JP2010116879A - Ignition control device or ignition control method for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems that a discharge pattern required by an internal combustion engine when an improvement in combustion varies depending on the circumstances regardless of a combustion system, that, for example, when lean limitations are expanded by homogeneous combustion or EGR is introduced into a combustion chamber in large quantity, it is considered desirable that a secondary current which reaches its peak immediately after the start of discharge be higher, that when stratified charge combustion is performed, it is considered desirable that a discharge period be made longer after securing a certain amount of secondary current, and that a request for ignition is not touched on when the combustion system is switched from the homogeneous combustion to the stratified charge combustion or from the stratified charge combustion to the homogeneous combustion. <P>SOLUTION: Each cylinder of the ignition control device includes one ignition plug 111 and at least two ignition coils 106. Each ignition coil 106 is controlled simultaneously or individually so that the ignition pattern can be varied with respect to the switching of the combustion system. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ignition control device or an ignition control method for an internal combustion engine. More specifically, the present invention relates to an ignition control device or an ignition control method that provides an appropriate discharge energy consumption mode (hereinafter, discharge pattern) according to a combustion method.

  As a spark ignition type internal combustion engine, an internal combustion engine having a plurality of ignition coils per cylinder is known for the purpose of improving ignitability and combustion stability. For example, in Patent Document 1, one ignition plug and two ignition coils are provided for one cylinder, and in stratified combustion, when the mixture in the combustion chamber has a rounded shape, the first ignition is performed. When the interval of the second ignition is narrowed and the shape of the air-fuel mixture is long, a technique for increasing the interval between the first and second ignitions can be cited.

Japanese Patent No. 3767383

  However, regardless of the combustion method, the discharge pattern required by the internal combustion engine when improving combustion differs depending on the situation. For example, when trying to expand the lean limit by homogeneous combustion, or when introducing a large amount of EGR into the combustion chamber, it is desirable that the secondary current peaking immediately after the start of discharge be higher. In the case of stratified combustion, it is desirable to increase the discharge time after securing a certain amount of secondary current. In addition, there is no mention of ignition requirements when the combustion method is switched from homogeneous combustion to stratified combustion or from stratified combustion to homogeneous combustion.

  In view of the above problems, in the present invention, each cylinder is provided with one ignition plug and at least two ignition coils, and each ignition coil is changed so as to change the ignition pattern in response to switching of the combustion system. Control simultaneously or individually.

  Combustion can be improved by performing optimal ignition control according to the combustion method of the internal combustion engine.

  Hereinafter, examples will be described in detail.

  FIG. 1 shows a configuration diagram relating to the first embodiment of the present invention. In the present embodiment, a multi-cylinder engine is mainly assumed. In the following drawings, one cylinder will be described for the sake of simplicity. FIG. 1 is a configuration diagram of an internal combustion engine (101) capable of typical stratified combustion. As a feature of the internal combustion engine (101), a fuel injection valve (108) capable of directly injecting fuel into the combustion chamber is provided. First, air in the atmosphere is drawn into the combustion chamber (109) from the intake passage (103) via an air filter (not shown). Further, an air flow sensor (not shown) for measuring the intake air amount and an electric throttle valve (not shown) for adjusting the intake air amount are provided in the intake passage (103), and the control unit (102 ) Calculates the intake air amount and controls an electric throttle valve (not shown). On the downstream side of the electric throttle valve (not shown), a TGV (105) that is a gas flow control valve and a partition plate (104) are provided, and an outlet is opened near the intake valve (107). By providing the intake passage, it is possible to generate a tumble flow (114) in which the air sucked into the combustion chamber (109) flows in the vertical direction with respect to the combustion chamber (109). At this time, in order to control the formation of the gas flow, it is necessary to control the amount of air supplied from the auxiliary intake passage, and the TGV (105) is used to control the amount of air supplied from the original intake passage (103). The ratio can be controlled. On the other hand, the fuel is sent to a high-pressure fuel pump (not shown) by a lift pump (not shown) that pumps up from a fuel tank (not shown), and is pressurized by a high-pressure fuel pump (not shown). The fuel is injected directly into the combustion chamber (109) by the fuel injection valve (108) through a gallery (not shown). When stratified combustion is performed, fuel is injected from the fuel injection valve (108) into the combustion chamber (109) during the compression stroke to form a combustible air-fuel mixture around the spark plug (111). In the figure, spray 1 (115) and spray 2 (116) correspond to this. The spray 1 (115) is directed to the piston (110), the fuel injection valve (108) injects, the fuel colliding with the crown surface of the piston (110) is wound upward, and toward the spark plug (111). Head over. The spray 2 is set so as to be directed directly from the fuel injection valve (108) toward the spark plug (111), and the spark plug (111) is combusted by igniting the air-fuel mixture as a lump of spray. However, every time (each combustion cycle), the air-fuel mixture does not always reach the spark plug at the same timing, and the air-fuel mixture does not necessarily have the same shape. Further, the air-fuel mixture after combustion is discharged to the atmosphere via the exhaust path (113) outside the combustion chamber (109) when the exhaust valve (112) is opened as exhaust gas. A catalyst (not shown) is provided in the exhaust path (113) for the purpose of purifying exhaust gas.

  The ignition control device according to the first embodiment will be described in more detail. The control unit (102) allows the spark plug (111) to discharge a spark at a predetermined timing based on the rotation angle of the crankshaft (not shown). Control. When the ignition signal (117, 118) is output from the control unit (102) to the ignition coil (106), since the ignition signal 1 (117) and the ignition signal 2 (118) can be controlled independently, simultaneous ignition is performed. In addition, individual ignition can be performed. Based on the respective ignition signals (117, 118), the ignition coil (106) charges or cuts off electric energy with a plurality of primary coils in the ignition coil (106). At the timing when the electric energy is interrupted by the ignition signal (117, 118), electric energy having a high voltage is generated on the secondary coil side in the ignition coil by the action of electromagnetic induction. The high-voltage electrical energy output from the secondary coil is sent to the spark plug (111) to generate a spark. At this time, a gap between the center electrode and the outer electrode of the spark plug (111) (hereinafter referred to as a spark gap). ), The required value of the secondary voltage at which the spark starts to fly (hereinafter referred to as the required secondary voltage) is determined. Therefore, when the secondary voltage supplied by the ignition coil (106) exceeds the required secondary voltage, A spark will be released, and the moment when this spark flies becomes the actual ignition timing. In other words, it can be said that the required secondary voltage is required from the internal combustion engine side. More specifically, the state around the spark plug (111) (pressure, temperature, humidity, air-fuel ratio, etc.) and the shape of the spark plug (111) And the material. Speaking from the ignition coil (106) side, it is required to supply a secondary voltage exceeding the required secondary voltage. In this figure, the primary coil of the ignition coil (106) is an ignition coil having two paths and one secondary coil, but two or more normal ignition coils are provided in parallel to the ignition plug (111). The same effect can be obtained also when discharging.

  Next, an explanation regarding the ignition signal and the ignition coil will be given with reference to FIG. FIG. 2 shows a result of measuring signals related to a conventional ignition control device (internal combustion engine including one ignition coil and one ignition plug). The top of the figure is the ignition signal (201) output from the control unit (102 in FIG. 1). The ignition signal (201) is normally at a low level, and when ignition is performed, the ignition signal (201) is at a high level. While the ignition signal (201) is at a high level, the primary in the ignition coil This is a period for charging (filling) the coil with electrical energy. This is called energization time (206). When the ignition signal (201) again becomes a low level, the ignition coil cuts off charging of the primary coil and starts discharging. This timing is called ignition timing (207). Next, the primary current will be described. The second primary current (202) from the top in the figure indicates that the current value increases as it goes upward in the figure, and that the electrical energy is charged in the primary coil as the current value increases. . The rising curve of the primary current accompanying charging depends on the internal inductance of the primary coil. If the inductance is large, the increase in the current value accompanying charging is delayed (it takes time to obtain the same current value). A large current can be stored. In general, the ignition coil has a current limiting circuit. For example, even if the energization time (206) is made longer than the time shown in the figure and the primary current (202) to be charged is increased, the ignition coil is constant. When the amount of current value is reached, the primary coil can no longer be charged with current. At the moment when the ignition signal (201) becomes a low level, the primary current (202) drops rapidly, which indicates that the electric energy in the primary coil has moved to the secondary coil. Further, the value of the primary current (202) that becomes the maximum value immediately before the primary current is cut off is referred to as the primary cut-off current (208). In the notation of the electric energy transferred from the primary coil to the secondary coil, the third from the top of FIG. 2 is the secondary voltage (203) and the fourth secondary current (204) from the top of FIG. The secondary voltage (203) and the secondary current (204) indicate that the values increase in the downward direction of the figure. The secondary voltage that can be supplied by the ignition coil is determined by the voltage applied to the primary coil and the ratio of the number of turns of the primary coil and the number of turns of the secondary coil (turn ratio). The secondary voltage that can be supplied must be high. When the required secondary voltage and the secondary voltage that can be supplied by the ignition coil are reversed, no spark is emitted from the spark plug, resulting in misfire. Specifically, there is a case where the required secondary voltage rises for some reason and the secondary voltage supplied from the ignition coil cannot satisfy this. On the other hand, the secondary current (204) is determined from the resistance value inside the ignition coil, the inductance of the secondary coil, and the like, and has a close relationship with the duration of the spark = discharge time (209). In general, an ignition coil having a longer discharge time (209) has a lower secondary current (204), while an ignition coil having a shorter discharge time (209) has a lower secondary current (204). Get higher. The discharge pattern (205) shows the discharge energy from the spark plug, and the change of the discharge energy can be confirmed. Since the discharge energy can be obtained by the equation of secondary voltage × secondary current × time, the area of the oblique line (210) corresponds to this in the figure. The larger the area of the discharge energy (210), the more effective the combustion stability can be expected when the combustion state of the internal combustion engine is poor.

  Next, the discharge pattern will be described with reference to FIG. FIG. 3 shows the discharge pattern (301) of a short discharge ignition coil having a short discharge time characteristic, the discharge pattern (302) of a long discharge ignition coil having a long discharge characteristic, and a short discharge ignition coil. It is the figure which showed the said discharge pattern (303) which can be obtained by igniting and a long discharge type ignition coil simultaneously. The discharge pattern (301) of the short discharge ignition coil is characterized in that the discharge time is shorter than the discharge pattern (302) of the long discharge ignition coil (305, 306). The peak discharge energy (310) at the ignition timing (in the figure: 304) is higher than the discharge energy peak (311) of the long discharge ignition coil. It can be said that the peak of the discharge energy is a high secondary current. This is because the secondary voltage is determined by the required secondary voltage (such as the operating state of the internal combustion engine), and therefore, if the operating state of the internal combustion engine is the same, the peak of the discharge energy is dominated by the secondary current. is there. Here, as specific usage, a short discharge type ignition coil (301) is used at the time of homogeneous combustion, and a long discharge type ignition coil (302) is used at the time of stratified combustion. The discharge pattern in the present invention (303) that combines both of the above-described discharge patterns and satisfying the discharge pattern and switching between stratified combustion and homogeneous combustion or between homogeneous combustion and stratified combustion can be achieved without impairing combustion stability. Smooth combustion switching can be performed.

  This will be described with reference to FIG. 4 as a specific control flow. First, it is determined whether the combustion is switched (S401). If the combustion is switched, an ignition signal is sent to a plurality of ignition coils simultaneously or individually. Then, the ignition coil is driven (S404). If it is not during combustion switching, it is further determined whether the combustion method is homogeneous combustion or stratified combustion (S402). In the case of homogeneous combustion, ignition control using a short discharge ignition coil is performed from the outline (S403). In the case of stratified combustion, ignition control using a long discharge ignition coil is performed (S405).

  Also, during stratified combustion, the air-fuel ratio may be lean between the electrodes of the spark plug (111) because the state of the air-fuel mixture differs during the combustion cycle, so both ignition coils are used simultaneously. However, it may be used in a state where the secondary current is high.

1 is a basic configuration diagram of the present invention. Conventional discharge energy explanatory drawing. Explanatory drawing of discharge energy of this invention. The flowchart of this invention.

Explanation of symbols

101 Internal combustion engine 102 Control unit 103 Intake path 104 Partition plate 105 Gas flow control valve 106 Ignition coil 107 Intake valve 108 Fuel injection valve 109 Combustion chamber 110 Piston 111 Exhaust valve 112 Exhaust path 114 Tumble flow 115 Spray 1
116 Spray 2
117 Ignition signal 1
118 Ignition signal 2

Claims (1)

In an ignition control device for an internal combustion engine that has at least two ignition coils for one ignition plug that ignites an air-fuel mixture for each cylinder, and performs switching between homogeneous combustion and stratified combustion,
One ignition coil has a property of high secondary current at the start of discharge, and the other ignition coil has at least one ignition coil having a property of long discharge time,
When the combustion of the internal combustion engine is homogeneous combustion, at least ignition is performed using an ignition coil having a property of a high secondary current at the start of discharge,
When the combustion of the internal combustion engine is stratified combustion, ignition is performed using an ignition coil having a property of at least a long discharge time,
When the combustion of the internal combustion engine is during combustion switching between homogeneous combustion and homogeneous combustion, at least both an ignition coil having a high secondary current property at the start of discharge and an ignition coil having a long discharge time property An ignition control device characterized by controlling.

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