JPH0711269B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention suppresses knocking of internal combustion engines such as automobiles.
The present invention relates to an ignition timing control device that performs MBT control to improve drivability.

(Prior Art) The ignition timing of an internal combustion engine must be determined according to the state of the engine so that the engine operates optimally. It is generally known that it is best to ignite near the minimum advance angle at the time of maximum torque, so-called MBT (Minimum advance for Best Torque), considering the efficiency and fuel efficiency of the engine.
The so-called MBT control of changing the ignition timing to T is performed.

However, in a certain engine state, knocking occurs when the ignition timing is advanced, and stable engine operation cannot be performed. For example, at low speed rotation and low load, the knocking limit comes before the MBT. Further, the knocking limit is easily affected by atmospheric conditions such as temperature and humidity.

Therefore, a method has been developed in which so-called knock control of controlling ignition timing depending on the presence or absence of knocking is used in combination with the above-mentioned MBT control.For example, such a method is disclosed in JP-A-58-82074. There is a described device.

In this device, the in-cylinder pressure is detected by the in-cylinder pressure sensor, and the ignition timing is adjusted so that the crank angle at which the pressure becomes maximum (hereinafter referred to as the combustion peak position) θpmax is at a predetermined position that maximizes the torque generated by the engine. Control MBT. In this case, in-cylinder pressure is A / D converted from TDC to ATDC 60 ° every 1 ° in order to obtain θpmax.

Further, at the same time, knocking is detected through a signal processing circuit using a signal for detecting the in-cylinder pressure, and when the knocking level exceeds a predetermined value, the ignition timing is retarded to avoid knocking with priority over MBT control. As a result, the torque generated by the engine is increased as much as possible while suppressing knocking, and the operating performance is improved.

(Problems to be Solved by the Invention) However, such a conventional ignition timing control device for an internal combustion engine is configured to detect θpmax and a knocking level from a cylinder pressure signal. When the ignition timing retard amount becomes large due to the above, the peak value of the cylinder pressure decreases, while the peak value of the engine compression pressure (so-called motoring pressure) that appears at the compression top dead center (TDC) has a large effect. Therefore, θpm
The ax detection accuracy tends to decrease.

Further, if the ignition timing is carelessly advanced by MBT control, knocking will be induced. Further, when the determination of θpmax or knocking level is erroneous from the erroneous determination of the in-cylinder pressure signal, the ignition timing is advanced or retarded too much, and the drivability of the engine is deteriorated.

(Object of the Invention) Therefore, the present invention prevents abnormal retardation / advancement by providing a limit value for the ignition timing correction amount in the knock control and the MBT control, respectively, and suppresses knocking while achieving effective MBT control. The purpose is to plan.

(Structure of the Invention) As shown in the basic conceptual diagram of the ignition timing control device for an internal combustion engine according to the present invention, a pressure detecting means a for detecting combustion pressure of the engine and an operation for detecting an operating state of the engine are provided. A state detecting means b, a knock detecting means c for detecting the knocking level of the engine based on the output of the pressure detecting means a, and a peak for detecting a combustion peak position where the combustion pressure becomes maximum based on the output of the pressure detecting means a. The position detecting means d, the first calculating means e for calculating the peak correction amount for correcting the ignition timing so that the combustion peak position becomes the predetermined position that maximizes the torque generated by the engine, and the knocking level becomes the predetermined value. Second calculation means f for calculating a knock correction amount for correcting the ignition timing, first correction amount limiting means g for setting a lower limit value and an upper limit value of the peak correction amount, and a peak correction amount Second correction amount limiting means h for setting the lower limit value and the upper limit value of the knock correction amount so as to be different from the upper limit value and the lower limit value.
And the basic ignition timing is set based on the operating state, and the basic ignition timing is set as the peak correction amount and the knock correction amount within the range of the upper limit value and the lower limit value set by the first correction amount limiting means and the second correction amount limiting means. Ignition timing setting means i that corrects accordingly,
Ignition means j for igniting the air-fuel mixture based on the output of the ignition timing setting means h is provided, and abnormal knocking / advancing is prevented to achieve knock control and MBT control.

(Example) Hereinafter, the present invention will be described with reference to the drawings.

2 to 6 are views showing an embodiment of the present invention.

First, the configuration will be described. In FIG. 2, reference numeral 1 denotes an engine, intake air is supplied from an air cleaner 2 to each cylinder through an intake pipe 3, and fuel is injected by an injector 4 based on an injection signal Si. A spark plug 5 is attached to each cylinder, and a high voltage pulse Pi from an ignition coil 7 is supplied to the spark plug 5 via a distributor 6. The ignition coil 7 generates a high voltage pulse Pi based on the ignition signal Sp. The ignition plug 5, the distributor 6 and the ignition coil 7 constitute an ignition means 8 for igniting an air-fuel mixture, and the ignition means 8 produces a high voltage pulse based on an ignition signal Sp.
Generate Pi and discharge it.

Then, the air-fuel mixture in the cylinder is ignited and exploded by the discharge of the high-pressure pulse Pi, becomes exhaust gas, and is exhausted through the exhaust pipe 9.

The flow rate Qa of the intake air is detected by the air flow meter 11 and controlled by the throttle valve 12 in the intake pipe 3. The combustion pressure of the engine 1 is detected by an in-cylinder pressure sensor (pressure detecting means) 13, and an output S ₁ of the in-cylinder pressure sensor 13 is input to a signal processing circuit 14. The signal processing circuit 14 outputs the output S _{1 of the in-} cylinder pressure sensor 13.
The integral value S and the combustion peak position θpmax corresponding to the physical quantity related to the combustion vibration energy are detected based on
The detailed configuration will be described later.

The crank angle of the engine 1 is the distributor 6
It is detected by the crank angle sensor 15 built into the engine, and the crank angle sensor 15 detects before the compression top dead center (TDC) of each cylinder at every explosion interval (120 ° crank angle for 6 cylinder engine and 180 ° for 4 cylinder engine). [H] at a predetermined position, eg BTDC 70 °
The reference position signal Ca that becomes a level pulse is output, and [H] is output for each unit angle (for example, 1 °) of the crank angle.
It outputs a unit signal C ₁ that becomes a level pulse. By counting the pulses of the signal Ca, the engine speed Ne
You can know. The air flow meter 11 and the crank angle sensor 15 form an operating state detecting means 16.

The signals from the sensors 11, 14 and 15 are input to the control unit (C / U) 20, and the control unit 20 controls the ignition timing based on these sensor information (other injection amount control is also available, but here Omitted).

The above-mentioned signal processing circuit 14 has a function as a knock detection means and a peak position detection means. Specifically, for example, as shown in FIG. 3, a charge amplifier 21, a multiplexer (MPX) 22, a bandpass filter (BPF). ) 23, rectifier 24,
It is composed of an integrator 25, a low-pass filter (LPF) 26, and a peak position detection circuit 27.

The in-cylinder pressure sensor 13 is provided for each cylinder (6 cylinders in this embodiment) (indicated by 13a to 13f in FIG. 3), and these in-cylinder pressure sensors 13a to 13f are formed as washers for the ignition plug 5. It is fastened together. The in-cylinder pressure sensors 13a to 13f convert the combustion pressure in the cylinder into electric charges by a piezoelectric element, and charge signals S ₁
Is output to the charge amplifier 21. The charge amplifier 21 is composed of a charge-voltage conversion amplifier, and outputs the charge output S ₁ to the voltage signal S ₂
And outputs to the multiplexer 22. The multiplexer 22 selectively outputs the signal S ₂ from the charge amplifier 21 to each of the cylinders based on the reference position signal Ca from the crank angle sensor 15 as a switching signal S ₃ to the bandpass filter 23 and the lowpass filter 26. Bandpass filter 23 is a signal
Frequency band corresponding to knocking vibration of S ₃ (for example,
Output to the rectifier 24 as a signal S ₃ passes only operation 5KHz～20kHz), the rectifier 24 outputs a signal S ₄ to the integrator 25 as a rectified signal S ₅ may also be) to full-wave rectification (half-wave rectification. The integrator 25 takes into consideration the elimination of noise during a predetermined crank angle,
For example, the rectified signal S ₅ is integrated only during 10 ° to 45 ° after the compression top dead center (TDC) and output as an integrated value S corresponding to a physical quantity related to the firing vibration energy.

On the other hand, the low-pass filter 26 cuts the high frequency component of the signal S ₃ and outputs it as the signal S ₆ to the peak position detection circuit 27,
The peak position detection circuit 27 detects the combustion peak position θpmax based on the signal S ₆ .

Referring again to FIG. 2, the control unit 20 has a function as a first calculating means, a second calculating means, a first correction amount limiting means, a second correction amount limiting means, and an ignition timing setting means, and CPU 31, ROM 32, RAM 33. And I / O port 34. The CPU31 fetches the external data required from the I / O port 34 according to the program written in the ROM32, and also exchanges data with the RAM, while processing values required for knock control and MBT control. And outputs the processed data to the I / O port 34 as necessary. The I / O port 34 receives signals from the operating state detecting means 16 and the signal processing circuit 14 and also receives I / O signals.
The ignition signal Sp is output from the port 34.

Next, the operation will be described.

Fig. 4 shows knock control and MBT written in ROM32.
It is a flowchart showing a control program, and this program is executed once every predetermined time.

First, read the integral value S, which is the output of the integrator 25 which represents the knock level at P _1, P _2, P ₃ each prescribed slice level integrated value S in alpha, compared with beta. Here, α corresponds to a dangerous knock level, and β corresponds to an unfavorable knock level, which is a criterion for determining a large knock and a small knock, respectively.

When S ≧ α, it is determined that the knock is large, and the processing for urgently retarding the ignition timing is performed in each step of P _{4 to} P ₆ . That is, the correction amount (hereinafter referred to as the ignition correction amount) n of the ignition timing is calculated in P ₄ according to the following equation. In this embodiment, this ignition correction amount n corresponds to the peak correction amount and the knock correction amount.

n = n'-Q ...... However, n: present ignition correction amount n ': preceding ignition correction amount Q: comparing the retard correction amount P ₅ in the ignition correction amount n advance angle limiting value C. The advance limit value (upper limit value) C is a value for limiting the excessive advance of the transition in such a case because the ignition timing may be set to the advance side for the MBT control.
When n> C, limit P to n = C at P ₆ and proceed to P ₇ , where n ≦ C
If, jump P ₆ and proceed to P ₇ . As a result, the ignition correction amount n is limited to within the advance limit value C.

On the other hand, when at P ₂ S <of α proceeds to P _3, it is determined whether or not the small knocking P _3. When S ≦ β, it is determined that the knock is small, and the process for gradually retarding the ignition timing is performed at P ₈ . In other words, it calculates the ignition correction amount n in accordance with the following equation in P _8, the process proceeds to P _7.

n = n'-P ... However, in the equation of P: retard correction amount, there is a relation of P <Q, and the ignition timing is retarded gently. This is because the driveability is deteriorated when the vehicle is retarded abruptly.

Next, at P ₇ , the ignition correction amount n is compared with the retard limit value D.
The retard limit value (lower limit value) D is a value for limiting excessive transition delay. When n <the D proceeds to P ₁₀ is limited to n = D in P _9, when the n ≧ D proceeds to P ₁₀ to jump P _9. As a result, the ignition correction amount n is limited to within the retard limit value D regardless of whether the knock is large or small. In addition, when the engine advances too much with a small knock, a large knock occurs, and n is limited to within C by the retard processing of this large knock. It goes without saying that a limit of C or less is added.

At P ₁₀ , based on the operating state, for example, the basic ignition timing ADVO is looked up from a predetermined table map using the intake air amount Qa and the rotation speed Ne as parameters, and this is corrected according to the following equation to calculate the final ignition timing ADV. Then this a
The ignition signal Sp is output at a timing corresponding to DV.

ADV = ADVO + n ...... For the above knock occurrence, when S <β in P ₃ , it is judged that there is no knock, and the MBT control processing is performed. That is, first, at P ₁₁ , the combustion peak position θpmax is read from the peak position detection circuit 27, and at P ₁₂ , the ignition correction amount n is compared with the retard limit value (lower limit value) B. Since the ignition timing may be set to the retard side for knock control because of the knock control, the retard limit value B is a value for limiting the transient delay too much for the MBT control in such a case. When n ≦ B, it is judged that the detection accuracy of θpmax is lowered because it is on the retard side more than necessary, and the ignition timing is gradually advanced without performing the MBT control in each step of P _{13 to} P ₁₅ . Perform processing. That is, in P ₁₃ , the ignition correction amount n is calculated according to the following equation.

n = n '+ O ...... However, O: advance angle correction amount and then, P _14, limits the P ₁₅ In the step P _5, the ignition correction amount n by performing the same processing at P ₆ advance angle within the limit value C in after, the process proceeds to P _10. As a result, the ignition timing is gradually advanced and a decrease in the detection accuracy of θpmax is avoided.

On the other hand, when n> B in P ₁₂ , the MBT control is performed, so that the process proceeds to steps after P ₁₆ . First, compared with the target value K the current θpmax at P ₁₆ (K = ATDC 10 ° to 20 ° value generated torque of the engine becomes maximum at the position). ? pmax> when K is determined that the shift to the advance side than the target value, performs MBT retard control at each step of the P ₁₇ to P _19. That is, in P ₁₇ , the ignition correction amount n is calculated according to the following equation.

n = n'-U ... However, in U: retard correction amount P ₁₈ , the ignition correction amount n is compared with the retard limit value B. n>
When B, limit P to n = B at P ₁₉ and proceed to P _10. When n ≧ B, jump P ₁₉ and proceed to P ₁₀ .

Further, when θpmax ≦ K, it is judged that it is equal to the target value or deviated to the retard side from this, and the MBT advance angle control is performed in each step of P _{20 to} P ₂₂ . That is, at P ₂₀ , the ignition correction amount n is calculated according to the following equation.

n = n '+ V ...... However, V: the advance angle correction amount P ₂₁ advance angle limit ignition correction amount n in (upper limit) is compared with A. When n ≧ A, P ₂₂ is used to limit n = A, and the process proceeds to P _10. When n> A, P ₂₂ is jumped to P ₁₀ .

In the above, the respective limit values A to D are set in the following relationship.

By setting A>φ> B, both advance and retard control can be performed with respect to the basic ignition timing ADVO, so that good MBT control can be performed by absorbing variations in the characteristics of each engine. Further, by setting C ≧ φ> D and setting | B | <| D |, the retard side gives priority to knock avoidance control.
By setting | A |> | C | under the condition of C ≧ φ> D, the MBT control can be mainly performed on the advance side.

As described above, since the limit value of the ignition correction amount n is appropriately set in each of the knock control and the MBT control, it is possible to prevent abnormal retardation / advance. Therefore, it becomes possible to solve the problems pointed out in the conventional example as follows.

(I) When the MBT control is performed when knocking does not occur, the ignition correction amount n (peak correction amount) is limited to be within the retard limit value B. Therefore, ignition is performed for knock control. If the timing is set to the retard side, it is possible to prevent the ignition timing from being excessively delayed.
It is possible to avoid a decrease in the detection accuracy of. Further, since the basic ignition timing is corrected within the range of the retard limit value B and the advance limit value A in accordance with the ignition correction amount n (peak correction amount), transitional advance and retard are generated. Can be prevented.

(II) When the knocking occurs, the ignition correction amount n (knock correction amount) is limited to within the advance angle limit value C. Therefore, when the ignition timing is set to the advance angle side for MBT control, It is possible to prevent the ignition timing from advancing excessively, and to avoid inducing knocking. Further, since the ignition correction amount n (knock correction amount) is limited within the range of the delay angle limit value D, it is possible to prevent the transitional delay of the ignition timing from being excessively delayed.

(III) It is possible to prevent the ignition timing from being retarded or advanced more than necessary even if there is an erroneous determination of the in-cylinder pressure signal, so that it is possible to avoid a decrease in drivability and a situation where the engine is seriously damaged.

From the above, it is possible to achieve effective MBT control while suppressing knocking, to always control the engine generated torque to the maximum, and to improve the driving performance.

(Effect) According to the present invention, when knocking does not occur,
When the MBT control is performed, the peak correction amount is limited so that it falls within the lower limit value.Therefore, if the ignition timing is set to the retard side for knock control, the transition of the ignition timing is too late. It is possible to prevent the deterioration of the detection accuracy of θpmax. Further, since the basic ignition timing is corrected within the range of the lower limit value and the upper limit value according to the ignition correction amount, it is possible to prevent the transitional advance angle and retard angle from occurring.

Also, when knocking occurs, the knock correction amount is limited to within the upper limit value, so when the ignition timing is set to the advanced side for MBT control, it prevents the ignition timing from advancing too transiently. You can avoid triggering knocking. Further, since the knock correction amount is limited within the range of the lower limit value, it is possible to prevent an excessive transition delay of the ignition timing. Further, even if there is an erroneous determination of the in-cylinder pressure signal, it is possible to prevent the ignition timing from being retarded or advanced more than necessary, and it is possible to prevent a situation in which the engine is seriously damaged. As a result, it is possible to improve the driving performance by suppressing the knocking and performing the MBT control effectively.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram of the present invention, FIGS. 2 to 4 are diagrams showing an embodiment of the present invention, and FIG.
FIG. 4 is a detailed block diagram of the signal processing circuit, and FIG. 4 is a flowchart showing programs for the knock control and the MBT control. 1 ... Engine, 8 ... Ignition means, 14 ... Signal processing circuit (knock detection means, peak position detection means), 16 ... Operating state detection means, 20 ... Control unit (first calculation means, second calculation means) Means, first correction amount limiting means, second correction amount limiting means, ignition timing setting means).

Claims (1)

[Claims] 1. A) pressure detecting means for detecting combustion pressure of the engine, b) operating state detecting means for detecting operating state of the engine, and c) knocking level of the engine based on output of the pressure detecting means. Knocking detection means for: d) peak position detection means for detecting a combustion peak position where the combustion pressure has a maximum value based on the output of the pressure detection means; and e) a predetermined position where the combustion peak position maximizes the torque generated by the engine. First calculation means for calculating a peak correction amount for correcting the ignition timing so that: f) second calculation means for calculating a knock correction amount for correcting the ignition timing so that the knocking level becomes a predetermined value; ) First correction amount limiting means for setting the lower limit value and the upper limit value of the peak correction amount, and h) The lower limit value of the knock correction amount so as to be different from the upper limit value and the lower limit value of the peak correction amount. And setting the upper limit
Correction amount limiting means, i) setting a basic ignition timing based on the operating state, and performing peak correction within the range of the upper limit value and the lower limit value set by the first correction amount limiting means and the second correction amount limiting means. Ignition timing control of an internal combustion engine, comprising: an ignition timing setting unit that corrects according to the amount and a knock correction amount; and j) an ignition unit that ignites an air-fuel mixture based on the output of the ignition timing setting unit. apparatus.