JP2017190760A - Igniter of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an igniter of an internal combustion engine capable of suppressing deterioration of driveability.SOLUTION: An igniter of an internal combustion engine includes: boost circuit containing a capacitor; an ignition coil configured to ignite an ignition plug of an internal combustion engine with electric power input from the boost circuit; a capacity acquisition unit configured to acquire the capacity of the capacitor; and a control unit configured to set an operation region, in which at least one of the rotational frequency and load of the internal combustion engine becomes smaller as the capacity of the capacitor becomes smaller, to a region in which lean combustion is performed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an ignition device for an internal combustion engine.

  An ignition coil and a booster circuit are sometimes used to ignite a spark plug of an internal combustion engine. The booster circuit includes a capacitor, and when the capacitor is discharged, power is supplied to the ignition coil and the spark plug is ignited (for example, Patent Document 1).

Japanese Patent Laid-Open No. 2002-242806

  However, when the capacity of the capacitor is reduced due to, for example, aging, the energy stored in the capacitor is reduced, and the power supplied to the ignition coil is also reduced. As a result, it becomes difficult to obtain energy for ignition of the spark plug, and ignition delay and misfire in the internal combustion engine occur, which may reduce drivability. In particular, when performing lean combustion, ignition delay and misfire are likely to occur.

  Accordingly, an object of the present invention is to provide an ignition device for an internal combustion engine that can suppress a decrease in drivability.

  The object is to provide a booster circuit including a capacitor, an ignition coil for igniting a spark plug of an internal combustion engine with electric power input from the booster circuit, a capacity acquisition unit for acquiring the capacity of the capacitor, and a capacity of the capacitor. A control unit that sets an operation region in which at least one of the rotational speed and load of the internal combustion engine is smaller as a region where lean combustion is performed can be achieved as the smaller the engine is.

  An ignition device for an internal combustion engine that can suppress a decrease in drivability can be provided.

FIG. 1 is a block diagram illustrating an ignition device. FIG. 2 is a diagram showing an operation region of the engine. FIG. 3 is a flowchart showing an example of control executed by the ECU.

  Hereinafter, the ignition device 100 of the present embodiment will be described with reference to the drawings. FIG. 1 is a block diagram illustrating an ignition device 100. The ignition device 100 is mounted on, for example, an automobile.

  As shown in FIG. 1, an ignition device 100 for an internal combustion engine includes an ECU 10 (Engine Control Unit, control unit), an engine 20 (internal combustion engine), a booster circuit 30, an ignition coil 40, and a detection unit 42.

  The engine 20 includes a fuel injection valve 22 and a spark plug 24, and is, for example, a gasoline engine. An intake path 21 and an exhaust path 23 are connected to the engine 20. Air is supplied to the engine 20 through the intake path 21. An air flow meter 26 provided in the intake path 21 measures the intake air amount. The fuel injection valve 22 injects fuel into a combustion chamber (not shown) of the engine 20. The spark plug 24 ignites and burns a mixture of fuel and air. Exhaust gas generated by the combustion is discharged from the exhaust path 23 to the outside of the vehicle. One end of the EGR path 25 is connected to the exhaust path 23, and the other end is connected to the intake path 21. A part of the exhaust gas returns to the engine 20 through the EGR path 25. An EGR valve 28 is provided in the middle of the EGR path 25, and the gas flow rate in the EGR path 25 changes according to the opening degree of the EGR valve 28.

  The booster circuit 30 is a circuit including a capacitor 32 and is electrically connected to the ignition coil 40. By discharging the electric charge charged in the capacitor 32, electric power is supplied to the ignition coil 40 and the ignition plug 24 is ignited. The capacitance C of the capacitor 32 may decrease due to changes over time, for example.

  The detection unit 42 is a circuit including, for example, a resistor, a capacitor, and a coil, and is electrically connected to the booster circuit 30. The detection unit 42 detects the capacitance C of the capacitor 32 of the booster circuit 30. Capacitance may be described as capacitance.

  The rotation speed sensor 44 detects the rotation speed of the engine 20. The accelerator opening sensor 46 detects the accelerator opening of the vehicle.

  The ECU 10 is a computer including a ROM (Read Only Memory), a RAM (Random Access Memory), a CPU (Central Processing Unit), and the like (not shown). The ECU 10 controls the booster circuit 30 to cause the capacitor 32 to perform discharge. The ECU 10 acquires the capacitance C of the capacitor 32 detected by the detection unit 42. As will be described later, the ECU 10 changes the fuel injection amount of the fuel injection valve 22 and the opening degree of the EGR valve 28 according to the capacity C of the capacitor 32.

  The ECU 10 acquires the intake air amount detected by the air flow meter 26, the rotational speed of the engine 20 detected by the rotational speed sensor 44, and the accelerator opening detected by the accelerator opening sensor 46. The ECU 10 estimates the load of the engine 20 based on the intake air amount and the accelerator opening. Further, the ECU 10 determines a region where the engine 20 performs lean combustion and a region where rich combustion is performed based on the load and the rotational speed.

  FIG. 2 is a diagram showing an operation region of the engine 20. The horizontal axis represents the engine speed and the vertical axis represents the load of the engine 20. The rotational speed R1 is greater than R2 and R3, and R2 is greater than R3. The load L1 is larger than L2 and L3, and L2 is larger than L3. As indicated by a broken line in FIG. 2, a region where the rotation speed is R1 or less and the load is L1 or less is defined as a region A1. As indicated by the dotted line, a region where the rotational speed is R2 or less and the load is L2 or less is defined as a region A2. As indicated by the solid line, a region where the rotational speed is R3 or less and the load is L3 or less is defined as a region A3. Regions A1 to A3 are regions where the engine 20 performs lean combustion. That is, the engine 20 performs lean combustion within each region, and performs rich combustion outside the region. The ECU 10 selects any one of the regions A1 to A3 as the operation region of the engine 20 according to the capacity C of the capacitor 32.

  FIG. 3 is a flowchart showing an example of control executed by the ECU 10. ECU10 acquires the capacity | capacitance C of the capacitor | condenser 32 detected by the detection part 42 (step S1).

  The ECU 10 determines whether or not the capacity C is equal to or less than a predetermined capacity C1 (step S2). If C is greater than C1 (No in step S2), the ECU 10 ends the control. On the other hand, when C is C1 or less (Yes in Step S2), the ECU 10 determines whether or not the capacity C is equal to or less than a predetermined capacity C2 smaller than C1 (Step S3).

  When the capacity C is larger than C2 (No in step S3), the ECU 10 selects an area A1 indicated by a broken line in FIG. 2 as an operation area of the engine 20 (step S4). After step S4, the ECU 10 ends the control.

  When the capacity C is equal to or smaller than C2 (Yes in step S3), the ECU 10 determines whether the capacity C is equal to or smaller than a predetermined capacity C3 smaller than C2 (step S5). When C is larger than C3 (No in step S5), the ECU 10 selects a region A2 indicated by a dotted line in FIG. 2 as an operation region of the engine 20 (step S6). When C is equal to or less than C3 (Yes in step S5), the ECU 10 selects the region A3 indicated by the solid line in FIG. 2 as the operation region of the engine 20 (step S7). After step S6 or S7, the ECU 10 ends the control.

  According to the present embodiment, the ECU 10 selects the operation region of the engine 20 from the regions A1 to A3 according to the capacity C of the capacitor 32. Specifically, as the capacity of the capacitor 32 decreases, an operation region with a low rotational speed and a low load is set as a region where lean combustion is performed. This narrows the region where lean combustion is performed and widens the region where rich combustion is performed. As a result, ignition delay and misfire are suppressed, and a decrease in drivability is suppressed.

  For example, the ECU 10 controls the fuel injection valve 22 in the rich combustion as compared with the lean combustion, and increases the fuel injection amount with respect to the intake amount. For this reason, the air-fuel mixture is easily ignited by the spark plug 24. Further, the ECU 10 reduces the opening of the EGR valve 28 and reduces the amount of EGR gas flowing through the EGR path 25 in the rich combustion as compared with the lean combustion. Thereby, the temperature of the engine 20 becomes high and it becomes easy to ignite. That is, even when the capacity of the capacitor 32 decreases and the energy supplied to the ignition coil 40 decreases, ignition by the spark plug 24 is facilitated. As a result, ignition delay and misfire are suppressed, and a decrease in drivability is suppressed.

  The ECU 10 selects the operation region from the three regions A1 to A3 shown in FIG. For example, the ECU 10 may select from two regions or may select from four or more regions. The smaller the capacity C of the capacitor 32, the lower the load and the lower rotation speed operation region is set as the lean combustion region. That is, the region where rich combustion is performed is widened, and the region where lean combustion is performed is narrowed.

  ECU10 made the area | region where load and the rotation speed were small, so that the capacity | capacitance C was small as the driving | operation area | region. ECU10 is good also considering the area | region where load is small or the area | region where rotation speed is small, for example as a driving | running area. That is, ECU10 should just make the area | region where at least one of a load and rotation speed is small the driving | operation area | region.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

10 ECU
DESCRIPTION OF SYMBOLS 20 Engine 21 Intake path 22 Fuel injection valve 23 Exhaust path 24 Spark plug 25 EGR path 26 Air flow meter 28 EGR valve 30 Booster circuit 32 Capacitor 40 Ignition coil 42 Detection part 44 Rotation speed sensor 46 Accelerator opening degree sensor 100 Ignition device

Claims (1)

A booster circuit including a capacitor;
An ignition coil for igniting an ignition plug of an internal combustion engine with electric power input from the booster circuit;
A capacity acquisition unit for acquiring the capacity of the capacitor;
An ignition device for an internal combustion engine, comprising: a control unit that sets an operation region in which at least one of a rotational speed and a load of the internal combustion engine is smaller as a capacity of the capacitor is smaller as a region where lean combustion is performed.

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