JP2001271664A - Knocking control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely avoid generation of knocking without lagging ignition timing any more, when ignition timing reaches a prescribed retard timing limit by generation of knocking. SOLUTION: The presence or the absence of generation of knocking is detected (S1) and ignition timing is retarded, when knock is generated (S3). When knocking is still generated, even after ignition timing reaches a prescribed retard timing limit, valve timing for an intake valve, more particularly, intake valve closing timing IVC is controlled to decreasing directions of intake air quantity and an effective compression ratio by a variable valve system (S2→S4). More specifically, a control is performed in the direction that the intake valve closing timing IVC is made later than a bottom dead center or in a direction that IVC is made earlier than the bottom dead center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a knock control device for an internal combustion engine, and more particularly to a knock control device using both ignition timing control and variable valve control (valve timing control).

[0002]

2. Description of the Related Art Conventionally, as a knock control device for an internal combustion engine, the presence or absence of knock (knock) has been detected, and the ignition timing has been retarded (retarded) when knock has occurred to avoid knock. What is well known.

On the other hand, as shown in Japanese Patent Application Laid-Open No. 8-2000025, a variable valve operating device for an internal combustion engine drives an intake valve and an exhaust valve using, for example, an electromagnetic drive device, and opens and closes these valves. Valve timing) can be arbitrarily controlled.

[0004]

In the conventional knock control device for an internal combustion engine, the occurrence of knock is dealt with by retarding the ignition timing. However, the knock control device is more effective by depositing the deposit in the combustion chamber. If the compression ratio exceeds the design value, if gasoline with extremely poor fuel properties is used, or if conditions such as an increase in intake air temperature overlap, it will not be possible to respond due to the ignition timing retard for knock control. Can be considered.

[0005] Further, if an attempt is made to increase the retard amount (retard limit) of the ignition timing, the exhaust gas temperature will increase. In view of such a conventional problem, the present invention uses a variable valve operating device without further delaying the ignition timing when the ignition timing reaches a predetermined retardation limit due to occurrence of knock. It is an object of the present invention to ensure that knock can be avoided.

[0006]

Therefore, according to the present invention, as shown in FIG. 1, a knock detecting means for detecting the occurrence of knock, and an ignition timing correction for delaying the ignition timing when knock occurs. A knock control device for an internal combustion engine, comprising: a knock control device for determining that the ignition timing has reached a predetermined retard limit; and a variable valve actuating valve when knock occurs at the retard limit of the ignition timing. Valve timing control means for controlling the valve timing of the intake valve in the direction of decreasing the intake air amount and the effective compression ratio.

That is, the presence or absence of knocking is detected, and the ignition timing is retarded when knocking occurs. If knocking still occurs even if the ignition timing reaches a predetermined retardation limit, the variable valve actuation is performed. The device controls the valve timing of the intake valve in the direction of decreasing the intake air amount and the effective compression ratio to avoid knocking.

In the invention according to a second aspect, the valve timing control means controls the intake valve closing timing to be later than the bottom dead center when knock occurs at the retard limit of the ignition timing. .

According to a third aspect of the present invention, the valve timing control means controls the intake valve closing timing to be earlier than the bottom dead center when knock occurs at the ignition timing retard limit. .

[0010] In the invention according to claim 4, the valve timing control means, when knocking occurs at the ignition timing retard limit, in a region where the base intake valve closing timing is near bottom dead center, the intake valve closing timing. Is controlled in a direction in which the intake valve closing timing of the base is lower than the bottom dead center.

In the invention according to claim 5, when no knock occurs, the valve timing control means gradually returns the valve timing to the base timing, and the ignition timing correction control means returns the valve timing to the base timing. After that, the ignition timing is gradually advanced.

In the invention according to claim 6, when the ignition timing limit has been determined by the retardation limit determining means to have reached a predetermined retardation limit, the ignition timing of the base is changed to the base for high-octane (high octane number) gasoline. Base ignition timing switching means for switching from ignition timing to base ignition timing for regular gasoline is provided.

[0013]

According to the first aspect of the present invention, when the ignition timing reaches a predetermined retardation limit, knocking still occurs, such as in the case of an abnormal situation that cannot be dealt with by normal knocking control. By controlling the valve timing of the intake valve in the direction of decreasing the intake air amount and the effective compression ratio by the valve device, knock can be reliably avoided.

According to this method, it is possible to suppress an increase in the exhaust gas temperature as compared with the case where the ignition timing is further retarded, and to reduce the effective compression ratio as compared with the case where the air is simply throttled by the throttle valve. Therefore, the maximum combustion pressure and temperature are reduced, and knocking can be avoided more reliably.

According to the second aspect of the present invention, when knock occurs at the ignition timing retard limit, the intake valve closing timing is controlled to be later than the bottom dead center, so that the intake air amount and the effective compression ratio are controlled. And knock can be reliably avoided.

According to the third aspect of the present invention, when knock occurs at the retarded limit of the ignition timing, the intake valve closing timing is controlled so as to be earlier than the bottom dead center, thereby causing a return to the intake system. Without reducing the intake air amount and the effective compression ratio, knocking can be reliably avoided.

According to the fourth aspect of the invention, when knock occurs at the ignition timing retard limit, the intake valve closing timing is advanced in a low rotation region where the base intake valve closing timing is near bottom dead center. By controlling in the direction, fine control of the timing, and without causing a return to the intake system,
Knock can be reliably avoided by reducing the intake air amount and the effective compression ratio. Further, in a middle-high rotation region where the base intake valve closing timing is after the bottom dead center, by controlling the intake valve closing timing in a late direction, fine control of the timing can reliably avoid knocking. .

According to the fifth aspect of the present invention, when knock does not occur, the valve timing is gradually returned to the base timing first, so that knock control based on normal ignition timing can be shifted as quickly as possible.

According to the sixth aspect of the invention, especially in the case of an engine of high octane gasoline specification, when it is determined that the ignition timing has reached a predetermined retardation limit, it is regarded that regular gasoline is used. By switching the ignition timing of the base from the base ignition timing for high-octane gasoline to the base ignition timing for regular gasoline, when actually using regular gasoline, the process shifts to valve timing control in which the torque rebounds greatly. Thus, it is possible to appropriately retard the ignition timing and avoid knocking.

[0020]

Embodiments of the present invention will be described below. FIG. 2 is a system diagram of an internal combustion engine showing one embodiment of the present invention.

A combustion chamber 3 defined by a piston 2 of each cylinder of an internal combustion engine (hereinafter referred to as an engine) 1 is provided with an electromagnetically driven intake valve 5 and an exhaust valve 6 so as to surround an ignition plug 4. I have. 7 is an intake passage, and 8 is an exhaust passage.

FIG. 3 shows the basic structure of an electromagnetic drive device (variable valve operating device) for the intake valve 5 and the exhaust valve 6. A plate-like mover 22 is attached to a valve shaft 21 of the valve body 20, and the mover 22 is biased to a neutral position by springs 23 and 24. The valve opening electromagnetic coil 25 is disposed below the movable element 22, and the valve closing electromagnetic coil 26 is disposed above the movable element 22.

Accordingly, when the valve is opened, the power supply to the upper valve closing electromagnetic coil 26 is stopped, and then the current is supplied to the lower valve opening electromagnetic coil 25 to attract the movable element 22 to the lower side. As a result, the valve body 20 is lifted to open the valve. vice versa,
When the valve is closed, the energization of the lower valve opening electromagnetic coil 25 is stopped, and then the upper valve closing electromagnetic coil 26 is energized to attract the movable element 22 to the upper side.
Is seated on the seat and the valve is closed.

Returning to FIG. 2, an electrically controlled throttle valve 9 is provided in the intake passage 7 upstream of the intake manifold. The intake passage 7 is also provided with an electromagnetic fuel injection valve 10 for each cylinder at each branch of the intake manifold.

Here, the operations of the intake valve 5, the exhaust valve 6, the electronically controlled throttle valve 9, the fuel injection valve 10 and the spark plug 4 are controlled by a control unit 11, which is synchronized with the engine rotation. And outputs a crank angle signal to thereby detect a crank angle position and an engine speed Ne.
2. An accelerator pedal sensor 13 for detecting an accelerator opening (accelerator pedal depression amount) APO, an air flow meter 14 for detecting an intake air amount Qa upstream of the throttle valve 9 in the intake passage 7, and other knock detection means. A signal is input from the sensor 15.

The knock sensor 15 is attached to a main body such as a cylinder block of the engine 1 and outputs a signal corresponding to engine vibration by a piezoelectric element. From the output signal, a signal of a specific frequency component related to knock vibration ( Knock signal). In addition, knock sensor 1
As 5, a knock type signal may be extracted from an output signal of a piezoelectric type in-cylinder pressure sensor formed in the shape of a washer and attached to the ignition plug 4.

The control of the ignition timing of the ignition plug 4 in the control unit 11 is performed based on the engine operating conditions, specifically, the engine speed Ne and the load (accelerator opening, cylinder intake air amount or fuel injection amount, etc.) TQ. With reference to the map, the base ignition timing ADVbase is determined and corrected by knock control, that is, corrected in accordance with the presence / absence of knock based on a signal from the knock sensor 15 to obtain the final ignition timing ADVbase. Is calculated.

Further, according to the present invention, when the ignition timing ADV reaches the retard limit by the knock control and knocking still occurs, the intake valve 5 and the exhaust valve 6 are controlled by the variable valve operating device.
By controlling the valve timing, particularly the intake valve closing timing IVC, knock control is performed.

The knock control will be described. FIG.
Is a flowchart of a knock control routine. In step 1 (referred to as S1 in the figure, the same applies hereinafter), the presence or absence of knock is detected based on a signal from knock sensor 15. Specifically, by extracting a signal (knock signal) of a specific frequency component related to knock vibration from a signal corresponding to engine vibration output from knock sensor 15,
The level of knock vibration is detected, and the presence or absence of knock is determined based on the magnitude of the knock vibration. This part is knock sensor 15
Together with knock detection means.

When knocking occurs (when knocking occurs), the process proceeds to step 2. In step 2, the ignition timing ADV is retarded by the ignition timing ADV due to the continuous occurrence of knock.
Is controlled to a predetermined retard limit (retard amount RET ≧
(Predetermined value). This part corresponds to the retard limit determining means.

If the retard limit has not been reached, the routine proceeds to step 3. In step 3, the ignition timing ADV is retarded by a predetermined value to avoid knocking. Specifically, the ignition timing retard amount RET is increased by a predetermined value ΔRET (RET = RET +
ΔRET), a base ignition timing (advance angle value) AD determined by referring to a map from the engine speed Ne and the load TQ.
After subtracting the retard amount RET from Vbase, the ignition timing ADV = A
DVbase-RET is calculated and controlled. This part corresponds to ignition timing correction control means.

If the ignition timing ADV reaches the predetermined retard limit due to the continuous retard (when the retard amount RET ≧ the predetermined value), the process proceeds from step 2 to step 4. Step 4
In order to avoid knocking at the retard limit, the valve timing of the intake valve 5 and the exhaust valve 6, particularly the intake valve closing timing IVC, is controlled by the variable valve device in the decreasing direction of the intake air amount and the effective compression ratio ( IVC control). This part corresponds to valve timing control means.

More specifically, as shown in FIG. 5B, the valve closing timing IVC during the knock control is different from the valve timing at full load (4/4) shown in FIG. Is controlled so as to be later than the bottom dead center BDC (I
VC), the intake valve closing timing IVC is controlled to be earlier than the bottom dead center BDC (early closing IVC) to reduce the intake air amount and the effective compression ratio. In FIG. 5, EVO indicates the exhaust valve opening timing, EVC indicates the exhaust valve closing timing, and IVO indicates the intake valve opening timing, which are constant.

More specifically, when knock occurs at the retard limit of the ignition timing, the base intake valve closing timing (base IVC)
In the low rotation region near (or before) BDC, the intake valve closing timing IVC is controlled to be advanced (early closing IVC), and the base intake valve closing timing (base IVC) is changed to BDC.
In the middle and high rotation range thereafter, the intake valve closing timing IVC is controlled to be delayed (IVC of late closing).

Comparing the early closing and the late closing, the late closing causes the intake air temperature to rise due to the return to the intake system and causes the measurement error of the intake air amount by the air flow meter. Is more advantageous, but when the base intake valve closing timing (base IVC) is after BDC,
If the valve is closed early, the amount of change in timing must be increased (slightly advancement will reduce the amount of intake air but increase the effective compression ratio). This is because it is not suitable for driving, and there is a fear of rebounding to drivability.

In the case of controlling as described above, the IVC control in step 4 in FIG. 4 is executed according to the IVC control subroutine in FIG. In step 41, it is determined whether or not the base IVC is near (or before) the BDC. If Yes, the process proceeds to step 42, where the IVC is advanced by a predetermined value (early closing). If No (when the base IVC is BDC or later), the process proceeds to step 42, where the IVC is delayed by a predetermined value (late closing).

By controlling the intake valve closing timing IVC in such a manner that the intake air amount and the effective compression ratio are controlled in a decreasing direction, knocking is still generated even if the ignition timing reaches a predetermined retardation limit. In an abnormal situation that cannot be dealt with by normal knock control, knock can be reliably avoided.

When no knock occurs (when no knock occurs),
Proceed from step 1 to step 5. In step 5, I
It is determined whether or not VC = base IVC. As a result, IV
When C is not the base IVC (when the knock control by the IVC is performed), the process proceeds to step 6, where the IVC is returned to the predetermined value and the base IVC side.

When IVC = base IVC (when knock control by IVC is not performed), the routine proceeds to step 7, where it is determined whether or not the ignition timing ADV is the base ignition timing ADVbase (ADV = base ADV).

As a result, if the ADV is not the base ADV, the routine proceeds to step 8, where the ignition timing ADV is advanced by a predetermined value. Specifically, the ignition timing retard amount RET is set to a predetermined value Δ
RET is reduced (RET = RET−ΔRET), the ignition timing ADV = ADVbase−RET is calculated by subtracting the retard amount RET from the base ignition timing ADVbase determined by referring to the map from the engine speed Ne and the load TQ, Control.

When ADV = base ADV, it goes without saying that the ignition timing ADV is maintained at the base ignition timing ADVbase. In the present flow, the ignition timing ADV is made to converge to the base ignition timing ADVbase when no knock occurs. When the knock is not generated, the ignition timing AD
V may be advanced to the knock limit.

Next, another embodiment of the present invention will be described. The high-octane gasoline-specification engine uses a high-octane gasoline map set on the advanced side as compared with the regular gasoline map as a map for setting the base ignition timing ADVbase.

FIG. 7 is a flowchart of a knock control routine in a high-octane gasoline engine. Steps 21 and 22 are added to the flow of FIG.
When the ignition timing ADV reaches the predetermined retard limit due to the continuous retard (when the retard amount RET ≧ the predetermined value), the process proceeds from step 2 to step 21.

In step 21, the base ignition timing ADV
It is determined whether or not the base setting map has already been switched from the high-octane gasoline map to the regular gasoline map (the map has been switched). If the map has not been switched yet, the process proceeds to step 22 to switch to the regular gasoline map. Switch. This part corresponds to the base ignition timing switching means.

As a result, from the base ignition timing ADVbase 'in the regular gasoline map, the current retard amount RE
T is calculated to control the ignition timing ADV = ADVbase'-RET, and the base ignition timing is switched from the base ignition timing for high-octane gasoline to the base ignition timing for regular gasoline. Can be greatly retarded up to the retard limit at.

As described above, in the high-octane gasoline engine, when it is determined that the ignition timing has reached the predetermined retardation limit, it is considered that regular gasoline is used, and the base ignition timing is changed to the high-octane gasoline. By switching from the base ignition timing for the regular gasoline to the base ignition timing for the regular gasoline, the ignition timing is appropriately retarded without actually shifting to the valve timing control when using the regular gasoline. Can be avoided.

If the map has been switched, that is, if the knock has been generated even after the map has been switched, the process proceeds from step 21 to step 4. In step 4, in order to avoid knocking at the retard limit, the valve timing of the intake valve 5 and the exhaust valve 6,
In particular, the intake valve closing timing IVC is controlled so as to decrease the intake air amount and the effective compression ratio (IVC control). Others are the same.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of the present invention.

FIG. 2 is a system diagram of an engine showing an embodiment of the present invention.

FIG. 3 is a basic structural diagram of an electromagnetic drive device of the intake and exhaust valves.

FIG. 4 is a flowchart of a knock control routine.

FIG. 5 is an explanatory diagram of valve timing.

FIG. 6 is a flowchart of an IVC control subroutine.

FIG. 7 is a flowchart of a knock control routine showing another embodiment.

[Explanation of symbols]

 Reference Signs List 1 engine 4 spark plug 5 electromagnetically driven intake valve 6 electromagnetically driven exhaust valve 9 electrically controlled throttle valve 10 fuel injection valve 11 control unit 12 crank angle sensor 13 accelerator pedal sensor 14 air flow meter 15 knock sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 43/00 301 F02D 43/00 301B 45/00 314 45/00 314Z 368 368A 368D F02P 5/152 F02P 5 / 15 D 5/153 F term (reference) 3G022 CA09 DA01 DA02 EA02 FA04 FB08 GA01 GA02 GA05 GA08 GA13 3G084 BA17 BA23 CA04 DA38 EA11 EB02 EB12 EC03 FA25 FA38 3G092 AA01 AA05 AA11 AB02 BA09 BB01 DA01 DA03 DA07 EA03 DD03 EA11 EA16 FA16 GA08 HA01X HA06Z HA13Z HA14Z HB01Z HC05X HC09X HE03Z HF08Z

Claims (6)

[Claims] 1. A knock control apparatus for an internal combustion engine, comprising: a knock detection means for detecting occurrence of knock; and an ignition timing correction control means for delaying ignition timing when knock occurs. A retard limit judging means for judging that the engine has reached the ignition timing, and when knock occurs at a retard limit of the ignition timing, the valve timing of the intake valve is controlled in a decreasing direction of the intake air amount and the effective compression ratio by a variable valve operating device. A knock control device for an internal combustion engine, comprising: valve timing control means. 2. The internal combustion engine according to claim 1, wherein the valve timing control means controls the intake valve closing timing to be later than the bottom dead center when knock occurs at the ignition timing retard limit. Engine knock control device. 3. The internal combustion engine according to claim 1, wherein the valve timing control means controls the intake valve closing timing to be earlier than the bottom dead center when knock occurs at the ignition timing retard limit. Engine knock control device. 4. The valve timing control means controls the intake valve closing timing to be advanced in a region where the base intake valve closing timing is near bottom dead center when knock occurs at the ignition timing retard limit. 2. The knock control device for an internal combustion engine according to claim 1, wherein in a region where the base intake valve closing timing is after the bottom dead center, the intake valve closing timing is controlled to be delayed. 5. When no knock occurs, the valve timing control means gradually returns the valve timing to the base timing, and the ignition timing correction control means controls the ignition timing after the valve timing is returned to the base timing. The knock control device for an internal combustion engine according to any one of claims 1 to 4, wherein the angle is gradually advanced. 6. When the ignition timing reaches a predetermined retardation limit, the ignition timing of the base is changed from the base ignition timing for high-octane gasoline to the base ignition timing for regular gasoline. The knock control device for an internal combustion engine according to any one of claims 1 to 5, further comprising a base ignition timing switching means for switching the ignition timing.