JP5174497B2 - Fuel injection amount correction method - Google Patents

Description

  The present invention relates to a fuel injection amount correction method using a parameter that can reflect an air-fuel ratio based on ion current.

Conventionally, an ion current generated in the combustion chamber of an internal combustion engine at each ignition can be detected, and an air-fuel ratio based on the ion current, such as a time period during which an ion current exceeding a predetermined value is detected and a peak value of the ion current, can be reflected. When a parameter is obtained and the fluctuation rate of this parameter becomes larger than a predetermined target value, it is considered that the fuel injection amount is increased by assuming that the air-fuel ratio is significantly leaner than the stoichiometric air-fuel ratio. (For example, see Patent Documents 1 and 2).
Japanese Patent Application Laid-Open No. 8-261047 JP-A-9-324690

  However, even if the variation rate of the parameter temporarily exceeds a predetermined value when the air-fuel ratio is not significantly leaner than the stoichiometric air-fuel ratio and the combustion state is good, the Patent Document 1 In the second aspect, since the fuel injection amount is increased every time it is determined that the variation rate of the parameter exceeds a predetermined value, there may be a problem that unnecessary increase is performed.

  The present invention is configured to solve such problems.

That is, the fuel injection amount correction method according to the present invention is a fuel injection amount correction method in which the fuel injection amount is increased by the correction amount when the internal combustion engine is started, and the correction amount is decreased when the combustion after starting is good. An ion current generated for each ignition in the combustion chamber of each ignition is detected, a parameter that can reflect the air-fuel ratio based on the ion current is obtained, a fluctuation rate of the parameter is calculated, and the fluctuation rate of the parameter is predetermined. When the fuel injection amount is increased when the value exceeds the value, and the fuel injection amount is increased, the fuel injection amount is not increased during the period until the ignition is performed a predetermined number of times thereafter, and the ion current get the instantaneous value of which can reflect the air-fuel ratio based on the ion current when detecting parameters, points after the increase of the fuel injection quantity in the case the instantaneous value of this parameter is an abnormal value Thereby increasing the fuel injection amount regardless of the number of increase of the fuel injection amount is performed even when the variation rate of the parameter does not exceed a predetermined value, when subjected to increasing the fuel injection quantity, Thereafter, during a period until ignition is performed a predetermined number of times, control is performed in which the fuel injection amount is not increased unless the instantaneous value is detected again as an abnormal value.

  In such a case, when the air-fuel ratio is not significantly leaner than the stoichiometric air-fuel ratio and the combustion state is good, an abnormal value of the parameter is detected with only one ignition, and the fluctuation rate increases due to that effect. Even if the fluctuation rate etc. temporarily exceeds a predetermined value, the fuel injection amount is not increased during the period until the ignition is performed a predetermined number of times after the fuel injection amount is increased once. The influence of a temporary abnormality can be eliminated and an unnecessary increase in the fuel injection amount can be prevented. Note that “the fuel injection amount is not increased during the period until the predetermined number of times of ignition” means that the determination itself as to whether the variation rate exceeds the predetermined value is not performed during the period until the predetermined number of times of ignition. Including.

The front SL obtains the instantaneous value of the parameter when detecting the ionic current, when the instantaneous value is an abnormal value in the fuel regardless of the number of ignitions after the increase of the fuel injection amount injected in this parameter When the fuel injection amount is increased and the fuel injection amount is increased, the fuel injection amount is increased in the period until the ignition is performed a predetermined number of times unless the instantaneous value is detected again as an abnormal value. Therefore, if the instantaneous value of the ion current is an abnormal value, it is considered that the combustion state has actually deteriorated, and the fuel injection amount is immediately increased regardless of the period after the fuel injection amount is increased. It is possible to deal with abnormalities by performing . Therefore, it is possible to quickly cope with the deterioration of the combustion state.

  According to the fuel injection amount correction method according to the present invention, when the air-fuel ratio is not significantly leaner than the stoichiometric air-fuel ratio and the combustion state is good, the abnormal value of the parameter is detected by only one ignition and the influence thereof is detected. Even if the fluctuation rate temporarily exceeds a predetermined value, the fuel injection amount is increased during the period until the ignition is performed a predetermined number of times after the fuel injection amount is increased once. Therefore, it is possible to eliminate the influence of a temporary abnormality and prevent an unnecessary increase in the fuel injection amount.

Prior to the description of the present invention, a similar fuel injection amount correction control method will be described with reference to the drawings as a reference example related to the present invention .

An engine 100 schematically shown in FIG. 1 is a four-cylinder engine for an automobile, and an intake system 1 is provided with a throttle valve 2 that opens and closes in response to an accelerator pedal (not shown). A tank 3 is provided. A fuel injection valve 5 is further provided in the vicinity of one end communicating with the surge tank 3, and the fuel injection valve 5 is controlled to be opened and closed by a control device 6 based on a basic injection amount TP described later. Yes. A spark plug 18 is attached at a position corresponding to the ceiling portion of the combustion chamber 10. Further, an O ₂ sensor 21 for measuring the oxygen concentration in the exhaust gas is attached to the exhaust system 20 at a position upstream of the three-way catalyst 22 disposed in a pipe line leading to a muffler (not shown). Yes. The engine 100 is not limited to four cylinders as in this embodiment, and may be a three-cylinder, six-cylinder, or twelve-cylinder engine.

The control device 6 is mainly composed of a microcomputer system including a central processing unit 7, a storage device 8, an input interface 9, and an output interface 11. The input interface 9 includes a surge The intake pressure signal a output from the intake pressure sensor 13 for detecting the pressure in the tank 3, the cylinder discrimination signal G1 output from the cam position sensor 14 for detecting the rotation state of the engine 100, and the crank angle reference position Signal G2, engine speed signal b, vehicle speed signal c output from the vehicle speed sensor 15 for detecting the vehicle speed, LL signal d from the idle switch 16 for detecting the opening / closing state of the throttle valve 2, cooling of the engine 100 water temperature signal e from the water temperature sensor 17 for detecting the coolant temperature, O ₂ sensor 21 as described above And La voltage signal h is input. On the other hand, the output interface 11 outputs a fuel injection signal f to the fuel injection valve 5 and an ignition pulse g to the spark plug 18. Although not shown, the control device 6 includes an A / D converter that converts an analog signal into a digital signal.

  The spark plug 18 is connected to a bias power source 24 for measuring the ion current Iion of the combustion chamber 30 through a high-voltage diode 23, and is connected between the input interface 9 and the bias power source 24 for measuring the ion current. A circuit 25 is connected. The bias power source 24 applies a bias voltage for measuring the ion current to the spark plug 18 when the ignition pulse g disappears. The ion current Iion flowing between the electrodes of the spark plug 18 due to the voltage application is measured by the ion current measuring circuit 25. The ionic current measurement circuit 25 has a comparator as a waveform shaping circuit, and is electrically connected to the input interface 9 of the electronic control unit 6 to convert the ionic current, which is an analog signal generated by voltage application, into a square wave. Waveform is shaped into (pulse) and output. The comparator compares a predetermined current value Iref having a strength corresponding to a preset threshold value of the ion current Iion with an ion current Iion input via the bias power supply 24, and the ion current Iion is the predetermined current value. An output signal Iout is output when Iref is exceeded. That is, the output signal Iout becomes a square wave that rises (turns on) when the ion current Iion exceeds the predetermined current value Iref and falls (turns off) when it falls below. The output terminal of the comparator is connected to the central processing unit 7 via the input interface 9 in order to measure a period during which the ion current Iion is equal to or greater than a predetermined threshold (hereinafter referred to as ion current generation time Ti). As the bias power source 24 and the ion current measuring circuit 25, various devices well known in the art can be applied.

The control device 6 uses the intake pressure signal a output from the intake pressure sensor 13 and the rotation speed signal b output from the cam position sensor 14 as main information, and various correction coefficients determined according to the engine state. The basic injection time TP is corrected to determine the fuel injection valve opening time, that is, the final injector energization time T, and the fuel injection valve 5 is controlled based on the determined energization time, so that fuel corresponding to the engine load is supplied to the fuel injection valve. A program for injecting air from 5 to the intake system 1 is incorporated. In addition, a feedback control program for performing feedback control based on the voltage signal output from the O ₂ sensor 21 is also incorporated in a steady operation state that is not a transient state such as starting or acceleration.

Further, the control device 6 generates an ion current Iion for each ignition in the combustion chamber 30 of the engine 100, measures the ion current generation time Ti, and calculates the variation rate F of the measured ion current generation time Ti. A current measurement program is also built-in. This ion current measurement program detects the ion current flowing in the combustion chamber 30 for each ignition, and measures the ion current generation time Ti. As a method for measuring the ion current generation time Ti, various methods known in the art can be used. In this reference example, it is noted that the ion current generation time Ti varies more greatly when the air-fuel ratio is larger than the stoichiometric air-fuel ratio and on the lean side than when the air-fuel ratio is around the stoichiometric air-fuel ratio. The current generation time Ti is a parameter that can reflect the air-fuel ratio in the claims. This ion current measurement program is executed for each ignition in the time period after the internal combustion engine is started until the O ₂ sensor 21 is activated.

In the ion current measurement program, the current fluctuation rate F is calculated by the following equation using the ion current generation time Ti obtained at this time. In other words, this fluctuation rate F is measured this time the ionic current generation time Ti _n and ion current generation time of two ion current generation time it was previously measured Ti i.e. the ion current generation time Ti measured last 3 times Ti The moving average Ti _av is calculated. Then, the average deviation ΔTi of the ion current generation time Ti measured the last three times is calculated, and the variation rate F is calculated from the average deviation ΔTi and the moving average Ti _av .

Ti _av = (Ti _n + Ti _n-1 + Ti _n-2 ) / 3
ΔTi = (| Ti _n -Ti _av | + | Ti _n-1 -Ti _av | + | Ti _n-2 -Ti _av |) / 3
F = ΔTi / Ti _av
However, Ti _n is the value of the current of the ion current generation time, the measured value before once and Ti _n-1, the measured value before twice and Ti _n-2. In this reference example , the ion current generation time Ti at the time of the last three ignitions is used to calculate the fluctuation rate F, but this number is arbitrary.

  In addition, the control device 6 detects the operating state of the engine 100 when the fluctuation rate F of the ion current generation time Ti is calculated, and calculates an allowable fluctuation rate Ft corresponding to the detected operating state. There is also a built-in program. Although not shown, the allowable fluctuation rate Ft is set with the engine speed NE indicating the operating state of the engine 100 and the intake pressure PM as parameters, and is stored in the storage device 8 as an allowable fluctuation rate map. Yes. The allowable fluctuation rate Ft is set to be smaller as the engine speed NE is lower and as the intake pressure PM is higher. In the case of the same intake pressure PM, the allowable fluctuation rate Ft is set to be approximately inversely proportional to the engine speed NE. . Note that the engine speed NE and the throttle opening, or the engine speed NE and the air flow rate may be set as parameters indicating the operating state. In other words, the items are not limited to these as long as they reflect the magnitude of the load with respect to the engine speed NE. Furthermore, the engine operating state indicated by the cooling water temperature, the lubricating oil temperature, the intake air temperature, or the like may be added to these parameters to detect the operating state of the engine.

  Then, the control device 6 executes the ionic current measurement program and the allowable fluctuation rate calculation program, and calculates the allowable fluctuation rate Ft calculated by the allowable fluctuation rate calculation program from the fluctuation rate F calculated by the ion current measurement program. A fuel injection amount correction program for determining that the air-fuel ratio is larger than the stoichiometric air-fuel ratio and on the lean side when it exceeds the fuel injection amount is incorporated.

When the fluctuation rate F of the ionic current generation time Ti exceeds the allowable fluctuation rate Ft, the fuel injection amount is increased on the assumption that the air-fuel ratio is larger than the theoretical air-fuel ratio and on the lean side. For example, the increase correction is not performed until ignition is performed three times. Further, in this reference example , even after three ignitions, the fuel injection amount increase correction is not performed until it is determined a predetermined number of times when the variation rate exceeds the allowable variation rate Ft. On the other hand, when it is determined that the fluctuation rate does not exceed the allowable fluctuation rate Ft, the fuel injection amount is decreased by a predetermined amount. Here, the amount by which the fuel injection amount is increased is the largest at the first time and is a value obtained by sequentially multiplying the predetermined amount by the second and subsequent times. The amount of increase correction is stored in a predetermined area of the storage device 8 as an increase table using the number CC of increase in the past as a parameter. In this reference example , the predetermined number of times is set to 3 times that is the same as the number of ignition times used for calculating the variation rate, but the number of ignition times used to calculate the variation rate is set to other than 3 times. Even in this case, it is desirable to set the predetermined number of times to be equal to the number of times of ignition used for the calculation of the variation rate or more than the number of times of ignition used to calculate the variation rate. This is because when an abnormal value of the ionic current generation time Ti is detected instantaneously only during one ignition, the abnormal value is reflected in the moving average and the average deviation because the abnormal value is detected. This is because it is only the number of times of ignition used for calculating the variation rate.

  A schematic procedure of processing performed by the fuel injection amount correction program will be described with reference to FIG. 2 which is a flowchart. Prior to this fuel injection amount correction program, the value of the counter C is set to 0 and the number CC of past increases is set to 0 in advance.

  In step S1, it is determined whether or not the obtained current fluctuation rate F exceeds the allowable fluctuation rate Ft. When the fluctuation rate F exceeds the allowable fluctuation rate Ft, the process proceeds to step S2. On the other hand, if it is below the target, the process proceeds to step S7.

In step S2, it is determined whether or not the number of times that the variation rate F has been determined to exceed the allowable variation rate Ft since the previous increase correction is a predetermined number, or three or more in the present reference example . Specifically, it is determined whether or not the value of the counter C is zero. If the value of the counter C is 0, the process proceeds to step S3. On the other hand, if the value of the counter C is 1 or more, the process proceeds to step S5.

  In step S3, an amount to increase the fuel injection amount is determined using the number CC of past increases as a parameter, and control is performed to inject an amount of fuel obtained by adding the determined amount to the previous fuel injection amount. Next, the process proceeds to step S4.

  In step S4, 1 is added to the number CC of past increases and the value of the counter C is set to 3. Then, this fuel injection amount correction program is temporarily terminated.

  In step S5, control for maintaining the fuel injection amount, that is, control for determining the same fuel injection amount as the previous fuel injection amount and injecting the determined amount of fuel injection is performed, and the process proceeds to step S6. .

  In step S6, 1 is subtracted from the value of the counter C. Then, this fuel injection amount correction program is temporarily terminated.

  In step S7, control for reducing the fuel injection amount by a predetermined amount, that is, control for determining a fuel injection amount by reducing the fuel injection amount by a predetermined amount from the previous fuel injection amount and injecting the determined amount of fuel injection is performed. Then, this fuel injection amount correction program is temporarily terminated.

  Hereinafter, processing actually performed in such a configuration will be described with reference to FIG. In FIG. 3, the state of whether or not the fluctuation rate F exceeds the allowable fluctuation rate Ft, the value of the counter C, and the amount by which the fuel injection amount is increased from the previous ignition (injection increase in the figure). , And the time lapse of the amount increased from the basic fuel injection amount (actual increase amount in the figure) is shown by a common time axis. Here, the moment of each ignition is indicated by a vertical broken line in the figure. Further, the state of whether or not the fluctuation rate F exceeds the allowable fluctuation rate Ft, the amount by which the fuel injection amount is increased, and the increase correction amount are shown in a bar graph. In FIG. 3A, when it is continuously detected that the air-fuel ratio is significantly leaner than the stoichiometric air-fuel ratio and the fluctuation rate F exceeds the allowable fluctuation rate Ft, b) shows the fluctuation rate F for some reason, for example, when an abnormal value of the ionic current generation time Ti is measured only at the time of one ignition even though the air-fuel ratio does not greatly exceed the stoichiometric air-fuel ratio. A case where the allowable fluctuation rate Ft is temporarily exceeded is shown.

  That is, in such a configuration, when it is continuously detected that the air-fuel ratio is significantly leaner than the stoichiometric air-fuel ratio and the fluctuation rate F exceeds the allowable fluctuation rate Ft, first, in step S1, the fluctuation rate F Is determined to exceed the allowable fluctuation rate Ft. Then, when it is determined for the first time that the fluctuation rate F exceeds the allowable fluctuation rate Ft, and when such a determination is made and the determination is made three times after the fuel injection amount is increased, a step is performed. In S2, it is determined that the value of the counter C is 0, and an increase correction is performed in Step S3. In step S4, the value of the counter C is reset to 3. That is, the control of steps S1, S2, S3, and S4 is sequentially performed. In other ignitions, even when it is determined that the fluctuation rate F exceeds the allowable fluctuation rate Ft, it is determined in step S2 that the value of the counter C is not 0, so the fuel injection amount in step S5 is maintained. Control is performed. Thereafter, control is performed to subtract 1 from the value of the counter C in step S6. That is, the control of steps S1, S2, S5, and S6 is sequentially performed. If the fluctuation rate F does not exceed the allowable fluctuation rate Ft, it is determined in step S3 that the fluctuation rate F does not exceed the allowable fluctuation rate Ft, and control is performed to reduce the fuel injection amount by a predetermined amount in step S7. That is, the control of steps S1 → S7 is sequentially performed. Therefore, in this case, the fuel injection amount is increased at 3 to 4 ignition intervals.

On the other hand, as described above, in FIG. 3B, the abnormal value of the ion current generation time Ti is measured, for example, only at the time of one ignition even though the air-fuel ratio does not greatly exceed the stoichiometric air-fuel ratio. For example, the fluctuation rate F temporarily exceeds the allowable fluctuation rate Ft for some reason. In the case shown in the figure, it is determined in step S1 that the fluctuation rate F exceeds the allowable fluctuation rate Ft. Only 3 times. That is, only when it is first measured that the fluctuation rate F exceeds the allowable fluctuation rate Ft, it is determined in step S2 that the value of the counter C is 0, and an increase correction is performed in step S3. In step S4, the value of the counter C is set to 3, and the control of steps S1, S2, S3, and S4 is sequentially performed. However, after that, when it is measured that the fluctuation rate F exceeds the allowable fluctuation rate Ft, it is determined in step S2 that the value of the counter C is not 0, so the fuel injection amount in step S5 is maintained. Control is performed. Thereafter, control is performed to subtract 1 from the value of the counter C in step S6. That is, the control of steps S1, S2, S5, and S6 is sequentially performed. If the fluctuation rate F does not exceed the allowable fluctuation rate Ft, it is determined in step S3 that the fluctuation rate F does not exceed the allowable fluctuation rate Ft, and control is performed to reduce the fuel injection amount by a predetermined amount in step S7. That is, the control of steps S1 → S7 is sequentially performed. Therefore, in this case, the increase correction is performed three times in the conventional configuration, whereas the increase correction is performed only once in the present reference example .

As described above, if the fuel injection amount correction method according to the present reference example is employed, the following effects can be obtained. That is, after it is determined that the variation rate F exceeds the allowable variation rate Ft and the fuel injection amount is increased, the variation rate F remains within the allowable variation rate Ft during and after the third ignition. Since the increase correction is not performed unless the determination exceeding 3 is performed three times, the ion current generation time is, for example, only in the case of one ignition even though the air-fuel ratio is not significantly leaner than the stoichiometric air-fuel ratio. When it is measured that the fluctuation rate F temporarily exceeds the allowable fluctuation rate Ft for some reason, such as when an abnormal value of Ti is measured, unnecessary increase correction can be prevented.

Subsequently, an embodiment of the present invention will be described with reference to the drawings.

The present embodiment has a configuration that differs from the above-described reference example only in the following points, and has the same configuration as the above-described reference example in the other portions.

In the ion current measurement program according to the present embodiment, the ion current generation time Ti is used as an instantaneous value of the ion current. In addition, after obtaining the ion current generation time Ti by the same process as the ion current measurement program according to the reference example described above, the process for determining whether or not the ion current generation time Ti is an abnormal value, the ion current generation time When Ti is an abnormal value, the process of setting the ion current abnormality flag FF to 1 is performed, and when the ion current generation time Ti is not an abnormal value, the process of setting the ion current abnormality flag FF to 0 is performed. Yes.

In the fuel injection amount correction program according to the reference example described above , as described above , after the increase correction is performed when the fluctuation rate F of the ion current generation time Ti exceeds the allowable fluctuation rate Ft, the fluctuation rate F is calculated as follows. When the allowable fluctuation rate Ft is exceeded, the fuel injection amount increase correction is not performed until a predetermined number of times, for example, three determinations, but in this embodiment, when the ion current generation time Ti is an abnormal value, That is, when the value of the ion current abnormality flag FF indicating that the ion current generation time Ti is an abnormal value is 1, the fuel injection amount increase correction is unconditionally performed. After performing the increase correction in this way, when the fluctuation rate F exceeds the allowable fluctuation rate Ft, it is determined a predetermined number of times, for example, three times, or it is detected that the ion current generation time Ti is an abnormal value again. The fuel injection amount increase correction is not performed until this time.

  It should be noted that the amount by which the fuel injection amount is increased is an increase correction when the value of the counter C is 0 and the variation rate F exceeds the allowable variation rate Ft (hereinafter referred to as variation rate determination increase correction), and the value of the counter C is Increase correction when the ion current generation time Ti is abnormal when it is not 0 (hereinafter referred to as composite determination increase correction), and the ion current generation time Ti is abnormal when the fluctuation rate does not exceed the allowable fluctuation rate Ft This is set for each of the increase corrections (hereinafter referred to as instantaneous value increase corrections) that have been received as values. In other words, the amount to be increased when performing fluctuation rate determination increase correction is stored in a predetermined area of the storage device 8 as a variation rate determination increase correction amount table using the number CC1 of the past change rate determination increase correction as a parameter. Yes. Further, the amount to be increased when performing the combined determination increase correction is stored in a predetermined area of the storage device 8 as a combined determination increase correction amount table using the number CC2 of the past combined determination increase correction as a parameter. The amount to be increased when the instantaneous value increase correction is performed is stored in a predetermined area of the storage device 8 as an instantaneous value increase correction amount table using the number CC3 of the past instantaneous value correction as a parameter. Here, the amount to be increased by the fluctuation rate determination increase correction, the combined determination increase correction, and the instantaneous value increase correction is the largest in the first time and is a value obtained by sequentially multiplying the predetermined decrease coefficient after the second time.

  A schematic procedure of processing performed by the fuel injection amount correction program will be described with reference to FIG. 4 which is a flowchart. Prior to this fuel injection amount correction program, the value of the counter C is set to 0 in advance. Further, the number CC1 of the past fluctuation rate determination increase correction, the number CC2 of the past combined determination increase correction, and the number CC3 of the past instantaneous value correction are also set to 0.

  In step S101, it is determined whether or not the ion current generation time Ti is an abnormal value, that is, whether or not the value of the ion current abnormality flag FF is 1. If the ion current generation time Ti is an abnormal value, the process proceeds to step S102. Otherwise, the process proceeds to step S108.

  In step S102, it is determined whether or not the number of times that the fluctuation rate F has been determined to exceed the allowable fluctuation rate Ft since the previous increase in the fuel injection amount is a predetermined number, or 3 or more in this embodiment. To do. Specifically, it is determined whether or not the value of the counter C is zero. If the value of the counter C is 0, the process proceeds to step S103. On the other hand, if the value of the counter C is 1 or more, the process proceeds to step S105.

  In step S103, an amount to increase the fuel injection amount is determined using the number CC3 of the past instantaneous value determination increase correction as a parameter, and control is performed to inject an amount of fuel obtained by adding the determined amount to the previous fuel injection amount. . Next, the process proceeds to step S104.

  In step S104, 1 is added to the number CC3 of the past instantaneous value increase correction. Then, this fuel injection amount correction program is temporarily terminated.

  In step S105, the value of the counter C is reset to 0, and then the process proceeds to step S106.

  In step S106, an amount to increase the fuel injection amount is determined using the number CC2 of the past combined determination increase correction as a parameter, and control is performed to inject an amount of fuel obtained by adding the determined amount to the previous fuel injection amount. Next, the process proceeds to step S107.

  In step S107, 1 is added to the number CC2 of the past combined determination increase correction, and the value of the counter C is set to 3. Then, this fuel injection amount correction program is temporarily terminated.

  In step S108, it is determined whether or not the obtained current fluctuation rate F exceeds the allowable fluctuation rate Ft. When the fluctuation rate F exceeds the allowable fluctuation rate Ft, the process proceeds to step S109. On the other hand, when the fluctuation rate F does not exceed the allowable fluctuation rate Ft, the process proceeds to step S114.

  In step S109, it is determined whether or not the number of times that the variation rate F has been determined to exceed the allowable variation rate Ft since the previous variation rate determination increase correction is a predetermined number, or 3 or more in this embodiment. . Specifically, it is determined whether or not the value of the counter C is zero. If the value of the counter C is 0, the process proceeds to step S110. On the other hand, if the value of the counter C is 1 or more, the process proceeds to step S105.

  In step S110, an amount to increase the fuel injection amount is determined using the number CC1 of the past fluctuation rate determination increase correction as a parameter, and control is performed to inject the amount of fuel obtained by adding the determined amount to the previous fuel injection amount. . Next, the process proceeds to step S111.

  In step S111, 1 is added to the number CC1 of the past fluctuation rate determination increase correction, and the value of the counter C is set to 3. Then, this fuel injection amount correction program is temporarily terminated.

  In step S112, control for maintaining the fuel injection amount, that is, control for determining the same fuel injection amount as the previous fuel injection amount and injecting the determined amount of fuel injection is performed. Next, the process proceeds to step S112.

  In step S113, 1 is subtracted from the value of the counter C. Then, this fuel injection amount correction program is temporarily terminated.

  In step S114, control for reducing the fuel injection amount by a predetermined amount, that is, control for determining the amount that is reduced by a predetermined amount from the previous fuel injection amount as the fuel injection amount and injecting the determined amount of fuel injection is performed. Then, this fuel injection amount correction program is temporarily terminated.

  Hereinafter, processing actually performed in such a configuration will be described with reference to FIGS. 5 and 6. 5 and 6 show the value of the ionic current abnormality flag FF, the state of whether or not the fluctuation rate F exceeds the allowable fluctuation rate Ft, the value of the counter C, and the fuel injection amount at the time of the previous ignition. The time lapse of the amount to be increased from (injection increase in the drawing) and the amount to increase from the basic fuel injection amount (actual increase in the drawing) is shown by a common time axis. Here, the moment of each ignition is indicated by a vertical broken line in the figure. Further, the value of the ionic current abnormality flag FF, the state of whether or not the fluctuation rate F exceeds the allowable fluctuation rate Ft, the amount by which the fuel injection amount is increased, and the increase correction amount are shown in a bar graph. In FIG. 5, when it is continuously detected that the air-fuel ratio is significantly leaner than the stoichiometric air-fuel ratio and the fluctuation rate F exceeds the allowable fluctuation rate Ft, FIG. Although the fuel ratio does not greatly exceed the stoichiometric air-fuel ratio, the fluctuation rate F temporarily exceeds the allowable fluctuation rate Ft for some reason, such as when an abnormal value of the ion current generation time Ti is measured only during one ignition. Each case is shown.

  That is, in such a configuration, when the ionic current generation time Ti is an abnormal value, as shown in FIG. 5, this abnormality does not occur regardless of the number of ignitions after the fuel injection amount is increased. Even if the fluctuation rate F is less than the allowable fluctuation rate Ft regardless of the value, the abnormal value of the ion current generation time Ti reflects that the air-fuel ratio is larger than the stoichiometric air-fuel ratio and is on the lean side. In step S101, it is determined that the ion current generation time Ti is an abnormal value, and if it is determined that the variation rate F after the previous increase correction exceeds the allowable variation rate Ft three times, in step S103. Instantaneous value increase correction is performed, and 1 is added to the number CC3 of the past instantaneous value increase correction performed in step S104. That is, the processes of steps S101 → S102 → S103 → S104 are sequentially performed. On the other hand, if the variation rate F after the previous increase correction exceeds the allowable variation rate Ft, the counter C value is reset to 0 in step S105 unless it is determined three times, and the combined determination increase correction is performed in step S106. In step S107, 1 is added to the number CC2 of the past combined determination increase correction. That is, the processes of steps S101 → S102 → S105 → S106 → S107 are sequentially performed. In addition, when the ion current generation time Ti is not an abnormal value and the fluctuation rate F exceeds the allowable fluctuation rate Ft, after the previous increase correction, the fluctuation rate F exceeds the allowable fluctuation rate Ft after three times are determined. If so, the variation rate determination increase correction is performed in step S109, and 1 is added to the number CC1 of the past variation rate determination increase correction performed in step S110. That is, the processes of steps S101 → S108 → S109 → S110 → S111 are sequentially performed. On the other hand, if it is not determined three times that the variation rate F after the previous increase correction exceeds the allowable variation rate Ft, the process of maintaining the fuel injection amount is performed in step S112, and the value of the counter C is incremented by 1 in step S113. Is subtracted. That is, the processes of steps S101 → S108 → S109 → S112 → S114 are sequentially performed. When the ion current generation time Ti is not an abnormal value and the fluctuation rate F does not exceed the allowable fluctuation rate Ft, a process of reducing the fuel injection amount by a predetermined amount is performed. That is, the processes of steps S101 → S108 → S114 are sequentially performed.

  On the other hand, as described above, FIG. 6 shows an abnormal value of the ion current generation time Ti for only one ignition for some reason, even though the air-fuel ratio does not greatly exceed the theoretical air-fuel ratio. In this case, the abnormal value of the ionic current generation time Ti is measured and the fluctuation rate F exceeds the allowable fluctuation rate Ft. If the fluctuation rate F does not exceed the allowable fluctuation rate Ft after three ignitions after the fluctuation rate F exceeds the allowable fluctuation rate Ft without detecting the abnormal value of the current generation time Ti again, the following processing is sequentially performed. Done. That is, in the ignition in which the abnormal value of the ionic current generation time Ti is measured and it is determined that the fluctuation rate F exceeds the allowable fluctuation rate Ft, the control in steps S101 → S102 → S103 → S104 is sequentially performed. In the ignition twice immediately after the ignition in which the abnormal value is detected, it is determined in step S101 that the ion current generation time Ti is not an abnormal value, and in step S108, it is determined that the fluctuation rate F exceeds the allowable fluctuation rate Ft. In S109, it is determined that the value of the counter C is not 0, and control for maintaining the fuel injection amount in step S112 and control for subtracting 1 from the value of the counter C in step S113 are performed. That is, the control in steps S101 → S108 → S109 → S112 → S113 is sequentially performed. In ignition after three times after the abnormal value is detected, it is first determined in step S101 that the ionic current generation time Ti is not an abnormal value, and the fluctuation rate F does not exceed the allowable fluctuation rate Ft in step S108. In step S114, the fuel injection amount is reduced by a predetermined amount. That is, the control of steps S101 → S108 → S114 is sequentially performed. Therefore, when the abnormal value of the ion current generation time Ti is measured only at one ignition and the fluctuation rate F exceeds the allowable fluctuation rate Ft, the increase correction is performed three times in the conventional configuration, whereas In this embodiment, the increase correction is performed only once.

As described above, if the fuel injection amount correction method according to this embodiment is employed, the same effects as those according to the reference example described above can be obtained. That is, after determining that the fluctuation rate F exceeds the allowable fluctuation rate Ft and increasing the fuel injection amount, the increase correction is performed unless the determination that the fluctuation rate F exceeds the allowable fluctuation rate Ft is performed three times. Therefore, even if the air-fuel ratio is not significantly leaner than the stoichiometric air-fuel ratio, it fluctuates temporarily for some reason, such as when an abnormal value of the ionic current generation time Ti is measured only during one ignition. When it is measured that the rate F exceeds the allowable variation rate Ft, unnecessary increase correction can be prevented.

  Further, in this embodiment, the fuel injection amount is increased when the ion current detection time Ti is an abnormal value, so that when the abnormal value of the ion current detection time Ti is detected, the combustion state is actually deteriorated. As a result, the fuel injection amount is immediately increased regardless of the number of times the determination that the fluctuation rate F exceeds the allowable fluctuation rate Ft is performed, so that the combustion can be stabilized more appropriately in response to the occurrence of an abnormality immediately. Can do.

  The present invention is not limited to the embodiment as described above.

For example, in the implementation described above, but so as to obtain the ionic current generation time Ti for each ignition, ignition every and second ignition intervals, etc., empty the ion current generation time Ti or the like at a predetermined ignition count interval A parameter that can reflect the fuel ratio may be measured, and it may be determined whether or not to increase the fuel injection amount using the variation rate.

  Whether or not to increase the fuel injection amount using a parameter fluctuation rate that can reflect the air-fuel ratio based on other ion currents, such as the peak value of the ion current, instead of the fluctuation rate of the ion current generation time Ti. It may be determined.

Furthermore, in the implementation described above, but so as to perform control to lose weight the amount of fuel injection each time fluctuation rate F is determined allowable variation rate when not exceeding Ft 1 times, fluctuation rate F is allowable variation If the rate Ft is not exceeded, control may be performed to reduce the fuel injection amount every time the predetermined number of times is determined twice or more. In this case, for example, whenever it is determined that the fluctuation rate F does not exceed the allowable fluctuation rate Ft, it is determined whether or not the value of the good determination counter CG is 0, and the value of the good determination counter CG is 0. Only when the value of the good judgment counter CG is set to a predetermined value, for example, 3, and when the value of the good judgment counter CG is not 0, the value of the second counter CG is set to 1. It is good to subtract. In this way, it is possible to reduce the fuel injection amount every time it is determined three times that the fluctuation rate F does not exceed the allowable fluctuation rate Ft.

In addition, in the implementation described above, each time fluctuation rate F is determined to exceed the predetermined variation rate Ft, of the determination from performing increasing correction of the fuel injection amount corresponding to the fluctuation rate F It is determined whether the number of times has reached the predetermined number (three times), and the fuel injection amount increase correction is performed only when the number of determinations has reached the predetermined number. For the predetermined number of ignitions immediately after the fuel injection amount increase correction is performed, it is not determined whether or not the fluctuation rate F exceeds the predetermined fluctuation rate Ft, and at least as long as the parameter related to the ionic current is not an abnormal value. The fuel injection amount may not be increased. Even in this case, when the parameter related to the ionic current is an abnormal value, control for increasing the fuel injection amount may be performed.

  In addition, various changes may be made without departing from the spirit of the present invention.

Schematic which shows the engine which concerns on the reference example relevant to this invention. The flowchart which shows the flow of control in the combustion time measurement program which concerns on the reference example . Explanatory drawing concerning the reference example . The flowchart which shows the flow of control in the combustion time measurement program which concerns on one Embodiment of this invention. Action | operation explanatory drawing which concerns on the same embodiment. Action | operation explanatory drawing which concerns on the same embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Engine 6 ... Control apparatus 18 ... Spark plug

Claims (1)

In the fuel injection amount correction method of increasing the fuel injection amount by the correction amount at the start of the internal combustion engine and decreasing the correction amount when the combustion after the start is good,
An ion current generated for each ignition in the combustion chamber of the internal combustion engine is detected, a parameter that can reflect the air-fuel ratio based on the ion current is obtained, a fluctuation rate of the parameter is calculated, and the fluctuation rate of the parameter is a predetermined value If it exceeds, increase the fuel injection amount,
When the fuel injection amount is increased, the fuel injection amount is not increased during the period until the ignition is performed a predetermined number of times thereafter.
And, when the ion current is detected, an instantaneous value of a parameter that can reflect the air-fuel ratio based on the ion current is acquired, and when the instantaneous value of the parameter is an abnormal value, the fuel injection amount is increased. The fuel injection amount is increased regardless of the number of subsequent ignitions, and the increase in the fuel injection amount is performed even when the variation rate of the parameter does not exceed a predetermined value.
When the fuel injection amount is increased, control for not increasing the fuel injection amount is executed unless it is detected again that the instantaneous value is an abnormal value during a period until the ignition is performed a predetermined number of times thereafter. A fuel injection amount correction method.

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