JPH06200763A - Intake control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide an intake control device generating no torque shock when the operation mode is changed between the Miller cycle operation and Otto cycle operation. CONSTITUTION:An intake throttle valve 14 is kept nearly fully opened during the Miller cycle operation, and the intake quantity is controlled by the control of the closing timing of an intake control valve 16. The intake control valve 16 is closed after an intake valve is closed during the Otto cycle operation, and the intake quantity is controlled by the opening of the intake throttle valve 14. When the depression quantity of an accelerator pedal is abruptly changed and the operation mode must be changed, the closing timing of the intake control valve 16 is made later than the closing timing during the Miller cycle operation and earlier than the closing timing during the Otto cycle operation, and the generation of a torque shock can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake control device for an internal combustion engine, and more particularly to an intake control device for an internal combustion engine which includes an intake throttle valve and an intake control valve to perform a Miller cycle operation.

[0002]

2. Description of the Related Art An intake control valve which is controlled to be opened and closed is provided in the middle of an intake passage for supplying intake air to a combustion chamber of an internal combustion engine, and the intake control valve is provided before the intake valve is opened. 2. Description of the Related Art An intake control device for performing a Miller cycle operation of an internal combustion engine by opening a valve and closing the intake valve during an opening period is known.

That is, during the Miller cycle operation, the amount of intake air supplied to the cylinder is not adjusted by the intake throttle valve, but
Pumping loss can be reduced by controlling and adjusting the opening timing and period of the intake control valve that is controlled to open and close. However, when the Miller cycle operation is performed at high load and high rotation, there is a problem in that the intake control valve is closed during the intake stroke, so the intake amount is insufficient and sufficient output cannot be obtained. To do.

In order to solve the above problems, a mirror cycle operation is performed at a low load and a low rotation, but an intake control device has been proposed which secures an output by performing an Otto cycle operation at a high load and a high rotation (Japanese Patent Laid-Open No. 2000-242242). Sho 61-10691
8).

[0005]

However, in the intake control device according to the above-mentioned proposal, when the low load low rotation state suddenly shifts to the high load high rotation state, the intake amount rapidly increases and torque shock occurs. Is inevitable. The present invention has been made in view of the above problems,
An object of the present invention is to provide an intake control device in which torque shock does not occur even when the operating mode is changed between the Miller cycle operating state and the Otto cycle operating state.

[0006]

An intake air control apparatus for an internal combustion engine according to the present invention is installed in an intake passage of an internal combustion engine and adjusts the amount of intake air supplied to the internal combustion engine by controlling its opening. Intake timing control that adjusts the amount of intake air that is installed in the intake flow path downstream of the throttle valve and the intake throttle valve and that is supplied to the internal combustion engine by controlling the intake supply period during which the combustion chamber and the intake passage are in communication And a first control means for adjusting the intake air amount by controlling the intake air supply period of the intake air timing control means according to the operating state of the internal combustion engine while opening the intake throttle valve to an opening degree where throttling loss does not occur. And second control means for adjusting the intake air amount by controlling the opening degree of the intake throttle valve according to the operating state of the internal combustion engine, the control state by the first control means and the control state by the second control means. When switching When the amount of change in the intake air supply period per unit time is equal to or greater than the predetermined value, the intake air supply period of the intake time control means is longer than the intake air supply period controlled by the first control means, and the second control is performed. And a transient control means for controlling the intake supply period shorter than the intake supply period controlled by the means.

[0007]

In the intake control device for the internal combustion engine according to the present invention, the Miller cycle operation is performed in the control state by the first control means, and the Otto cycle operation is performed in the control state by the second control means. If the amount of change in the intake air supply period per unit time is greater than or equal to a predetermined value when switching between the control state by the first control means and the control state by the second control means, the intake air supply period of the intake control means Is controlled to be longer than the intake air supply period during the Miller cycle operation and shorter than the intake air supply period during the Otto cycle operation to realize a smooth change in the operating state.

[0008]

1 and 2 are block diagrams of an embodiment of an intake control device for an internal combustion engine according to the present invention, in which a combustion chamber 4 formed by a cylinder block 1, a piston 2 and a cylinder head 3 is provided. The air-fuel mixture is supplied from the intake port 6 via the pair of intake valves 5.

Combustion gas generated in the combustion chamber is discharged to the exhaust passage through a pair of exhaust valves 7. The intake port 6 is connected to a surge tank 9 by an intake branch pipe 8, and the surge tank 9 is connected to an air cleaner 11 via an intake pipe 10. The surge tank 9 also serves as a branch portion of an intake branch pipe connected to another cylinder. An air flow meter 12 is provided in the intake pipe 10, and a step motor 13 is provided downstream thereof.
And an intake throttle valve 14 driven by. An intake control valve 16 opened and closed by an electromagnetic actuator 15 is arranged in the intake branch pipe 8.

Further, a fuel injection valve 17 for injecting fuel toward the intake port 6 is attached to the intake branch pipe 8 downstream of the intake control valve 16. Control unit 2 of intake control device
0 is configured as, for example, a microcomputer system, and is connected to an accelerator opening sensor 22 that detects a depression amount of an accelerator pedal 21, a rotation speed sensor 23 that detects an internal combustion engine speed, and an air flow meter 12, and the internal combustion engine state quantity Read.

A command signal for driving the step motor 13 that drives the intake throttle valve 13 and the electromagnetic actuator 15 that drives the intake control valve 16 is output from the controller. FIG. 3 is a flowchart of the main control routine executed by the control unit. In step 31, it is determined whether or not the flag MODE indicating the operation mode is “1”.

If a positive determination is made in step 31, that is, if the mirror cycle operation is being performed, step 32 is performed.
And the Miller cycle control routine is executed. On the contrary, if a negative determination is made in step 31, that is, if the Otto cycle operation is being performed, the routine proceeds to step 33, where the Otto cycle control routine is executed. FIG. 4 shows the flag MO
This is a DE setting routine, and interrupt processing is performed at predetermined fixed time intervals.

In step 41, the accelerator depression amount Ac detected by the accelerator opening sensor 22 is read, and in step 42, the accelerator depression amount ΔAc is the absolute difference between the accelerator depression amount Ac read this time and the accelerator depression amount Acb read last time. Calculate as a value. Step 43
The accelerator depression amount ΔAc is a predetermined threshold ΔA
Whether or not it is equal to or greater than co is determined, and if a negative determination is made, this routine is terminated without performing any processing.

If an affirmative decision is made in step 43, the routine proceeds to step 44, where it is judged if the accelerator depression amount Ac read this time is larger than the accelerator depression amount Acb read last time. When an affirmative decision is made in step 44, the routine proceeds to step 45, where the first switching routine is executed and then the routine proceeds to step 47.

On the contrary, if a negative decision is made in step 44, the routine proceeds to step 46, where the second switching routine is executed and the routine proceeds to step 47. In step 47, the accelerator depression amount Acb read last time is replaced with the accelerator depression amount Ac read this time, and this routine is finished. Figure 1 is the first
It is a flow chart of a switching routine, and executes control at the time of switching from Miller cycle operation to Otto cycle operation.

In step 451, the closing timing θc of the intake control valve during the Miller cycle operation corresponding to the accelerator pedal depression amount Acb before the accelerator pedal depression amount is increased is obtained. The closing timing of the intake control valve during the Miller cycle operation can be expressed as a function of the accelerator depression amount. In step 452, the difference Δθ between the intake valve closing timings θICV and θc is calculated.

Next, at step 453, Δθ is a predetermined value θlimi
It is determined whether or not it is greater than t, and if a negative determination is made, the process directly proceeds to step 457. If an affirmative decision is made in step 453, the routine proceeds to step 454, where the intake control valve closing period θc
Is increased by a predetermined value α, and in step 455 the valve closing period θ
Output c. If the predetermined value α is set to a constant value, it is possible to change the operation mode while maintaining the change rate constant.

Α = Δθ / N However, if N is selected as a predetermined number of cycles, it becomes possible to complete the switching of the operation mode after the predetermined cycle N.

Further, α = 60Δθ / (NeT) where Ne is the internal combustion engine speed (rpm) and T is a predetermined time (second), the operation mode switching is completed after a predetermined time T. It becomes possible.

In step 456, the intake control valve closing period θ
It is determined whether or not c is greater than the intake valve closing timing θICV, and if a negative determination is made, the process returns to step 454. That is, when the amount of change in the depression of the accelerator pedal is larger than the predetermined value θ limit, the valve closing timing during the Otto cycle operation is not immediately set, but the valve closing timing is delayed by the predetermined value α to prevent the occurrence of torque shock.

If an affirmative decision is made in step 456, the operation proceeds to step 457, in which the flag MODE indicating the operation mode is set to "0" and thereafter the Otto cycle operation is carried out. Figure 6
Is a flowchart of a second switching routine, which executes control at the time of switching from Otto cycle operation to Miller cycle operation. In step 461, the closing timing θm of the intake control valve during the Miller cycle operation corresponding to the accelerator pedal depression amount Ac after the accelerator pedal depression amount is reduced is determined.

In step 462, the intake valve closing timing θIC
Calculate the difference Δθ between V and the current closing timing θc of the intake control valve. Next, at step 463, it is judged if Δθ is larger than a predetermined value θlimit, and if a negative judgment is made, the routine proceeds directly to step 467. If an affirmative decision is made in step 463, the routine proceeds to step 464, where the intake control valve closing period θc is reduced by α, and in step 465 the valve closing period θc is output.

In step 466, the intake control valve closing period θ
It is determined whether or not c is smaller than the intake valve closing timing θm during the Miller cycle operation. If a negative determination is made, step 4
Return to 64. That is, when the amount of change in depression of the accelerator pedal is larger than the predetermined value θlimit, the valve closing timing during the mirror cycle operation is not immediately set, but the valve closing timing is advanced by the predetermined value α to prevent the occurrence of torque shock.

If an affirmative decision is made in step 466, the operation proceeds to step 467, the flag MODE indicating the operation mode is set to "1", and then the mirror cycle operation is carried out. FIG. 7 is a flow chart of the Miller cycle control routine executed in step 32 of the control routine.
In step 21, the accelerator pedal depression amount Ac is read, in step 322, the intake control valve opening φ is determined, and in step 323, the intake control valve closing timing θc is determined as a function of the accelerator pedal depression amount Ac.

FIG. 8 is an example of a graph for determining the intake control valve opening φ and the intake control valve closing timing θc, in which the horizontal axis represents the accelerator pedal depression amount Ac and the vertical axis represents the intake control valve. The opening φ and the intake control valve closing timing θc are set. That is, when the accelerator pedal depression amount Ac is larger than the predetermined value Aco, the intake control valve opening φ is fully opened, and the intake control valve closing timing θc becomes large in proportion to the accelerator pedal depression amount Ac, and the mirror cycle operation is performed. It is possible to increase the intake air amount while continuing.

At step 324, the intake control valve opening φ is output, and at step 325, the intake control valve closing timing θc is output, and this routine is ended. FIG. 9 is a flowchart of the Otto cycle control routine executed in step 33 of the control routine. In step 331, the accelerator pedal depression amount Ac is read, and in step 332, the intake control valve opening φ is proportional to the accelerator pedal depression amount Ac. Set to a value that is set in step 323, and the intake control valve closing timing θc is set in step 323.
Is set to a fixed value θco that is greater than the intake valve closing timing θICV.

Then, in step 334, the intake control valve opening φ is output, in step 335, the intake control valve closing timing θc is output, and this routine is ended. FIG. 10 is an explanatory view of the operation of the present invention, in which the horizontal axis represents the rotation angle of the internal combustion engine and the vertical axis represents the valve lift of the intake valve and the intake control valve. That is, the intake valve opens near the top dead center, reaches the maximum opening while the piston is descending, and closes near the bottom dead center.

During the Miller cycle operation, the intake control valve opens at the time W1 before the intake valve opens, and closes at the time W2 when the intake valve is open. That is, intake air corresponding to an area M surrounded by the valve lift curve a of the intake valve and the valve lift curve b of the intake control valve is supplied to the cylinder. Moreover, since there is no throttle in the intake passage, no throttle loss occurs.

Further, the intake amount during the Miller cycle operation is determined by the closing timing W2 of the intake control valve and the accelerator pedal depression amount A.
It can be adjusted by controlling according to c. On the other hand, during the Otto cycle operation, in order to open the intake control valve longer than the period during which the intake valve is open, the intake control valve is closed at a timing W0 that is later than bottom dead center. And

Assuming now that the accelerator pedal of the vehicle in the idling state is suddenly depressed, the Otto in order to output the torque corresponding to the accelerator pedal depression amount Ac of the internal combustion engine which is in the Miller cycle operation. It will be operated in a cycle. Therefore, it is necessary to change the closing timing of the intake control valve from W2 to W0, but the intake control device according to the present invention does not change it all at once, but by sequentially changing W2 → W3 → W4 → W0. The occurrence of torque shock due to the change of the operation mode is prevented.

When the accelerator pedal is suddenly released, the closing timing of the intake control valve is changed to W0 → W4 → W3 → W2 contrary to the above. In the above embodiment, the intake control valve is installed in the intake branch pipe between the intake throttle valve and the intake valve, but the intake control valve is a so-called variable valve system that changes the opening / closing timing of the intake valve itself. It is obvious that the present invention can be applied to the omitted intake control device.

[0032]

According to the intake control device for an internal combustion engine of the present invention, the amount of change in the intake supply period per unit time when switching between the first control means and the second control means is equal to or greater than a predetermined value. In this case, by transiently setting the intake air supply period of the intake air supply means to be shorter than the intake air supply period during the Miller cycle operation and longer than the intake air supply period during the Otto cycle operation, the operation mode switching of the internal combustion engine can be smoothly performed. Therefore, the torque shock can be prevented.

[Brief description of drawings]

FIG. 1 is a configuration diagram (1) of an embodiment.

FIG. 2 is a configuration diagram (2) of the embodiment.

FIG. 3 is a flowchart of a main control routine.

FIG. 4 is a flowchart of a flag setting routine.

FIG. 5 is a flowchart of a first switching routine.

FIG. 6 is a flowchart of a second switching routine.

FIG. 7 is a flowchart of a Miller cycle control routine.

FIG. 8 is a graph for determining an intake throttle valve opening and an intake control valve closing timing.

FIG. 9 is a flowchart of an Otto cycle control routine.

FIG. 10 is an explanatory diagram of an operation.

[Explanation of symbols]

 5 ... Intake valve 6 ... Intake port 8 ... Intake branch pipe 9 ... Surge tank 13 ... Step motor 14 ... Intake throttle valve 16 ... Intake control valve 17 ... Fuel injection valve

Claims (1)

[Claims] 1. An intake throttle valve installed in an intake passage of an internal combustion engine for adjusting the amount of intake air supplied to the internal combustion engine by controlling its opening, and an intake passage downstream of the intake throttle valve. Intake timing control means that adjusts the amount of intake air that is installed and is supplied to the internal combustion engine by controlling the intake air supply period in which the combustion chamber communicates with the intake flow passage, and the intake throttle valve that opens to prevent loss of throttle. The first intake air amount according to the operating state of the internal combustion engine and the intake amount is adjusted according to the operating state of the internal combustion engine by controlling the intake air supply period of the intake timing control means. And a second control means for adjusting the opening degree of the intake throttle valve by controlling the opening degree of the intake throttle valve, the control state by the first control means and the control by the second control means. Status When the amount of change in the intake air supply period per unit time is greater than or equal to a predetermined value when switching, the intake air supply period of the intake timing control means is longer than the intake air supply period controlled by the first control means, and An intake control device for an internal combustion engine, comprising: transient control means for controlling during an intake supply period shorter than the intake supply period controlled by the second control means.