion K1 based on the processing result that the sample data Dt exceeds the upper threshold value th1. It becomes possible to discriminate it from a thing. As described above, the gain setting circuit 150 according to the present embodiment grasps the danger that the sample data Dt reaches the upper limit value Vp, reduces the gain value based on this, and sets the sample data Dt in the range Vp˜ It can be accommodated in Vq.

  Further, as shown in the figure, if the lower threshold th2 is set, it can be understood that a part of the sample data is lower than the lower threshold th2, and as a result, the occurrence of the damaged portion K2 or K3 of the sample data Dt is detected. It becomes possible to detect. Then, the gain value is increased with reference to the determination result, and the sample data Dt can be accommodated in the range Vp to Vq. The lower threshold th2 is preferably set according to the characteristics of the ion current waveform. In the present embodiment, since the peak value of the sample data Dt is compared with the thresholds th1 and th2, the lower threshold th2 is set to a level sufficiently higher than the lower limit value Vq. That is, the upper thresholds th1 and th2 are set with a predetermined level difference Δth and biased to the upper limit value Vp.

  As shown in FIG. 6A, when the distribution range ΔS1 of the sample data Dt is relatively narrow, the level difference Δth between the upper threshold th1 and the lower threshold th2 is set to be large, so that a gain value provided in advance is set. Can be effectively utilized. In addition, by setting the level difference Δth to be large, the lower threshold value th2 approaches the lower limit value Vq. For this reason, if the distribution range ΔS1 of the sample data Dt is to be increased as much as possible, the gain setting circuit 150 can instantly detect this and quickly increase the gain value.

  On the other hand, as shown in FIG. 6B, when the distribution range ΔS2 of the sample data Dt is wide, it is preferable to narrow the level difference Δth between the thresholds. In particular, the lower threshold th2 may be raised to the Vp side. Thereby, even when the combustion state is strong, it is possible to effectively use all the gain values G1 to G4.

  Returning to FIG. 3, the description of the main routine of the gain setting program will be continued. When the process S113 is completed, a gain switching process is executed (S114). The process S114 starts a subroutine for determining the set gain, and details will be described later.

  As described above, when the process S112 detects a falling edge, the gain setting is newly performed, and then the process proceeds to process S115. If no falling edge is detected, the process proceeds to step S115 without changing the gain setting.

  The process S115 is preset in advance by the program so that the process starts at the timing when the waveform of the ion current converges. In step S115, it is determined whether or not the sample data Dt has been updated to new data. If the data Dt has changed, the inspection target data is extracted from the sample data Dt, and the data is stored in the memory circuit. (Process S116). In the present embodiment, data Dt (peak) corresponding to the peak value is extracted from the sample data Dt. Thus, since the peak value of the waveform is taken as an inspection measure that represents the characteristics of the combustion state, data Dt (peak) is extracted.

  The memory circuit used in the present embodiment sorts the memory region M1 for storing data Dt (peak) for a plurality of past data and the plurality of past data Dt (peak) in descending order (or in ascending order). And a memory area M2 to be stored. In step S115, first, new data Dt (peak) is recorded in the memory area M1, and then sort processing is performed when the data is transferred to the memory circuit M2. For this reason, the memory circuit M2 can output the past maximum data Dt (peak) and the past minimum data Dt (peak) by accessing a specific memory address. Hereinafter, the past maximum data Dt (peak) is referred to as data Dmax, and the past minimum data Dt (peak) is referred to as data Dmin. In step S115, when a plurality of past data is stored in the memory circuit M1, the use area of the memory circuit can be reduced by adopting a ring buffer configuration.

  As shown in the figure, after the process S115 (S116) is completed, the above-described processes are repeated according to the next activation event. In this way, the data Dt (peak) is sequentially updated as the ignition cycle progresses.

  FIG. 4 shows a flowchart of a subroutine corresponding to the gain setting process S114. First, in process S211, the basic gain Gbsc is specified. The basic gain Gbsc is determined based on the control parameter of the internal combustion engine. In the present embodiment, the rotational speed information Ne and the intake pressure information Pb are used. The gain setting circuit 150 acquires these information Ne and Pb via the communication line Ld. Thus, since the basic gain Gbsc is set based on the control parameter of the internal combustion engine, it fulfills a function of specifying a general tendency as to which gain value is preferable.

  After the process S211 is completed, the value of the integrated gain Gint is calculated in processes S212 to S216. First, in step S212, the data Dmin indicating the past minimum value of the peak value is compared with the upper threshold value th1, and if Dmin> th1, the sample data Dt indicates a risk of sticking to the upper limit value Vp. The gain Gint is counted down by one. On the other hand, in the case of Dmax <th2, there is a danger that the sample data Dt sticks to the lower limit value Vq, so the integrated gain Gint is incremented by one. On the other hand, if neither Dmin> th1 nor Dmax <th2, it is determined that the gain setting is preferable, and the count value is set to zero.

  As described above, in the processes S212 to S216, integration is performed based on the relationship between the upper threshold th1 and the data Dmin (one of the sample data) or the relationship between the lower threshold th2 and the data Dmax (one of the sample data). The gain int is determined. Thus, the integrated gain is counted up / counted down according to the variation / variation of the sample data Dt, and is a value that varies due to the variation / variation.

  In the process S217, an addition value (addition gain sum) of the basic gain Gbsc and the integrated gain Gint is calculated. As described above, the gain value calculated from both gains reflects both information on the tendency associated with the driving state and the occurrence of data variation and fluctuation. In this embodiment, a gain function that reflects both pieces of information is created by the sum of the basic gain Gbsc and the integrated gain Gint. However, the method of calculating this gain function is not limited to this, and is currently known. Various modifications are possible using the technique.

  When the process S217 is completed, a correction process for the integrated gain Gint is executed (S218). As a specific example, consider a scene in which the current addition gain value Gsum has reached the maximum gain G1, and then a subroutine is started and processing S217 is executed. At this time, when a new addition gain value Gsum is calculated by the process S217 and the integrated gain Gint is counted up, the addition gain Gsum exceeds the maximum gain G1. In this case, in process S218, the integrated gain Gint is corrected to zero, and the added gain value Gsum is maintained at the maximum gain G1 (hereinafter, this added gain value is referred to as a corrected added gain Gsum [m]). As described above, in the process S218, it is possible to select any of the prepared gain values G1 to G4 by providing the reset windup function. This process provides the reset windup function even when the addition gain Gsum is below the minimum gain value G4.

  In step S218, the corrected addition gain value Gsum [m] is set as the basic gain Gbsc in the subroutine that is activated next time. As a result, the next basic gain Gbsc reflects both the tendency associated with the operating state and the presence / absence of variation in sample data and occurrence of fluctuations.

  When the process S218 ends, in the signal command process S219, a command signal Vsw representing the corrected addition gain Gsum [m] is generated, and the signal Vsw is output from the output port. This command signal Vsw is applied to the gain switching circuit 140 to reconfigure the internal circuit network so as to give a gain corresponding to the corrected addition gain Gsum [m]. When the process S219 is completed, the subroutine is set in a standby state and waits for the next execution command of the gain switching process S114.

  If the above-described processing is not defined in the gain switching program, as shown in FIG. 7A, when temporary disturbance occurs in the sample data Dt, the gain value is switched one step immediately after the detection (G1). → G2). Here, if the turbulence immediately stops, the gain value is set lower than necessary, so that the sample data Dt appears offset to the Vq side. In this case, as shown in the drawing, data corruption portions K2 and K3 are generated, and the reliability of the analysis processing performed by the control unit 110 is lowered.

  Further, as shown in FIG. 7B, if the gain value is switched immediately after the turbulence of the sample data Dt, it becomes difficult to specify an appropriate gain value, and chattering is induced. In such a case, since the quality deterioration of the sample data Dt takes a long time, the analysis result of the control unit 110 is greatly affected.

  On the other hand, in the present embodiment, for example, data Dmin for the past eight cycles (inspection cycle including the first cycle and the second cycle) is compared with the upper threshold th1. Therefore, as shown in FIG. 8A, when the peak value of the waveform exceeds the upper threshold th1 continuously for 8 cycles or more, the gain value is lowered by one step. As described above, in the present embodiment, the necessity of gain value switching is accurately determined, thereby avoiding unnecessary gain switching and permitting necessary gain switching processing.

  FIG. 8B shows how turbulence occurs in the sample data Dt. In such a case, in the present embodiment, the number of sticking dangerous states is counted, and if the count value is small, it is understood that turbulence occurs in the sample data Dt. As described above, in the present embodiment, by counting the danger state of sticking, gain switching due to temporary turbulence is eliminated, and an appropriate gain value to be set is maintained. This appropriate gain value refers to the fact that information on the tendency associated with the operating state and the presence or absence of variation in sample data is reflected.

  It should be noted that the switching of the gain setting described above is preferably performed independently for each cylinder of the internal combustion engine. This is because if there are variations in the ion current detection circuit, cylinder shape errors, etc., the sample data of the ion current is also affected accordingly. Therefore, if gain setting is performed separately for each cylinder, the optimum gain value for that cylinder is set for each cylinder, so that a problem such as sample data loss can be avoided more effectively.

  Although the embodiments have been described above, the invention described in the claims is not limited to such embodiments. For example, in the gain setting process, the rate of change of the integrated gain may be reduced as the change in the added value proceeds. That is, if the offset amount between the gain values is set to be small as Vp or Vq approaches, the sample data Dt becomes difficult to cross with Vp or Vq, and as a result, an appropriate gain value is selected.

  Further, although the control unit 110 is configured to receive the sample data Dt via the communication line Ld, the signal Vig may be directly received from the gain switching circuit 140. In this case, the control unit 110 receives the information related to the gain setting from the gain setting circuit 150, so that the value of the input sample data Dt can be correctly grasped.

  In addition, the gain setting circuit may execute processing for determining a fact inappropriate for gain switching. For example, if the peak value of the sample data does not exceed the lower threshold value in spite of increasing the gain value, there is a suspicion that the discharge operation with the spark plug has not been implemented for some reason in that cylinder. is there. Further, if the peak value of the sample data always exceeds the upper threshold value even though the gain value is set low, there is a suspicion that the sensor, the operational amplifier, or the like is faulty. As described above, when the sticking state of the sample data appears remarkably, it is preferable to determine that the sample data is inappropriate data, assuming that a malfunction has occurred in the devices such as the spark plug, the ignition coil, and the sensor. At this time, it is better to stop the switching of the gain setting. Further, the determination result information that is abnormal may be output to the control unit, or the process of transmitting the sample data to the control unit may be disabled. As a result, inappropriate data is not used in the control unit, so that the reliability of the analysis processing performed in the control unit is improved.

  DESCRIPTION OF SYMBOLS 10 Internal combustion engine control system, 100 Ion current detection apparatus for internal combustion engines, 110 Engine control unit, Ne rotational speed information, Pb intake pressure information, 120 ignition coil, PG spark plug, I1 discharge current, I2 ion current, 130 Current detection circuit , 140 gain switching circuit, 150 gain setting circuit, Via first detection signal, Vig second detection signal, Vsw command signal, 150 gain setting circuit, Dt sample data, th1 upper threshold, th2 lower threshold, S113 threshold setting processing , S114 Gain setting process, ΔS setting threshold difference, Gsum addition gain (addition value), Gbsc basic gain, Gint integrated gain.

Claims (10)

A current detection circuit that detects an ionic current generated in response to an ignition operation of the internal combustion engine and outputs a first detection signal proportional to the current value of the ionic current, and a gain that is applied to the first detection signal is switched. A gain switching circuit for changing and outputting the signal value of the second detection signal, and a gain setting circuit for outputting a gain switching command signal to the gain switching circuit,
The gain setting circuit includes:
A threshold setting process for setting each of an upper threshold given as a reference for lowering the gain and a lower threshold given as a reference for raising the gain;
Based on the gains of both the integrated gain determined by the relationship between the upper threshold value or the lower threshold value and the sample data of the ion current, and the basic gain determined by the parameter that controls the internal combustion engine. A gain setting process for setting a command signal , and
The upper threshold and the lower threshold, the out of the information related to the rotation speed or the intake pressure or charging efficiency of the internal combustion engine, at least one of the set ion current detecting apparatus for an internal combustion engine, wherein isosamples based on the information. A current detection circuit that detects an ionic current generated in response to an ignition operation of the internal combustion engine and outputs a first detection signal proportional to the current value of the ionic current, and a gain that is applied to the first detection signal is switched. A gain switching circuit for changing and outputting the signal value of the second detection signal, and a gain setting circuit for outputting a gain switching command signal to the gain switching circuit,
  The gain setting circuit includes:
  A threshold setting process for setting each of an upper threshold given as a reference for lowering the gain and a lower threshold given as a reference for raising the gain;
  Based on the gains of both the integrated gain determined by the relationship between the upper threshold value or the lower threshold value and the sample data of the ion current, and the basic gain determined by the parameter that controls the internal combustion engine. A gain setting process for setting a command signal, and
  The threshold value setting process sets a small difference between the upper threshold value and the lower threshold value when the distribution range of the sample data is wide, and sets the difference between the upper threshold value and the lower threshold value when the distribution range of the sample data is narrow. An ion current detector for an internal combustion engine, characterized in that the difference is set large. A current detection circuit that detects an ionic current generated in response to an ignition operation of the internal combustion engine and outputs a first detection signal proportional to the current value of the ionic current, and a gain that is applied to the first detection signal is switched. A gain switching circuit for changing and outputting the signal value of the second detection signal, and a gain setting circuit for outputting a gain switching command signal to the gain switching circuit,
  The gain setting circuit includes:
  A threshold setting process for setting each of an upper threshold given as a reference for lowering the gain and a lower threshold given as a reference for raising the gain;
  Based on the gains of both the integrated gain determined by the relationship between the upper threshold value or the lower threshold value and the sample data of the ion current, and the basic gain determined by the parameter that controls the internal combustion engine. A gain setting process for setting a command signal, and
  The integrated gain is set based on a peak value extracted from the sample data. A current detection circuit that detects an ionic current generated in response to an ignition operation of the internal combustion engine and outputs a first detection signal proportional to the current value of the ionic current, and a gain that is applied to the first detection signal is switched. A gain switching circuit for changing and outputting the signal value of the second detection signal, and a gain setting circuit for outputting a gain switching command signal to the gain switching circuit,
  The gain setting circuit includes:
  A threshold setting process for setting each of an upper threshold given as a reference for lowering the gain and a lower threshold given as a reference for raising the gain;
  Based on the gains of both the integrated gain determined by the relationship between the upper threshold value or the lower threshold value and the sample data of the ion current, and the basic gain determined by the parameter that controls the internal combustion engine. A gain setting process for setting a command signal, and
  The gain setting process sets the command signal based on an addition value of the integrated gain and the basic gain,
  The ionic current detection apparatus for an internal combustion engine, wherein the gain setting process reduces the rate of change of the integrated gain as the change of the added value proceeds. When the addition value is newly calculated after the addition value indicates the maximum gain, and the new addition value indicates a value exceeding the maximum gain,
5. The ion current detection apparatus for an internal combustion engine according to claim 4 , wherein the gain setting process corrects the integrated gain to zero. When the addition value is newly calculated after the addition value indicates the minimum gain, and the new addition value indicates a value lower than the minimum gain,
5. The ion current detection apparatus for an internal combustion engine according to claim 4 , wherein the gain setting process corrects the integrated gain to zero. A current detection circuit that detects an ionic current generated in response to an ignition operation of the internal combustion engine and outputs a first detection signal proportional to the current value of the ionic current, and a gain that is applied to the first detection signal is switched. A gain switching circuit for changing and outputting the signal value of the second detection signal, and a gain setting circuit for outputting a gain switching command signal to the gain switching circuit,
The gain setting circuit includes:
A threshold setting process for setting each of an upper threshold given as a reference for lowering the gain and a lower threshold given as a reference for raising the gain;
Based on the gains of both the integrated gain determined by the relationship between the upper threshold value or the lower threshold value and the sample data of the ion current, and the basic gain determined by the parameter that controls the internal combustion engine. A gain setting process for setting a command signal, and
In the gain switching circuit, a resistance value for setting a plurality of gain values is set, and the resistance value increases a change amount of the resistance value according to a decrease setting of the gain value. an internal combustion engine for an ion current detector that. 8. The parameter according to claim 1, wherein the parameter for controlling the internal combustion engine indicates at least one of information related to the rotational speed, intake pressure, or charging efficiency of the internal combustion engine. An ion current detection device for an internal combustion engine according to claim 1. The integrated gain includes inspection data including ion current sample data generated in the first combustion cycle and ion current sample data generated in the second combustion cycle that is a cycle earlier than the first combustion cycle. The ion current detection device for an internal combustion engine according to any one of claims 1 to 8 , wherein the ion current detection device is set based on a plurality of data having different cycles. An internal combustion engine control device that defines an ignition timing, an ignition coil that generates a high voltage in accordance with the ignition timing, an ion current detection device for an internal combustion engine according to any one of claims 1 to 9 , An internal combustion engine control system comprising:

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