JP2022104094A - Control device of internal combustion engine - Google Patents

Abstract

To suppress deviation between a target intake air amount and an actual intake air amount in changing a valve timing.SOLUTION: A control device of an internal combustion engine for controlling an intake air amount into a cylinder according to a valve timing and a throttle opening based on a target intake air amount in the internal combustion engine including a variable valve timing device includes: a valve timing control section determining a target valve timing calculated on the basis of the target intake air amount and controlling the variable valve timing device to achieve the target valve timing; and a throttle opening control section starting a control of the throttle opening at a timing of starting a control of the variable valve timing device to achieve the target valve timing.SELECTED DRAWING: Figure 3

Description

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

Recently, an internal combustion engine equipped with a variable valve timing device capable of changing the opening / closing timing of an intake valve or an exhaust valve is known (see, for example, Patent Document 1). Patent Document 1 describes an internal combustion engine that adjusts the throttle opening according to fluctuations in the intake air amount calculated based on the valve timing, the throttle opening, and the engine speed in a transient operating state in which the valve timing changes. The control device is disclosed. In such a conventional control device, for example, when the valve opening timing of the intake valve is changed to the advance angle side, the increase in the intake air amount due to the change in the valve timing is taken into consideration, and this is offset to increase the intake air amount. The throttle opening is controlled to the closed side so as to decrease. This alleviates the torque step.

Japanese Patent Application Laid-Open No. 2003-83116

However, the control of the conventional throttle valve is performed based on the actual valve timing detected by a device such as a cam angle sensor that detects the actual valve timing. Therefore, in the transitional period when the valve timing changes, the change in the intake air amount due to the change in the throttle opening may be delayed or deviated from the change in the intake air amount due to the change in the valve timing. Further, the throttle valve is farther from the combustion chamber to which the intake air is introduced as compared with the intake valve and the exhaust valve, and an intake manifold having a large volume is provided in the path from the throttle valve to the combustion chamber. ing. Therefore, while the change in the intake air amount due to the change in valve timing appears immediately, the change in the intake air amount due to the operation of the throttle valve may cause a response delay (transportation delay). .. For these reasons, the amount of intake air actually sucked into the cylinder of the internal combustion engine may deviate from the target intake air amount. Such a deviation can also occur in the internal combustion engine disclosed in Patent Document 1.

Therefore, it is an object of the control device of the internal combustion engine disclosed in the present specification to suppress the deviation between the target intake air amount and the actual intake air amount when the valve timing is changed.

The internal combustion engine control device disclosed in the present specification is an internal combustion engine provided with a variable valve timing device, which controls the amount of intake air into the cylinder according to the valve timing and the throttle opening based on the target intake air amount. A valve timing control unit that sets a target valve timing calculated based on the target intake air amount and controls the variable valve timing device so as to be the target valve timing, and the valve timing. It is provided with a throttle opening degree control unit that starts control of the throttle opening degree in accordance with the timing at which the control unit starts control of the variable valve timing device so as to be the target valve timing.

The control device of the internal combustion engine disclosed in the present specification can suppress the deviation between the target intake air amount and the actual intake air amount when the valve timing is changed.

FIG. 1 is a schematic diagram showing an engine system including a control device for an internal combustion engine according to the first embodiment. FIG. 2 is a flowchart illustrating the control executed by the ECU included in the engine system of the first embodiment. FIG. 3 is a time chart showing changes in valve timing, throttle opening degree, and intake air amount in the engine system of the first embodiment together with a comparative example. FIG. 4 is a flowchart illustrating control in the second embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the dimensions, ratios, etc. of each part may not be shown so as to completely match the actual ones. Also, depending on the drawing, details may be omitted.

(First Embodiment)
[Engine system configuration]
First, a schematic configuration of the engine system 100 of the embodiment will be described with reference to FIG. The engine system 100 includes an internal combustion engine 1 fueled by gasoline and a control device. The control device includes an air flow meter 13, a crank angle sensor 30, an ECU (Electronic Control Unit) 40, an accelerator pedal opening sensor 70, a gear position sensor 71, a vehicle speed sensor 72, and the like. The accelerator pedal opening sensor 70 detects the amount of depression of the accelerator pedal by the driver. The gear position sensor 71 determines the gear selected by the driver. The vehicle speed sensor 72 detects the vehicle speed of the vehicle on which the engine system 100 is mounted. The internal combustion engine 1 can use a conventionally known alternative fuel for gasoline such as ethanol or natural gas instead of gasoline. Further, the internal combustion engine may be a diesel engine.

The internal combustion engine 1 includes a plurality of cylinders 2 in a cylinder block (only one cylinder 2 is shown in FIG. 1). A piston 3 is slidably housed in each cylinder 2, and the piston 3 forms a combustion chamber 2a with a cylinder head arranged on the upper side of the cylinder block. The piston 3 is connected to the crankshaft 5 via a connecting rod 4. The combustion chamber 2a is provided with an injector 6 for injecting fuel into the cylinder and a spark plug 7. The fuel injected from the injector 6 is made into an air-fuel mixture in the combustion chamber 2a and ignited by the spark plug 7. The ignited air-fuel mixture burns and explodes, pushing down the piston 3. The pushed-down piston 3 transmits the explosive force to the crankshaft 5 via the connecting rod 4 to rotate the crankshaft 5. A crank angle sensor 30 is provided in the vicinity of the crankshaft 5. The engine rotation speed of the internal combustion engine 1 is detected by the crank angle sensor 30. The injector 6 may be provided in the intake pipe 10 in the vicinity of the combustion chamber 2a.

The internal combustion engine 1 is provided with an intake port 8 and an exhaust port 9 so as to face the combustion chamber 2a, an intake pipe 10 forming an intake passage is connected to the intake port 8, and an exhaust port 9 is exhausted. The exhaust pipe 11 forming the passage is connected.

The intake pipe 10 is provided with an air cleaner 12, an air flow meter 13, a throttle valve 17, and an intake manifold 18 in this order from the upstream side of the intake flow. The throttle valve 17 is provided with a throttle opening sensor 17a. The air flow meter 13 detects the amount of air flowing in the intake pipe 10. The throttle valve 17 adjusts the amount of air sent into the combustion chamber 2a. The throttle opening sensor 17a detects the opening of the throttle valve 17. The intake pipe 10 is branched by an intake manifold 18 and is connected to an intake port 8 of each cylinder.

The exhaust pipe 11 is provided with an exhaust manifold 20 and a catalyst 21 in this order from the upstream side of the exhaust flow. The catalyst 21 purifies the exhaust gas.

The internal combustion engine 1 includes an intake valve 23 that opens and closes an intake port 8 and an exhaust valve 24 that opens and closes an exhaust port 9. The intake valve 23 and the exhaust valve 24 open and close with the rotation of the intake camshaft and the exhaust camshaft (not shown) which are drive-connected to the crankshaft 5. As a result, the intake valve 23 and the exhaust valve 24 are driven to open and close at predetermined timings in synchronization with the rotation of the crankshaft 5 and corresponding to the reciprocating movement of each piston 3. The internal combustion engine 1 is an intake VVT mechanism 25 which is a variable valve mechanism that variably sets the valve timing which is the opening / closing timing of the intake valve 23, and a variable valve mechanism which variably sets the valve timing which is the opening / closing timing of the exhaust valve 24. A certain exhaust VVT mechanism 26 is provided. The intake VVT mechanism 25 and the exhaust VVT mechanism 26 form a variable valve timing device.

A cam angle sensor 31a on the intake side is provided in the vicinity of the intake camshaft, and a cam angle sensor 31b on the exhaust side is provided in the vicinity of the exhaust camshaft. The cam angle sensor 31a detects the phase of the actual valve timing of the intake camshaft. The cam angle sensor 31b detects the phase of the actual valve timing of the exhaust camshaft.

The ECU 40 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a storage device, and the like. The ECU 40 controls the internal combustion engine 1 by executing a program stored in a ROM or a storage device. The ECU 40 is electrically connected to the air flow meter 13, the throttle opening sensor 17a, the crank angle sensor 30, and the cam angle sensors 31a and 31b, and receives signals from these sensors. Further, the ECU 40 is electrically connected to the throttle valve 17, the intake VVT mechanism 25, and the exhaust VVT mechanism 26, transmits signals to them, and controls their operations. In addition to these, various sensors for controlling the engine system 100 are electrically connected to the ECU 40. For example, the ECU 40 is electrically connected to the accelerator pedal opening sensor 70, the gear position sensor 71, and the vehicle speed sensor 72, and receives signals from these. Based on the signals acquired by these various sensors, the ECU 40 controls each part included in the engine system 100, including the control of the intake VVT mechanism 25, the exhaust VVT mechanism 26, and the throttle valve 17. In the following description, the control related to the control of the intake air amount into the cylinder will be described.

The ECU 40 functions as a valve timing control unit and a throttle opening degree control unit. The ECU 40, which functions as a valve timing control unit, calculates the target valve timing based on the operating state of the internal combustion engine 1, for example, the engine rotation speed and the target intake air amount (target torque) calculated based on the accelerator opening. do. Then, the ECU 40 transmits a control signal to one or both of the intake VVT mechanism 25 and the exhaust VVT mechanism 26 so that the opening / closing timing of the intake valve 23 and the exhaust valve 24 becomes the calculated target valve timing. The ECU 400, which functions as a throttle opening degree control unit, sets the throttle opening degree according to the target valve timing calculated by the valve timing control unit, and transmits a control signal to the throttle valve 17.

In the engine system 100 of the present embodiment, the control signal is transmitted to the throttle valve at the timing of transmitting the control signal to the control of the intake VVT mechanism 25 and the exhaust VVT mechanism 26. Hereinafter, an example of the control will be described with reference to FIGS. 2 and 3 together with a comparative example. Unlike the embodiment, the throttle opening in the comparative example is not controlled according to the target valve timing, but is controlled according to the actual valve timing. FIG. 3 shows not only the engine system 100 but also changes in valve timing, throttle opening degree, and intake air amount for the comparative example as a time chart.

In the following description, first, the control executed by the ECU 40 will be described with reference to the flowchart shown in FIG. 2, and the timing of each event and the time transition of each change amount will be described. Then, the effect of this embodiment will be described together with the time chart for the comparative example shown in FIG.

In step S1, the ECU 40 acquires the target intake air amount and the engine speed. The target intake air amount is calculated and acquired based on the information acquired by the accelerator pedal opening sensor 70, the gear position sensor 71, and the vehicle speed sensor 72. On the other hand, the engine speed is calculated and acquired based on the detected value of the crank angle sensor 30.

The ECU 40 calculates the target valve timing in step S2, which is executed following step S1. The target valve timing is calculated based on the target intake air amount acquired in step S1 and the engine speed. The target valve timing is variously set depending on the combination of the target intake air amount and the engine speed. Here, a case where the valve opening timing of the intake valve 23 is changed to the advance side by the intake VVT mechanism 25 will be described. ..

The ECU 40 calculates the target throttle opening degree based on the target valve timing calculated in step S2 in step S3, which is executed following step S2. Here, when the valve opening timing of the intake valve 23 is changed to the advance angle side, the intake air amount into the cylinder changes to the increasing side, so that the torque step caused by this increase in the intake air amount is alleviated. The throttle valve 17 is controlled to the closed side. The target throttle opening is calculated based on a map created based on the relationship between the target valve timing and the target throttle opening acquired in advance by an experiment.

In step S4 following step S3, the ECU 40 transmits a control signal for driving the actuator included in the intake VVT mechanism 25 so as to be the target valve timing calculated in step S2. Further, the ECU 40 transmits a control signal for driving the actuator included in the throttle valve 17 so as to have the target throttle opening degree calculated in step S3 in accordance with the transmission timing of the control signal.

Here, referring to FIG. 3, the control signal related to the valve timing setting and the control signal related to the throttle opening degree setting are transmitted at time t1. In FIG. 3, both the valve timing control signal and the throttle opening control signal are shown by solid lines. The actual operation of the valve timing and the actual operation of the throttle opening are both shown by the broken lines.

In the actual operation of the valve timing, a response delay occurs with respect to the control signal due to the operation delay of the actuator included in the intake VVT mechanism 25. Therefore, the actual operation starts at time t3, and the response delay is generally eliminated at time t5. On the other hand, in the actual operation of the throttle opening, a response delay occurs with respect to the control signal due to the operation delay of the actuator included in the throttle valve 17. The actual operation of the throttle opening starts at time t2, which roughly coincides with the time t3 at which the actual operation of the valve timing starts, and the response delay of the throttle opening is also eliminated at about time t5, and the target valve timing and the valve The timing matches the actual operation.

In this way, by transmitting the control signal of the throttle opening according to the transmission timing of the control signal for setting the target valve timing instead of the actual valve timing, the response delay occurs in the intake VVT mechanism 25. The period and the period in which the response delay occurs in the throttle valve 17 can be overlapped. As a result, as shown in FIG. 3, the intake air amount in the present embodiment substantially coincides with the target intake air amount and the actual intake air amount.

Here, the effect of the control in the present embodiment will be described in more detail with reference to the time chart of the comparative example in FIG. In the comparative example, the throttle opening is controlled not according to the target valve timing but according to the actual valve timing. That is, the cam angle sensor 30a detects the actual valve timing that changes according to the target valve timing, and controls the throttle opening degree according to the detected value. Therefore, the control signal of the throttle opening coincides with the time t3 at which the actual operation of the valve timing starts. Then, the actual operation of the throttle opening starts at the time t4, which is later than the time t3.

As a result, the throttle opening coincides with the actual operation of the throttle opening at the time t6 later than the time t5 at which the target valve timing and the actual operation of the valve timing coincide. As described above, in the comparative example, although the change of the intake valve 23 to the advance angle side is completed, the change of the throttle opening degree is not completed. Further, the intake valve 23 is close to the combustion chamber 2a, and when the valve opening timing of the intake valve 23 changes to the advance angle side, the intake air amount changes immediately. On the other hand, since the throttle valve 17 is far from the combustion chamber 2a and the intake manifold 18 having a large volume exists between the combustion chamber 2a and the combustion chamber 2a, the change in the intake air amount into the cylinder tends to be delayed. As a result, in FIG. 3, as shown by the broken line in the graph of the intake air amount of the comparative example, the actual intake air amount becomes larger than the target intake air amount. Such a state causes a torque step.

On the other hand, in the present embodiment, the control signal is transmitted so as to be the target valve timing, and the control signal of the throttle opening is transmitted in accordance with this timing. As a result, the response delay of the valve timing and the response delay of the throttle valve 17 coincide with each other, and the deviation between the target intake air amount and the actual intake air amount is suppressed.

As described above, according to the present embodiment, it is possible to suppress the deviation between the target intake air amount and the actual intake air amount when the valve timing is changed.

(Second embodiment)
Next, a second embodiment will be described with reference to FIG. In the first embodiment, the timing of transmitting the control signal as the target valve timing and the timing of transmitting the control signal as the target throttle opening are matched. On the other hand, in the second embodiment, it is expected to increase depending on the advance angle based on the first expected intake air amount when the target timing valve is set and the second expected intake air amount when the actual valve timing is maintained. The amount of air is calculated and this amount of air is corrected. Since the hardware configuration itself is common to the first embodiment, detailed description thereof will be omitted.

In step S11, the ECU 40 acquires the target intake air amount and the engine speed. This is done in the same manner as in step S1 in the first embodiment. Next, the ECU 40 calculates the target valve timing in step S12. The calculation of the target valve timing is also performed in the same manner as in step S2 in the first embodiment. The ECU 40 calculates the first expected intake air amount in step S13 following step S12. The first expected intake air amount is the intake air amount expected to be realized when the valve timing is switched to the target valve timing, and is calculated based on the target valve timing calculated in step S12. The first expected intake air amount is calculated based on a map created based on the relationship between the target valve timing and the first expected intake air amount acquired in advance by the experiment.

The ECU 40 executes steps S14 and S15 in parallel with steps S12 and S13. The ECU 40 acquires the actual valve timing at that time in step S14. The actual valve timing is acquired as a detection value of the cam angle sensor 31a. The ECU 40 calculates the second expected intake air amount in step S15, which is performed following step S14. The second expected intake air amount is the intake air amount expected when the actual valve timing is maintained, and is calculated based on the actual valve timing acquired in step S14. The second expected intake air amount is calculated based on a map created based on the relationship between the actual valve timing and the second expected intake air amount obtained in advance by the experiment.

In step S16, the ECU 40 calculates the intake air amount (expected intake air increase amount) that is expected to increase by advancing the valve opening timing of the intake valve 23. The expected intake air increase amount is calculated as the difference between the first expected intake air amount and the second expected intake air amount.

The ECU 40 calculates the correction target intake air amount in step S17 following step S16. The corrected target intake air amount is calculated by subtracting the expected intake air increase amount calculated in step S16 from the target intake air amount acquired in step S11.

The ECU 40 calculates the target throttle opening degree in step S18 following step S17. This target throttle opening degree is calculated based on the corrected target intake air amount calculated in step S17. Then, in step S19, the ECU 40 sends a control command for setting the valve timing and a control command for setting the throttle opening degree.

In this way, by using the target valve timing and setting the throttle opening in advance in consideration of the change in the intake air amount, the target intake air amount when the valve timing is changed can be obtained as in the first embodiment. It is possible to suppress the deviation from the actual intake air amount.

In both the first embodiment and the second embodiment described above, the case where the intake VVT mechanism 25 is operated to change the valve timing of the intake valve 23 to the advance angle side has been described. As a mode in which the valve timing is changed, it is conceivable that the valve timing of the intake valve 23 is changed to the retard side, or the exhaust VVT mechanism 26 is used to advance or retard the exhaust valve 24. .. In this way, when the intake air amount is affected by changing the valve timing, the throttle opening is adjusted together with the valve timing change. Then, the adjustment of the throttle opening degree is executed according to the target valve timing. As a result, it is possible to offset the response delay of each part and suppress the deviation between the target intake air amount and the actual intake air amount.

The above-described embodiment is merely an example for carrying out the present invention, the present invention is not limited thereto, and various modifications of these examples are within the scope of the present invention, and further, the present invention. It is self-evident from the above description that various other embodiments are possible within the scope.

1 Internal combustion engine 8 Intake port 9 Exhaust port 10 Intake pipe 11 Exhaust pipe 18 Intake manifold 20 Exhaust manifold 21 Catalyst 23 Intake valve 24 Exhaust valve 25 Intake VVT mechanism 26 Exhaust VVT mechanism 30 Crank angle sensor 31a, 31b Cam angle sensor 40 ECU 70 Accelerator pedal opening sensor 71 Gear position sensor 72 Vehicle speed sensor 100 Engine system

Claims (1)

In an internal combustion engine equipped with a variable valve timing device, it is a control device for an internal combustion engine that controls the intake air amount into the cylinder according to the valve timing and the throttle opening based on the target intake air amount.
A valve timing control unit that sets a target valve timing calculated based on the target intake air amount and controls the variable valve timing device so as to be the target valve timing.
A throttle opening control unit that starts controlling the throttle opening in accordance with the timing at which the control of the variable valve timing device is started so that the valve timing control unit becomes the target valve timing.
, Equipped with an internal combustion engine control device.

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