JP5028353B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device, and more particularly, to a control device that reduces exhaust during starting.

  In recent years, there has been a demand for further reduction of engine exhaust in accordance with tightening regulations for automobile engine exhaust in various countries around the world, such as North America, Europe, and Japan. In order to improve the performance of catalysts and the accuracy of catalyst control and meet the latest or future exhaust regulations, the amount of HC (hydrocarbon) discharged in tens of seconds after engine startup before catalyst activation is reduced. Reduction is the main issue.

  It is known that retarding the ignition timing is effective in reducing HC before catalyst activation. In particular, when the ignition timing is retarded, the thermal efficiency is lowered, so that it is necessary to increase the fuel amount (air amount) in order to maintain the equal torque, and accordingly, the amount of heat generated by combustion increases. As the amount of generated heat increases, the exhaust temperature also rises, and the unburned fuel burns in the combustion chamber and the exhaust pipe, thereby greatly reducing the HC concentration. Furthermore, the activation of the catalyst is accelerated by the exhaust gas temperature increase.

JP 2007-303354 A JP-A-8-122099 Japanese Patent Laid-Open No. 9-88680

  As shown in FIG. 20, the effect of reducing HC by the retard varies with the air-fuel ratio. In particular, it can be seen that the air-fuel ratio 15 to 16 has the highest HC reduction effect. From this, it can be seen that in order to minimize the HC emission amount from the engine, the air-fuel ratio should be controlled to 15 to 16 and retarded as much as possible. Further, as shown in FIG. 21, it is understood that the air-fuel ratio should be controlled to 14 to 15 and retarded as much as possible in consideration of the exhaust temperature which is an effective element for the early activation of the catalyst.

  On the other hand, it is known that when the air-fuel ratio is made lean, the stability of combustion deteriorates. It is also known that the combustion stability deteriorates when the amount of retard is increased. In a practical environment, many disturbances such as variations in fuel properties, manufacturing errors of various devices, and changes over time must occur, so robustness against these disturbances must be ensured, that is, both the air-fuel ratio and the retard amount are stable. A margin must be ensured, and as shown in FIG. 20, the air-fuel ratio and the retard amount could not be set to the conditions that minimize the HC concentration or the conditions that maximize the exhaust temperature.

  Under such circumstances, a number of methods for optimizing the air-fuel ratio on board using parameters having a correlation with the air-fuel ratio, such as rotational fluctuations, have been proposed in the very initial stage of startup, such as Patent Document 1. Also, a number of methods for optimizing the ignition timing (retard amount) on-board using parameters having a correlation with combustion stability such as rotational fluctuation have been proposed, such as Patent Document 2.

  However, as described above, in order to obtain the maximum HC reduction effect by the retard, there are almost no applications related to “a method for optimizing both the air-fuel ratio and the retard amount on board”.

  Patent Document 3 discloses an invention in which the ignition timing is retarded until the target rotational fluctuation is reached, and when the ignition timing (retard amount) is less than a predetermined value, the fuel amount is increased. However, in the present invention, since the ignition timing is first retarded, as shown in FIG. 20, even if the retard is performed, the HC reduction effect is small in the setting at the time of securing the stable margin. In addition, when the retard amount is smaller than the predetermined value, the HC emission amount is rather increased because the fuel amount is increased (in order to reduce the air-fuel ratio).

  In summary, at the time of starting (before catalyst activation), in order to minimize the HC discharged from the engine, it is necessary to optimize both the air-fuel ratio and the ignition timing. There was no effective control method to optimize at the same time.

  In view of the above circumstances, the present invention proposes an effective control method for simultaneously optimizing the air-fuel ratio and the ignition timing. That is, means for extracting a first frequency (band) component, means for extracting a second frequency (band) component, and the first frequency (band) component from the time series signal of the engine operating state Engine control means, comprising: means for calculating a parameter for controlling the air-fuel ratio, and means for calculating a parameter for controlling the ignition timing based on the second frequency (band) component. Propose the device. That is, frequency analysis is performed on a time-series signal representing the operating state (combustion state) of the engine, such as an output signal of a sensor attached to the engine, and the frequency component is divided into a first frequency (band) component and a second frequency ( The air-fuel ratio is controlled based on the first frequency (band) component, and the ignition timing is controlled based on the second frequency (band) component. By analyzing the frequency of the time series signal representing the engine operating state (combustion state) and extracting the components in two bands, the one-dimensional time series information is separated into two pieces of information, and the engine operating state Based on this information, it is possible to independently control the air-fuel ratio and the ignition timing.

  In addition, an engine control device is proposed in which the operating state of the engine is at least an engine rotational speed or an N-th order differential value (N = 1, 2,...) Of the engine rotational speed. That is, the engine operating state is best based on the in-cylinder pressure (combustion pressure), and the engine speed or the Nth order differential value of the engine speed has a causal relationship between the in-cylinder pressure and physical (mechanical). Therefore, the signal is used. For example, angular acceleration, which is a first-order differential component of engine rotation speed, has a substantially linear relationship with in-cylinder pressure.

  Also, an engine control device is proposed in which the operating state of the engine is based on at least the pressure in the combustion chamber.

  That is, as described above, the engine operating state is based on the in-cylinder pressure (combustion pressure), so this is clearly stated.

  Also, an engine control device is proposed in which the operating state of the engine is based on engine torque.

  That is, as described above, the engine operating state is best based on the in-cylinder pressure (combustion pressure), and the engine torque has a causal relationship between the in-cylinder pressure and physical (mechanical). It is clearly stated that the signal is used.

  In addition, the engine control device is characterized in that the second frequency (band) component includes at least a higher frequency component than the first frequency (band) component.

  That is, as described above, the air-fuel ratio and the ignition timing are controlled independently by extracting the frequency components of the time-series signal representing the engine operating state (combustion state) in two bands. As shown in FIG. 5, the relative relationship between the two bands specifies that the second frequency (band) component includes at least a higher frequency component than the first frequency (band) component. It is. Since the second frequency (band) component is higher in frequency than the first frequency (band) component, the control period (control responsiveness) of the ignition timing control controlled based on the second frequency (band) component is also The control cycle (control responsiveness) is faster than the air-fuel ratio control controlled based on the first frequency (band) component. That is, when it is desired to design the control speed (responsiveness) of the ignition timing control faster than the control speed (responsiveness) of the air-fuel ratio control, the band separation is performed as described in the claims.

  In addition, the engine control device is characterized in that the second frequency (band) component includes at least a component having a frequency lower than that of the first frequency (band) component.

  That is, as described above, the air-fuel ratio and the ignition timing are controlled independently by extracting the frequency components of the time-series signal representing the engine operating state (combustion state) in two bands. As shown in FIG. 6, the relative relationship between the two bands specifies that the first frequency (band) component includes at least a higher frequency component than the second frequency (band) component. It is. Since the first frequency (band) component is higher in frequency than the second frequency (band) component, the control cycle (control responsiveness) of the air-fuel ratio control controlled based on the first frequency (band) component is also The control cycle (control responsiveness) is faster than the ignition timing control controlled based on the second frequency (band) component. That is, when it is desired to design the control speed (responsiveness) of the air-fuel ratio control faster than the control speed (responsiveness) of the ignition timing control, the band separation is performed as described in the claims.

  In addition, the engine control apparatus is characterized in that the first frequency band and the second frequency band are determined (changed) based on an operating state of the engine.

  That is, as described above, the band to be separated is determined by how the control speed (responsiveness) of the air-fuel ratio control and the control speed (responsiveness) of the ignition timing control are designed. In this claim, it is specified that the band to be separated is not changed, but is changed based on the operating state (operating condition) of the engine. In other words, the control speed (responsiveness) of the air-fuel ratio control and the control speed (responsiveness) of the ignition timing control are dynamically changed on-board for more flexible control, and the control speed to the above-mentioned HC minimum condition Is faster and at the same time is more robust.

  In addition, an engine control apparatus is provided that includes means for calculating a parameter for controlling the air-fuel ratio so that the first frequency component falls within a predetermined range A.

  That is, as described above, the first frequency component is a value obtained by frequency analysis of a time-series signal representing the operating state (combustion state) of the engine. When the air-fuel ratio is made lean, the engine operating state (combustion state) becomes unstable, which also appears in the first frequency component. Therefore, the air-fuel ratio can be indirectly detected from the value of the first frequency component. Using this characteristic, the value of the first frequency component corresponding to the desired air-fuel ratio range is set to the predetermined range A, and the parameter (fuel injection) for controlling the air-fuel ratio so that the first frequency component falls within the predetermined range A The air-fuel ratio is controlled to a desired air-fuel ratio range by correcting the amount). The desired air-fuel ratio range is, for example, the air-fuel ratio range of 15 to 16 in order to minimize the HC emission amount from the engine as described above. In consideration of the exhaust temperature, which is an effective factor for the early activation of the catalyst, it is desirable to set the air-fuel ratio in the range of 14-15. Then, as will be described later, the ignition timing is retarded as much as possible (to the determined stability limit) based on the second frequency component.

  Also, an engine control device is proposed in which the predetermined range A is provided with means for determining based on the ignition timing.

  That is, as described above, when the air-fuel ratio is made lean, the engine operating state (combustion state) becomes unstable, which also appears in the first frequency component. However, this level of instability changes depending on the ignition timing even if the air-fuel ratio is constant. Therefore, in order to uniquely detect the air-fuel ratio from the value of the first frequency component, the predetermined range A that is the first frequency component value corresponding to the desired air-fuel ratio range is determined according to the ignition timing. It is.

  Further, in order to minimize the HC discharged from the engine, an engine control device is proposed in which the predetermined range A is set so that the air-fuel ratio becomes a value corresponding to 15 to 16.

  That is, as described above, it is understood that the HC reduction effect is the highest at the air-fuel ratio of 15 to 16. From this, it can be seen that in order to minimize the HC emission amount from the engine, the air-fuel ratio should be controlled to 15 to 16 and retarded as much as possible. Therefore, it is clearly stated that the predetermined range A is a value corresponding to an air-fuel ratio of 15 to 16.

  In addition, when the temperature of exhaust gas discharged from the engine is maximized, the engine control device is proposed in which the predetermined range A is set so that the air-fuel ratio becomes a value corresponding to 14 to 15. .

  That is, as described above, when the exhaust temperature, which is an effective element for the early activation of the catalyst, is taken into consideration, it can be understood that the air-fuel ratio should be controlled to 14 to 15 and retarded as much as possible. Therefore, it is specified that the predetermined range A is set to a value corresponding to an air-fuel ratio of 14 to 15.

  In addition, an engine control apparatus is provided that includes means for calculating a parameter for controlling the ignition timing so that the second frequency component falls within a predetermined range B.

  That is, as described above, the air-fuel ratio is controlled such that the first frequency component is within the predetermined range A. On the other hand, the ignition timing is retarded as much as possible at an air-fuel ratio corresponding to the predetermined range A, whereby HC reduction and exhaust temperature increase can be obtained more effectively.

  When the ignition timing is retarded, the engine operating state (combustion state) becomes unstable, which also appears in the second frequency component. Therefore, it is possible to indirectly detect the stability of the engine (combustion) from the value of the second frequency component. Using this characteristic, the value of the second frequency component corresponding to the desired engine (combustion) stability is set to a predetermined range B, and the ignition timing is retarded until the second frequency component reaches the predetermined range B. Thus, an HC reduction effect and an exhaust temperature increase effect are obtained.

  Also, an engine control device is proposed in which the predetermined range B is set to a value corresponding to the engine stability limit.

  That is, as described above, the ignition timing is retarded as much as possible in the air-fuel ratio corresponding to the predetermined range A, so that HC reduction and exhaust temperature increase can be obtained more effectively. This possible degree is a value corresponding to a stability limit (commercial limit) generally set by each engine. From this, the value of the second frequency component corresponding to the stability limit is set to the predetermined range B, and the ignition timing is retarded until the second frequency component reaches the predetermined range B, thereby reducing the HC and increasing the exhaust temperature. The effect is obtained to the maximum.

  It is also detected that the means for setting the target air-fuel ratio, the means for detecting directly or indirectly that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio, and that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio. A control device for an engine is provided, characterized by comprising means for changing the first frequency band and the second frequency band between when it is not detected and when it is detected.

  In other words, as described above, both the HC reduction effect and the exhaust temperature rise effect cannot be obtained by merely retarding the ignition timing unless the air-fuel ratio is controlled within a predetermined range.

  That is, the precondition for carrying out the retard control is that the air-fuel ratio is controlled within a predetermined range. Therefore, as described in the present claim, when the air-fuel ratio is not controlled in the vicinity of the target air-fuel ratio, the air-fuel ratio is controlled in an early stage in order to control the air-fuel ratio. The first frequency band to be used is changed. For example, as will be described later, it is conceivable to set the first frequency band wider than the second frequency band (up to a higher frequency side) to speed up the responsiveness of the air-fuel ratio control.

  In addition, an engine control device is proposed in which the first frequency band is wider than the second frequency band when it is not detected that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio. To do.

  That is, as described above, it is specified that the first frequency band is wider than the second frequency band (up to higher frequency side), so that the responsiveness of the air-fuel ratio control is increased. .

  Also, an engine control device is proposed in which the first frequency band is made wider than the second frequency band when the engine is started (particularly immediately after the engine is started).

  That is, as described above, both the HC reduction effect and the exhaust temperature rise effect cannot be obtained by simply retarding the ignition timing unless the air-fuel ratio is controlled within a predetermined range. That is, the effect of the retard control can be obtained only after the air-fuel ratio is controlled within the predetermined range. On the other hand, when the engine is started, both the target air-fuel ratio and the target ignition timing (target retard amount) are generally returned to the default setting values. This default setting value must ensure robustness against many disturbances such as variations in fuel properties, manufacturing errors of various devices and changes with time. For example, as shown in FIG. It is a set value. When realizing the minimum HC condition and the maximum exhaust temperature condition from the default setting values, it is necessary to give priority to controlling the air-fuel ratio within a predetermined range as described above. Therefore, it is effective to make the control speed of the air-fuel ratio as fast as possible. Therefore, as described in this claim, the first frequency band used for air-fuel ratio control is more than the second frequency band used for ignition timing control. Widen (up to higher frequencies).

  The means for directly or indirectly detecting that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio is such that when the component of the first frequency band is within a predetermined range, the air-fuel ratio is the target air-fuel ratio. An engine control device is characterized in that it is determined that the engine is controlled in the vicinity.

  That is, as described above, the air-fuel ratio can be indirectly detected from the value of the first frequency component. Using this characteristic, the value of the first frequency component corresponding to the desired air-fuel ratio range is set to the predetermined range A, and the parameter (fuel injection) for controlling the air-fuel ratio so that the first frequency component falls within the predetermined range A The air-fuel ratio is controlled to a desired air-fuel ratio range by correcting the amount). Therefore, as described in the claims, when the component of the first frequency band is within the predetermined range, it is determined that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio.

  Further, the means for directly or indirectly detecting that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio is that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio when the fuel correction speed is within a predetermined range. An engine control apparatus characterized by judging is proposed.

  That is, as described above, the air-fuel ratio can be indirectly detected from the value of the first frequency component. Using this characteristic, the value of the first frequency component corresponding to the desired air-fuel ratio range is set to the predetermined range A, and the parameter (fuel injection) for controlling the air-fuel ratio so that the first frequency component falls within the predetermined range A The air-fuel ratio is controlled to a desired air-fuel ratio range by correcting the amount). Therefore, as described in the claims, as the air-fuel ratio approaches the target air-fuel ratio, the fuel injection amount correction speed generally becomes smaller. Therefore, when the fuel correction speed is within the predetermined range (when small), it is determined that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio.

  An engine control apparatus characterized in that the first frequency component and / or the second frequency component is a value obtained by performing a weighted moving average process on an absolute value of a time-series signal of the operating state of the engine. suggest.

That is, as a method of calculating the frequency component,
・ Fourier transform is performed to obtain the power spectrum of the target frequency band.
• Use a filter process such as a bandpass filter to convert the signal into a time-series signal with components only in the target frequency band.

  And so on. However, these methods all have a large calculation load when mounted on a microcomputer, and are not suitable for mass production controllers. Therefore, although the accuracy is somewhat inferior to that of the above method, the calculation load is small and the method described in the claims is specified as a method suitable for mounting. First, by calculating the absolute value of the time series signal, the power of the signal is obtained. Thereafter, the passband is limited by weighted moving average processing. The moving average process has a function of a first-order low-pass filter, but the pass band can be controlled to some extent by making the coefficient weighted.

  As described above, the present invention is a control system that simultaneously optimizes the air-fuel ratio and the ignition timing at the start (before catalyst activation), while ensuring robustness according to various disturbances that occur in a practical environment. It becomes possible to minimize the HC discharged from the engine.

Example 1
FIG. 22 is a system diagram showing this embodiment. In the engine 9 composed of multiple cylinders, air from outside passes through the air cleaner 1 and flows into the cylinder through the intake manifold 4 and the collector 5. The amount of inflow air is adjusted by the electronic throttle 3. The airflow sensor 2 detects the inflow air amount. The crank angle sensor 15 outputs a crankshaft rotation angle of 1 ° and a signal for each combustion cycle. The water temperature sensor 14 detects the coolant temperature of the engine. The accelerator opening sensor 13 detects the amount of depression of the accelerator 6 and thereby detects the driver's required torque. The signals of the throttle opening sensor 13, the airflow sensor 2, the throttle opening sensor 17, the crank angle sensor 15 and the water temperature sensor 14 attached to the electronic throttle 3 are sent to the control unit 16, and the engine operation is performed from these sensor outputs. By obtaining the state, the main engine operation amount of the air amount, fuel injection amount, and ignition timing is optimally calculated. The fuel injection amount calculated in the control unit 16 is converted into a valve opening pulse signal and sent to the fuel injection valve 7. Further, a drive signal is sent to the spark plug 8 so as to be ignited at the ignition timing calculated by the control unit 16. The injected fuel is mixed with air from the intake manifold and flows into the cylinder of the engine 9 to form an air-fuel mixture. The air-fuel mixture explodes by a spark generated from the spark plug 8 at a predetermined ignition timing, and the combustion pressure depresses the piston to serve as engine power. The exhaust after the explosion is sent to the three-way catalyst 11 through the exhaust manifold 10. A part of the exhaust gas is recirculated to the intake side through the exhaust gas recirculation pipe 18. The recirculation amount is controlled by the exhaust gas recirculation amount adjusting valve 19. The A / F sensor (air-fuel ratio sensor) 12 is attached between the engine 9 and the three-way catalyst 11 and has a linear output characteristic with respect to the oxygen concentration contained in the exhaust gas. The relationship between the oxygen concentration in the exhaust gas and the air-fuel ratio is substantially linear, and therefore the air-fuel ratio can be obtained by the A / F sensor 12 that detects the oxygen concentration. The control unit 16 calculates the air-fuel ratio upstream of the three-way catalyst 11 from the signal of the A / F sensor 12, and is rich or lean from the signal of the catalyst downstream O ₂ sensor 20 to the O ₂ concentration or stoichiometry downstream of the three-way catalyst. Is calculated. Further, F / B control is performed to sequentially correct the fuel injection amount or the air amount so that the purification efficiency of the three-way catalyst 11 is optimized using the outputs of both sensors. The intake air temperature sensor 29 detects the intake air temperature, and the in-cylinder pressure (combustion pressure) sensor 30 detects the in-cylinder pressure (combustion pressure).

FIG. 33 shows the inside of the control unit 16. The control unit 16 includes an A / F sensor 12, a throttle valve opening sensor 17, an airflow sensor 2, a crank angle sensor 15, a water temperature sensor 14, an accelerator opening sensor 13, a catalyst downstream O ₂ sensor 20, an intake air temperature sensor 29, Each sensor output value of the in-cylinder pressure sensor 30 is input, and after signal processing such as noise removal is performed by the input circuit 24, it is sent to the input / output port 25. The value of the input port is stored in the RAM 23 and is processed in the CPU 21. A control program describing the contents of the arithmetic processing is written in the ROM 22 in advance. A value representing each actuator operation amount calculated according to the control program is stored in the RAM 23 and then sent to the input / output port 25. The ignition plug operation signal is set to an ON / OFF signal that is ON when the primary coil in the ignition output circuit is energized and is OFF when the primary coil is not energized. The ignition timing is when the ignition is switched from ON to OFF. The spark plug signal set at the output port is amplified to a sufficient energy required for combustion by the ignition output circuit 26 and supplied to the spark plug. The fuel injection valve drive signal is set to an ON / OFF signal that is ON when the valve is open and OFF when the valve is closed. The fuel injection valve drive circuit 27 amplifies the fuel injection valve 7 to a sufficient energy to open the fuel injection valve 7. Sent to. A drive signal for realizing the target opening degree of the electronic throttle 3 is sent to the electronic throttle 3 via the electronic throttle drive circuit 28. Hereinafter, the control program written in the ROM 22 will be described.

  FIG. 24 is a block diagram showing the entire control, and includes the following arithmetic units.

・ Basic fuel injection amount calculation unit (Fig. 25)
-Fuel injection amount correction permission section (FIG. 26)
-Fuel injection amount correction value calculation unit (FIG. 27)
・ Basic ignition timing calculator (Fig. 28)
・ Ignition timing correction permission section (Fig. 29)
・ Ignition timing correction amount calculation unit (Fig. 30)
The “basic fuel injection amount calculation unit” calculates the basic fuel injection amount (Tp). The “fuel injection amount correction permission unit” determines whether or not to correct the basic fuel injection amount (Tp). That is, it is determined whether or not to correct the fuel injection amount so that the air-fuel ratio falls within a predetermined range. When the correction is performed, the fuel injection amount correction permission flag Fp_fuel_hos = 1 is set. If not, set Fp_fuel_hos = 0. The “fuel injection amount correction value calculation unit” calculates the fuel injection amount correction value (Alpha) so that the air-fuel ratio falls within a predetermined range based on the output Ne of the crank angle sensor 15 when Fp_fuel_hos = 1. .

  The basic ignition timing (Adv0) is calculated by the “basic ignition timing calculation unit”. The “ignition timing correction permission unit” determines whether or not to correct the basic ignition timing (Adv0). That is, based on the output Ne of the crank angle sensor 15, it is determined whether or not the ignition timing retard correction is performed up to a predetermined engine (combustion) stability. When correction is performed, the ignition timing correction permission flag Fp_adv_hos = 1 is set. If not, set Fp_adv_hos = 0. In the “ignition timing correction amount calculation unit”, when Fp_adv_hos = 1, the ignition timing retard correction amount (Adv_hos) is calculated to a predetermined stability based on the output Ne of the crank angle sensor 15.

  Details of each control (arithmetic unit, permission unit) will be described below.

<Basic fuel injection amount calculation unit (FIG. 25)>
This calculation unit calculates the basic fuel injection amount (Tp). Specifically, the calculation is performed using the formula shown in FIG. Here, Cyl represents the number of cylinders. K0 is determined based on injector specifications (relationship between fuel injection pulse width and fuel injection amount).

<Fuel injection amount correction permission unit (FIG. 26)>
This calculation unit (permission unit) determines whether or not to correct the basic fuel injection amount (Tp). Specifically, as shown in FIG.
1) Time after starting Tas ≦ Tcold
And 2) When the state of TgNe−K1 ≦ Ne ≦ TgNe + K2 has continued for K3 [the number of combustion] or more.
Fp_fuel_hos = 1.

In addition,
Tcol in condition 1) corresponds to the time required for the three-way catalyst 11 to be activated. Therefore, the period in which condition 1) is satisfied means that the three-way catalyst 11 is in an inactive state. ing.
Condition 2) determines a state in which the engine speed after startup converges near the target speed during idling. TgNe is a target rotational speed in the idle operation after the start. Further, it is preferable to determine each parameter K1, K2, and K3 empirically.

  When Fp_fuel_hos = 1, the fuel injection amount correction value (Alpha) is calculated by the “fuel injection amount correction value calculation unit (FIG. 37)” described below.

<Fuel injection amount correction value calculation unit (FIG. 27)>
Here, when Fp_fuel_hos = 1, the correction value of the fuel injection amount is calculated based on the output of the crank angle sensor 15 so that the air-fuel ratio falls within a predetermined range. Specifically, as shown in FIG. 27, the following processing is performed.

  The amount of change in rotational speed per cycle, that is, the angular acceleration dNe is calculated from the output value of the crank angle sensor 15.

After calculating the absolute value of dNe, the band pass filter 1 is applied.
The air-fuel ratio index (ind_abf) is obtained from the output value of the bandpass filter 1 and the ignition timing (Adv) with reference to the table.
The difference Dind_abf between the air-fuel ratio index (ind_abf) and the target air-fuel ratio index (Tind_abf) is obtained.
A fuel injection amount correction value (Alpha) is obtained by PI control from the deviation (Dind_abf).

  The absolute value of angular acceleration (dNe) correlates with the stability of the engine (combustion). By applying the bandpass filter 1 to the value, only a component in a predetermined frequency band is extracted. In this embodiment, the bandpass filter 1 is designed to extract a low frequency component. As will be described later, the ignition timing correction amount (Adv_hos) calculated by the ignition timing correction amount calculation unit (FIG. 30) is calculated based on the value obtained by applying the bandpass filter 2 to the absolute value of the angular acceleration (dNe). Is done. The band pass filter 2 is designed to extract a high frequency component. That is, by designing the band-pass filter 1 and the band-pass filter 2 to be different from each other, the fuel injection amount (air-fuel ratio) and the ignition timing are independently controlled based on the stability of the engine. In addition, since there are many books and documents about the design method of a band pass filter, it does not elaborate here.

  A table for obtaining the air-fuel ratio index (ind_abf) from the output value of the bandpass filter 1 and the ignition timing (Adv) may be determined based on the characteristics (experimental results) of each engine.

  The target air-fuel ratio index (Tind_abf) is set to a value corresponding to 15 to 16 in order to minimize the HC emission amount from the engine. When considering even the exhaust gas temperature, which is an effective factor for the early activation of the catalyst, the air / fuel ratio is set to a value corresponding to 14-15.

  When Fp_fuel_hos = 0, Alpha maintains the previous value.

<Basic ignition timing calculation unit (FIG. 28)>
This calculation unit calculates the basic ignition timing (Adv0). Specifically, as shown in FIG. 28, the basic ignition timing (Adv0) is obtained from the actual air amount (Qa) and the engine speed (Ne) with reference to a table. It is desirable to set the table so that it is MBT. However, in each operating condition, a value that takes stability into account (a torque correction margin is provided from MBT so that torque correction is possible in the case of sudden instability. It ’s also good.

<Ignition timing correction permission section (FIG. 29)>
This calculation unit (permission unit) determines whether or not to correct the basic ignition timing (Adv0). Specifically, as shown in FIG.
1) Time after starting Tas ≦ Tcold
And 2) When the state of TgNe−K1 ≦ Ne ≦ TgNe + K2 has continued for K3 [the number of combustion] or more.
Let Fp_adv_hos = 1.

In addition,
Tcol in condition 1) corresponds to the time required for the three-way catalyst 11 to be activated. Therefore, the period in which condition 1) is satisfied means that the three-way catalyst 11 is in an inactive state. ing.
Condition 2) determines a state in which the engine speed after startup converges near the target speed during idling. TgNe is a target rotational speed in the idle operation after the start. Further, it is preferable to determine each parameter K1, K2, and K3 empirically.

  When Fp_adv_hos = 1, the ignition timing correction amount (Adv_hos) is calculated by the “ignition timing correction amount calculation unit (FIG. 30)” described below.

<Ignition timing correction amount calculation unit (FIG. 30)>
Here, when Fp_adv_hos = 1, the ignition timing retard correction amount (Adv_hos) is calculated to a predetermined stability based on the output of the crank angle sensor 15. Specifically, as shown in FIG. 30, the following processing is performed.

  The amount of change in rotational speed per cycle, that is, the angular acceleration dNe is calculated from the output value of the crank angle sensor 15.

After calculating the absolute value of dNe, the band pass filter 2 is applied to calculate the stability index (ind_stab ility).
When ind_stability is smaller than the predetermined range B_ind, Adv_hos = Adv_hos (previous value) −Rtd1.
When ind_stability is larger than the predetermined range B_ind, Adv_hos = Adv_hos (previous value) + Adv 1 is set.
When ind_stability is within the predetermined range B_ind, Adv_hos = Adv_hos (previous value).

  The absolute value of angular acceleration (dNe) correlates with the stability of the engine (combustion). By applying the bandpass filter 2 to the value, only a component in a predetermined frequency band is extracted. In this embodiment, the bandpass filter 2 is designed to extract a high frequency component. As described above, the fuel injection amount correction value (Alpha) calculated by the fuel injection amount correction value calculation unit (FIG. 27) is obtained by applying the bandpass filter 1 to the absolute value of the angular acceleration (dNe). Calculated based on the value. The bandpass filter 1 is designed to extract a low frequency component. That is, by designing the band-pass filter 1 and the band-pass filter 2 to be different from each other, the fuel injection amount (air-fuel ratio) and the ignition timing are independently controlled based on the stability of the engine. In addition, since there are many books and documents about the design method of a band pass filter, it does not elaborate here.

  It is desirable to set B_ind to a value equivalent to the stability limit. Rtd1, Adv1, etc. are parameters that determine the retard speed and the advance speed. The faster (larger), the better the effect of reducing exhaust can be expected, but the ignition timing control system tends to become unstable accordingly. It may be determined empirically according to engine characteristics (responsiveness, etc.).

  According to this embodiment, after the engine is started, on-board, the air-fuel ratio is controlled to the optimum range based on the low frequency component of the output signal of the crank angle sensor 15, and the ignition timing is set to the stability limit based on the high frequency component. Control up to. In this case, the response of the air-fuel ratio control is relatively slow, and the response of the ignition timing control is relatively fast. In addition, since the air-fuel ratio and the ignition timing are optimized and controlled independently, the HC minimization potential of the engine can be used up regardless of various disturbances that occur in a practical environment.

(Example 2)
In the first embodiment, the air-fuel ratio is controlled to the optimum range based on the low frequency component in the output signal of the crank angle sensor 15, and the ignition timing is controlled to the stability limit based on the high frequency component.

  In contrast, in the second embodiment, the air-fuel ratio is controlled within the optimum range based on the high-frequency component in the output signal of the crank angle sensor 15, and the ignition timing is controlled to the stability limit based on the low-frequency component. Therefore, although the configuration is the same as that of the first embodiment, the bandpass filter 1 in FIG. 27 is designed to extract a high frequency component, and the bandpass filter 2 in FIG. 30 is designed to extract a low frequency component. To do.

  In this case, the responsiveness of the air-fuel ratio control is relatively fast, and the responsiveness of the ignition timing control is relatively slow. In addition, since the air-fuel ratio and the ignition timing are optimized and controlled independently, the HC minimization potential of the engine can be used up regardless of various disturbances that occur in a practical environment.

(Example 3)
In the first and second embodiments, the air-fuel ratio and the ignition timing are controlled using signals from the crank angle sensor 15 of the engine. On the other hand, in the third embodiment, the air-fuel ratio is controlled to the optimum range based on the low frequency component in the output signal of the in-cylinder pressure sensor 30, and the ignition timing is controlled to the stability limit based on the high frequency component.

  FIG. 22 is a system diagram showing the present embodiment, which is the same as the first embodiment and will not be described in detail.

  FIG. 23 shows the inside of the control unit 16, which is the same as that of the first embodiment, and therefore will not be described in detail.

  FIG. 31 is a block diagram showing the entire control, and includes the following arithmetic units.

・ Basic fuel injection amount calculation unit (Fig. 25)
-Fuel injection amount correction permission section (FIG. 26)
-Fuel injection amount correction value calculation unit (FIG. 32)
・ Basic ignition timing calculator (Fig. 28)
・ Ignition timing correction permission section (Fig. 29)
・ Ignition timing correction amount calculation unit (Fig. 33)
The “basic fuel injection amount calculation unit” calculates the basic fuel injection amount (Tp). The “fuel injection amount correction permission unit” determines whether or not to correct the basic fuel injection amount (Tp). That is, it is determined whether or not to correct the fuel injection amount so that the air-fuel ratio falls within a predetermined range. When the correction is performed, the fuel injection amount correction permission flag Fp_fuel_hos = 1 is set. If not, set Fp_fuel_hos = 0. The “fuel injection amount correction value calculation unit” calculates the fuel injection amount correction value (Alpha) based on the output P of the in-cylinder pressure sensor 30 so that the air-fuel ratio falls within a predetermined range when Fp_fuel_hos = 1. .

  The basic ignition timing (Adv0) is calculated by the “basic ignition timing calculation unit”. The “ignition timing correction permission unit” determines whether or not to correct the basic ignition timing (Adv0). That is, based on the output P of the in-cylinder pressure sensor 30, it is determined whether or not the ignition timing retard correction is performed up to a predetermined engine (combustion) stability. When correction is performed, the ignition timing correction permission flag Fp_adv_hos = 1 is set. If not, set Fp_adv_hos = 0. In the “ignition timing correction amount calculation unit”, when Fp_adv_hos = 1, the ignition timing retard correction amount (Adv_hos) is calculated to a predetermined stability based on the output P of the in-cylinder pressure sensor 30.

  Details of each control (arithmetic unit, permission unit) will be described below.

<Basic fuel injection amount calculation unit (FIG. 25)>
This calculation unit calculates the basic fuel injection amount (Tp). Specifically, it is shown in FIG. 25, but it is the same as that of the first embodiment, and will not be described in detail.

<Fuel injection amount correction permission unit (FIG. 26)>
This calculation unit (permission unit) determines whether or not to correct the basic fuel injection amount (Tp). Specifically, it is shown in FIG. 26, but since it is the same as the first embodiment, it will not be described in detail.

<Fuel injection amount correction value calculation unit (FIG. 32)>
Here, when Fp_fuel_hos = 1, the correction value of the fuel injection amount is calculated based on the output P of the in-cylinder pressure sensor 30 so that the air-fuel ratio falls within a predetermined range. Specifically, as shown in FIG. 32, the following processing is performed.

-From the output value P of the in-cylinder pressure sensor 30, the combustion pressure work (indicated mean effective pressure) W per cycle is obtained.
-The band pass filter 1 is applied to the combustion pressure work (W).
The air-fuel ratio index (ind_abf) is obtained from the output value of the bandpass filter 1 and the ignition timing (Adv) with reference to the table.
The difference Dind_abf between the air-fuel ratio index (ind_abf) and the target air-fuel ratio index (Tind_abf) is obtained.
A fuel injection amount correction value (Alpha) is obtained by PI control from the deviation (Dind_abf).

  The combustion pressure work (W) correlates with the stability of the engine (combustion). By applying the bandpass filter 1 to the value, only a component in a predetermined frequency band is extracted. In this embodiment, the bandpass filter 1 is designed to extract a low frequency component. As will be described later, the ignition timing correction amount (Adv_hos) calculated by the ignition timing correction amount calculation unit (FIG. 33) is calculated based on the value obtained by applying the bandpass filter 2 to the angular combustion pressure work (W). The The band pass filter 2 is designed to extract a high frequency component. That is, by designing the band-pass filter 1 and the band-pass filter 2 to be different from each other, the fuel injection amount (air-fuel ratio) and the ignition timing are independently controlled based on the stability of the engine.

  A table for obtaining the air-fuel ratio index (ind_abf) from the output value of the bandpass filter 1 and the ignition timing (Adv) may be determined based on the characteristics (experimental results) of each engine.

  The target air-fuel ratio index (Tind_abf) is set to a value corresponding to 15 to 16 in order to minimize the HC emission amount from the engine. When considering even the exhaust gas temperature, which is an effective factor for the early activation of the catalyst, the air / fuel ratio is set to a value corresponding to 14-15.

  When Fp_fuel_hos = 0, Alpha maintains the previous value.

<Basic ignition timing calculation unit (FIG. 28)>
This calculation unit calculates the basic ignition timing (Adv0). Specifically, it is shown in FIG. 28, but since it is the same as the first embodiment, it will not be described in detail.

<Ignition timing correction permission section (FIG. 29)>
This calculation unit (permission unit) determines whether or not to correct the basic ignition timing (Adv0). Specifically, although shown in FIG. 29, it is the same as that of the first embodiment, and thus will not be described in detail.

<Ignition timing correction amount calculation unit (FIG. 33)>
Here, when Fp_adv_hos = 1, the ignition timing retard correction amount (Adv_hos) is calculated to a predetermined stability based on the output of the in-cylinder pressure sensor 30. Specifically, as shown in FIG. 33, the following processing is performed.

-From the output value P of the in-cylinder pressure sensor 30, the combustion pressure work (indicated mean effective pressure) W per cycle is obtained.
-Apply the bandpass filter 2 to the combustion pressure work (W) and calculate the stability index (ind_stability).
When ind_stability is smaller than the predetermined range B_ind, Adv_hos = Adv_hos (previous value) −Rtd 1
When ind_stability is larger than the predetermined range B_ind, Adv_hos = Adv_hos (previous value) + Adv 1 is set.
When ind_stability is within the predetermined range B_ind, Adv_hos = Adv_hos (previous value).

  The absolute value of the combustion pressure work (W) correlates with the stability of the engine (combustion). By applying the bandpass filter 2 to the value, only a component in a predetermined frequency band is extracted. In this embodiment, the bandpass filter 2 is designed to extract a high frequency component. As described above, the fuel injection amount correction value (Alpha) calculated by the fuel injection amount correction value calculation unit (FIG. 32) applies the bandpass filter 1 to the absolute value of the combustion pressure work (W). It is calculated based on the obtained value. The bandpass filter 1 is designed to extract a low frequency component. That is, by designing the band-pass filter 1 and the band-pass filter 2 to be different from each other, the fuel injection amount (air-fuel ratio) and the ignition timing are independently controlled based on the stability of the engine.

  It is desirable to set B_ind to a value equivalent to the stability limit. Rtd1, Adv1, etc. are parameters that determine the retard speed and the advance speed. The faster (larger), the better the effect of reducing exhaust can be expected, but the ignition timing control system tends to become unstable accordingly. It may be determined empirically according to engine characteristics (responsiveness, etc.).

  According to this embodiment, after starting the engine, the air-fuel ratio is controlled to the optimum range based on the low frequency component of the output signal of the in-cylinder pressure sensor 30, and the ignition timing is set to the stability limit based on the high frequency component. Control up to. In this case, the response of the air-fuel ratio control is relatively slow, and the response of the ignition timing control is relatively fast. In addition, since the air-fuel ratio and the ignition timing are optimized and controlled independently, the HC minimization potential of the engine can be used up regardless of various disturbances that occur in a practical environment.

  On the other hand, among the output signals of the in-cylinder pressure sensor 30, the bandpass filters 1 and 2 are configured so that the air-fuel ratio is controlled to the optimum range based on the high frequency component and the ignition timing is controlled to the stable limit based on the low frequency component. May be designed. In this case, the responsiveness of the air-fuel ratio control is relatively fast, and the responsiveness of the ignition timing control is relatively slow.

Example 4
In Examples 1 to 3, the control start timing of the air-fuel ratio and the ignition timing is set to be the same (the control start conditions are the same).

  As described above, both the HC reduction effect and the exhaust temperature rise effect cannot be obtained by simply retarding the ignition timing unless the air-fuel ratio is controlled within a predetermined range. That is, the precondition for carrying out the retard control is that the air-fuel ratio is controlled within a predetermined range. On the other hand, when the engine is started, both the target air-fuel ratio and the target ignition timing (target retard amount) are generally returned to the default setting values. This default setting value must ensure robustness against many disturbances such as variations in fuel properties, manufacturing errors of various devices, and changes over time, and is stable apart from the minimum HC condition or maximum exhaust temperature condition. The margin is set to be secured. When realizing the minimum HC condition and the maximum exhaust temperature condition from the default setting values, it is necessary to give priority to controlling the air-fuel ratio within a predetermined range as described above. Therefore, it is effective to make the control speed of the air-fuel ratio as fast as possible. Therefore, in the present embodiment, the air-fuel ratio is first controlled by using the entire frequency band for the output signal of the crank angle sensor 15, so that the air-fuel ratio can be set earlier than the HC minimum condition (15 to 15). 16) Or the exhaust temperature is controlled to the highest condition (14 to 15). After that, it is separated into two frequency band components, the air-fuel ratio is controlled based on the first frequency band, and the ignition timing is controlled based on the second frequency band.

  FIG. 22 is a system diagram showing the present embodiment, which is the same as the first embodiment and will not be described in detail.

  FIG. 23 shows the inside of the control unit 16, which is the same as that of the first embodiment, and therefore will not be described in detail.

  FIG. 34 is a block diagram showing the entire control, and includes the following arithmetic units.

・ Basic fuel injection amount calculation unit (Fig. 25)
-Fuel injection amount correction permission section (FIG. 26)
・ Fuel injection amount correction value calculator (Fig. 35)
・ Basic ignition timing calculator (Fig. 28)
・ Ignition timing correction permission section (Fig. 36)
・ Ignition timing correction amount calculation unit (Fig. 30)
The “basic fuel injection amount calculation unit” calculates the basic fuel injection amount (Tp). The “fuel injection amount correction permission unit” determines whether or not to correct the basic fuel injection amount (Tp). That is, it is determined whether or not to correct the fuel injection amount so that the air-fuel ratio falls within a predetermined range. When the correction is performed, the fuel injection amount correction permission flag Fp_fuel_hos = 1 is set. If not, set Fp_fuel_hos = 0. The “fuel injection amount correction value calculation unit” calculates the fuel injection amount correction value (Alpha) so that the air-fuel ratio falls within a predetermined range based on the output Ne of the crank angle sensor 15 when Fp_fuel_hos = 1. .

  The basic ignition timing (Adv0) is calculated by the “basic ignition timing calculation unit”. The “ignition timing correction permission unit” determines whether or not to correct the basic ignition timing (Adv0). That is, based on the output Ne of the crank angle sensor 15, it is determined whether or not the ignition timing retard correction is performed up to a predetermined engine (combustion) stability. In this determination, a condition as to whether the air-fuel ratio is controlled within a predetermined range is added. More specifically, when the air-fuel ratio index 1 (ind_abf1) is within a predetermined range, it is determined that the air-fuel ratio is controlled within the predetermined range. When correcting the ignition timing, the ignition timing correction permission flag Fp_adv_hos = 1 is set. If not, set Fp_adv_hos = 0. In the “ignition timing correction amount calculation unit”, when Fp_adv_hos = 1, the ignition timing retard correction amount (Adv_hos) is calculated to a predetermined stability based on the output Ne of the crank angle sensor 15.

  Details of each control (arithmetic unit, permission unit) will be described below.

<Basic fuel injection amount calculation unit (FIG. 25)>
This calculation unit calculates the basic fuel injection amount (Tp). Specifically, it is shown in FIG. 25, but it is the same as that of the first embodiment, and will not be described in detail.

<Fuel injection amount correction permission unit (FIG. 26)>
This calculation unit (permission unit) determines whether or not to correct the basic fuel injection amount (Tp). Specifically, it is shown in FIG. 26, but since it is the same as the first embodiment, it will not be described in detail.

<Fuel injection amount correction value calculation unit (FIG. 35)>
Here, when Fp_fuel_hos = 1, the correction value of the fuel injection amount is calculated based on the output of the crank angle sensor 15 so that the air-fuel ratio falls within a predetermined range. Specifically, as shown in FIG. 35, the following processing is performed.

The amount of change in rotational speed per cycle, that is, the angular acceleration dNe is calculated from the output value of the crank angle sensor 15.
After calculating the absolute value of dNe, the band pass filter 1 is applied.
The air-fuel ratio index 1 (ind_abf1) is obtained from the output value of the bandpass filter 1 and the ignition timing (Adv) with reference to the table.
After the absolute value of dNe is calculated, the low pass filter 2 is applied.
The air-fuel ratio index 2 (ind_abf2) is obtained from the output value of the low-pass filter 2 and the ignition timing (Adv) with reference to the table.
-When the ignition timing correction permission flag (Fp_adv_hos) is 0, the air-fuel ratio index (ind_abf) is set to the air-fuel ratio index 1 (ind_abf1).
・ When the ignition timing correction permission flag (Fp_adv_hos) is 1, the air-fuel ratio index (ind_abf) is set to the air-fuel ratio index 2 (ind_abf2).
The difference Dind_abf between the air-fuel ratio index (ind_abf) and the target air-fuel ratio index (Tind_abf) is obtained.
A fuel injection amount correction value (Alpha) is obtained by PI control from the deviation (Dind_abf).

  As will be described later, the ignition timing correction permission flag (Fp_adv_hos) is 0 when the air-fuel ratio is not controlled within the predetermined range. At this time, since it is necessary to quickly control the air-fuel ratio within a predetermined range, the air-fuel ratio control is first performed on the output signal of the crank angle sensor 15 by using almost the entire frequency band, so that the earlier The air-fuel ratio is controlled to the minimum HC condition (15 to 16) or the maximum exhaust temperature condition (14 to 15). Therefore, the pass band of the band pass filter 1 is designed to be almost the entire band.

  As will be described later, the ignition timing correction permission flag (Fp_adv_hos) is 1 when the air-fuel ratio is controlled within a predetermined range. At this time, since it is necessary to control the ignition timing more quickly than the air-fuel ratio to the stability limit, the band used for air-fuel ratio control is limited to a narrow range of the low frequency band, and the remaining band components are the ignition timing. Used for control (described later). For this purpose, the pass band of the low-pass filter 2 is designed to be a narrow range of the low frequency band.

  The table for obtaining the air-fuel ratio index (ind_abf) from the output value of the bandpass filter 1 and the ignition timing (Adv) may be determined based on the characteristics (experimental results) of each engine. Similarly, the table for obtaining the air-fuel ratio index (ind_abf) from the output value of the low-pass filter 2 and the ignition timing (Adv) may be determined based on the characteristics (experimental results) of each engine.

  The target air-fuel ratio index (Tind_abf) is set to a value corresponding to 15 to 16 in order to minimize the HC emission amount from the engine. When considering even the exhaust gas temperature, which is an effective factor for the early activation of the catalyst, the air / fuel ratio is set to a value corresponding to 14-15.

  When Fp_fuel_hos = 0, Alpha maintains the previous value.

<Basic ignition timing calculation unit (FIG. 28)>
This calculation unit calculates the basic ignition timing (Adv0). Specifically, it is shown in FIG. 28, but since it is the same as the first embodiment, it will not be described in detail.

<Ignition timing correction permission section (FIG. 36)>
This calculation unit (permission unit) determines whether or not to correct the basic ignition timing (Adv0). Specifically, as shown in FIG.
1) Time after starting Tas ≦ Tcold
And 2) When the state of TgNe−K1 ≦ Ne ≦ TgNe + K2 lasts for K3 [number of combustions] or more and 3) When the state of Tg_ind_abf1-K4 ≦ ind_abf1 ≦ Tg_ind_abf1 + K5 lasts for more than K6 [numbers of combustion]
When
Let Fp_adv_hos = 1.

In addition,
Tcol in condition 1) corresponds to the time required for the three-way catalyst 11 to be activated. Therefore, the period in which condition 1) is satisfied means that the three-way catalyst 11 is in an inactive state. ing.
Condition 2) determines a state in which the engine speed after startup converges near the target speed during idling. TgNe is a target rotational speed in the idle operation after the start. Further, it is preferable to determine each parameter K1, K2, and K3 empirically.
Condition 3) is when the air-fuel ratio is controlled within a predetermined range. The set values of Tg_ind_abf1, K4, and K5, which are parameters that determine the predetermined range, set the air-fuel ratio as a value corresponding to 15 to 16 in order to minimize the HC emission amount from the engine. When considering even the exhaust gas temperature, which is an effective factor for the early activation of the catalyst, the air / fuel ratio is set to a value corresponding to 14-15.

  When Fp_adv_hos = 1, the ignition timing correction amount (Adv_hos) is calculated by the “ignition timing correction amount calculation unit (FIG. 33)” described below.

<Ignition timing correction amount calculation unit (FIG. 30)>
Here, when Fp_adv_hos = 1, the ignition timing retard correction amount (Adv_hos) is calculated to a predetermined stability based on the output of the crank angle sensor 15. Although specifically shown in FIG. 30, since it is the same as Example 1, it does not elaborate.

  In this embodiment, air-fuel ratio control is first performed on the output signal of the crank angle sensor 15 using the entire frequency band, so that the air-fuel ratio is reduced to the HC minimum condition (15 to 16) or the exhaust gas earlier. Control to the highest temperature condition (14-15). Then, it is separated into two frequency band components, the air-fuel ratio is controlled based on the first frequency band, and the ignition timing is controlled based on the second frequency band. Therefore, it is possible to control to the optimum condition in a shorter period.

(Example 5)
In the fourth embodiment, as a first stage, air-fuel ratio control is performed on the output signal of the crank angle sensor 15 using the entire frequency band. As a result, the air-fuel ratio was quickly controlled to the minimum HC condition (15 to 16) or the maximum exhaust temperature condition (14 to 15). After that, as a second stage, it was separated into two frequency band components, the air-fuel ratio was controlled based on the first frequency band, and the ignition timing was controlled based on the second frequency band. In particular, as a condition for shifting from the first stage to the second stage, that is, as a determination as to whether the air-fuel ratio is controlled within a predetermined range, whether the air-fuel ratio index 1 (ind_abf1) is within the predetermined range is determined. It was judged.

  On the other hand, in this embodiment, when the fuel correction speed is within a predetermined range (when small), it is determined that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio.

  FIG. 22 is a system diagram showing the present embodiment, which is the same as the first embodiment and will not be described in detail.

  FIG. 23 shows the inside of the control unit 16, which is the same as that of the first embodiment, and therefore will not be described in detail.

  FIG. 34 is a block diagram showing the entire control, and includes the following arithmetic units.

・ Basic fuel injection amount calculation unit (Fig. 25)
-Fuel injection amount correction permission section (FIG. 26)
-Fuel injection amount correction value calculation unit (FIG. 38)
・ Basic ignition timing calculator (Fig. 28)
・ Ignition timing correction permission section (Fig. 39)
・ Ignition timing correction amount calculation unit (Fig. 30)
The “basic fuel injection amount calculation unit” calculates the basic fuel injection amount (Tp). The “fuel injection amount correction permission unit” determines whether or not to correct the basic fuel injection amount (Tp). That is, it is determined whether or not to correct the fuel injection amount so that the air-fuel ratio falls within a predetermined range. When the correction is performed, the fuel injection amount correction permission flag Fp_fuel_hos = 1 is set. If not, set Fp_fuel_hos = 0. The “fuel injection amount correction value calculation unit” calculates the fuel injection amount correction value (Alpha) so that the air-fuel ratio falls within a predetermined range based on the output Ne of the crank angle sensor 15 when Fp_fuel_hos = 1. .

  The basic ignition timing (Adv0) is calculated by the “basic ignition timing calculation unit”. The “ignition timing correction permission unit” determines whether or not to correct the basic ignition timing (Adv0). That is, based on the output Ne of the crank angle sensor 15, it is determined whether or not the ignition timing retard correction is performed up to a predetermined engine (combustion) stability. In this determination, a condition as to whether the air-fuel ratio is controlled within a predetermined range is added. More specifically, when the change amount of the fuel injection amount correction value (Alpha) is within a predetermined range (when small), it is determined that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio.

  When correcting the ignition timing, the ignition timing correction permission flag Fp_adv_hos = 1 is set. If not, set Fp_adv_hos = 0. In the “ignition timing correction amount calculation unit”, when Fp_adv_hos = 1, the ignition timing retard correction amount (Adv_hos) is calculated to a predetermined stability based on the output Ne of the crank angle sensor 15.

  Details of each control (arithmetic unit, permission unit) will be described below.

<Basic fuel injection amount calculation unit (FIG. 25)>
This calculation unit calculates the basic fuel injection amount (Tp). Specifically, it is shown in FIG. 25, but it is the same as that of the first embodiment, and will not be described in detail.

<Fuel injection amount correction permission unit (FIG. 26)>
This calculation unit (permission unit) determines whether or not to correct the basic fuel injection amount (Tp). Specifically, it is shown in FIG. 26, but since it is the same as the first embodiment, it will not be described in detail.

<Fuel injection amount correction value calculation unit (FIG. 38)>
Here, when Fp_fuel_hos = 1, the correction value of the fuel injection amount is calculated based on the output of the crank angle sensor 15 so that the air-fuel ratio falls within a predetermined range. Specifically, as shown in FIG. 38, the following processing is performed.

The amount of change in rotational speed per cycle, that is, the angular acceleration dNe is calculated from the output value of the crank angle sensor 15.
After calculating the absolute value of dNe, the band pass filter 1 is applied.
The air-fuel ratio index 1 (ind_abf1) is obtained from the output value of the bandpass filter 1 and the ignition timing (Adv) with reference to a table.
After the absolute value of dNe is calculated, the low pass filter 2 is applied.
The air-fuel ratio index 2 (ind_abf2) is obtained from the output value of the low-pass filter 2 and the ignition timing (Adv) with reference to the table.
-When the ignition timing correction permission flag (Fp_adv_hos) is 0, the air-fuel ratio index (ind_abf) is set to the air-fuel ratio index 1 (ind_abf1).
・ When the ignition timing correction permission flag (Fp_adv_hos) is 1, the air-fuel ratio index (ind_abf) is set to the air-fuel ratio index 2 (ind_abf2).
The difference Dind_abf between the air-fuel ratio index (ind_abf) and the target air-fuel ratio index (Tind_abf) is obtained.
A fuel injection amount correction value (Alpha) is obtained by PI control from the deviation (Dind_abf).

  As will be described later, the ignition timing correction permission flag (Fp_adv_hos) is 0 when the air-fuel ratio is not controlled within the predetermined range. At this time, since it is necessary to quickly control the air-fuel ratio within a predetermined range, the air-fuel ratio control is first performed on the output signal of the crank angle sensor 15 by using almost the entire frequency band, so that the earlier The air-fuel ratio is controlled to the minimum HC condition (15 to 16) or the maximum exhaust temperature condition (14 to 15). Therefore, the pass band of the band pass filter 1 is designed to be almost the entire band.

  As will be described later, the ignition timing correction permission flag (Fp_adv_hos) is 1 when the air-fuel ratio is controlled within a predetermined range. At this time, since it is necessary to control the ignition timing more quickly than the air-fuel ratio to the stability limit, the band used for air-fuel ratio control is limited to a narrow range of the low frequency band, and the remaining band components are the ignition timing. Used for control (described later). For this purpose, the pass band of the low-pass filter 2 is designed to be a narrow range of the low frequency band.

  The table for obtaining the air-fuel ratio index (ind_abf) from the output value of the bandpass filter 1 and the ignition timing (Adv) may be determined based on the characteristics (experimental results) of each engine. Similarly, the table for obtaining the air-fuel ratio index (ind_abf) from the output value of the low-pass filter 2 and the ignition timing (Adv) may be determined based on the characteristics (experimental results) of each engine.

  The target air-fuel ratio index (Tind_abf) is set to a value corresponding to 15 to 16 in order to minimize the HC emission amount from the engine. When considering even the exhaust gas temperature, which is an effective factor for the early activation of the catalyst, the air / fuel ratio is set to a value corresponding to 14-15.

  When Fp_fuel_hos = 0, Alpha maintains the previous value.

<Basic ignition timing calculation unit (FIG. 28)>
This calculation unit calculates the basic ignition timing (Adv0). Specifically, it is shown in FIG. 28, but since it is the same as the first embodiment, it will not be described in detail.

<Ignition timing correction permission section (FIG. 39)>
This calculation unit (permission unit) determines whether or not to correct the basic ignition timing (Adv0). Specifically, as shown in FIG.
1) Time after starting Tas ≦ Tcold
And 2) When the state of TgNe−K1 ≦ Ne ≦ TgNe + K2 lasts for more than K3 [the number of combustion] and 3) When the state of Tg_Dalpha−K7 ≦ | Dalpha | ≦ Tg_Dalpha + K8 continues for more than K9 [the number of combustion]
Let Fp_adv_hos = 1.

  Here, Dalpha is a difference value from the previous calculation value of the fuel injection amount correction value (Alpha).

Note that Tcol in condition 1) corresponds to the time required for activation of the three-way catalyst 11, and therefore the three-way catalyst 11 is in an inactive state during the period in which condition 1) is satisfied. I mean.
Condition 2) determines a state in which the engine speed after startup converges near the target speed during idling. TgNe is a target rotational speed in the idle operation after the start. Further, it is preferable to determine each parameter K1, K2, and K3 empirically.
Condition 3) is when the air-fuel ratio is controlled within a predetermined range. The set values of Tg_Dalpha, K7, and K8, which are parameters that determine the predetermined range, may be determined empirically from the convergence of Dalpha when the actual air-fuel ratio is within the predetermined range <ignition timing correction amount calculation unit ( (Fig. 30)>
Here, when Fp_adv_hos = 1, the ignition timing retard correction amount (Adv_hos) is calculated to a predetermined stability based on the output of the crank angle sensor 15. Although specifically shown in FIG. 30, since it is the same as Example 1, it does not elaborate.

(Example 6)
In Examples 1 to 5, a filter was used as a method for extracting frequency components. In particular, in the fourth and fifth embodiments, with respect to the output signal of the crank angle sensor 15, first, by setting almost the entire frequency band as the pass band of the bandpass filter and performing only the air-fuel ratio control, The air-fuel ratio was controlled to the HC minimum condition (15 to 16) or the exhaust temperature maximum condition (14 to 15) at an early stage.

  On the other hand, in this embodiment, statistical processing is used as a method for extracting all frequency bands. Specifically, the standard deviation of the angular acceleration calculated from the output signal of the crank angle sensor 15 is used as a component of the previous frequency band.

  FIG. 22 is a system diagram showing the present embodiment, which is the same as the first embodiment and will not be described in detail.

  FIG. 23 shows the inside of the control unit 16, which is the same as that of the first embodiment, and therefore will not be described in detail.

  FIG. 37 is a block diagram showing the entire control, and includes the following arithmetic units.

・ Basic fuel injection amount calculation unit (Fig. 25)
-Fuel injection amount correction permission section (FIG. 26)
-Fuel injection amount correction value calculation unit (FIG. 40)
・ Basic ignition timing calculator (Fig. 28)
・ Ignition timing correction permission section (Fig. 39)
・ Ignition timing correction amount calculation unit (Fig. 41)
The “basic fuel injection amount calculation unit” calculates the basic fuel injection amount (Tp). The “fuel injection amount correction permission unit” determines whether or not to correct the basic fuel injection amount (Tp). That is, it is determined whether or not to correct the fuel injection amount so that the air-fuel ratio falls within a predetermined range. When the correction is performed, the fuel injection amount correction permission flag Fp_fuel_hos = 1 is set. If not, set Fp_fuel_hos = 0. The “fuel injection amount correction value calculation unit” calculates the fuel injection amount correction value (Alpha) so that the air-fuel ratio falls within a predetermined range based on the output Ne of the crank angle sensor 15 when Fp_fuel_hos = 1. .

  The basic ignition timing (Adv0) is calculated by the “basic ignition timing calculation unit”. The “ignition timing correction permission unit” determines whether or not to correct the basic ignition timing (Adv0). That is, based on the output Ne of the crank angle sensor 15, it is determined whether or not the ignition timing retard correction is performed up to a predetermined engine (combustion) stability. In this determination, a condition as to whether the air-fuel ratio is controlled within a predetermined range is added. More specifically, when the change amount of the fuel injection amount correction value (Alpha) is within a predetermined range (when small), it is determined that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio.

  When correcting the ignition timing, the ignition timing correction permission flag Fp_adv_hos = 1 is set. If not, set Fp_adv_hos = 0. In the “ignition timing correction amount calculation unit”, when Fp_adv_hos = 1, the ignition timing retard correction amount (Adv_hos) is calculated to a predetermined stability based on the output Ne of the crank angle sensor 15.

  Details of each control (arithmetic unit, permission unit) will be described below.

<Basic fuel injection amount calculation unit (FIG. 25)>
This calculation unit calculates the basic fuel injection amount (Tp). Specifically, it is shown in FIG. 25, but it is the same as that of the first embodiment, and will not be described in detail.

<Fuel injection amount correction permission unit (FIG. 26)>
This calculation unit (permission unit) determines whether or not to correct the basic fuel injection amount (Tp). Specifically, it is shown in FIG. 26, but since it is the same as the first embodiment, it will not be described in detail.

<Fuel injection amount correction value calculation unit (FIG. 40)>
Here, when Fp_fuel_hos = 1, the correction value of the fuel injection amount is calculated based on the output of the crank angle sensor 15 so that the air-fuel ratio falls within a predetermined range. Specifically, as shown in FIG. 40, the following processing is performed.
The amount of rotation speed fluctuation per cycle, that is, the angular acceleration dNe is calculated from the output value of the crank angle sensor 15.
When the ignition timing correction permission flag (Fp_adv_hos) is 0, the fuel injection amount correction value 1 (Alpha1) is set as the fuel injection amount correction value (Alpha).
When the ignition timing correction permission flag (Fp_adv_hos) is 1, the fuel injection amount correction value 2 (Alpha2) is set as the fuel injection amount correction value (Alpha).
The fuel injection amount correction value 1 (Alpha 1) is obtained as follows.
Calculate the standard deviation s_dNe of dNe.
When s_dNe is smaller than the predetermined range A_dNe, Alpha1 = Alpha1 (previous value) −Lean1.
When s_dNe is larger than the predetermined range A_dNe, Alpha1 = Alpha1 (previous value) + Rich1.
When s_dNe is in the predetermined range A_dNe, Alpha1 = Alpha1 (previous value).
-The fuel injection amount correction value 2 (Alpha 2) is obtained as follows.
Also, after calculating the absolute value of dNe, weighted moving average processing is performed.
-The air-fuel ratio index (ind_abf) is obtained from the calculated value of the weighted moving average process and the ignition timing (Adv) by referring to the table.
The difference Dind_abf between the air-fuel ratio index (ind_abf) and the target air-fuel ratio index (Tind_abf) is obtained.
A fuel injection amount correction value 2 (Alpha 2) is obtained from the deviation (Dind_abf) by PI control.

  As will be described later, the ignition timing correction permission flag (Fp_adv_hos) is 0 when the air-fuel ratio is not controlled within the predetermined range. At this time, since it is necessary to quickly control the air-fuel ratio within a predetermined range, the air-fuel ratio control is first performed on the output signal of the crank angle sensor 15 by using almost the entire frequency band, so that the earlier The air-fuel ratio is controlled to the minimum HC condition (15 to 16) or the maximum exhaust temperature condition (14 to 15). For this purpose, standard deviation calculation is performed so that the pass band is the entire band.

  As will be described later, the ignition timing correction permission flag (Fp_adv_hos) is 1 when the air-fuel ratio is controlled within a predetermined range. At this time, since it is necessary to control the ignition timing more quickly than the air-fuel ratio to the stability limit, the band used for air-fuel ratio control is limited to a narrow range of the low frequency band, and the remaining band components are the ignition timing. Used for control (described later). Therefore, the weighting coefficient of the weighted moving average is designed so that the pass band is in a narrow range of the low frequency band.

  A table for obtaining the air-fuel ratio index (ind_abf) from the calculated value of the weighted moving average process and the ignition timing (Adv) may be determined based on the characteristics (experimental results) of each engine. The target air-fuel ratio index (Tind_abf) is set to a value corresponding to 15 to 16 in order to minimize the HC emission amount from the engine. When considering even the exhaust gas temperature, which is an effective factor for the early activation of the catalyst, the air / fuel ratio is set to a value corresponding to 14-15.

  When Fp_fuel_hos = 0, Alpha maintains the previous value.

<Basic ignition timing calculation unit (FIG. 28)>
This calculation unit calculates the basic ignition timing (Adv0). Specifically, it is shown in FIG. 28, but since it is the same as the first embodiment, it will not be described in detail.

<Ignition timing correction permission section (FIG. 39)>
This calculation unit (permission unit) determines whether or not to correct the basic ignition timing (Adv0). Specifically, it is shown in FIG. 39, but it is the same as the fifth embodiment, and therefore will not be described in detail.

<Ignition timing correction amount calculation unit (FIG. 41)>
Here, when Fp_adv_hos = 1, the ignition timing retard correction amount (Adv_hos) is calculated to a predetermined stability based on the output of the crank angle sensor 15. Specifically, as shown in FIG. 41, the following processing is performed.
The amount of rotation speed fluctuation per cycle, that is, the angular acceleration dNe is calculated from the output value of the crank angle sensor 15.
Calculate the standard deviation s_dNe of dNe.
When s_dNe is smaller than the predetermined range B_dNe, Adv_hos = Adv_hos (previous value) −Rtd1.
When s_dNe is larger than the predetermined range B_dNe, Adv_hos = Adv_hos (previous value) + Adv1.
When s_dNe is in the predetermined range B_dNe, Adv_hos = Adv_hos (previous value).
It is desirable to set B_dNe to a value equivalent to the stability limit. Rtd1, Adv1, etc. are parameters that determine the retard speed and the advance speed. The faster (larger), the better the effect of reducing exhaust can be expected, but the ignition timing control system tends to become unstable accordingly. It may be determined empirically according to engine characteristics (responsiveness, etc.).

  In the above embodiment, at the time of engine start (before catalyst activation), the air-fuel ratio and ignition timing that minimizes HC are always controlled while ensuring robustness according to various disturbances that occur in a practical environment. To do. Therefore, HC can be significantly reduced as compared with the conventional setting of the air-fuel ratio and ignition timing in consideration of the stability margin.

An engine control apparatus as one embodiment of the invention according to claim 1. An engine control apparatus as one embodiment of the invention according to claim 2. An engine control apparatus as one embodiment of the invention according to claim 3. An engine control apparatus as one embodiment of the invention according to claim 4. An engine control apparatus as one embodiment of the invention according to claim 5. An engine control apparatus as one embodiment of the invention according to claim 6. An engine control apparatus as one embodiment of the invention according to claim 7. An engine control apparatus as one embodiment of the invention according to claim 8. An engine control apparatus as one embodiment of the invention according to claim 9. An engine control apparatus as one embodiment of the invention according to claim 10. An engine control apparatus as one embodiment of the invention according to claim 11. An engine control apparatus as one embodiment of the invention according to claim 12. An engine control apparatus as one embodiment of the invention according to claim 13. An engine control apparatus as one embodiment of the invention according to claim 14. An engine control apparatus as one embodiment of the invention according to claim 15. An engine control apparatus as one embodiment of the invention according to claim 16. An engine control apparatus as one embodiment of the invention according to claim 17. An engine control apparatus as one embodiment of the invention according to claim 18. An engine control apparatus as one embodiment of the invention according to claim 19. Relationship between air-fuel ratio and HC concentration in exhaust. Relationship between air-fuel ratio and exhaust temperature. The engine control system figure in Examples 1-6. The figure showing the inside of the control unit in Examples 1-6. The block diagram showing the whole control in Examples 1-2. The block diagram showing the basic fuel injection amount calculating part in Examples 1-6. The block diagram showing the fuel injection amount correction | amendment permission part in Examples 1-6. The block diagram showing the fuel injection amount correction value calculating part in Examples 1-2. The block diagram showing the basic ignition timing calculating part in Examples 1-6. The block diagram showing the ignition timing correction | amendment permission part in Examples 1-3. The block diagram showing the ignition timing correction amount calculating part in Examples 1, 2, 4, and 5. FIG. 10 is a block diagram illustrating the entire control in the third embodiment. FIG. 9 is a block diagram illustrating a fuel injection amount correction value calculation unit according to a third embodiment. FIG. 9 is a block diagram illustrating an ignition timing correction amount calculation unit in the third embodiment. FIG. 10 is a block diagram illustrating the entire control in the fourth embodiment. FIG. 10 is a block diagram illustrating a fuel injection amount correction value calculation unit according to a fourth embodiment. FIG. 10 is a block diagram showing an ignition timing correction permission unit in the fourth embodiment. The block diagram showing the whole control in Examples 5 and 6. FIG. FIG. 10 is a block diagram illustrating a fuel injection amount correction value calculation unit according to a fifth embodiment. The block diagram showing the ignition timing correction | amendment permission part in Example 5, 6. FIG. FIG. 10 is a block diagram illustrating a fuel injection amount correction value calculation unit according to a sixth embodiment. FIG. 10 is a block diagram showing an ignition timing correction amount calculation unit in the sixth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air cleaner 2 Air flow sensor 3 Electronic throttle 4 Intake manifold 5 Collector 6 Accelerator 7 Fuel injection valve 8 Spark plug 9 Engine 10 Exhaust manifold 11 Three-way catalyst 12 A / F sensor 13 Accelerator opening sensor 14 Water temperature sensor 15 Crank angle sensor 16 Control Unit 17 Throttle opening sensor 18 Exhaust gas recirculation pipe 19 Exhaust gas recirculation amount control valve 20 Catalyst downstream O ₂ sensor 21 CPU mounted in control unit
22 ROM mounted in the control unit
23 RAM mounted in the control unit
24 Input circuit 25 of various sensors mounted in the control unit 25 Output port 26 Ignition output circuit 27 that outputs a drive signal at an appropriate timing to the spark plug 27 Fuel injection valve drive circuit 28 that outputs an appropriate pulse to the fuel injector Throttle drive circuit 29 Intake air temperature sensor 30 In-cylinder pressure sensor

Claims (12)

Means for calculating the absolute value of the first derivative of the engine speed;
Means for extracting a low frequency component from the absolute value;
Means for extracting a high frequency component from the absolute value;
Means for calculating a parameter for controlling the air-fuel ratio so that the air-fuel ratio index determined from the low frequency component of the absolute value and the ignition timing is within a predetermined range A;
An engine control device comprising: means for calculating a parameter for controlling the ignition timing so that the high frequency component of the absolute value falls within a predetermined range B. In claim 1,
The engine control device according to claim 1, wherein the frequency band of the low frequency component and the frequency band of the high frequency component are determined based on an operating state of the engine. In claims 1 and 2,
An engine control apparatus comprising means for determining the predetermined range A based on ignition timing. In Claims 1-3,
When minimizing HC discharged from the engine, the predetermined range A is set so that the air-fuel ratio becomes a value corresponding to 15 to 16. In claims 1 to 4,
To maximize the temperature of the exhaust gas emitted from the engine,
The engine control apparatus, wherein the predetermined range A is set so that the air-fuel ratio becomes a value corresponding to 14-15. In claims 1-5,
The engine control apparatus is characterized in that the predetermined range B is set to a value corresponding to an engine stability limit. In any one of Claims 1-6,
Means for directly or indirectly detecting that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio;
When it is not detected that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio, and when it is detected,
An engine control apparatus comprising means for changing the frequency band of the low frequency component and the frequency band of the high frequency component. In claim 7,
When it is not detected that the air-fuel ratio is controlled near the target air-fuel ratio,
The engine control device characterized in that the frequency band of the low frequency component is wider than the frequency band of the high frequency component. In claims 7 and 8,
Immediately after engine start, the engine control device is characterized in that the frequency band of the low frequency component is wider than the frequency band of the high frequency component. In claim 7,
Means for directly or indirectly detecting that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio,
When the low frequency component is within a predetermined range, it is determined that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio. In claim 7,
The means for directly or indirectly detecting that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio determines that the air-fuel ratio is controlled in the vicinity of the target air-fuel ratio when the fuel correction speed is within a predetermined range. An engine control device. In any one of Claims 1-11,
The low frequency component and / or the high frequency component is
An engine control apparatus characterized in that an absolute value of a time-series signal of the engine operating state is a value obtained by weighted moving average processing.

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