JP5995613B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that controls an internal combustion engine that performs ignition by applying a current to a spark plug.

  Conventionally, in an internal combustion engine that performs ignition by applying a current to a spark plug, ignition is performed according to the following procedure. First, current is applied to the primary coil of the spark plug. Here, the magnitude I (t) of the current applied to the primary coil side is the battery voltage E, the primary circuit resistance R, the primary coil self-inductance L, and the elapsed time from the start of current application. If t is t, the following (Equation 1) is satisfied. That is, the graph showing the change with time of the current magnitude I (t) is as shown in FIG.

Next, the application of current to the primary coil is stopped, and an induced current is generated in the secondary coil, thereby generating a large voltage V between the center electrode and the ground electrode to generate a spark. Here, the magnitude of the voltage V satisfies the following (Equation 2), where i is the magnitude of the current immediately before the application of the current to the primary coil is stopped.

That is, the magnitude of the voltage generated in the primary coil and the secondary coil is proportional to the magnitude of the current just before the application of the current to the primary coil is stopped. For these reasons, when the time for applying the current to the spark plug is short, the voltage generated between the center electrode and the ground electrode is reduced, and the power consumed until ignition is reduced. Therefore, when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, it is noted that ignition is possible even when the voltage between the center electrode of the spark plug and the ground electrode is low. When it is richer than the fuel ratio, it is known to perform control to delay the time for applying current to the spark plug by delaying the timing for starting application of current to the spark plug (for example, Patent Document 1). See).

By the way, when performing a slow deceleration by reducing the accelerator operation amount, a negative pressure is generated downstream of the throttle valve, so that the fuel (port wet) adhering to the intake port is vaporized and introduced into the cylinder. A phenomenon called deceleration rich occurs in which the fuel becomes rich in fuel. At that time, if an O ₂ sensor is provided on the exhaust passage side to detect the air-fuel ratio, the output signal of the O ₂ sensor indicates that it is on the rich side. The air-fuel ratio feedback control is performed so that the fuel injection amount approaches, and the fuel injection amount decreases.

Here, when the accelerator operation amount increases after the phenomenon called deceleration rich as described above occurs, and the throttle opening increases accordingly, the amount of fresh air introduced into the cylinder increases. However, the output signal of the O ₂ sensor provided on the exhaust passage side reflects the increase in the amount of fresh air, indicating that it is on the lean side, and there is a time lag before the fuel injection amount increase control is performed. To do. In such a state, since the fuel adhering to the intake port is immediately after vaporization, newly injected fuel tends to adhere to the intake port, and the ratio of the fuel in the air-fuel mixture introduced into the cylinder is reduced. . Therefore, the air-fuel mixture actually introduced into the cylinder is significantly leaner than the stoichiometric air-fuel ratio.

Therefore, when the control for delaying the timing of starting the application of the current to the spark plug is performed based on the output signal of the O ₂ sensor when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, the above-described case is performed. While the period when such a phenomenon occurs, the output signal of the O ₂ sensor indicates that it is on the rich side, whereas the air-fuel mixture that is actually introduced into the cylinder is significantly leaner than the stoichiometric air-fuel ratio. Therefore, troubles such as misfire are likely to occur.

Japanese Utility Model Publication No. 5-57362

  The present invention pays attention to the above points. In the control device for an internal combustion engine that performs control to reduce ignition energy when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, and performs feedback control of air-fuel ratio control, An object is to suppress the occurrence of the above-described malfunction such as misfire when the throttle valve opening increases after the phenomenon called deceleration rich occurs.

In order to solve the above problems, the control apparatus for an internal combustion engine according to the present invention performs the following control. That is, the control apparatus for an internal combustion engine according to the present invention controls an internal combustion engine configured to inject fuel into an intake port and ignite an air-fuel mixture by spark ignition through an ignition plug, and to output an air-fuel ratio sensor output signal. A control device for an internal combustion engine that performs feedback control of air-fuel ratio based on the output signal of the air-fuel ratio sensor when the output signal of the air-fuel ratio sensor indicates the rich side, and the output signal of the air-fuel ratio sensor is decreased in performed when the control to increase the ignition energy, which shows that, by the time that the output signal of the air-fuel ratio sensor continues a state in which indicates that the rich side during deceleration reaches a predetermined time If you are controls to increase the ignition energy when it is detected that the throttle opening is increased.

  If such control is performed, the state in which the output signal of the air-fuel ratio sensor is on the rich side when a phenomenon called deceleration rich occurs during deceleration operation continues for a predetermined time. Focusing on the fact that when the throttle opening subsequently increases, the air-fuel ratio introduced into the cylinder is predicted to be significantly leaner, and the ignition energy is increased regardless of the output signal of the air-fuel ratio sensor. Occurrence of problems such as misfire can be suppressed.

  According to the present invention, when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, the control for reducing the ignition energy is performed and the control device for the internal combustion engine that performs the feedback control of the air-fuel ratio control is referred to as deceleration rich. It is possible to suppress the occurrence of a malfunction such as misfire as described above when the opening of the throttle valve increases after the occurrence of the phenomenon.

1 is a schematic configuration diagram of an internal combustion engine in an embodiment of the present invention. The circuit diagram of the spark ignition device in the embodiment. The figure which shows the time-dependent change of the electric current applied to the primary coil of the ignition plug in the embodiment. Schematic which shows the effect | action by the air fuel ratio control in the embodiment. The flowchart which shows the example of a procedure of the process which the control apparatus of the embodiment performs.

  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 a coil case together with an igniter 13 that is a semiconductor switching element.

  When the igniter 13 receives an ignition signal i from an ECU (Electronic Control Unit) 0, which is a combustion state determination device for an internal combustion engine, the igniter 13 is first ignited to cause a current to flow to the primary side of the ignition coil 14, and the ignition immediately thereafter. The igniter 13 is extinguished at the timing, 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. 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 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. Further, an O ₂ sensor 43 for measuring the oxygen concentration in the exhaust gas is disposed upstream of the three-way catalyst 41 on the exhaust passage 4.

  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 (so-called required load), and a brake that is output from a sensor that detects the amount of depression of the brake pedal Stepping amount signal d, intake air temperature / intake pressure signal e output from a temperature / pressure sensor for detecting intake air temperature and intake pressure in intake passage 3 (especially surge tank 33), water temperature sensor for detecting engine cooling water temperature Output from the cam angle sensor at a plurality of cam angles of the cooling water temperature signal f output from the intake camshaft or exhaust camshaft. A cam angle signal (G signal) g, a voltage signal h or the like to be output from the O ₂ sensor 43 are inputted.

  From the output interface, an ignition signal i is output to the igniter 13 of the spark plug 12, a fuel injection signal j is output to the injector 11, an opening operation signal k is output to the throttle valve 32, and the like.

  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, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, and ignition timing are determined. As the operation parameter determination method itself, a known method can be adopted. Accordingly, the ECU 0 applies various control signals i, j, k corresponding to the operation parameters via the output interface.

Further, as shown in FIG. 4, the ECU 0 performs air-fuel ratio feedback control based on the voltage signal h output from the O ₂ sensor 43. That is, control is performed to decrease the fuel injection amount when the voltage signal h indicates the rich side, while increasing the fuel injection amount when the voltage signal h indicates the lean side. Do. Since this feedback control is performed by a method similar to that known as air-fuel ratio feedback control performed by this type of internal combustion engine control device, detailed description thereof is omitted.

In addition, by executing the current application timing control program, the ECU 0 reduces the ignition energy and indicates that the voltage signal h is on the lean side when the voltage signal h indicates the rich side. Control is performed to increase the ignition energy when indicated. In addition, when the state indicating that the voltage signal h is rich during deceleration operation continues for a predetermined time, it is considered that a phenomenon called deceleration rich has occurred, Thereafter, when the throttle opening increases, control is performed to increase the ignition energy. More specifically, as shown in FIG. 3, when the voltage signal h indicates the lean side, the length t ₁ of the period from the start of application of current to the spark plug 12 to ignition. If the voltage signal h indicates that the voltage signal h is on the rich side, the application start time of the current to the spark plug 12 is delayed to shorten the length t ₂ until ignition, The amount of electric power shared by the spark plug is reduced to reduce the consumption of electric power supplied from the battery, and consequently the fuel consumption. On the other hand, when a phenomenon called deceleration rich has occurred, when the throttle opening subsequently increases, the air-fuel mixture supplied to the combustion chamber as described above is greatly reduced to the lean side. Therefore, when it is detected that the throttle opening is increased, control is performed to sufficiently lengthen the period from the start of application of current to the spark plug 12 to ignition, I try to prevent misfires.

  The control procedure by this current application timing control program will be described below with reference to FIG. 5 which is a flowchart.

First, when the voltage signal h indicates the lean side, the length of the period from the start of application of current to the spark plug 12 to ignition is set to the first time t ₁ . In other words, the application of current to the spark plug 12 is started at a time that goes back from the ignition timing by the first time t ₁ . On the other hand, when the voltage signal h indicates that it is on the rich side and the time during which the voltage signal h remains on the rich side is less than the predetermined time, application of current to the spark plug 12 is started. Is set to a _second time t ₂ shorter than the first time t ₁ . In other words, the application of current to the spark plug 12 is started at a time that goes back by the second time t ₂ from the ignition timing. That is, application of current to the spark plug 12 is started at a timing delayed from the case where the voltage signal h indicates the lean side. Further, when the time during which the voltage signal h is on the rich side has continued for a predetermined time, the current to the spark plug 12 is not detected until it is detected that the opening of the throttle valve 32 has increased. The length of the period from the start of application to ignition is set to the second time t _2, and after detecting that the throttle opening has increased, the period from the start of application of current to the spark plug 12 until the ignition is reached. The length is set to the first time t ₁ .

That is, as shown in FIG. 4, when the opening degree of the electronic throttle valve 32 decreases as the driver performs an operation to decelerate the vehicle, as described above, the fuel adhering to the intake port (port wet) When a phenomenon called “deceleration rich” in which the air-fuel mixture is vaporized and the air-fuel mixture is rich in fuel occurs, the state where the voltage signal h is on the rich side continues, and when this state continues for a predetermined time or longer, the ECU 0 This deceleration rich is detected. If the opening of the electronic throttle valve 32 increases from this state, the leanness of the strength occurs as shown in the figure, so that ignition can be performed more reliably even in the state where the leanness of the strength has occurred. Therefore, the length of the period from the start of application of current to the spark plug 12 to ignition is set to the first time t ₁ , and a larger voltage is generated between the center electrode and the ground electrode of the spark plug 12. Control to do so.

  That is, the following effects can be obtained by performing the control according to the present embodiment. Specifically, when the voltage signal h indicates that it is on the rich side, it is usually possible to control the ignition energy to be reduced, thereby reducing the power consumption of the battery and thus reducing the fuel consumption. On the other hand, a significant leaning of the air-fuel ratio when the throttle valve opening increases after deceleration rich occurs is predicted based on the length of time that the voltage signal h remains rich When it is assumed that deceleration rich has occurred, i.e., when the significant leaning is predicted, the ignition energy is increased when it is detected that the throttle opening is increased. The occurrence of defects can be suppressed.

  The present invention is not limited to the embodiment described above, and various modifications may be made without departing from the spirit of the present invention.

0 ... Control unit (ECU)
11 ... injector 12 ... spark plug 32 ... throttle valve 43 ... air-fuel ratio sensor (O ₂ sensor)
h: Output signal (voltage signal) of the air-fuel ratio sensor

Claims (1)

Control of an internal combustion engine configured to inject fuel into an intake port and ignite an air-fuel mixture by spark ignition via an ignition plug, and control of the internal combustion engine to perform air-fuel ratio feedback control based on an output signal of an air-fuel ratio sensor A device,
When the output signal of the air-fuel ratio sensor indicates the rich side, the ignition energy is reduced, and when the output signal of the air-fuel ratio sensor indicates the lean side, the ignition energy is increased. ,
If the time when the output signal of the air-fuel ratio sensor during deceleration operation indicates that the rich side has continued reaches a predetermined time, when it is detected that the throttle opening is increased A control device for an internal combustion engine, which performs control to increase ignition energy.

Images