JP2011226311A - Method for correcting intake air amount of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately suppress troubles occurring at acceleration by inspecting precisely the cause of the decrease in an engine output accompanied with the increase in inner EGR gas at acceleration of an internal combustion engine.SOLUTION: The internal combustion engine includes a variable valve timing control device which adjusts a valve overlapping amount when both an air suction valve and an air exhaust valve are opened simultaneously corresponding to an operation status of the internal combustion engine by controlling both valves so that at least one valve timing thereof attains a target valve timing. When the variable valve timing control device detects the operation status of the internal combustion engine in operation, and determines that the detected operation status of the internal combustion engine is accelerated, the device sets the correction amount of an intake air based on the operation delay of the variable valve timing control device relative to the target valve timing and the changed amount of the valve timing.

Description

  The present invention relates to an intake air amount correction method for an internal combustion engine including a variable valve timing control device.

  Conventionally, for example, in an internal combustion engine having a variable valve timing control device that controls the opening / closing timing (valve timing) of an intake valve, the opening timing of the intake valve relative to the exhaust valve is advanced or retarded so The fuel consumption is improved.

  In an internal combustion engine equipped with such a variable valve timing control device, the variable valve timing control device is accelerated from an operating state in which the variable valve timing control device is not operated, while maintaining a constant speed after increasing the throttle opening. When the engine operates suddenly, an overlap state in which the intake valve and the exhaust valve open simultaneously occurs, and so-called internal EGR (exhaust gas recirculation) gas due to exhaust gas blow-back increases. In this case, as the internal EGR gas increases, the engine output (torque) decreases, engine speed fluctuations occur, and an operating state in which the feeling of acceleration is temporarily hindered appears.

  In view of such a change in the operating state of the internal combustion engine, for example, in Patent Document 1, a valve timing set value for adjusting the valve timing based on the engine speed and the engine load is set. If the difference between the optimal valve timing during full load operation at the engine speed at the time and the valve timing setting value is within a predetermined value, the valve timing is set based on the set valve timing setting value and the current valve timing value. It is shown that the operating amount of timing is determined.

  However, the above-described stagnation phenomenon during acceleration is affected by the engine speed, the responsiveness of the variable valve timing control device, and the like. Since the operation amount is only limited based on the optimum valve timing at the time of full load operation, it is difficult to accurately solve the problem during acceleration.

JP-A-7-253032

  Therefore, the present invention pays attention to the above points, and at the time of acceleration of the internal combustion engine, by carefully examining the factors when the engine output decreases with the increase of the internal EGR gas, it is possible to accurately suppress defects during acceleration. With the goal.

  That is, the intake air amount correction method for an internal combustion engine according to the present invention controls the operation state of the internal combustion engine by controlling the valve timing of at least one of the intake valve and the exhaust valve to be the target valve timing. Accordingly, a variable valve timing control device that adjusts the valve overlap amount when both valves are open at the same time is provided. The variable valve timing control device detects the operating state of the internal combustion engine during operation and detects the internal combustion engine. When the engine operating state is determined to be acceleration, the correction amount of the intake air amount is set based on the operation delay of the variable valve timing control device with respect to the target valve timing and the change amount of the valve timing. .

  With such a configuration, when it is determined that the internal combustion engine is in an accelerating operation state while the variable valve timing control device is operating, the control starts when the variable valve timing control device controls the valve. The correction amount of the intake air amount is set based on the control delay from when the valve is actually operated until the actual operation of the valve and the change amount of the valve timing of the operated valve. Therefore, even if the internal EGR gas increases due to the acceleration of the variable valve timing control device, the intake air amount is corrected, so that fluctuations in the engine speed are suppressed and fluctuations in the engine output are suppressed. It is possible to experience an acceleration feeling corresponding to

  In order to improve the fluctuation of the engine output with higher accuracy, it is preferable to set the correction amount of the intake air amount based on the operation delay and the change amount, and further the update speed of the target valve timing.

  The present invention is configured as described above, and when the variable valve timing control device is operating, even if the internal combustion engine is in an acceleration operation state, the control delay of the variable valve timing control device and the change in the valve timing are changed. By setting a correction amount of the intake air amount based on the amount and correcting the intake air amount, fluctuations in the engine speed can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS Structure explanatory drawing which shows schematic structure of embodiment of this invention. The flowchart which shows the outline of the control procedure of the embodiment. Action | operation explanatory drawing of the same embodiment.

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

  A three-cylinder engine 100 schematically showing the configuration of one cylinder in FIG. 1 is mounted on, for example, an automobile. The engine 100 includes an intake system 1, a cylinder 2, and an exhaust system 5. The intake system 1 is provided with a throttle valve 11 that opens and closes in response to an accelerator pedal (not shown), and an intake manifold 12 that integrally has a surge tank 13 is attached downstream of the throttle valve 11. Further, a bypass circuit 14 that bypasses the throttle valve 11 is provided, and a flow rate control valve 15 that controls the flow rate of air is provided in the bypass circuit 14. The bypass circuit 14, the flow rate control valve 15, and the electronic control device 4 described later constitute an idle rotation control device.

  A spark plug 8 is attached to the ceiling portion of the combustion chamber 23 formed in the upper part of the cylinder 2. A fuel injection valve 3 is attached to an intake port side end of the intake manifold 12. The fuel injection valve 3 is controlled by an electronic control device 4 described later.

  The engine 100 includes a variable valve timing mechanism 9 for changing the opening / closing timing of the intake valve 21. The variable valve timing mechanism 9 uses a so-called oscillating cylinder mechanism, and includes a rotor fixed to the intake camshaft 91, a housing fitted outside the rotor, and an electromagnetic for rotating the housing relative to the rotor. An oil control valve 92 that is a four-way switching control valve, a pair of gears 94 and 95 that are attached to the housing and fixed to the exhaust camshaft 93 so as to mesh with each other, and attached to the end of the exhaust camshaft 93 A crank sensor 96 that outputs a crank angle signal and a cylinder discrimination signal, and a timing sensor 97 that is attached to the end of the intake camshaft 91 and outputs an exhaust cam signal each time it rotates 240 ° CA (crank angle); It is the structure provided with. The variable valve timing mechanism 9 and the electronic control device 4 constitute a variable valve timing control device.

  In such a configuration, the opening / closing timing of the intake valve 21, that is, the valve timing, is changed by the variable valve timing mechanism 9 operated by the opening / closing timing signal p output from the electronic control device 4. That is, when the variable valve timing mechanism 9 receives the opening / closing timing signal p, the oil control valve 92 controls the direction and amount of hydraulic fluid flowing into and out of the housing. As a result, the relative angle of the housing with respect to the rotor changes, and a desired rotational phase difference is generated between the intake camshaft 91 and the exhaust camshaft 93 to variably control the valve timing. That is, the opening / closing timing of the intake valve 21 and the opening / closing timing of the exhaust valve 24 are changed by changing the opening / closing timing of the intake valve 21 while the exhaust valve 24 is always opened / closed with respect to the rotation of the crankshaft. The relative phase difference can be freely changed within a predetermined angle range. In this way, by adjusting the valve timing of the intake valve 21, the overlap amount when the intake valve 21 and the exhaust valve 24 are simultaneously opened can be adjusted, and the internal EGR gas amount is controlled appropriately. be able to.

  The electronic control unit 4 is mainly configured by a microcomputer system including a central processing unit 41, a storage unit 42, an input interface 43, and an output interface 44. The central processing unit 41 controls the operation of the engine 100 by executing various programs described below stored in the storage device 42. Information necessary for operation control of the engine 100 is input to the central processing unit 41 via the input interface 43, and the central processing unit 41 sends control signals to the fuel control valve 3, the oil control valve 92, and the like. And output via the output interface 44.

Specifically, the input interface 43 outputs an air flow rate signal a output from the air flow meter 71 for detecting the air flow rate flowing into the intake manifold 12, and an output from the rotation speed sensor 72 for detecting the engine speed. The rotation speed signal b, the vehicle speed signal c output from the vehicle speed sensor 73 for detecting the vehicle speed, the IDL signal d output from the idle switch 74 for detecting the open / closed state of the throttle valve 11, and the cooling of the engine 100 A water temperature signal f output from the water temperature sensor 76 for detecting the water temperature, a voltage signal h output from the O ₂ sensor 51, and the like are input. On the other hand, from the output interface 44, the ignition signal m for the spark plug 8, the fuel injection signal n for the fuel injection valve 3, the correction amount signal o for the flow control valve 15, and the oil control of the variable valve timing mechanism 9. An opening / closing timing signal p or the like is output to the valve 92.

  In such a configuration, the electronic control unit 4 is set according to the operating state using the air flow rate signal a output from the air flow meter 71 and the rotation speed signal b output from the rotation speed sensor 72 as main information. The fuel injection amount is calculated using the coefficient to determine the fuel injection time corresponding to the fuel injection amount, that is, the energization time for the fuel injection valve 3, and the fuel injection valve 3 is controlled by the determined energization time. Is injected into the intake system 1. Such fuel injection control itself may apply what is known in this field.

  Further, the electronic control unit 4 detects the operating state of the engine 100 while the variable valve timing control unit is operating, and determines that the detected operating state of the engine 100 is acceleration when the variable valve timing control unit is operating. An intake air amount correction program for setting a correction amount of the intake air amount based on the operation delay of the timing mechanism 9, the amount of change in valve timing, and the update speed of the target valve timing is stored. The operation of the intake air amount correction program will be described below with reference to FIG. Note that the operation region in which the variable valve timing control device is operated and the setting of the target valve timing at that time may be the same as those widely known in this field, and thus description thereof will be omitted.

  In such an operation state, first, in step S1, it is determined whether or not the engine 100 is in an acceleration operation state during the valve timing control. Whether or not the valve timing of the intake valve 21 is under control is determined by the presence or absence of a control signal for the oil control valve 92. When the control signal is output to the variable valve timing mechanism 9, It is determined that the valve timing is being controlled. During acceleration, the change rate per unit time of the throttle valve 11 is measured and determined.

  If it is determined in step S1 that the acceleration is during valve timing control, a correction amount for the intake air intake amount is set in step S2. The correction amount is set based on the operation delay of the variable valve timing mechanism 9 with respect to the target valve timing, the change amount of the valve timing, and the update speed of the target valve timing. In this case, an update speed of the target valve timing is set using a map based on the opening degree of the throttle valve 11 and the vehicle speed at the time of execution of the intake air amount correction program. The update speed of the target valve timing refers to an interval at which the target valve timing is updated according to the operating state of the engine 100, and is set to a larger value as the throttle opening increases and the vehicle speed increases. For example, the minimum value is 0 and the maximum value is 1.

  Next, the operation delay indicated by the time from the output of the valve timing operation signal to the variable valve timing mechanism 9 until the variable valve timing mechanism 9 actually operates, and the actual valve timing change amount (change in the operation angle). Based on the amount (advance amount)), a map in which the basic correction amount is set is searched, and the basic correction amount corresponding to the operation delay and the change amount of the valve timing at the same time the program is executed is obtained. . Then, the obtained basic correction amount is divided by the update speed of the target valve timing, and the correction amount of the intake air amount is calculated and set. The basic correction amount is set so as to increase as the response delay increases and as the valve timing change amount increases. Therefore, in an operating state in which the response delay and the amount of change in valve timing are large, the correction amount increases when the update speed of the target valve timing is small.

  Thereafter, in step S3, the intake air amount is corrected and increased by the set correction amount. This correction of the intake air amount is executed by controlling the amount of air passing through the detour 14 by controlling the opening degree of the flow control valve 15.

  In step S4, it is determined whether or not the acceleration has ended based on the change rate of the throttle opening. If the acceleration has not ended, the process returns to step S2 to set a correction amount for the intake air amount and correct the intake air amount by the correction amount set in step S3. The end of acceleration is determined by determining that the rate of change of the opening degree of the throttle valve 11 has fallen below a reference value for determination.

  In step S5, the correction amount of the intake air amount that has been performed so far is gradually reduced, that is, attenuated. In this way, by attenuating the correction amount of the intake air amount, the rotational fluctuation due to the end of the correction of the intake air amount is suppressed.

  In such a configuration, when the engine 100 is accelerated in an operation state in which the valve timing is controlled, as shown in FIG. 3, the correction amount of the intake air amount is corrected for the period until the acceleration is completed. And continue to increase. The correction amount is set based on the update speed of the target valve timing, the response delay of the valve timing, and the amount of change set based on the opening of the throttle valve 11 and the vehicle speed.

  During this time, even when the internal EGR gas amount increases at the time when the operation starts corresponding to the target valve timing at which the valve timing is actually updated, the engine speed and the engine torque are the same as in the conventional case indicated by the one-dot chain line. Thus, it moves in the direction of accelerating smoothly and continuously without descending temporarily.

  Therefore, by setting the correction amount of the intake air amount based on the update speed of the target valve timing set based on the opening degree of the throttle valve 11 and the vehicle speed, the response delay and the change amount of the valve timing, the acceleration of the engine 100 is increased. The correction amount of the intake air amount can be accurately set according to the state. For this reason, even if the internal EGR gas amount increases and the combustion decreases by controlling the valve timing according to the operating state during acceleration, the intake air amount is increased, so the engine speed and engine output Variations can be suppressed. In addition, during acceleration, it is possible to suppress the looseness that temporarily decreases the acceleration feeling, and it is possible to maintain good drivability.

  In the above-described embodiment, the correction amount of the intake air amount is set by correcting the basic correction amount based on the response delay of the valve timing and the change amount of the valve timing with the update speed of the target valve timing. The configuration may be such that the intake air amount is corrected to be increased by the correction amount.

  Further, in the above-described embodiment, the description has been given of the one that can change the valve timing of the intake valve, but a variable valve timing control device that makes the valve timing of the exhaust valve variable instead of the intake valve may be used. In addition, the configuration may be such that both the intake valve and the exhaust valve are variable. In addition, the variable valve timing mechanism may change each valve timing by an electromagnetic actuator other than the hydraulic control type as described above.

  In the so-called electronic throttle in which the throttle valve is opened and closed by an electromagnetic actuator, the bypass circuit 14 and the flow control valve 15 described above can be omitted. In the case of an electronic throttle, the increase correction of the intake air amount by the set correction amount may be performed by adjusting the opening of the throttle valve.

  Instead of the air flow meter, the intake pipe pressure may be detected in a surge tank, for example, and the intake air amount may be set based on the engine speed and the intake pipe pressure.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  An example of utilization of the present invention is an internal combustion engine that includes a variable valve timing mechanism and performs internal EGR control.

4 ... Electronic control unit 9 ... Variable valve timing mechanism 21 ... Intake valve 24 ... Exhaust valve

Claims (2)

The internal combustion engine controls the valve timing of at least one of the intake valve and the exhaust valve so as to become the target valve timing, so that the valve overlap when both valves are open simultaneously according to the operating condition of the internal combustion engine Equipped with a variable valve timing control device to adjust the amount,
Detecting the operating state of the internal combustion engine when the variable valve timing control device is operating,
An internal combustion engine that sets a correction amount of an intake air amount based on an operation delay of a variable valve timing control device with respect to a target valve timing and a change amount of the valve timing when it is determined that the detected operating state of the internal combustion engine is acceleration Correction method for air intake.   2. The intake air amount correction method for an internal combustion engine according to claim 1, wherein the correction amount of the intake air amount is set based on the operation delay and change amount, and further the update speed of the target valve timing.

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