JP2011106343A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent fluctuation of engine rotation from being promoted to generate a surge in a vehicle, when the fluctuation of engine rotation occurs caused by unsteadiness of a driving system during normal operation of an internal combustion engine at a middle or high load. <P>SOLUTION: Target load factor is calculated based on an accelerator manipulated quantity and an engine speed. An intake adjusting mechanism for adjusting the load factor of the engine 1 so as to achieve the target load factor, is put into operation when a predetermined delay time elapses after the target load factor is calculated. During normal operation of the engine 1 at a middle or high load, the delay time is changed from a normal value, when current engine speed is within a resonant range where engine speed is periodically fluctuated caused by the vehicular driving system, and the periodical fluctuation of the actual load factor of the engine 1 based on the fluctuation of the engine speed resonates with the engine speed fluctuation. In addition, also fuel injection timing of a fuel injection valve 4 is changed simultaneously with the change of the delay time. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  An internal combustion engine mounted on a vehicle such as an automobile includes an intake adjustment mechanism that adjusts an in-cylinder air amount when the intake valve is closed, and a fuel injection valve that injects fuel into the intake passage of the engine. Yes. In such an internal combustion engine, the intake air adjustment mechanism is operated based on the accelerator operation amount to adjust the in-cylinder air amount when the intake valve is closed, and an amount of fuel corresponding to the in-cylinder air amount is injected into the fuel. The fuel is injected from the valve, supplied to the cylinder of the internal combustion engine through the intake passage, and driven by burning the air-fuel mixture consisting of air and fuel in the cylinder. Therefore, when the accelerator operation is performed by the driver of the automobile, the amount of the air-fuel mixture burned in the cylinder of the internal combustion engine is adjusted according to the accelerator operation amount at that time, and the engine output becomes the output request by the accelerator operation. It is adjusted to the corresponding value. As the intake adjustment mechanism, a throttle valve provided in the intake passage of the internal combustion engine is used, or as disclosed in Patent Document 1, opening / closing characteristics such as valve timing, maximum lift amount, and operating angle of the intake valve are variable. In an internal combustion engine equipped with a variable valve mechanism, the variable valve mechanism can be used.

In recent years, it has been proposed to control the intake adjustment mechanism and the fuel injection valve as follows in order to meet demands for improving fuel consumption and exhaust emission of an internal combustion engine.
That is, the in-cylinder air amount corresponding to the output required for the internal combustion engine at that time is calculated as the target in-cylinder air amount based on the accelerator operation amount and the engine speed at every predetermined cycle. Then, based on the target in-cylinder air amount, the intake adjustment mechanism is operated in such a manner that the fuel consumption of the internal combustion engine is optimal so that the in-cylinder air amount when the intake valve is closed becomes the target in-cylinder air amount. Further, in order to inject an amount of fuel corresponding to the target in-cylinder air amount from the fuel injection valve, an injection amount command value is calculated based on the target in-cylinder air amount, and an amount of fuel corresponding to the injection amount command value is calculated. Is injected from the fuel injection valve. Regarding the operation start timing of the intake adjustment mechanism based on the target in-cylinder air amount and the fuel injection timing in the fuel injection from the fuel injection valve based on the injection amount command value, the injected fuel from the fuel injection valve is the internal combustion engine. When reaching the cylinder, the in-cylinder air amount is adjusted to the target in-cylinder air amount.

  Here, in order for the fuel injected from the fuel injection valve to reach the cylinder of the internal combustion engine, after calculating the target in-cylinder air amount, the injection amount command value based on the target in-cylinder air amount is calculated, Further, it takes a relatively long time to inject fuel based on the same injection amount command value and for the injected fuel to reach the cylinder. Therefore, the operation of the intake adjustment mechanism based on the target in-cylinder air amount is started after a predetermined delay time has elapsed since the calculation of the target in-cylinder air amount. The delay time is based on the operation of the intake adjustment mechanism based on the target in-cylinder air amount when the fuel injected from the fuel injection valve reaches the inside of the cylinder of the internal combustion engine based on the injection amount command value. The in-cylinder air amount is set to a value at which the in-cylinder air amount is adjusted to the target in-cylinder air amount. As described above, the operation of the intake adjustment mechanism based on the target in-cylinder air amount is started after the delay time has elapsed since the calculation of the target in-cylinder air amount. When the fuel injected from the valve reaches the cylinder of the internal combustion engine, the cylinder air amount is adjusted to the target cylinder air amount.

  By controlling the intake air adjustment mechanism and the fuel injection valve as described above, the intake air adjustment mechanism operates to optimize the fuel consumption of the internal combustion engine so that fuel consumption can be improved, and when the intake valve is closed It becomes possible to set the air-fuel ratio of the air-fuel mixture in the cylinder to a value suitable for improving the exhaust emission of the internal combustion engine.

JP 2006-138233 A (paragraphs [0002], [0011] to [0013], FIGS. 3 and 5)

  By the way, during steady operation at a medium and high load in an internal combustion engine, as shown by a solid line in FIG. 9A due to the rattling in the drive system of the automobile and the relatively high output of the internal combustion engine. Periodic engine speed fluctuations may occur. When the periodic engine rotation fluctuation as described above occurs, the target in-cylinder air amount calculated based on the engine rotation speed and the accelerator operation amount is also indicated by the two-dot chain line in FIG. It fluctuates periodically according to the rotation fluctuation. In other words, when the engine speed increases, the target in-cylinder air amount decreases to suppress it, and when the engine speed decreases, the target in-cylinder air amount increases to suppress it. go.

  When the target in-cylinder air amount is calculated in accordance with such engine rotation fluctuation, the intake adjustment mechanism is controlled based on the target in-cylinder air amount, and the actual in-cylinder air amount when the intake valve closes is the target. The amount of air in the cylinder is adjusted. However, the actual in-cylinder air amount varies with the transition of the target in-cylinder air amount (the two-dot chain line in FIG. 9B) due to the delay time described above and the response delay of the intake to the operation of the intake adjustment mechanism. On the other hand, as shown by the solid line in FIG. Thus, even if the change in the actual in-cylinder air amount is delayed with respect to the change in the target in-cylinder air amount, the actual change in the in-cylinder air amount is directly opposite to the engine rotation change (solid line in FIG. 9A). If the engine stays in a state shifted from ¼ to ¼ of the cycle of the engine rotation fluctuation, the periodic engine rotation fluctuation can be effectively suppressed.

  However, the period of the engine rotation fluctuation varies depending on the engine speed region where the fluctuation occurs. When the cycle of engine rotation fluctuation changes, the cycle of fluctuation of the target in-cylinder air amount calculated based on the engine rotation speed at that time also changes, and consequently the cycle of fluctuation of the actual in-cylinder air amount also changes. Accordingly, depending on the engine speed region where the current engine speed exists, the actual fluctuation in the cylinder air amount may vary as shown in the solid line in FIG. 10B (see the solid line in FIG. 10A). ), The fluctuations of these fluctuations occur, and the engine rotation fluctuations are promoted as indicated by broken lines in the figure, which may cause vibrations (surges) in the longitudinal direction of the automobile.

  In Patent Document 1, the drive frequency of the hydraulic control valve is disclosed in the engine rotational speed region where the drive pulse of the hydraulic control valve used for valve timing control of the intake valve and the ignition / injection timing that causes a decrease in power supply voltage resonate. A technique for performing valve timing control by switching between the above and avoiding the resonance is disclosed. However, such a technique cannot solve the above-described problem of occurrence of surge.

  The present invention has been made in view of such circumstances, and its purpose is that when engine rotation fluctuations due to rattling of the drive system occur during steady operation at medium to high loads of an internal combustion engine, An object of the present invention is to provide a control device for an internal combustion engine that can suppress the occurrence of a surge in a vehicle by promoting engine rotation fluctuations.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to a first aspect of the present invention, there is provided an intake adjustment mechanism for adjusting an in-cylinder air amount when an intake valve of an internal combustion engine mounted on a vehicle is closed, and fuel in an intake passage of the internal combustion engine. A fuel injection valve for injecting fuel, a calculation means for calculating a target in-cylinder air amount based on an accelerator operation amount and an engine speed at a predetermined period, and an amount corresponding to the calculated target in-cylinder air amount Injection control means for injecting fuel from a fuel injection valve; and after the delay time has elapsed since the calculation of the target in-cylinder air amount, the in-cylinder air is operated by operating the intake adjustment mechanism based on the target in-cylinder air amount. Intake control means for adjusting the amount to the target in-cylinder air amount, and the delay time is calculated such that the fuel injected from the fuel injection valve after the target in-cylinder air amount is calculated enters the cylinder of the internal combustion engine. Before you reach In a control device for an internal combustion engine in which the in-cylinder air amount is set to a value adjusted to the target in-cylinder air amount based on an operation of the intake air adjustment mechanism by an intake air control unit, During the normal operation of the engine and causing periodic engine rotation fluctuations caused by the vehicle drive system, and the periodic fluctuation of the in-cylinder air amount based on the engine rotation fluctuations resonates with the engine rotation fluctuations. A change means for changing the delay time when the current engine speed exists in the resonance region to be changed, and the injection control means, after the change when the delay time is changed by the change means, The fuel injection of the fuel injection valve so that the fuel injected from the fuel injection valve reaches the cylinder of the internal combustion engine at a timing when the cylinder air amount at the target becomes the target cylinder air amount. It was summarized as to change the timing.

  According to the above configuration, during steady operation at a medium and high load of the internal combustion engine, periodic engine rotation fluctuations caused by the drive system of the vehicle are caused, and periodic fluctuations in the in-cylinder air amount based on the engine rotation fluctuations are generated. When the current engine rotational speed exists in a resonance region that resonates with the engine rotational fluctuation, the delay time is changed through the changing means. Further, when such a delay time is changed, the fuel injected from the fuel injection valve reaches the cylinder of the internal combustion engine at a timing when the cylinder air amount after the change becomes the target cylinder air amount. Thus, the fuel injection timing of the fuel injection valve is changed. As described above, by changing the delay time, the delay range of the actual in-cylinder air amount change with respect to the calculated in-cylinder air amount change is changed, and the actual in-cylinder air amount fluctuation is changed by the engine rotation fluctuation. Resonance is avoided. As a result, it is possible to suppress the occurrence of a surge in the vehicle due to the engine rotational fluctuation being promoted due to the resonance.

  According to a second aspect of the present invention, in the first aspect of the present invention, when the change means changes the delay time, the change width is changed from 1/4 to 3/4 of one cycle of the engine rotation fluctuation. The gist is to set the value within the range.

  In order to avoid resonance when the engine speed is in the resonance region and the actual fluctuation in the cylinder air amount resonates with the engine rotation fluctuation during steady operation at medium and high loads of the internal combustion engine The actual transition of the in-cylinder air amount may be shifted to the advance side or the delay side within a range of ¼ to ¾ of one cycle of the engine rotation fluctuation with respect to the engine rotation fluctuation. According to the above configuration, the range of change in the delay time is set to a value within a range of 1/4 to 3/4 of one cycle of the engine rotation fluctuation, so that the actual in-cylinder air amount is changed by the change in the delay time. The resonance between the fluctuation and the engine rotation fluctuation can be avoided accurately, and as a result, the occurrence of a surge in the vehicle can be suppressed accurately.

  According to a third aspect of the invention, in the first or second aspect of the invention, the delay time is the fastest from the completion of calculation of the target in-cylinder air amount to the fuel injection at the fuel injection valve, and the fuel It is preset to a value suitable for the engine operating condition in which the fuel injected from the injection valve reaches the cylinder of the internal combustion engine in the slowest state, and the change from the set value is performed through the changing means. And the injection control means controls the arrival of the fuel into the cylinder when the fuel injected from the fuel injection valve is in an engine operating state where the arrival of the fuel into the cylinder is faster than the latest state. The gist is that the fuel injection timing of the fuel injection valve is adjusted to the retard side in accordance with the engine operating state so that the internal air amount becomes the target in-cylinder air amount.

  When the delay time is set in advance as described above, the resonance region is the engine low rotation region, and the region where the delay time should be changed is limited to the engine low rotation region. As described above, since the region where the delay time should be changed is limited to the engine low-speed region, it is possible to suppress frequent change of the delay time. In addition, when the engine operating state where the fuel injected from the fuel injection valve reaches the cylinder faster than the latest state, the fuel injection timing of the fuel injection valve is adjusted to the retarded side according to the state. The Therefore, even when the delay time is set in advance as described above, the fuel injection from the fuel injection valve reaches the inside of the cylinder even if the engine operation state becomes faster than the latest state. The fuel injected from the valve can reach the cylinder in a state where the cylinder air amount becomes the target cylinder air amount.

  According to a fourth aspect of the present invention, in the invention according to the third aspect, the changing means changes the set delay time so as to increase the delay time, and the injection control is performed. The gist is to change the fuel injection timing of the fuel injection valve to the retard side in accordance with the change to the increase side of the delay time by the changing means.

  According to the above configuration, the delay time is changed to an increase side when the current engine rotation speed exists in the resonance region during steady operation at a medium and high load of the internal combustion engine. In other words, the adjustment of the actual in-cylinder air amount to the target in-cylinder air amount is delayed. Further, when the delay time is changed to the increase side, the fuel injection timing of the fuel injection valve is changed to the retard side accordingly. As described above, by changing the delay time to the increase side, the delay width of the transition of the actual cylinder air amount with respect to the calculated transition of the target cylinder air amount is changed to the increase side, and the actual cylinder air amount is changed. Is avoided from resonating with engine rotation fluctuations.

  In the invention of claim 5, in the invention of claim 3, the changing means changes the set delay time so as to reduce the delay time, and the injection control is performed. The means calculates an injection amount command value based on the target in-cylinder air amount, and injects an amount of fuel corresponding to the injection amount command value from the fuel injection valve. The delay time by the changing means When the change to the decrease side is made, it is possible to realize fuel injection earlier than usual by using the previous value as the injection amount command value, and in that state, the change to the decrease side of the delay time is made. The gist is to change the fuel injection timing of the fuel injection valve to the advance side.

  According to the above configuration, the delay time is changed to a decreasing side when the current engine speed is in the resonance region during steady operation at a medium to high load of the internal combustion engine. In other words, the adjustment of the actual in-cylinder air amount to the target in-cylinder air amount is accelerated. Further, when the delay time is changed to the decrease side, the fuel injection timing of the fuel injection valve is changed to the advance side accordingly. Specifically, instead of calculating the injection amount command value based on the target in-cylinder air amount, by using the previous value as the injection amount command value as it is, the time required for calculating the injection amount command value is omitted and more than usual. Early fuel injection can be realized, and in this state, the fuel injection timing of the fuel injection valve is changed to the advance side in accordance with the change to the decrease time of the delay time. As described above, by changing the delay time to the decreasing side, the delay range of the actual in-cylinder air amount transition to the calculated in-cylinder air amount transition is changed to the decreasing side, and the actual in-cylinder air amount Is avoided from resonating with engine rotation fluctuations.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole engine with which the control apparatus of this embodiment is applied. The timing chart which shows the transition (valve opening / closing characteristic) of the lift amount of an intake valve and an exhaust valve with respect to the change of a crank angle. The timing chart which shows the transition (valve opening / closing characteristic) of the lift amount of an intake valve and an exhaust valve with respect to the change of a crank angle. The timing chart which shows the transition (valve opening / closing characteristic) of the lift amount of an intake valve and an exhaust valve with respect to the change of a crank angle. The graph which shows the fuel consumption optimal operation line of opening-and-closing characteristics, such as the operating angle of an intake valve, and valve timing. (A) And (b) is a time chart which shows transition of an engine speed and a load factor. The flowchart which shows the change procedure of delay time and fuel injection timing. The flowchart which shows another example of the change procedure of delay time and fuel-injection timing. (A) And (b) is a time chart which shows transition of engine rotational speed and cylinder air quantity. (A) And (b) is a time chart which shows transition of engine rotational speed and cylinder air quantity.

Hereinafter, an embodiment in which the present invention is embodied in a control device for an automobile engine will be described with reference to FIGS.
In the engine 1 shown in FIG. 1, a throttle valve 13 is provided in an intake passage 3 connected to the combustion chamber 2 (inside the cylinder) so as to be opened and closed, and air is taken into the cylinder through the intake passage 3. The fuel injected from the fuel injection valve 4 is supplied into the cylinder through the intake passage 3. When the air / fuel mixture is ignited by the spark plug 5, the air / fuel mixture burns, the piston 6 reciprocates, and the crankshaft 7 that is the output shaft of the engine 1 rotates. On the other hand, the air-fuel mixture after combustion in the cylinder is sent out from the cylinder to the exhaust passage 8 as exhaust gas.

  In the engine 1, the combustion chamber 2 and the intake passage 3 are connected and cut off by the opening / closing operation of the intake valve 9, and the combustion chamber 2 and the exhaust passage 8 are connected and cut off by the opening / closing operation of the exhaust valve 10. . The intake valve 9 and the exhaust valve 10 are opened and closed with the rotation of the intake camshaft 11 and the exhaust camshaft 12 to which the rotation of the crankshaft 7 is transmitted.

  The engine 1 is provided between the intake valve timing variable mechanism 16 provided on the intake camshaft 11 and the intake valve 9 of the intake camshaft 11 as a variable valve mechanism that varies the opening / closing characteristics of the intake valve 9. The variable valve lift mechanism 14 is provided. The variable valve lift mechanism 14 changes the maximum lift amount and the operating angle of the intake valve 9 in synchronization with each other as shown in FIG. 2 through rotational driving of the electric motor 15 within a predetermined rotation angle range. . The intake side valve timing variable mechanism 16 (FIG. 1) is driven by controlling the hydraulic pressure acting on the mechanism 16 through a hydraulic circuit, and the relative rotation phase (valve timing) of the intake camshaft 11 with respect to the crankshaft 7 is controlled. To change. Through the driving of the intake side valve timing varying mechanism 16, both the valve opening timing and the valve closing timing of the valve 9 are maintained while the valve opening period (operating angle) of the intake valve 9 is kept constant as shown in FIG. It is advanced or retarded.

  Further, the engine 1 shown in FIG. 1 is provided on the exhaust camshaft 12 as a variable valve mechanism that makes the opening / closing characteristics of the exhaust valve 10 variable, and the relative rotational phase of the exhaust camshaft 12 with respect to the crankshaft 7 (valve An exhaust-side valve timing variable mechanism 17 that can change the timing is also provided. The exhaust side valve timing varying mechanism 17 is driven by controlling the hydraulic pressure acting on the mechanism 17 through a hydraulic circuit. Through the driving of the exhaust side valve timing variable mechanism 17, both the valve opening timing and the valve closing timing of the valve 10 are maintained while the valve opening period (operating angle) of the exhaust valve 10 is kept constant as shown in FIG. It is advanced or retarded.

Next, the electrical configuration of the control device for the engine 1 in the present embodiment will be described with reference to FIG.
The control device includes an electronic control device 21 that executes various controls relating to the engine 1. The electronic control unit 21 is a CPU that executes various arithmetic processes related to the above control, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores the arithmetic results of the CPU, etc. Input / output ports for input / output.

Various sensors shown below are connected to the input port of the electronic control unit 21.
An accelerator position sensor 28 that detects an operation amount (accelerator operation amount) of an accelerator pedal 27 that is depressed by an automobile driver.

A throttle position sensor 30 that detects the opening (throttle opening) of the throttle valve 13 provided in the intake passage 3.
An air flow meter 32 that detects the amount of air taken into the combustion chamber 2 (inside the cylinder) through the intake passage 3.

A crank position sensor 34 that outputs a signal corresponding to the rotation of the crankshaft 7 and is used for calculation of the engine rotation speed, calculation of the crank angle, and the like.
A position sensor 35 that is used to detect the rotation angle of the electric motor 15 within the predetermined rotation angle range and to determine the operating angle and the maximum lift amount of the intake valve 9.

  Intake used to output a signal corresponding to the rotation position of the intake shaft 11 based on the rotation of the intake camshaft 11 to obtain the relative rotation phase of the intake camshaft 11 with respect to the crankshaft 7 (valve timing of the intake valve 9). Cam position sensor 36;

  Exhaust gas used to output a signal corresponding to the rotational position of the shaft 12 based on the rotation of the exhaust camshaft 12 and to determine the relative rotation phase of the exhaust camshaft 12 with respect to the crankshaft 7 (valve timing of the exhaust valve 10). Cam position sensor 37;

  The output port of the electronic control unit 21 includes drive circuits for the fuel injection valve 4, the throttle valve 13, the variable valve lift mechanism 14 (electric motor 15), the intake side valve timing variable mechanism 16, the exhaust side valve timing variable mechanism 17, and the like. Etc. are connected.

  Then, the electronic control unit 21 grasps the engine operating state based on the detection signals input from the various sensors, and outputs command signals to various driving circuits connected to the output port according to the grasped engine operating state. . In this way, various operation controls of the engine 1 such as intake control and fuel injection amount control in the engine 1 are performed through the electronic control unit 21.

  In the engine 1, a throttle valve 13, an intake side valve timing variable mechanism 16, as an intake air adjustment mechanism that adjusts an in-cylinder air amount (air amount in the combustion chamber 2) when the intake valve 9 is closed, And the variable valve lift mechanism 14 is used. In the engine 1, the intake air amount adjusting mechanism is operated based on the accelerator operation amount to adjust the in-cylinder air amount, and an amount of fuel corresponding to the in-cylinder air amount is injected from the fuel injection valve 4. Then, the air is supplied into the cylinder of the engine 1 through the intake passage 3 and is driven by burning an air-fuel mixture consisting of air and fuel in the cylinder. Therefore, when the accelerator operation is performed by the driver of the automobile, the amount of the air-fuel mixture burned in the cylinder of the engine 1 is adjusted according to the accelerator operation amount at that time, and the engine output is set to the output request by the accelerator operation. It is adjusted to the corresponding value. In this embodiment, the parameter representing the in-cylinder air amount when the intake valve 9 is closed is the load ratio of the engine 1 based on the full load state of the engine 1 and is in the range of 0 to 100%. The value load factor is used. Incidentally, the load of the engine 1 is the amount of air sucked into the cylinder per cycle of the engine 1 and has the same meaning as the in-cylinder air amount when the intake valve 9 is closed. .

Next, control of the intake adjustment mechanism and the fuel injection valve 4 in the engine 1 will be described in detail.
In recent years, there has been a demand for further improvements in fuel consumption and exhaust emission of the engine 1, and the intake adjustment mechanism and the fuel injection valve 4 are controlled as follows in order to meet these demands.

  That is, based on the accelerator operation amount and the engine speed for each predetermined cycle, the load factor corresponding to the output required for the engine 1 at that time is calculated as the target load factor KL. Then, based on the target load factor KL, the intake adjustment mechanism is operated in such a manner that the fuel consumption of the engine 1 is optimal so that the actual load factor of the engine 1 becomes the target load factor KL. Specifically, the opening and closing characteristics of the intake valve 9 by driving variable valve mechanisms such as the variable valve lift mechanism 14 and the intake side valve timing variable mechanism 16, that is, the maximum lift amount and the operating angle, and the valve timing can be varied to change the engine 1. The load factor is adjusted to the target load factor KL. In this case, compared with the case where the load factor is adjusted only by adjusting the opening degree of the throttle valve 13, the opening degree of the valve 13 can be adjusted to the open side value. Adjustment is performed to reduce the pump loss of the engine 1 and to improve the fuel consumption of the engine 1.

  Further, when operating variable valve mechanisms such as the variable valve lift mechanism 14 and the intake side valve timing variable mechanism 16 based on the target load factor KL so that the actual load factor of the engine 1 becomes the target load factor KL, The fuel consumption of the engine 1 can also be improved by performing as follows. That is, the target load factor KL can be obtained so that the load factor at which the engine output becomes a value corresponding to the accelerator operation amount can be obtained, and the opening / closing characteristics of the intake valve 9 are optimized by reducing the pump loss and the like. Based on this, the variable valve lift mechanism 14 and the variable intake valve timing mechanism 16 are operated.

  Here, if the accelerator operation amount is changed while maintaining the steady state of the engine 1 such as gradually changing the accelerator operation amount, the target load factor KL changes accordingly, and consequently the opening / closing characteristics of the intake valve 9 ( The maximum lift amount and operating angle, and valve timing) also change. The curve representing the transition of the operating angle and valve timing of the intake valve 9 that changes in this way indicates the operating angle (maximum lift amount) and valve timing of the intake valve 9 that can optimize the fuel consumption of the engine 1 by reducing pump loss or the like. It becomes the fuel consumption optimal operation line that represents the transition. Incidentally, this optimum fuel consumption operation line is, for example, as shown by a solid line in FIG. Then, when adjusting the load factor based on the accelerator operation amount to adjust the engine output to a value corresponding to the driver's output request for the engine 1, the operating angle and valve timing of the intake valve 9 are on the fuel efficiency optimum operating line. The fuel consumption of the engine 1 is thereby brought to the best state.

  On the other hand, when the target load factor KL is calculated on the basis of the accelerator operation amount and the engine speed for each predetermined cycle, the target load is calculated so that the fuel corresponding to the target load factor KL is injected from the fuel injection valve 4. An injection amount command value is calculated based on the rate KL, and an amount of fuel corresponding to the injection amount command value is injected from the fuel injection valve 4.

  In addition, with respect to the fuel injection timing in the fuel injection from the fuel injection valve 4 based on the injection amount command value based on the operation start timing of the intake adjustment mechanism based on the target load factor KL, the injected fuel from the fuel injection valve 4 is the engine. When reaching one cylinder, the actual load factor of the engine 1 is adjusted to the target load factor KL.

  In order for the fuel injected from the fuel injection valve 4 to reach the cylinder of the engine 1, after calculating the target load factor KL, the injection amount command value is calculated based on the target load factor KL, and the injection amount is further increased. A relatively long time is required until the fuel is injected based on the command value and the injected fuel reaches the cylinder. Therefore, the operation of the intake air adjustment mechanism based on the target load factor KL is started after a predetermined delay time has elapsed since the target load factor KL was calculated. The delay time is determined by the operation of the intake adjustment mechanism based on the target load factor KL when the fuel injected from the fuel injection valve 4 based on the injection amount command value reaches the cylinder of the engine 1. Is set to a value at which the load factor is adjusted to the target load factor KL. In this manner, the operation of the intake air adjustment mechanism based on the target load factor KL is started after the delay time has elapsed after the target load factor KL is calculated, so that the fuel injection valve 4 is based on the injection amount command value. When the fuel injected from the fuel reaches the cylinder of the engine 1, the actual load factor is adjusted to the target load factor KL.

  By controlling the intake adjustment mechanism and the fuel injection valve 4 as described above, the intake adjustment mechanism operates to optimize the fuel consumption of the engine 1 to improve the fuel consumption, and the intake valve 9 is closed. The air-fuel ratio of the air-fuel mixture in the cylinder at that time can be set to an appropriate value for improving the exhaust emission of the engine 1.

  Next, how to set the delay time related to the operation start timing of the intake adjustment mechanism based on the target load factor KL, and how to adjust the fuel injection timing in the fuel injection from the fuel injection valve 4 based on the injection amount command value Will be described more specifically.

  The delay time is the fastest from the completion of calculation of the target load factor KL to the fuel injection at the fuel injection valve 4, and the arrival of the injected fuel from the fuel injection valve 4 into the cylinder of the engine 1 is the slowest state. Is set in advance to a value (for example, 32 ms) suitable for the engine operating condition. On the other hand, the fuel injection timing of the fuel injection valve 4 is the fastest timing (advanced as much as possible) in the engine operating state where the arrival of the injected fuel from the fuel injection valve 4 into the cylinder of the engine 1 becomes the slowest state. Side timing). Further, in the engine operating state where the fuel injected from the fuel injection valve 4 reaches the cylinder of the engine 1 faster than the latest state, the arrival of the injected fuel into the cylinder is caused by the actual arrival of the engine 1 in the cylinder. The fuel injection timing of the fuel injection valve 4 is adjusted to the retarded side in accordance with the engine operating condition so that the load factor can be achieved with the target load factor KL.

  By the way, during steady operation at a medium and high load in the engine 1, due to the rattling in the drive system of the automobile and the relatively high output of the engine 1, as shown by the solid line in FIG. Periodic engine speed fluctuations may occur. When such periodic engine rotation fluctuation occurs, the target load factor KL calculated based on the engine rotation speed and the like also periodically changes, and the engine is controlled by controlling the intake air adjustment mechanism based on the target load factor KL. The actual load factor of 1 follows the target load factor KL with the intention of suppressing the engine rotation fluctuation. Note that the actual load factor at this time changes with a delay corresponding to the delay time or the response delay of the intake air with respect to the operation of the intake air adjusting mechanism with respect to the change of the target load factor KL.

  Normally, even if the actual load factor transition is delayed with respect to the target load factor KL, the actual load factor variation is directly opposite to the engine rotation variation (solid line in FIG. 6A). From this state, it stays in a state shifted by ¼ of the cycle of the engine rotation fluctuation, and the periodic engine rotation fluctuation can be effectively suppressed. However, since the cycle of the engine rotation fluctuation varies depending on the engine rotation speed region where the fluctuation occurs, the actual load factor fluctuation may vary depending on the engine rotation speed region where the engine rotation fluctuation occurs. As shown by the solid line in (b), the engine rotation fluctuation (solid line in FIG. 6A) is almost overlapped. In this way, when the actual load factor variation substantially overlaps with the engine rotation variation, resonance of those variations occurs, and the engine rotation variation is promoted as shown by the broken line in FIG. There is a risk of vibration (surge) in the direction.

  The engine rotation speed region (hereinafter referred to as the resonance region) in which the actual load factor variation substantially overlaps with the engine rotation variation is related to the delay time described above. Since this value is set in advance (32 ms), the engine is in a low engine speed range of 900 to 1100 rpm, for example. Incidentally, one cycle of the engine speed fluctuation in this resonance region is about 130 ms (for example, 128 ms), and when the engine speed fluctuation in such a period occurs, the actual load factor fluctuation and the engine speed fluctuation described above are Resonance occurs.

  Next, the countermeasure of this embodiment regarding the problem of the occurrence of surge in the automobile due to the above-described cause will be described with reference to FIG. This figure is a flowchart showing a change processing routine for changing the delay time described above and changing the fuel injection timing in accordance with the change. This change processing routine is periodically executed through the electronic control device 21 by, for example, a time interruption at predetermined time intervals.

  In this routine, it is determined whether or not the change in the accelerator operation amount is so small that it can be determined that the engine 1 is in steady operation (S101), and whether or not the engine 1 is operating at medium and high loads (S102). Such a determination is made. In S102, for example, when the load factor of the engine 1 is 30% or more, it is determined that the engine 1 is operating at a medium to high load. Further, in the case of an automobile equipped with a continuously variable transmission (CVT), the CVT is controlled so that the load factor of the engine 1 does not become excessively high. When it is in the range of 70%, it may be determined that the engine 1 is operating at a medium to high load.

  When a negative determination is made in either S101 or S102, that is, when the engine 1 is not in a steady operation at a medium or high load, the delay time is set to a normal value (in this example, 32 ms) (S104). . In this case, fuel is injected from the fuel injection valve 4 at the normal fuel injection timing (S105).

  Specifically, in the engine operating state where the arrival of the injected fuel from the fuel injection valve 4 into the cylinder of the engine 1 is in the latest state, the fuel injection at the fuel injection valve 4 is completed after the calculation of the target load factor KL is completed. The fuel injection from the fuel injection valve 4 is performed at the fastest timing (advanced timing as much as possible). The engine operating state in which the fuel injected from the fuel injection valve 4 reaches the slowest state in the cylinder of the engine 1 is, for example, when the engine speed is low, for example, the engine speed is less than the upper limit value of the resonance region. For example, the situation is low.

  Further, in the engine operating situation where the fuel injected from the fuel injection valve 4 reaches the cylinder of the engine 1 faster than the latest state, the arrival of the injected fuel into the cylinder is caused by the actual load factor of the engine 1. The fuel injection timing of the fuel injection valve 4 is adjusted to the retarded side according to the engine operating condition so that the fuel can be performed in a state where the target load factor KL is reached. The engine operating state in which the fuel injected from the fuel injection valve 4 reaches the cylinder of the engine 1 faster than the slowest state is, for example, when the engine speed is high, for example, the engine speed is the upper limit of the resonance region. For example, the situation is high when it is higher than the value.

  On the other hand, when an affirmative determination is made in both S101 and S102, that is, when the engine 1 is in steady operation at a medium to high load, whether or not the current engine speed is in the resonance region is determined. A determination is made (S103), and if a negative determination is made here, the processing of S104 and S105 described above is executed. On the other hand, if an affirmative determination is made in the process of S103, the delay time is changed from the normal value (32 ms) to the increasing side (S106). The width of the change in the delay time at this time is a value within a range of 1/4 to 3/4 of one cycle of engine rotation fluctuation (128 ms in this example) within the resonance region, for example, 1/4 of the above one cycle. (32 ms). For this reason, in the process of S106, the delay time is changed from the normal value (32 ms) to the increase side by 32 ms to be 64 ms.

  After the change to the increase side of the delay time is performed in this way, the fuel injected from the fuel injection valve 4 at the timing when the actual load factor of the engine 1 after the change becomes the target load factor KL. The fuel injection timing of the fuel injection valve 4 is changed to the retard side by the amount corresponding to the change to the increase side of the delay time so as to reach the cylinder of the engine 1 (S107).

  By changing the delay time in the processes of S106 and S107 and changing the fuel injection timing in accordance with the change, the fluctuation of the actual load factor of the engine 1 deviates from the engine rotation fluctuation, and these fluctuations overlap. Disappear. Therefore, it is avoided that the fluctuation of the actual load factor of the engine 1 resonates with the engine rotation fluctuation (solid line in FIG. 6A) as shown by the solid line in FIG. 6B. As a result, it is avoided that the engine rotation fluctuation is promoted as shown by the broken line in FIG. 6A, and as a result, generation of a surge in the automobile is avoided.

According to the embodiment described in detail above, the following effects can be obtained.
(1) During steady operation at a medium and high load of the engine 1, periodic engine rotation fluctuations caused by rattling of the driving system of the automobile are caused, and the cycle of the actual load factor of the engine 1 based on the engine rotation fluctuations When the current engine rotational speed exists in a resonance region where a typical fluctuation resonates with the engine rotational fluctuation, the delay time is changed to the increase side. In other words, the adjustment of the actual load factor of the engine 1 to the target load factor KL is delayed. Further, when such a change to the delay time is made, the fuel injected from the fuel injection valve 4 is injected into the engine at the timing when the actual load factor of the engine 1 after the change becomes the target load factor KL. The fuel injection timing of the fuel injection valve 4 is changed to the retard side in accordance with the change to the increase side of the delay time so as to reach the inside of one cylinder. As described above, by changing the delay time to the increase side, the delay width of the actual load factor transition with respect to the calculated transition of the target load factor KL is changed to the increase side, and the fluctuation of the actual load factor is Resonance with fluctuations is avoided. As a result, it is possible to suppress the occurrence of a surge in the automobile due to the engine rotation fluctuation being promoted due to the resonance.

  (2) When the engine 1 is in steady operation at medium and high loads and the engine rotation speed exists in the resonance region, and the actual load factor fluctuation of the engine 1 resonates with the engine rotation fluctuation, the resonance is avoided. In order to achieve this, the actual load factor may be shifted to the advance side or the delay side within a range of ¼ to ¾ of one cycle of the engine rotation fluctuation with respect to the engine rotation fluctuation. Here, regarding the change of the delay time, the range of the change is within a range of ¼ to ¾ of one cycle of engine rotation fluctuation, more specifically, 1 / one cycle of engine rotation fluctuation. A value of 4 is assumed. For this reason, it is possible to accurately avoid the resonance between the fluctuation of the actual load factor and the fluctuation of the engine rotation by changing the delay time, and it is possible to appropriately suppress the occurrence of a surge in the automobile.

  (3) The delay time is the fastest from the completion of calculation of the target load factor KL to the fuel injection at the fuel injection valve 4 and the arrival of the injected fuel from the fuel injection valve 4 into the cylinder of the engine 1 is the maximum. It is set in advance to a value that is suitable for the engine operating state in which the engine is in the slow state. When the delay time is set in advance as described above, the resonance region is the engine low rotation region, and the region where the delay time should be changed is limited to the engine low rotation region. As described above, since the region where the delay time should be changed is limited to the engine low-speed region, it is possible to suppress frequent change of the delay time. In addition, when the engine operating state is such that the fuel injected from the fuel injection valve 4 arrives in the cylinder faster than the latest state, the fuel injection timing of the fuel injection valve 4 is adjusted to the retarded side according to that state. Is done. For this reason, even when the delay time is set in advance as described above, the fuel injection from the fuel injection valve 4 reaches the in-cylinder engine even when the engine operating state becomes faster than the latest state. The injection fuel from the valve 4 can reach the cylinder in a state where the actual load factor becomes the target load factor KL.

In addition, the said embodiment can also be changed as follows, for example.
In the above-described embodiment, when changing the delay time, the change is performed so as to increase the delay time. However, instead of this, the above-described change may be performed so as to decrease the delay time. In this case, the change of the delay time and the change of the fuel injection timing associated therewith are performed through the change processing routine of FIG. This change processing routine is different from the routine only in the processing (S206, S207) corresponding to S106 and S107 of the change processing routine of FIG.

  In the change processing routine of this example (FIG. 8), when the engine 1 is in steady operation at a medium to high load (both YES in S201 and S202) and the current engine speed is in the resonance region (S203: YES). The delay time is changed from a normal value to a decreasing side (S206). The width of the change in the delay time at this time is a value within a range of 1/4 to 3/4 of one cycle of engine rotation fluctuation in the resonance region, for example, 1/4 of one cycle of the engine rotation fluctuation. Value. Thereafter, the injection amount command value is set to the previous value, and the fuel injected from the fuel injection valve 4 at the timing when the actual load factor of the engine 1 after the change of the delay time becomes the target load factor KL. The fuel injection timing of the fuel injection valve 4 is changed to the advance side by the amount corresponding to the change to the decrease side of the delay time (S207).

  As described above, in this example, when the current engine rotation speed exists in the resonance region during steady operation at a medium and high load of the engine 1, the delay time is changed to the decrease side. In other words, the adjustment of the actual load factor of the engine 1 to the target load factor KL is accelerated. Further, when the delay time is changed to the decrease side, the fuel injection timing of the fuel injection valve 4 is changed to the advance side accordingly. Specifically, instead of calculating the injection amount command value based on the target load factor KL, by using the previous value as the injection amount command value as it is, the time required for calculating the injection amount command value can be omitted earlier than usual. In this state, the fuel injection timing of the fuel injection valve 4 is changed to the advance side in accordance with the change to the decrease side of the delay time. By changing the delay time to the decreasing side as described above, the delay width of the actual load factor transition with respect to the calculated transition of the target load factor KL is changed to the decreasing side, and the fluctuation of the actual load factor is Resonance with fluctuations is avoided. When the previous value is used as the injection amount command value, the accelerator operation amount is substantially constant and the appropriate value of the injection amount command value remains the previous value. Use does not cause deterioration of engine operation.

  -Although the value of 1/4 of one cycle of engine rotation fluctuation was exemplified as the range of change of the delay time, it is appropriately changed to a value other than 1/4 value within the range of 1/4 to 3/4. May be. By the way, from the viewpoint of making the actual load factor fluctuation of the engine 1 after the change of the delay time the opposite of the engine speed fluctuation, and thereby converging the engine speed fluctuation quickly, the range of the delay time change is the engine speed fluctuation. It is preferable that the value be 1/2 of one period.

  As the intake adjustment mechanism, only the throttle valve 13 may be used, or only the variable valve mechanism (the valve lift variable mechanism 14 and the intake valve timing variable mechanism 16) on the intake valve 9 side may be used.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Combustion chamber, 3 ... Intake passage, 4 ... Fuel injection valve, 5 ... Spark plug, 6 ... Piston, 7 ... Crankshaft, 8 ... Exhaust passage, 9 ... Intake valve, 10 ... Exhaust valve, 11 DESCRIPTION OF SYMBOLS ... Intake camshaft, 12 ... Exhaust camshaft, 13 ... Throttle valve, 14 ... Valve lift variable mechanism, 15 ... Electric motor, 16 ... Intake side valve timing variable mechanism, 17 ... Exhaust side valve timing variable mechanism, 21 ... Electronic control Device (calculation means, injection control means, intake control means, change means), 27 ... accelerator pedal, 28 ... accelerator position sensor, 30 ... throttle position sensor, 32 ... air flow meter, 34 ... crank position sensor, 35 ... position sensor, 36: intake cam position sensor, 37: exhaust cam position sensor.

Claims (5)

An intake adjustment mechanism that adjusts an in-cylinder air amount when an intake valve of an internal combustion engine mounted on a vehicle is closed, a fuel injection valve that injects fuel into an intake passage of the internal combustion engine, and a predetermined cycle Calculation means for calculating a target in-cylinder air amount based on the accelerator operation amount and the engine rotational speed, injection control means for injecting an amount of fuel corresponding to the calculated target in-cylinder air amount from a fuel injection valve, and the target Intake control means for operating the intake adjustment mechanism based on the target in-cylinder air amount after a delay time has elapsed since the in-cylinder air amount is calculated, and adjusting the in-cylinder air amount to the target in-cylinder air amount; The delay time is an operation of the intake adjustment mechanism by the intake control means when the fuel injected from the fuel injection valve reaches the cylinder of the internal combustion engine after the target cylinder air amount is calculated. Based on The controller of an internal combustion engine wherein the cylinder air quantity is set to a value that is a state of being adjusted to the target cylinder air quantity Te,
The internal combustion engine is in steady operation at a medium to high load, causes periodic engine rotation fluctuations caused by the drive system of the vehicle, and periodic fluctuations in the in-cylinder air amount based on the engine rotation fluctuations are When there is a current engine rotation speed in a resonance region that resonates with engine rotation fluctuation, the change means for changing the delay time,
When the delay time is changed by the changing means, the injection control means injects from the fuel injection valve at a timing when the cylinder air amount after the change becomes the target cylinder air amount. A control apparatus for an internal combustion engine, wherein the fuel injection timing of the fuel injection valve is changed so that the injected fuel reaches the cylinder of the internal combustion engine. 2. The internal combustion engine control according to claim 1, wherein, when the change unit changes the delay time, the range of the change is set to a value within a range of ¼ to ¾ of one cycle of the engine rotation fluctuation. apparatus. The delay time is the fastest from the completion of calculation of the target in-cylinder air amount to the fuel injection at the fuel injection valve, and the arrival of the injected fuel from the fuel injection valve into the cylinder of the internal combustion engine is the slowest. It is set in advance to a value that is suitable for the engine operating state to be in a state, and the change from the set value is performed through the changing means,
The injection control means determines that the fuel reaches the cylinder when the fuel injected from the fuel injection valve reaches the cylinder faster than the latest state. 3. The internal combustion engine according to claim 1, wherein the fuel injection timing of the fuel injection valve is adjusted to the retard side in accordance with the engine operating condition so that the amount can be achieved in a state where the amount becomes the target in-cylinder air amount. Control device. The changing means changes the set delay time so as to increase the delay time.
4. The internal combustion engine according to claim 3, wherein the injection control means changes the fuel injection timing of the fuel injection valve to the retarded angle side when the change time is changed to increase the delay time. 5. Control device. The changing means changes the set delay time so as to reduce the delay time.
The injection control means calculates an injection amount command value based on the target in-cylinder air amount, and injects an amount of fuel corresponding to the injection amount command value from the fuel injection valve. When the delay time is changed to the decrease side, the previous value is used as the injection amount command value, so that fuel injection earlier than usual can be realized, and in that state, the delay time is reduced to the decrease side. The control device for an internal combustion engine according to claim 3, wherein the fuel injection timing of the fuel injection valve is changed to the advance side in accordance with the change.

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