JP2016089631A - Igniter of spark ignition type internal combustion engine and manufacturing method of igniter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize a characteristic of an igniter added to a spark ignition type internal combustion engine, and to contribute to further improvement of efficiency as a whole.SOLUTION: In an igniter of a spark ignition type internal combustion engine which excites spark discharge between electrodes of an ignition plug installed at a cylinder, the igniter comprises: an ignition coil in which a winding ratio between a primary-side coil and a secondary-side coil is selected so that a fuel consumption rate reaches a best value or the vicinity of the best value in a reference operation region being a prescribed operation region which is a reference, or a primary voltage setting part which applies a primary voltage having a magnitude which is selected so that the fuel consumption rate reaches the best value or the vicinity of the best value in the reference operation region to the primary-side coil of the ignition coil; and a control part which inputs electric energy larger than electric energy inputted into the ignition coil in the reference operation region in an operation region other than the reference operation region.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an ignition device applied to a spark ignition internal combustion engine mounted on a vehicle or the like.

  In a spark ignition type internal combustion engine, a spark plug for igniting an air-fuel mixture filled in a cylinder receives a voltage induced by an ignition coil and causes a spark discharge between a center electrode and a ground electrode. To do.

  An igniter having a semiconductor switching element is provided on an electric circuit for energizing the ignition coil. When the igniter semiconductor switch is ignited, a current flows to the primary side of the ignition coil. The primary current flowing through the primary coil increases while firing the semiconductor switch. Thereafter, when the semiconductor switch is extinguished at an appropriate spark ignition timing, a high voltage is generated on the primary side of the ignition coil by the self-induction action at the moment when the primary current is cut off. Then, a higher induced voltage is generated in the secondary side coil sharing the magnetic circuit and magnetic flux with the primary side. By applying this high induced voltage to the center electrode of the spark plug, a spark discharge is generated between the center electrode and the ground electrode.

  The magnitude of the electric energy input to the spark plug for spark ignition depends on the magnitude of the primary current flowing through the primary coil of the ignition coil when the semiconductor switch is extinguished. That is, the longer the energization time for the primary side coil, the greater the electrical energy input to the secondary side coil and hence the spark plug.

  As the electrical energy input to the spark plug, that is, the spark discharge energy, increases, the ignitability of the air-fuel mixture in the cylinder improves and the combustion becomes better. The energy can be expected to increase (see the following patent document).

JP 2014-163348 A

  The turn ratio between the primary coil and the secondary coil of the ignition coil is induced by the secondary coil and applied to the electrode of the spark plug together with the magnitude of the primary voltage applied to the primary coil during ignition. It affects the initial value of the secondary voltage (or spark discharge starting voltage) as well as the duration of the spark discharge that occurs between the electrodes of the spark plug. The initial value of the secondary voltage may be rephrased as the initial value of the secondary current that flows through the electrode of the spark plug due to the spark discharge.

  Basically, the higher the initial value of the secondary voltage, the shorter the duration of the spark discharge. Conversely, the lower the initial value of the secondary voltage, the longer the duration of the spark discharge. However, the optimal initial value of the secondary voltage and the duration of the spark discharge are not always constant, and are considered to change according to the current operating conditions of the internal combustion engine.

  For example, spark discharge is more likely to occur in low-load operating regions where the air-fuel mixture is less likely to ignite and the airflow rate in the cylinder is slow, the air-fuel ratio of the air-fuel mixture is lean, and regions where the fuel injection amount is generally low. There is certainly an aspect that the mixture can be ignited more reliably by lasting longer.

  However, in a relatively high load operating region with a large amount of fuel injection, the air-fuel mixture is easily ignited and flame propagation is good, and it is not necessary to sustain the spark discharge for a long time. In other words, it can be said that the electric energy consumed for the long-lasting spark discharge is wasted in the operation region. Further, when the flow velocity of the airflow in the cylinder is high, the significance of the long duration of the spark discharge becomes small. Rather, it seems that a higher initial value of the secondary voltage applied to the spark plug is more effective for stabilizing ignition combustion and improving thermal-mechanical energy conversion efficiency. In addition, if the initial value of the secondary voltage is increased, smoldering such as carbon that adheres to and accumulates on the electrode of the spark plug can be removed by oxidation with spark discharge (so to speak, it is burned out). This is advantageous for maintaining the performance over a wide range.

  An object of the present invention is to optimize characteristics of an ignition device associated with a spark ignition type internal combustion engine and to contribute to further improvement in overall efficiency.

  According to the present invention, there is provided an ignition device for a spark ignition type internal combustion engine that ignites an air-fuel mixture in a cylinder by causing a spark discharge between electrodes of an ignition plug installed in the cylinder, wherein the reference is a predetermined operating region as a reference. An ignition coil in which the turns ratio of the primary coil and the secondary coil is selected so that the fuel consumption rate is the best value or near the best value in the operation region, and / or the fuel consumption rate is the best value in the reference operation region. Or a primary voltage setting unit for applying a primary voltage of a magnitude selected to be close to the best value to the primary coil of the ignition coil, and in the operation region other than the reference operation region, the ignition coil in the reference operation region An ignition device is provided that includes a control unit that inputs larger electric energy to the ignition coil.

  The reference operation region is preferably an operation region in which ignition of the air-fuel mixture is relatively easy and good combustion can be easily obtained, for example, an operation region with a medium load or a high load. By optimizing the ignition coil turns ratio and / or the primary voltage so that the fuel consumption rate approaches the best in this reference operation region, the duration of the spark discharge in the operation region is necessary and sufficient for the ignition combustion of the air-fuel mixture. The length can be adjusted.

  In addition, in an operation region other than the reference operation region, particularly in an operation region where ignition of the air-fuel mixture is more difficult than in the reference operation region, electric energy input to the ignition coil is more than that in the reference operation region. By increasing the value, the initial value of the secondary voltage (or secondary current) applied to the spark plug and the duration of the spark discharge are increased to improve the ignition and combustion of the air-fuel mixture.

  According to the present invention, there is provided a method for producing an ignition device for a spark ignition type internal combustion engine, wherein the primary coil of the ignition coil is set so that the fuel consumption rate is at or near the best value in a reference operation region that is a predetermined operation region as a reference. Of the primary voltage applied to the primary coil of the ignition coil so that the turn ratio between the side coil and the secondary coil is selected and / or the fuel consumption rate is at or near the best value in the reference operation region. The size is selected.

  ADVANTAGE OF THE INVENTION According to this invention, the characteristic of the ignition device accompanying a spark ignition type internal combustion engine can be optimized, and it can contribute to the further improvement of the whole efficiency.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The circuit diagram of the ignition device of 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 typically the relationship between ignition energy and the fuel consumption rate of an internal combustion engine. The figure which shows typically the relationship between the secondary voltage induced by the secondary side coil of an ignition coil, and the duration of a spark discharge in a reference | standard driving | operation area | region. The figure which shows typically the relationship between the characteristic parameter (typically the turn ratio of an ignition coil) of an ignition device, and the fuel consumption rate of the internal combustion engine in a reference | standard driving | operation area | region. The figure which shows typically the relationship between the secondary voltage induced by the secondary side coil of an ignition coil, and the duration of a spark discharge in operation areas other than a reference | standard operation area.

  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 type four-stroke 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.

  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 exhaust gas recirculation device 2 realizes a so-called high-pressure loop EGR in which a part of the exhaust gas flowing through the exhaust passage 4 is returned to the intake passage 3 and mixed with the intake air. The EGR device 2 includes an external 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 passage 21. And an EGR valve 23 that controls the flow rate of the EGR gas flowing through the EGR passage 21. 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.

  FIG. 2 shows an electric circuit of the internal combustion engine ignition device of the present embodiment. 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 a coil case together with an igniter 13 having a semiconductor switching element 131 such as an IGBT (Insulated Gate Bipolar Transistor).

  When the igniter 13 receives an ignition signal i from an ECU (Electronic Control Unit) 0 serving as a control unit in the present embodiment, first, the semiconductor switch 131 of the igniter 13 is ignited, and a current flows to the primary side of the ignition coil 14. The semiconductor switch 131 is extinguished at the timing of the spark ignition immediately after that, 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 (low voltage system) circuit including 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 one-dot chain line (the solid line will be described later). Assuming that the primary side electric circuit including the battery 17 and the primary side 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 that of 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. The semiconductor switch 131 is ignited while the magnitude of the primary current (voltage across the resistor 133) is equal to or less than a specified value, while the semiconductor switch 131 is extinguished when the magnitude exceeds the specified value. As a result, the primary current is clipped to the specified value as indicated by the alternate long and short dash line in FIG.

  The ignition coil 14 in the present embodiment is larger than a conventional coil that can generate discharge energy much larger than the energy required at the minimum for spark ignition of the air-fuel mixture filled in the cylinder 1. It has an inductance.

  The spark discharge energy required to ignite the air-fuel mixture filled in the combustion chamber of the cylinder 1 is usually about 30 mJ to 50 mJ. The conventional ignition coil is assumed to generate a spark discharge voltage exclusively upon application of such electric energy. Therefore, the heat resistance limit of the ignition coil is only enough to withstand energy of about 30 mJ to 50 mJ.

  On the other hand, in this embodiment, it is considered to increase the energy of the spark discharge as necessary, and electric energy of 100 mJ to 130 mJ at the maximum is applied to the ignition coil 14. When a large electric energy of 100 mJ is applied to a conventional ignition coil, there is a concern that it may be overheated and damaged. The ignition coil 14 in this embodiment can store much larger electric energy than that required for spark ignition of the air-fuel mixture, and even if such large electric energy is applied. It has high heat resistance so as not to cause damage due to heat generation. Of course, it is possible to avoid wasting energy by applying only a minimum amount of electrical energy necessary for spark ignition to the ignition coil 14.

In FIG. 3, the time point t ₁ is the ignition timing of the cylinder 1. At this time t ₁ , the semiconductor switch 131 of the igniter 13 associated with the cylinder 1 is extinguished, the energization of the primary coil of the ignition coil 14 associated with the cylinder 1 is cut off, and the ignition coil 14 generates The induced voltage is applied to the center electrode of the spark plug 12 of the cylinder 1.

Time t ₀ is a start time of energization of the primary coil of the ignition coil 14 in a normal state. That is, the period from time t ₀ to time t ₁ is the energization time for the primary coil of the ignition coil 14. In FIG. 3, the primary current flowing through the primary side coil in a normal state is drawn with a solid line.

In turn, the time point t ₀ ′ is a start point of energization of the primary coil of the ignition coil 14 when the electric energy for spark discharge input to the spark plug 12 is increased more than usual. That is, the period from time t ₀ ′ to time t ₁ is the energization time for the primary coil of the ignition coil 14. Since the energization start time t ₀ ′ is earlier than the normal energization start time t ₀ , the energization time in this case is longer than the normal energization time. In FIG. 3, the primary current in this case is drawn by a one-dot chain line.

As already described, the primary current flowing through the primary coil of the ignition coil 14 increases after the ignition of the semiconductor switch 131 (time t ₀ or time t ₀ ′). Accordingly, the primary current flowing through the primary coil at the ignition timing t ₁ becomes larger as the energization start time t ₀ ′ is advanced. An increase in the primary current means an increase in electrical energy applied to the ignition coil 14. As a result, the primary current is induced by the extinction of the semiconductor switch 131 (time t ₁ ) and applied to the center electrode of the ignition plug 12. This means that the induced voltage increases.

In short, as the energization start time t ₀ ′ is advanced (the primary current flowing through the primary coil at the ignition timing t ₁ is increased), the electric energy input to the spark plug 12 is increased. As a result, the voltage of the spark discharge generated between the center electrode of the spark plug 12 and the ground electrode is increased, and the duration of the spark discharge is also increased.

  In the igniter 13, the primary voltage induced in the primary coil of the ignition coil 14 is suppressed to a predetermined value for the purpose of protecting the semiconductor switch 131 from a high voltage, for example, a primary using a Zener diode 134, for example. A voltage setting unit is provided. When the semiconductor switch 131 is an IGBT, the voltage clamp Zener diode 134 is interposed between the collector and the gate of the IGBT 131, the anode is connected to the gate of the IGBT 131, and the cathode is connected to the collector of the IGBT 131. The zener diode 134 clips the magnitude of the primary voltage induced in the primary coil of the ignition coil 14 by extinguishing the IGBT 131 to a certain value within a range of 350 V to 500 V, for example, and the primary voltage is higher than that. It works to prevent a great increase.

  The igniter 13 also 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 the upper limit value.

  The ECU 0 of the present embodiment can detect an ionic current generated in the combustion chamber of the cylinder 1 during fuel combustion, and can determine the combustion state with reference to the ionic current.

  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 ionic current is drawn with a broken line, and the combustion pressure is drawn with a solid 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.

  A generator 18 serving as a power supply source for energizing the ignition coil 14, opening / closing driving of the valves 23 and 32, and an electrical system mounted on the vehicle, etc., generates engine torque from a crankshaft that is an output shaft of the internal combustion engine. The supplied power is generated and the generated power is stored in the in-vehicle power storage device 17.

  The generator 18 may be an alternator conventionally used as a generator for automobiles, or may be a motor generator having a function as an electric motor for driving a crankshaft of an internal combustion engine or an axle (and drive wheels) of a vehicle. It may be an ISG (Integrated Starter Generator). The internal combustion engine and the generator 18 are connected via, for example, a winding transmission device having a belt and a pulley as elements.

  The IC regulator or controller 181 attached to the generator 18 receives a control signal m issued from the ECU 0 and commanding a target value of the output voltage of the generator 18. Then, in order to make the terminal voltage of the power storage device 17 (or the power supply voltage supplied to the electrical system) follow the commanded target voltage, the semiconductor switching element is switched and applied to the excitation (field) winding. PWM (Pulse Width Modulation) control for adjusting the magnitude of the current is performed. The output voltage of the generator 18 increases as the excitation current flowing through the excitation winding increases.

  The generator 18 that generates power is a mechanical load when viewed from the internal combustion engine. When the output voltage of the generator 18 exceeds the terminal voltage of the power storage device 17, the power storage device 17 is charged and power is supplied from the generator 18 to various electric loads of the electrical system. That is, the generator 18 works to generate electric energy by consuming energy of rotation of the crankshaft of the internal combustion engine. The amount of charge to the power storage device 17 and the amount of power supplied to the electrical load depend on the potential difference between the output voltage of the generator 18 and the terminal voltage of the power storage device 17.

  Conversely, when the output voltage of the generator 18 is less than or close to the terminal voltage of the power storage device 17, the power storage device 17 is not charged, and no power is supplied from the generator 18 to the electrical load of the electrical system (power storage). The electric load may be supplied from the device 17). That is, the generator 18 does not perform work that consumes the energy of rotation of the crankshaft of the internal combustion engine, or the work is reduced.

  In short, when a high power generation voltage is commanded from the ECU 0 to the generator 18, the mechanical load of the generator 18 with respect to engine rotation increases, and when a low power generation voltage is commanded, the mechanical load of the generator 18 with respect to engine rotation decreases.

  Further, the IC regulator or controller 181 receives a control signal m issued from the ECU 0 and commands the upper limit value of the excitation current, and detects it via the magnitude of the excitation current flowing through the excitation winding of the generator 18. Limit the excitation current to the commanded upper limit or less. More specifically, the IC regulator or controller 181 controls fDUTY, which is a DUTY ratio of the excitation current flowing through the excitation winding. The upper limit of the excitation current is intended to prevent the mechanical rotation on the internal combustion engine 100 from becoming excessive and the engine rotation from becoming unstable. Therefore, for example, the upper limit value of the excitation current is lower when the refrigerant compression compressor (not shown) of the air conditioner mounted on the vehicle is operating and when it is not operating.

  Clipping to the upper limit value of the excitation current has priority over following the target voltage value of the power generation voltage of the generator 18. That is, even if the terminal voltage of the power storage device 17 is still less than the target voltage commanded from the ECU 0, the IC regulator or controller 181 has the excitation current flowing through the excitation winding of the generator 18 at the upper limit commanded from the ECU 0. If so, do not increase the excitation current any further.

  The generator 18 performs regenerative braking when the vehicle is decelerated, and can recover the kinetic energy of the vehicle as electric energy. The ECU 0 performs excitation that flows through the excitation winding of the generator 18 when the amount of depression of the accelerator pedal by the driver becomes 0 or less than a predetermined value close to 0, that is, when deceleration of the internal combustion engine and the vehicle is requested. A control signal m for raising the upper limit value of the current and the output voltage of the generator 18 is supplied to the IC regulator or controller 181.

  The power storage device 17 is a battery (lead battery, lithium ion battery, nickel metal hydride battery, or the like), a capacitor, or the like. A plurality of types of power storage devices 17 may be combined and mounted on the vehicle.

  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 b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. An accelerator opening signal c output from a sensor that detects the amount or the opening of the throttle valve 32 as an accelerator opening (so-called required engine load), an intake air temperature in the intake passage 3 (particularly, the surge tank 33), and From an intake air temperature / intake pressure signal d output from a temperature / pressure sensor that detects intake air pressure, a sensor that detects a terminal voltage and / or terminal current (particularly, battery voltage and / or battery current) of the in-vehicle power storage device 17. The output voltage / current signal e is output from a water temperature sensor that detects the cooling water temperature indicating the temperature of the internal combustion engine. A coolant temperature signal f, a brake signal g output from a sensor (such as a brake switch or a master cylinder pressure sensor) that detects that the brake pedal is depressed or the amount of depression of the brake pedal, and an air-fuel mixture in the combustion chamber of the cylinder 1 A current signal h or the like output from a circuit for detecting an ionic current generated by the combustion of is input.

  From the output interface, the ignition signal i for the igniter 13, the fuel injection signal j for the injector 11, the opening operation signal k for the throttle valve 32, the opening operation signal l for the EGR valve 23, the generator A control signal m or the like for controlling the generator 18 is output to an IC regulator or controller 181 attached to 18.

  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). The ECU 0 applies various control signals i, j, k, l and m corresponding to the operation parameters via the output interface.

  The required value for the required EGR rate, that is, the EGR rate, which is the ratio of the EGR gas in the air-fuel mixture filled in the cylinder 1, is highest in the medium load region where the load of the internal combustion engine is medium, and the load decreases from there. It decreases, and it decreases as the load increases. The required EGR rate is 0 and the opening degree of the EGR valve 23 is also 0 in an idle operation or a low load operation region close to this, or in a high load operation region where the accelerator opening is fully open (full load) or close to full open.

  The ECU 0 of the present embodiment determines the magnitude of the electric energy input to the ignition coil 14 and the spark plug 12 to ignite the air-fuel mixture filled in the cylinder 1 according to the current operating range of the internal combustion engine [engine speed, engine Load (or intake pressure in surge tank 33, intake (fresh air) amount or fuel injection amount filled in cylinder 1)], current internal combustion engine temperature (particularly, cooling water temperature), air-fuel ratio of the air-fuel mixture, and the like Decide accordingly.

  In the memory of the ECU 0, parameters indicating the operation region of the internal combustion engine, the cooling temperature, the air-fuel ratio, etc., the magnitude of the electric energy input to the spark plug 12, in other words, the energization time to the primary coil of the ignition coil 14 Map data that defines the relationship between and is stored. The energization time of the primary coil is determined when the absolute value of the amount of change in the engine speed per unit time is not more than a predetermined value, that is, when the internal combustion engine is in a steady operation state where neither acceleration nor deceleration is performed. It is determined in advance experimentally (by testing or fitting) so that it is stable and the engine torque becomes maximum or close to maximum. The ECU 0 knows the energization time to the primary coil of the ignition coil 14 by searching the map using the current operation region of the internal combustion engine, the coolant temperature, the air-fuel ratio, and the like as keys. Further, this energization time may be corrected by the current terminal voltage (in particular, battery voltage) of the power storage device 17 that applies a voltage to the primary coil of the ignition coil 14. In this case, the energization time is extended as the terminal voltage of the power storage device 17 is lower.

  FIG. 5 shows the relationship between the magnitude of the electric energy input to the spark plug 12 to cause spark discharge and the fuel consumption rate of the internal combustion engine in the steady operation state in a certain operation region [engine speed, engine load]. Is schematically shown. The fuel consumption rate is the amount of fuel consumed by the internal combustion engine for traveling the vehicle for a unit distance or the amount of fuel consumed by the internal combustion engine for outputting unit horsepower.

W ₀ represents electric energy of about 30 mJ that has been input to the spark plug 12 in the past. When the electric energy input to the spark plug 12, that is, the energy of spark discharge, is increased from the conventional value W ₀ , the combustibility of the air-fuel mixture in the cylinder 1 is improved and the cylinder 1 is extracted by heat-mechanical energy conversion. Mechanical energy increases. In other words, the engine torque output from the internal combustion engine increases. The effect of improving the heat-mechanical energy conversion efficiency due to the increase in ignition energy appears more greatly in the low load operation region, the operation region where the EGR rate is large, or the situation of lean air-fuel ratio.

However, the electrical energy input to the spark plug 12 is originally generated by the generator 18 that is driven by the transmission of rotational torque from the internal combustion engine. Increasing the electrical energy input to the spark plug 12 means increasing mechanical energy that the generator 18 consumes for power generation. For this reason, in order to generate the amount of increase in the mechanical energy output from the internal combustion engine by increasing the electrical energy input to the spark plug 12 and the increase in the electrical energy input to the spark plug 12 by the generator 18. There is a point W _{B at} which the amount of mechanical energy spent in excess is balanced. Increasing the electric energy input to the spark plug 12 above W _B will rather deteriorate the efficiency and reduce the fuel efficiency of the vehicle.

Therefore, ECU0 is a W _B or its neighboring point corresponding to each operating region, sets the ignition energy in the operating region. However, depending on the operating region, W _B may be approximately equal to W ₀ , ie, the ignition energy may not be increased substantially or at all. For example, in a relatively high load operating region where the fuel injection amount is large, the air-fuel mixture is easily ignited in the first place, the flame propagation is good, and the heat-mechanical energy conversion efficiency by increasing the electric energy input to the spark plug 12 The improvement effect of is expected to be negligible, and there may be no clear difference between W _B and W ₀ .

If the reference operating region is defined as an operating region in which the mixture can be easily ignited and good combustion is easily obtained, for example, a specific operating region within the range of medium load or high load, ignition is performed in the reference operating region. The electric energy W _B input to the coil 14 and thus to the spark plug 12 becomes a predetermined value between 30 mJ and 50 mJ, which is about 30 mJ, which is conventionally input to the spark plug 12, or slightly larger.

In contrast, the magnitude of the electrical energy W _B to be inputted to the ignition plug 12 in the operating region other than the nominal operating region, it takes a more values in the reference operation range. In particular, in the ignition difficult operating area the air-fuel mixture in comparison with the reference operating range increases than electrical energy W _B electrical energy W _B to be inputted to the ignition plug 12 in the reference operation range. The electric energy W _{B at} that time reaches 100 mJ to 130 mJ at the maximum as already described.

  Thus, in the internal combustion engine ignition device of the present embodiment, the turn ratio of the primary side coil and the secondary side coil that defines the characteristics of the ignition coil 14 is set so that the fuel consumption rate is the best value or near the best value in the reference operation region. Is selected to be

  FIG. 6 shows a secondary voltage (in other words, spark discharge) induced by the secondary coil and applied to the electrode of the spark plug 12 when electric energy of a certain magnitude is input to the primary coil of the ignition coil 14. This shows the relationship between the secondary current flowing through the electrode of the spark plug 12 and the duration of the spark discharge. In FIG. 6, the alternate long and short dash line represents the relationship between the secondary voltage and the duration of the spark discharge in an ignition device employing a conventional ignition coil. The size of the hatched area corresponds to the magnitude of the electric energy input to the ignition coil 14. In the conventional ignition device, the spark discharge generated between the electrodes of the spark plug 12 continues longer than the minimum duration T required to properly ignite the air-fuel mixture and burn the air-fuel mixture in the reference operation region. It was. It is a waste of electrical energy that the spark discharge lasts longer than the time duration T necessary and sufficient for the combustion of the air-fuel mixture.

  In FIG. 6, the solid line represents the relationship between the secondary voltage and the duration of the spark discharge when the ignition coil 14 is selected according to the present invention. The size of the shaded area corresponds to the magnitude of the electric energy input to the ignition coil 14. Needless to say, this is equivalent to the size of the hatched area. In the ignition device of the present embodiment, the duration of the spark discharge is approximately equal to or slightly longer than the duration T necessary and sufficient to properly ignite the air-fuel mixture in the reference operation region. Instead, the initial value of the secondary voltage is higher than that of the conventional ignition device. An increase in the initial value of the secondary voltage has the effect of making the ignition of the air-fuel mixture more reliable.

FIG. 7 shows the relationship between the characteristic parameters of the ignition device, here the turn ratio of the ignition coil 14, and the fuel consumption rate of the internal combustion engine in the reference operating region. The primary voltage applied to the primary coil of the ignition coil 14 at the ignition timing is V ₁ , the secondary voltage induced to the secondary coil as a result of the primary voltage being applied to the primary coil is V ₂ , and the primary coil If the number of turns is N ₁ and the number of turns of the secondary coil is N ₂ ,
V ₂ ≒ V ₁ × (N ₂ / N ₁ )
This relationship is established. If the turn ratio (N ₂ / N ₁ ) of the ignition coil 14 is changed, the initial value of the secondary voltage V ₂ changes, and the duration of the spark discharge generated between the electrodes of the spark plug 12 also changes due to its side effects. In the present embodiment, ignition coils having various turns ratios are selected, and among them, the turn ratio ignition coil 14 in which the fuel consumption rate of the internal combustion engine in the reference operation region takes the best value F _B or a value close thereto. Is selected and used in the ignition system. In the ignition device mounted with the ignition coil 14 selected in this way, the duration of the spark discharge in the reference operation region becomes shorter and the initial value of the secondary voltage becomes higher than in the conventional ignition device.

An operation region in which the air-fuel mixture is less likely to ignite than the reference operation region, specifically, a region where the engine load is lower than the reference operation region, and an EGR rate is higher than the reference operation region (the amount of fresh air charged into the cylinder 1 is In the (less) region, the electric energy W _B input to the ignition coil 14 is increased more than that in the reference operation region. As a result, as shown by a broken line in FIG. 8, the duration of the spark discharge is longer and the initial value of the secondary voltage is higher than the reference operation region (represented by the solid line). As a result, the ignitability to the air-fuel mixture is improved, and combustion is surely and favorable. As in FIG. 6, the size of the shaded area corresponds to the amount of electrical energy input to the ignition coil 14.

In this embodiment, a spark ignition internal combustion engine ignition device that ignites an air-fuel mixture in a cylinder 1 by causing a spark discharge between the electrodes of a spark plug 12 installed in the cylinder 1, which is a predetermined operation as a reference. in the reference operating region is a region, under the condition that the inputs ignition energy of a predetermined size to the ignition coil 14, and a primary coil so that the fuel consumption rate becomes the best value F _B or best value F _B near two an ignition coil 14 which turns ratio the next coil is selected, the operation region other than the reference operating region, a large electric energy W _B than the electrical energy W _B to enter in the reference operation range in the ignition coil 14 An ignition device including a control unit 0 that inputs to the ignition coil 14 is configured.

  According to the present embodiment, in a situation where the ignitability of the air-fuel mixture can be improved and the effect of improving the thermal-mechanical energy conversion efficiency can be expected, the electric energy input to the ignition coil 14 and thus the spark plug 12, in other words, the energy of the spark discharge. The air-fuel mixture filled in the cylinder 1 can be stably ignited and burned.

  In the first place, it is not necessary to increase the electric energy input to the spark plug 12 in the reference operation region where the air-fuel mixture is easily ignited and the flame propagation is good or in the operation region close to the reference operation region. Moreover, it is avoided that the spark discharge between the electrodes of the spark plug 12 lasts longer than the duration T required for ignition of the mixture, and instead the initial value of the secondary voltage is increased. As a result, it is possible to improve the ignitability of the air-fuel mixture in the operating region and further improve the heat-mechanical energy conversion efficiency. In addition, if the secondary voltage applied to the electrode of the spark plug 12 is increased, carbon or the like that adheres to and accumulates on the electrode of the spark plug 12 is oxidized and removed during the spark discharge. Effective for maintaining performance over a long period of time.

  Accordingly, it is possible to realize stabilization of ignition and combustion of the air-fuel mixture and improvement of drivability, reduction of electric energy consumed for spark ignition, and improvement of overall fuel efficiency of the internal combustion engine.

The present invention is not limited to the embodiment described in detail above. For example, in the above embodiment, the turns ratio of the primary side coil and the secondary side coil of the ignition coil 14 is adjusted so that the fuel consumption rate becomes the best value F _B or near the best value F _B in the reference operation region. . However, instead of this, or together with this, the magnitude of the primary voltage applied to the primary coil is adjusted so that the fuel consumption rate becomes the best value F _B or near the best value F _B in the reference operation region. Also good.

Again, the primary voltage applied to the primary coil of the ignition coil 14 at the ignition timing is V ₁ , and the secondary voltage induced in the secondary coil as a result of the primary voltage being applied to the primary coil is V _2. If the number of turns of the primary coil is N ₁ and the number of turns of the secondary coil is N ₂ ,
_{V2 ≒ V 1 × (N 2} / N 1)
This relationship is established. If the primary voltage V ₁ applied to the primary coil is changed, the initial value of the secondary voltage V ₂ changes, and the duration of the spark discharge generated between the electrodes of the spark plug 12 also changes as a side effect. The magnitude of the primary voltage V ₁ applied to the primary coil can be adjusted through the design or selection of the primary voltage setting unit 314. Specifically, the Zener diodes 314 having various magnitudes of breakdown voltage, that is, the clamp voltage V ₁ are selected and selected from them (under the condition that a predetermined magnitude of ignition energy is input to the ignition coil 14). The zener diode 314 having the breakdown voltage V ₁ is selected so that the fuel consumption rate of the internal combustion engine in the reference operation region takes the best value F _B or a value close thereto, and is adopted in the ignition device. The ignition device mounted with the Zener diode 314 selected in this way has a shorter duration of spark discharge in the reference operation region and a higher initial value of the secondary voltage than the conventional ignition device.

  The present invention can also be applied to a CDI (Capacitor Discharge Ignition) type ignition device. In this case, the capacitor that applies the primary voltage to the primary coil of the ignition coil corresponds to the primary voltage setting unit referred to in the present invention.

  The magnitude of the electrical energy input to the spark plug 12 installed in each of the plurality of cylinders 1 included in the internal combustion engine may be equal for each cylinder 1 or may be different for each cylinder 1.

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

  The present invention can be used for an ignition device of a spark ignition type internal combustion engine mounted on a vehicle or the like.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 11 ... Injector 12 ... Spark plug 13 ... Igniter 131 ... Semiconductor switch (IGBT)
134: Primary voltage setting unit (Zener diode)
14 ... Ignition coil b ... Crank angle signal c ... Accelerator opening signal i ... Ignition signal

Claims (2)

An ignition device for a spark ignition internal combustion engine that ignites an air-fuel mixture in a cylinder by causing a spark discharge between electrodes of a spark plug installed in the cylinder,
Ignition coil in which the turn ratio of the primary side coil and the secondary side coil is selected so that the fuel consumption rate becomes the best value or near the best value in the reference operation region, which is a predetermined operation region as a reference, or the reference operation A primary voltage setting unit for applying a primary voltage of a magnitude selected so that the fuel consumption rate is the best value or near the best value in the region to the primary coil of the ignition coil;
An ignition device comprising: a control unit that inputs electric energy larger than electric energy input to the ignition coil in the reference operation region in an operation region other than the reference operation region. A method for producing an ignition device for a spark ignition type internal combustion engine that ignites an air-fuel mixture in a cylinder by inducing spark discharge between electrodes of an ignition plug installed in the cylinder,
Select the turn ratio between the primary coil and the secondary coil of the ignition coil so that the fuel consumption rate is at or near the best value in the reference operation region, which is a predetermined operation region that serves as a reference, or the reference operation A method for producing an ignition device, characterized in that the magnitude of the primary voltage applied to the primary coil of the ignition coil is selected so that the fuel consumption rate is at or near the best value in the region.

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