JP2014163348A - Control device of spark-ignition type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a spark-ignition type internal combustion engine which optimizes electricity-conduction time to a primary coil of an ignition coil for spark ignition and, thereby, suppresses waste of unnecessary energy.SOLUTION: Upon the conduction of electricity to a primary coil of an ignition coil prior to spark ignition by means of an ignition plug disposed on a cylinder, the necessary time (from a time point t' to a time point t) until the extent of primary current flowing through the primary coil from the starting of the conduction of electricity reaches a value sufficient for causing spark discharge on the ignition plug is learned. At a chance of the ignition afterward, a preliminary time determined based on the present state of a battery and a load and an EGR rate of an internal combustion engine is added to the necessary time learned beforehand and, thereafter, the timing t'' when the conduction of electricity to the primary coil is started is determined. Thereby, a wasteful energization time (from a time point tto a time point t) until shutting off the primary current after the extent of the primary current comes to the extent sufficient for causing the spark discharge is shortened.

Description

  The present invention relates to a control device for controlling a spark ignition internal combustion engine.

  In a spark ignition type internal combustion engine, an air-fuel mixture in a combustion chamber is ignited by an ignition plug provided in a cylinder. At the time of ignition, the spark plug receives a voltage applied from the ignition coil and generates a spark discharge between the center electrode and the ground electrode.

  An ignition coil is a set of a primary side coil and a secondary side coil that share a magnetic circuit and magnetic flux with each other, and induces a high induced voltage in the secondary side coil at the moment when the current flowing through the primary side coil is cut off. is there. Therefore, prior to spark ignition, it is necessary to flow a primary current of a certain magnitude or more to the primary coil in advance. Switching between energization / cutoff of the primary current is performed via an igniter using a semiconductor switching element (see, for example, Patent Document 1 below).

  When energization is started by applying a DC voltage supplied from the power battery to the primary coil, the primary current increases. The speed of the increase decreases with the passage of time, and eventually saturates to an amount of current corresponding to the ratio between the applied DC voltage and the resistance in the circuit.

  The induced voltage required to cause a spark discharge in the spark plug, in other words, the magnitude of the primary current before the interruption is smaller than the saturation current amount. Recent igniters are equipped with a current limiting function that suppresses excessive primary current. This type of igniter constantly senses the primary current flowing through the primary coil, and ignites the semiconductor switch while the magnitude of the primary current is below a predetermined value, while when it exceeds the predetermined value, the semiconductor switch Is extinguished to clip the primary current to a predetermined value (see, for example, Patent Document 2 below).

JP 2012-084432 A JP 2008-045514 A

  If the magnitude of the primary current before the interruption is insufficient, the induced voltage generated in the secondary coil after the interruption of the primary current becomes low, which adversely affects the ignition and combustion of the air-fuel mixture. Therefore, conventionally, in order to sufficiently increase the primary current, it has been customary to set the time for energizing the primary side coil as long as possible without exceeding the heat generation limit of the coil.

  For this reason, in many cases, the current limiting function of the igniter is working immediately before the spark discharge. Of the time during which the primary side coil is energized, the current limiting period in which the current limiting function of the igniter operates does not contribute to the spark discharge itself and is essentially unnecessary. In other words, electric energy was wasted during the current limiting period, and the waste was accumulated, leading to a reduction in fuel consumption.

  An object of the present invention is to optimize the energization time to the primary coil of the ignition coil and suppress waste of unnecessary energy.

  In order to solve the above-described problem, in the present invention, when energizing the primary coil of the ignition coil prior to spark ignition by the spark plug provided in the cylinder, the energization is started and then the primary coil flows. The time required for the primary current to reach a value sufficient to cause a spark discharge in the spark plug is learned, and in the subsequent ignition opportunity, the current power battery is In consideration of a spare time determined based on at least one of an index value representing a state, an index value representing an internal combustion engine load, or an index value representing an EGR (Exhaust Gas Recirculation) rate, the primary current is cut off and a spark is generated. A control device for a spark ignition type internal combustion engine, wherein a starting point of energization to a primary coil is determined by calculating backward from a time point at which ignition should be caused Configured.

  ADVANTAGE OF THE INVENTION According to this invention, the electricity supply time to the primary side coil of an ignition coil can be optimized, and waste of unnecessary energy can be suppressed.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The circuit diagram of the spark ignition device in the embodiment. The figure which shows transition of the primary current which flows through the primary side coil of an ignition coil in the period from ignition of an igniter to spark ignition. The figure which shows each transition of the combustion pressure and the ionic current in the cylinder of an internal combustion engine. The figure which shows each transition of the ignition signal and the electric current signal which flows through the electrode of a spark plug in the period from ignition of an igniter to spark ignition. The figure which shows each transition of the ignition signal and the electric current signal which flows through the electrode of a spark plug in the period from ignition of an igniter to spark ignition. The figure which shows each transition of the ignition signal and the electric current signal which flows through the electrode of a spark plug in the period from ignition of an igniter to spark ignition. The figure which shows the relationship between a battery voltage and the reserve time defined based on this. The figure which shows the relationship between the load of an internal combustion engine, and the reserve time defined based on this. The figure which shows the relationship between the load of an internal combustion engine, and the reserve time defined based on this. The figure which shows the relationship between the load of an internal combustion engine, and the reserve time defined based on this. The figure which shows the relationship between an EGR rate and the reserve time defined based on this.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition gasoline engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1.

  FIG. 2 shows an electric circuit for spark ignition. The spark plug 12 receives spark voltage generated by the ignition coil 14 and causes spark discharge between the center electrode and the ground electrode. The ignition coil 14 is integrally incorporated in the coil case together with the igniter 13 including the semiconductor switching element 131.

  When the igniter 13 receives an ignition signal i from an ECU (Electronic Control Unit) 0, which is a control device for the internal combustion engine, first, the semiconductor switch 131 of the igniter 13 is ignited and a current flows to the primary side of the ignition coil 14, immediately thereafter. At this spark ignition timing, the semiconductor switch 131 extinguishes and this current is cut off. Then, a self-induction action occurs, and a high voltage is generated on the primary side. Since the primary side and the secondary side share the magnetic circuit and the magnetic flux, a higher induced voltage is generated on the secondary side. The induced voltage on the secondary side reaches 10 kV to 30 kV. This high induction voltage is applied to the center electrode of the spark plug 12, and a spark discharge occurs between the center electrode and the ground electrode.

  The primary coil of the ignition coil 14 is connected to the in-vehicle power supply battery 17 via the semiconductor switch 131. When the semiconductor switch 131 is ignited and a DC voltage supplied from the battery 17 is applied to the primary side coil to start energization, the primary current flowing through the primary side coil increases.

FIG. 3 illustrates the transition of the primary current after the start of energization of the primary coil. In FIG. 3, the case where the current limiting function does not work is drawn with a broken line, and the case where the current limiting function works is drawn with a chain line (the solid line will be described later). Assuming that the electric circuit including the battery 17 and the primary coil is an RL series circuit, the primary current I (t) when the DC voltage E is applied at time t = 0 is
I (t) = {1-e- ^{(R / L) t} } E / R
It becomes. That is, the primary current increases as a transient phenomenon, but the rate of increase gradually decreases. When a sufficiently long time elapses, the primary current saturates to E / R as shown by the broken line in FIG.

  The igniter 13 has a current limiting function that suppresses excessive primary current. This current limiting function is similar to off-the-shelf igniters that are popular today. Specifically, the control circuit 132 constantly measures the primary current in the form of the voltage across the resistor 133 via the detection resistor 133. Then, the semiconductor switch 131 is ignited while the magnitude of the primary current (voltage across the resistor 133) is equal to or less than the predetermined value, while the semiconductor switch 131 is extinguished when it exceeds the predetermined value. As a result, the primary current is clipped to a predetermined value as indicated by a chain line in FIG.

  Further, the igniter 13 has a function of forcibly shutting off the energization of the primary coil when detecting abnormal heat generation such that the temperature of the ignition coil 14 or the igniter 13 itself exceeds a threshold value.

  The ECU 0 detects an ionic current generated in the combustion chamber of the cylinder 1 during the explosion combustion of the fuel, and refers to the ionic current to determine the combustion state.

  As shown in FIG. 2, in this embodiment, a circuit for detecting an ionic current is added to the electric circuit for spark ignition. This detection circuit includes a bias power supply unit 15 for effectively detecting an ionic current and an amplification unit 16 that amplifies and outputs a detection voltage corresponding to the amount of the ionic current. The bias power supply unit 15 includes a capacitor 151 that stores a bias voltage, a Zener diode 152 for increasing the voltage of the capacitor 151 to a predetermined voltage, current blocking diodes 153 and 154, and a load that outputs a voltage corresponding to the ion current. A resistor 155. The amplifying unit 16 includes a voltage amplifier 161 typified by an operational amplifier.

  The capacitor 151 is charged during arc discharge between the center electrode and the ground electrode of the spark plug 12, and then an ion current flows through the load resistor 155 by the bias voltage charged in the capacitor 151. The voltage between both ends of the resistor 155 generated by the flow of the ionic current is amplified by the amplifying unit 16 and received by the ECU 0 as the ionic current signal h.

  FIG. 4 illustrates respective transitions of the ionic current and the combustion pressure in the cylinder 1 (in-cylinder pressure) in normal combustion. In FIG. 4, the ion current is indicated by a solid line, and the combustion pressure is indicated by a broken line. The ionic current cannot be detected during the discharge for ignition. In the case of normal combustion, the ionic current decreases by a chemical reaction before the compression top dead center after the end of spark ignition, and then increases again by thermal dissociation. In addition, the ionic current reaches a maximum almost simultaneously with the peak of the combustion pressure.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  The internal combustion engine is often accompanied by an external EGR device 2. An external EGR device 2 shown in FIG. 1 realizes a so-called high-pressure loop EGR, and an EGR passage 21 that communicates the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3; An EGR cooler 22 provided on the EGR passage 21 and an EGR valve 23 that opens and closes the EGR passage 21 and controls the flow rate of the EGR gas flowing through the EGR passage 21 are used as elements. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined location downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3, particularly to the surge tank 33.

  The ECU 0 that controls operation of the internal combustion engine is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal (N signal) b output from an engine rotation sensor that detects the rotation angle of the crankshaft and the engine speed, An accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal or the opening of the throttle valve 32 as an accelerator opening (required load), an index value (battery voltage, battery current, Battery status signal d output from a battery sensor that detects battery temperature (at least one or all of the battery temperatures), and output from a temperature / pressure sensor that detects intake air temperature and intake air pressure in intake passage 3 (especially surge tank 33) Cooling output from a water temperature sensor that detects the intake air temperature / intake pressure signal e and the cooling water temperature of the engine Detects temperature signal f, cam angle signal (G signal) g output from cam angle sensor at multiple cam angles of intake camshaft or exhaust camshaft, and ion current generated with combustion of air-fuel mixture in combustion chamber The current signal h and the like output from the circuit to be input are input.

  From the output interface, an ignition signal i for the igniter 13 of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and an opening operation signal for the EGR valve 23. l etc. are output.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed, the intake air amount, etc., the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, required EGR rate (or EGR rate) Various operating parameters such as volume). As the operation parameter determination method itself, a known method can be adopted. The ECU 0 applies various control signals i, j, k, and l corresponding to the operation parameters via the output interface.

  In addition, the ECU 0 of the present embodiment uses a circuit that detects an ionic current flowing through the electrode of the spark plug 12 during combustion, so that the energization time of the primary coil of the ignition coil 14, that is, the igniter 13 Learning control for learning the ignition timing of the semiconductor switch 131 is performed.

  FIGS. 5 to 7 show the time-series transition of the ignition signal i given from the ECU 0 to the igniter 13 and the value of the current signal h acquired by the ECU 0 through the circuit for detecting the ionic current. The current signal h represents the current flowing through the electrode of the spark plug 12 and also represents the magnitude of the resistance between both electrodes of the spark plug 12.

FIG. 5 shows the transition of the signals i and h before the completion of the learning of the ignition timing of the semiconductor switch 131. The ECU 0 ignites the semiconductor switch 131 prior to spark ignition and energizes the primary coil of the ignition coil 14. Then, the semiconductor switch 131 is extinguished at a time t ₁ when a sufficient energization time has elapsed from the time t _{0 of} ignition, and the power supply to the primary coil of the ignition coil 14 is interrupted.

The current signal h in the case of normal combustion is noticeable after the time t ₂ when a spark discharge period caused between the two electrodes of the spark plug 12 with the extinction of the semiconductor switch 131 has elapsed. It includes the signal of the ion current generated in More specifically, the signal due to LC resonance appears at time t _2, then the ion current signal due to combustion appears.

When the semiconductor switch 131 is ignited, spike noise is generated and superimposed on the current signal h. In addition, the current signal h oscillates during a period from the time point t ₃ before the extinction of the semiconductor switch 131 to the time point t _{1 of the} extinction. This vibration is due to the function of the current limiting function of the igniter 13. That is, the increasing primary current reaches the specified value at time t _3, and when the primary current exceeds the specified value, the control circuit 132 momentarily cuts off the semiconductor switch 131 (and when the primary current falls below the specified value). Since the operation of re-igniting the semiconductor switch 131 is repeatedly performed, vibrational noise is applied to the ion current detection circuit, and this noise is superimposed on the current signal h.

Of the time during which the primary side coil is energized, the current limiting period from the time point t ₃ to the time point t ₁ at which the current limiting function of the igniter operates does not contribute to the spark discharge itself and is essentially unnecessary. As long as the primary current reaches the specified value, the primary current has already become large enough to induce an induced voltage in the secondary side coil sufficient for spark ignition by the spark plug 12. The electrical energy consumed by continuing energization of the primary coil during the current limiting period is completely wasted.

Therefore, the ECU 0 of the present embodiment starts the energization of the primary side coil, and then the time point t ₃ when the magnitude of the primary current flowing through the primary side coil reaches a value sufficient to cause spark discharge in the spark plug 12. To learn. Then, at a subsequent ignition opportunity, a time point t ₀ ′ at which energization of the primary coil is started is determined using the previously learned time point t ₃ . The aim is to make the current limiting period as short as possible.

ECU0 refers to a current signal h which is obtained during the energization of the primary coil via the circuit for detecting an ion current, the time t ₃ when a current signal h from the arc time t ₀ point of the semiconductor switches 131 starts to vibrate Measure the elapsed time until. It can be said that the elapsed time from the time point t ₀ to the time point t ₃ is a time required until the magnitude of the primary current reaches a sufficient value.

Alternatively, the length of the current limiting period from time t ₃ to time t ₁ when the current signal h oscillates may be measured. The energization time of the primary coil, that is, the time t ₀ when the semiconductor switch 131 is ignited and the time t ₁ when the arc is extinguished are given to the ECU ₀ . If the length of the current limiting period is subtracted from the energization time to the primary coil, the time required for the primary current to reach a sufficient value can be obtained.

The ECU 0 stores the measured time t ₃ (the elapsed time from the time t ₀ to the time t ₃ or the elapsed time from the time t ₃ to the time t ₁ ) in the memory as a learning value. Needless to say, the time point t ₃ suggests the time required for the magnitude of the primary current to reach a value sufficient to cause a spark discharge in the spark plug 12.

The learning at the time point t ₃ can be performed in a wide operating range [engine speed, required load]. The learning at the time point t ₃ is performed not only in the acceleration transition period and the deceleration transition period but also in the steady period in which the operation region is relatively stable and stable.

However, in a high speed region where the engine speed is above a predetermined threshold value, it is desirable not to learn the time t _3. In the high rotation range, the frequency of the expansion stroke in each cylinder 1 is high, and the ratio of the time during which the primary coil of the ignition coil 14 is energized (relative to one cycle of intake, compression, expansion, and exhaust) increases, and ignition is performed. The coil 14 generates heat. When the temperature of the ignition coil 14 becomes significantly high, the igniter 13 forcibly cuts off the energization. However, if learning at the time t ₃ is performed at this time, erroneous learning occurs. Therefore, learning is not performed in the high rotation range.

The learning at the time point t ₃ is performed only when the internal combustion engine has been warmed up, that is, when the condition that the coolant temperature is equal to or higher than a predetermined value is satisfied. Since the resistance of the electric circuit including the primary coil varies depending on the temperature, if learning is performed before the warm-up is completed, there is a risk of erroneous learning. Stated in accordance with the above equation for the primary current I (t), I (t) changes as the resistance R changes. Therefore, it is not performed when the internal combustion engine is not warmed up.

By using the learning value at time point t ₃ , it is possible to determine the energization start time point t ₀ ′ that minimizes the current limiting period. FIG. 6 shows a signal i when the semiconductor switch 131 is ignited from an ideal energization start time t ₀ ′ that does not take into account a preparatory time, which will be described later, at a stage after the learning of the ignition timing of the semiconductor switch 131 is completed. , H shows the transition. The ECU 0 assumes that the semiconductor switch 131 is extinguished in time with the ignition timing set in accordance with the operation region, the presence or absence of knocking, etc., and the primary current flowing through the primary coil immediately before the extinction time t _1. The ignition time t ₀ ′ of the semiconductor switch is determined so that the value increases to the vicinity of the specified value.

Specifically, ECU0 is, the elapsed time from the new ignition point t ₀ 'to the arc extinguishing time t ₁ is, from the arc time t ₀ point measured in the past learning to the starting point t ₃ of the current limiting time period The time point t ₀ ′ is determined so as to be approximately equal to the elapsed time. Alternatively, the time difference of transition from the starting time t ₀ in the past learning to the new starting time t ₀ ′ is the length of the current limiting period measured in the past learning, that is, from the starting time t _{3 of the} current limiting period. The time point t ₀ ′ is determined so as to be approximately equal to the elapsed time until the arc extinguishing time point t ₁ .

If so, the current limiting period is minimized. In FIG. 3, the transition of the primary current when the semiconductor switch 131 is ignited from the energization start time t ₀ that does not depend on the learning value t ₃ is drawn with a chain line, and the ideal energization start time t ₀ based on the learned value t _3. The transition of the primary current when the semiconductor switch 131 is ignited from 'is drawn by a solid line.

However, it is not always appropriate to start energization of the primary coil from the ideal energization start time t ₀ ′.

First, the increasing speed of the primary current flowing through the primary side coil varies depending on the amount of charge of the battery 17 at that time and other conditions. Stated in accordance with the above equation for the primary current I (t), I (t) changes as the battery voltage E changes. When the semiconductor switch 131 is ignited from the ideal energization start time t ₀ ′ under the condition where the battery voltage is low, the primary current does not reach the necessary and sufficient level at the time t ₁ when extinguishing this, A sufficiently high voltage cannot be induced in the secondary coil.

  Furthermore, the ease of ignition of the air-fuel mixture by spark discharge and the stability of combustion of the air-fuel mixture are affected by the load (output) of the internal combustion engine at that time, the EGR rate of the intake air, and the like. During high-load operation, the amount of intake air and fuel injected into the cylinder 1 is large, and the pressure and density of the air-fuel mixture in the cylinder 1 at the ignition timing are high, causing spark discharge between the electrodes of the spark plug 12. Therefore, a larger applied voltage is required.

  During low load operation, the intake air amount and fuel injection amount charged into the cylinder 1 are small, and the pressure and density of the air-fuel mixture in the cylinder 1 at the ignition timing are low. To ensure ignition and combustion, it is desirable to lengthen the spark discharge time, and for that purpose, it is necessary to store as much electrical energy as possible in the ignition coil 14.

  In addition, when the EGR rate of the air-fuel mixture is high, combustion tends to become unstable in the first place.

In any case, if the semiconductor switch 131 is ignited from the ideal energization start time t ₀ ′, the magnitude of the primary current at the extinction time t ₁ may be insufficient.

Therefore, in the present embodiment, the required time learned in the past is determined based on an index value representing the current state of the power supply battery 17, an index value representing the current load of the internal combustion engine, and an index value representing the current EGR rate. upon adding the preliminary time being, by calculating back from the time point t ₁ to cut off the ignition timing or primary current has been decided to determine the energization start time point t ₀ '' to the primary side coil.

FIG. 7 shows transitions of the signals i and h when the semiconductor switch 131 is ignited from the energization start time t ₀ ″ with the preliminary time taken into account. The elapsed time from the energization start time t ₀ ″ to the ideal time t ₀ ′ is a preliminary time determined by the ECU ₀ . The energization start time t ₀ ″ is advanced by this reserve time, the time for energizing the primary coil is lengthened, and the possibility that the primary current becomes insufficient at the extinction time t ₁ of the semiconductor switch 131 is reduced.

  An example of the index value indicating the state of the battery 17 is the terminal voltage of the battery 17. As shown in FIG. 8, the ECU 0 of the present embodiment sets a longer standby time as the current battery voltage is lower. The rate of change of the standby time with respect to the battery voltage (the slope of the characteristic curve) is small in a region where the battery voltage is relatively high and large in a region where the battery voltage is relatively low. This is because the lower the battery voltage, the higher the possibility that ignition by spark discharge will fail.

  Examples of index values representing the load of the internal combustion engine include the pressure in the surge tank 33, the accelerator opening, the intake air amount filled in the cylinder 1, and the like. If importance is placed on ignitability during low-load operation (it is assumed that the possibility of ignition failure is low at medium and high loads), as shown in FIG. 9, the current surge tank 33 is low (or the accelerator is open). The smaller the degree, the smaller the intake amount), the longer the reserve time is set. On the other hand, if importance is placed on ignitability during high-load operation (it is assumed that the possibility of ignition failure is low at low to medium loads), as shown in FIG. Alternatively, a longer reserve time is set as the accelerator opening degree is larger and the intake air amount is larger.

  If both the low load operation and the high load operation are emphasized, as shown in FIG. 11, a longer reserve time is set as the surge tank 33 is lower in a relatively low load operation region, and a relatively high In the operating region of the load, a longer reserve time is set as the surge tank 33 is higher. In the medium load region, the spare time is the shortest.

  Examples of the index value representing the EGR rate include the required EGR rate calculated by the ECU 0, the opening degree of the EGR valve 23, and the like. As shown in FIG. 12, the ECU 0 sets a longer reserve time as the current required EGR rate is higher (or as the opening degree of the EGR valve 23 is larger).

The ECU ₀ ignites the semiconductor switch 131 at the ignition time t ₀ ″ determined in consideration of the above-described preliminary time, so that the primary side coil at the arc extinguishing time t ₁ that matches the timing of the ignition timing. It is possible to realize a state in which the primary current flowing through is increased to the vicinity of the specified value. In other words, the energization time to the primary coil is controlled by feedforward control that corrects the energization start time t ₀ ′, which depends on the learned value t ₃ learned in the past, according to the current state of the battery 17 and the internal combustion engine, which can change every moment. Can be optimized to ensure spark discharge in the spark plug 12 and ignition of the air-fuel mixture.

Moreover, as shown in FIG. 7, the length of the current limiting period (from time t ₃ to time t ₁ ) during which the primary current is clipped to the specified value, which is a wasteful energization time, is reduced as much as possible. Energy consumption can be reduced.

Learning time t _3, and the control of the timing t ₀ '' of the ignition of the semiconductor switch 131 using the time t ₃ when the learning is performed individually for each cylinder 1. The learning value at the time point t ₃ is different for each cylinder 1, and the ignition timing t ₀ ″ of the semiconductor switch 131 can also be different for each cylinder 1.

If the battery is sufficiently charged, depending on the situation of the internal combustion engine, the reserve time may be 0, and the energization start time t ₀ ″ may be equal to the ideal time t ₀ ′.

The preparatory time based on the state of the battery 17, the preparatory time based on the load of the internal combustion engine, and the preparatory time based on the EGR rate may be all taken into consideration to determine the energization start time t ₀ ″. The energization start time t ₀ ″ may be determined by taking into account only a part.

In the present embodiment, a circuit that detects an ionic current that flows through the electrode of the spark plug 12 during combustion is used, and when the primary coil of the ignition coil 14 is energized prior to the spark ignition by the spark plug 12, the energization is performed. The time required for the primary current flowing through the primary coil to reach a value sufficient to cause spark discharge in the spark plug 12 (learned value t ₃ ) is learned. At the time of ignition, it is determined based on at least one of an index value representing the current state of the power supply battery 17, an index value representing the load of the internal combustion engine, and an index value representing the EGR rate, at the previously learned required time. The spark ignition type is characterized in that, after taking into account the reserve time, the primary current is cut off and the ignition start time t ₀ ″ is determined by calculating backward from the time t ₁ at which spark ignition should occur. The control device 0 for the internal combustion engine was configured.

  According to this embodiment, it is possible to reduce the waste of electric energy caused by continuing to energize the primary side coil even though the primary current is already large enough to cause a spark discharge. . As a result, it contributes to further improvement of fuel consumption.

In addition, the energization time required for the primary current to reach a sufficient value after energization of the primary coil can vary depending on the state of charge of the battery 17 connected to the primary coil. . In addition, the ease of ignition by spark discharge and the stability of combustion are affected by the load of the internal combustion engine, the EGR rate, etc. at that time. In determining the energization start time t ₀ ″ for the primary side coil, the ignition time is determined by adding the spare time according to the current battery charge state, engine load, EGR rate, etc. to the required time learned in the past. And the certainty of combustion is increased.

  Furthermore, the individual difference of the ignition coil 14 or the individual difference of the electric circuit of the ignition system can be absorbed through learning of the required time.

  By shortening the time during which the ignition coil 14 is energized (decreasing the current limiting period), overheating of the ignition coil 14 is suppressed, and the life of the ignition system including the ignition coil 14 is also extended. .

  The present invention is not limited to the embodiment described in detail above. For example, in the above-described embodiment, the ECU 0 acquires the oscillating current signal h that flows through the secondary coil of the ignition coil 14 via the ion current detection circuit, and performs learning based on this. However, as long as the current h flowing through the secondary coil can be detected, the circuit does not need to be used for the detection of the ionic current generated during combustion.

In addition to this, a circuit that can directly measure the magnitude of the primary current flowing through the primary coil is provided, and the ECU 0 constantly samples and measures the primary current through this circuit, and the primary current causes spark discharge. It is also possible to know the required time (arrival time t ₃ ) required to reach a specified value sufficient to do as the learning value.

  The EGR rate (or EGR amount) taken into consideration for determining the reserve time may be an internal EGR rate, or may be an EGR rate obtained by combining the external EGR rate and the internal EGR rate. When the internal combustion engine includes a VVT (Variable Valve Timing) mechanism that can change the opening / closing timing of the intake valve and / or the exhaust valve, the valve timing realized by the VVT mechanism, or the intake valve The valve overlap period during which both the exhaust valve and the exhaust valve are opened is considered to be an index value representing the internal EGR rate, and a longer preliminary time may be set as the value increases.

  Other specific configurations of each part can be variously modified without departing from the spirit of the present invention.

  The present invention can be applied to control of an internal combustion engine mounted on a vehicle or the like.

0 ... Control unit (ECU)
1 ... cylinder 12 ... to the ignition plug 13 ... igniter 14 ... ignition coil 17 ... Power Battery d ... battery condition signal i ... ignition signal h ... current signal t 0 _'... primary coil is determined based on the required time learned Energization start time t ₀ ″: Energization start time to the primary coil determined based on the learned required time plus the preliminary time t ₃ ... The value of the primary current is sufficient to cause spark discharge Time to increase to

Claims (1)

When energizing the primary coil of the ignition coil prior to the spark ignition by the spark plug provided in the cylinder, the magnitude of the primary current flowing through the primary coil after starting the energization causes spark discharge in the spark plug. Learn how long it takes to reach a value sufficient to trigger,
At the subsequent ignition opportunity, based on at least one of an index value representing the current state of the power supply battery, an index value representing the load of the internal combustion engine, and an index value representing the EGR rate at the previously learned required time. A control device for a spark ignition type internal combustion engine characterized by determining a start time of energization to a primary coil by calculating backward from a time point at which a primary current is cut off and spark ignition should be caused in consideration of a predetermined reserve time .

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