JPH0742927B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

Detailed Description of the Invention

(Industrial field of application) The present invention suppresses knocking of internal combustion engines such as automobiles.
The present invention relates to an ignition timing control device for an internal combustion engine that performs MBT control to improve drivability. (Prior Art) Generally, considering the efficiency and fuel efficiency of an engine, the minimum advance angle at the time of maximum torque, so-called MBT (Minimum advance for Best Torqu
It is known that it is best to ignite in the vicinity of e), but in certain operating conditions of the engine, knocking may occur before MBT and stable operation may not be possible. Therefore, a so-called knock control that controls the ignition timing depending on the presence or absence of knocking is used in combination with the above MBT control.For example, such a method is disclosed in JP-A-58-82074. Some are listed. In this device, the pressure in the combustion chamber (hereinafter, referred to as in-cylinder pressure) is detected, and the crank angle at which the pressure becomes maximum (hereinafter, referred to as
The ignition timing is MBT controlled so that θpmax comes to a predetermined position that maximizes the torque generated by the engine. Further, at the same time, knocking is detected by passing a signal for detecting in-cylinder pressure through a signal processing circuit, and when the knocking level exceeds a predetermined value, ignition timing is retarded to suppress knocking with priority over MBT control. . When knocking is suppressed, the ignition timing is controlled by MBT again to maximize the torque generated by the engine. This is intended to increase the torque generated by the engine as much as possible while suppressing knocking and improve the driving performance. (Problems to be solved by the invention) However, in such a conventional ignition timing control device for an internal combustion engine, while the detected knocking level is lower than a predetermined value, MBT control is performed to obtain the maximum torque. The ignition timing is corrected up to the specified ignition timing, and the knocking suppression control is prioritized over the MBT control only when the detected knocking level exceeds a predetermined value. In the following cases (specifically, at the time of advancement after returning after knocking), there is a problem that the correction speed of the MBT control is slow. That is, in general, in knocking avoidance control, the knock level is completely

Instead of setting it to [0], the vicinity of the trace knock near the critical point where knocking occurs is set as the control target. This is because if the knocking level is advanced as much as possible within the range of the predetermined value or less, the output is improved. In this case, from the viewpoint of the accuracy of knock control, a state in which about 10% of the knocking data detected near the above-described control knock target knock knock exceeds a predetermined value (hereinafter, referred to as knock suppression determination standard) It is considered preferable, and this state is a criterion for determining whether knocking is suppressed (whether the ignition timing is retarded). Therefore, when the detected knocking data exceeds the knock suppression determination standard, the ignition timing is retarded, and when it falls below the same determination standard, the MBT control is performed. This means that 1/10 of the actually detected knocking data exceeds the predetermined value, which means that knocking is not completely zero. On the other hand, when the knock suppression judgment criterion is not more than, the ignition timing is corrected by the MBT control, but because of the above-described knock suppression mode, the advance correction amount by the MBT control is delayed for one knock cycle to suppress knocking. It should be about 1/10 of the angle correction amount. Therefore, for example, even if the actual knocking level is significantly lower after the knocking is suppressed, the ignition timing is MBT controlled at a relatively slow advance speed because of concern about the knocking. In such a case, the MBT control response speed decreases, and there is room for improvement in terms of improving drivability. That is, there is a specific relationship from the one side called knock suppression between the correction speeds of the knock correction amount and the MBT correction amount.
It does not always meet the requirements of the MBT control side for the response speed of T control. (Object of the Invention) Therefore, the present invention holds the MBT correction amount immediately before the shift when shifting to the knock suppression processing (or changes it depending on the knock situation), and based on this held value after the knock suppression ends.
By starting the MBT control, the purpose is to speed up the response speed of the MBT control when returning after knock suppression and improve the drivability of the engine. (Means for Solving the Problems) In order to achieve the above object, the ignition timing control device for an internal combustion engine according to the present invention has a basic concept diagram shown in FIG. 1, in which knock detection for detecting knocking occurring in the engine is detected. Means a
A pressure detecting means b for detecting the engine cylinder pressure; an operating state detecting means c for detecting the operating state of the engine; and a knock for correcting the ignition timing based on the output of the knock detecting means a so as to suppress the knocking. First to calculate the correction amount
The calculating means d, the maximum timing detecting means e for detecting the crank angle at which the in-cylinder pressure is maximum based on the output of the pressure detecting means b as the in-cylinder pressure maximum timing, and the in-cylinder pressure maximum timing is for maximizing the engine generated torque. When calculating the MBT correction amount for correcting the ignition timing so as to match the predetermined position and shifting to knock suppression processing, the value of the MBT correction amount immediately before this transition is held, or the held value is set to the knock correction amount. The second calculation means f, which changes remarkably according to the knocking level, and the basic ignition timing is set based on the operating state of the engine, and the basic ignition timing is corrected according to the knock correction amount and the MBT correction amount. MB when suppression processing ends
An ignition timing setting means g for starting the MBT correction processing based on the held value of the T correction amount, and an ignition means h for igniting the air-fuel mixture based on the output of the ignition timing setting means g are provided. (Operation) In the present invention, when the knock suppression process is performed, MB immediately before the shift is performed.
The T correction amount is held (or this is changed depending on the knock situation), and MB is based on this held value after knock suppression is completed.
T control is started. Therefore, the response speed of the MBT control at the time of recovery after knock suppression is increased, and the drivability of the engine is improved. (Example) Hereinafter, the present invention will be described with reference to the drawings. 2 to 11 are views showing a first embodiment of the present invention. First, the configuration will be described. In FIG. 2, reference numeral 1 denotes an operating state detecting means, and the operating state detecting means 1 is composed of a plurality of sensors for detecting various parameters related to the operating state of the engine. That is, the operating state detecting means 1 is composed of the crank angle sensor 2, the air flow meter 3, the throttle valve opening sensor 4, and the cylinder discrimination sensor 5. The crank angle sensor 2 is at a predetermined position before the compression top dead center (TDC) of each cylinder at every explosion interval (120 ° crank angle in a 6-cylinder engine, 180 ° in a 4-cylinder engine), for example, BTDC 70 ° [H] level. Outputs the reference position signal REF that becomes the pulse of, and the unit angle of crank angle (for example, 2 °)
A unit signal POS that becomes a pulse of [H] level is output every time. The engine speed Ne can be known by counting the pulses of the signal REF, and this processing is performed by the control unit described later. The air flow meter 3 detects an intake air amount Qa to the engine, and the throttle valve opening sensor 4 detects an opening Cv of the throttle valve. Since the throttle valve opening sensor 4 is a sensor for detecting the load of the engine, it is not limited to the sensor for detecting the throttle valve opening Cv, and may be a sensor for detecting the intake negative pressure, for example. Further, the cylinder discrimination sensor 5 discriminates a specific cylinder (for example, the first cylinder), and a cylinder discrimination signal is detected at a predetermined crank angle position (for example, BTDC80 ° of the first cylinder) before the compression top dead center of the specific cylinder. REF−
Output i. Therefore, this cylinder discrimination signal REF-i
Is output once every two revolutions of the crankshaft. The output of the driving state detecting means 1 is inputted to the control unit 6, and the control unit 6 is further inputted with a signal from the knock detecting means 7. The knock detection means 7 is composed of a pressure sensor 8 and a knock detection circuit 9. The pressure sensor 8 is composed of, for example, a piezoelectric element incorporated in a cylinder gasket between the cylinder head and the cylinder block, and outputs a pressure signal Pa corresponding to the pressure (cylinder pressure) in the combustion chamber of the engine via a charge amplifier (not shown). Output to the control unit 6 and the knocking detection circuit 9. The knocking detection circuit 9 is composed of a bandpass filter (BPF) 10 and a waveform shaping circuit 11, as shown in FIG. The bandpass filter 10 passes only the high frequency component Pa ′ (see FIG. 4 (b)) of 6 to 15 kHz, which is particularly included when knocking occurs, from the pressure signal Pa (see FIG. 4 (a)) to shape the waveform. The signal is output to the circuit 11, and the waveform shaping circuit 11 half-wave rectifies the high-frequency component Pa ′ and forms an envelope signal from the half-wave rectified signal (envelope detection), as shown in FIG. It outputs to the control unit 6 as a knocking signal S _N according to the knocking level. In this knocking detection circuit 9, the pressure signal Pa
May be smoothed to form a background level corresponding to the normal noise level of the engine, and the difference between the formed level and the maximum level of the envelope signal may be output as the knocking signal S _N. Referring again to FIG. 2, the control unit 6 has functions as a maximum timing detecting means, a first computing means, a second computing means and an ignition timing setting means, and the CPU 21, ROM22, RAM23.
And input / output interface, registers, counters,
It is composed of a microcomputer including an input / output control circuit 24 and the like having an A / D converter, a high frequency cut filter and the like built therein. The CPU21 fetches the external data required from the input / output control circuit 24 according to the program written in the ROM22, and exchanges the data with the RAM23, while performing the processing required for knock avoidance control and MBT control. The value is arithmetically processed, and the processed data is output to the input / output control circuit 24 as necessary. The input / output control circuit 24 receives signals from the operating state detecting means 1, the pressure sensor 8 and the knocking detection circuit 9 and outputs an ignition signal Sp from the input / output control circuit 24. The ignition signal Sp is input to the ignition means 25, and the ignition means 25
Is composed of ignition plugs 26a to 26f, an ignition coil 27, a power supply 28, a distributor 29, and a power transistor Q ₁ . The ignition means 25 controls ON / OFF of the power transistor Q ₁ based on the ignition signal Sp to generate a high voltage Pi on the secondary side of the ignition coil 27, and also distributes this high voltage Pi to a distributor 29 to generate an ignition plug 26. Supply to ~ 26f and ignite the mixture. Note that this ignition timing control (ON / OFF control of the power transistor Q ₁ ) is performed by a value (advanced ignition timing) corresponding to an ignition timing determined in an advance value (ADV) register (not shown) provided inside the input / output control circuit 24. Angle value) is set, the values of these registers are compared with the count value for counting the position signal POS, and when they match, the power transistor Q ₁
Turn ON or OFF. Next, the operation will be described. FIG. 5 is a flow chart showing a program for ignition timing control, and this program is started each time the reference position signal REF is input from the crank angle sensor 2. First, the knocking signal S _N is A / D converted at P ₁ and stored in the RAM 23 as data X corresponding to the knocking level. Then RAM on P ₂
The knocking level data X stored in 10 is compared with a predetermined reference value Xo, for example, a value at which the knocking level detected at the time of trace knocking exceeds at a frequency of about 10% to determine whether knocking has occurred. Accordingly, the knock correction amount β is obtained by an arithmetic expression described later (see subroutine SUB-1 in FIG. 8). At P ₃ , it is determined whether or not the knock correction amount β is equal to the advance limit value (0 ° in this embodiment),
When β = 0, the MBT control is performed, and the MBT correction amount γ is obtained by the arithmetic expression described later on P ₄ (FIG. 9, subroutine SUB
-2). On the other hand, it is determined that when the beta ≠ 0 is in the knock suppression control, the process proceeds to P ₅ to jump P _4. Therefore, during the knock suppression control, the original MBT control is stopped, but at this time, the MBT correction amount γ is held at the value immediately before the shift to the knocking process, as described later. At P ₅ , the basic ignition timing ADVφ corresponding to the operating state at that time is looked up from the table map as shown in FIG. ₆ , and at P ₆ , the basic ignition timing ADVφ is knocked correction amount β.
Then, the final ignition timing ADV is calculated according to the following equation by performing correction based on the MBT correction amount γ. The ADV = ADVφ + β + γ ...... Finally, set on the basis of the ADV at P ₇ a value of (70-ADV) to the register of the output control circuit 24, and outputs an ignition signal Sp at a predetermined ignition timing. The output process of the ignition signal Sp is specifically performed as follows. Value obtained by subtracting the final ignition timing ADV from 70 ° CA (70 ° -AD
V) is output to the register of the input / output control circuit 24, and then the processing of this processing program is once ended. Then, every time the above processing is performed, when the value (70-ADV) is written in the register of the input / output control circuit 24, the ignition signal Sp is formed and the power of the ignition means 25 is generated as follows. Output to transistor Q ₁ . That is, in the input / output control circuit 24, the counter value is reset to zero when the reference position signal REF is input from the crank angle sensor 2 as shown in, for example, FIGS. Each time the signal POS is input, the value of the counter is incremented at the rising and falling edges. Therefore, this counter value is incremented by 1 every 1 ° CA. On the other hand, (70-ADV) is written in the register at a predetermined timing as described above, and the comparator compares the value of this register with the value of the above counter, and when both match, ignition is performed. The signal Sp is output to the power transistor Q ₁ of the ignition means 25. When the above ignition signal Sp is output to the power transistor Q ₁ , this power transistor Q ₁
Q ₁ is switched from on to off, whereby the high voltage generated on the secondary side of the ignition coil 28 is sent via the distributor 30 to the ignition plug (one of 26a to 27f) in the ignition order to cause ignition. Done. FIG. 8 is a flowchart showing a knock control subroutine. First, at P ₁₁ , the knocking level data X is compared with the reference value Xo. When X> Xo, it is determined that knocking has occurred and the ignition timing is retarded, so that the present knock correction amount β _new is calculated in P ₁₂ according to the following equation. β _new = β _old -1 °, where β _{old is the} previous value. On the other hand, when X ≦ Xo, it is determined that knocking is suppressed and the ignition timing is advanced to advance β according to the following equation at P _13.
ask for _new . β _new = β _old + 0.1 ° ...... In this way, the ignition timing is corrected depending on whether knocking occurs. At this time, the retard correction is performed in 1 ° CA units, and the advance correction is performed in 0.1 ° CA units more slowly. Next, at P ₁₄ , the knock correction amount β is set to the advance limit value [0
Angle] and the retard limit value (for example, -10 °), check whether or not it is in the range regulated, and if it is not within this range, limit β at this time to any of the limit values, If there is, that value is adopted as β. FIG. 9 is a flowchart showing a subroutine of MBT control. First of all, this time of the MBT correction γ _new according to the formula in the P ₂₁
Ask for. However, γ _{old is the} previous value M is a constant of 1 or more, where K is the target value for MBT control, and the crank angle that maximizes the torque generated by the engine, for example, a predetermined value in the range of ATDC 10 ° to 20 ° Is set. Then, MBT correction amount γ is advance-angle limit value at P ₂₂ (e.g., + 10 °) was checked whether the range is restricted by the retarded limit value (e.g. -10 °), be in the range For example, γ this time is limited to one of the limit values, and if it is in this range, that value is adopted as γ. In this way, the MBT correction amount γ is calculated within a range of 10 ° before and after with the target position K as the center, and feedback control that follows the so-called target is performed. Here, the calculation of the in-cylinder pressure maximum timing θpmax is performed as follows. The pressure signal Pa based on the pressure sensor 5 shown in FIG. 10 (a) has a high frequency component removed by the high frequency cutoff filter in the input / output control circuit 11, and becomes a pressure signal P as shown in FIG. 10 (b). P is A / D converted at the timing of the unit angle signal POS. On the other hand, the input / output control circuit 11
The unit angle signal POS (see (c) in the figure) is being counted by the counter inside, and this counter shows the cylinder discrimination signal REF.
-I (see (d) in the figure) is cleared every 360 counts. First, the maximum value of the A / D converted pressure signal P is detected in a certain section where the counter counts 60, for example, the section of 60 to 120, and the lower limit value of the certain section, for example, 60 is subtracted from the detected value. The value is α. Next, θ′pmax is calculated according to the following equation, and the average value α obtained by averaging the remaining 2 data obtained by removing the maximum and minimum 2 data from the 4 latest data among them is the top dead center at the maximum cylinder pressure time. Is detected as the crank angle θpmax. θ′pmax = 2α−70 ... FIG. 11 is a timing chart showing the operation of this embodiment. The calculation of each correction amount is based on the data before one ignition. For example, θpmax detected at Tn is calculated at the next T _n-1 .
It is used to calculate the MBT correction amount γ. The same applies to the relationship between the knocking level data X and the knock correction amount β. When the knocking level data X continues to be below the reference value Xo, the knocking correction amount β is

[0] (Advance limit value)
Therefore, the knock control is not performed, and the feedback correction of the MBT control is performed based on the detected information of θpmax (section A
reference). As a result, convergence control is performed so that θpmax matches the target value K. The feedback correction at this time is performed within a range of ± 10 ° around the target value K, and the correction speed is 0.1 ° / every ignition, and this speed is the same as the conventional one. On the other hand, when the knocking level data X exceeds the reference value Xo in the section A, it is determined that knocking has occurred, and knock suppression processing based on the knock correction amount β is performed from the next ignition, and section B (knock suppression processing section). Move to. At this time, focusing on the MBT correction amount γ, M
Since the BT control is temporarily stopped, the calculation of the MBT correction amount γ based on the sensor information of θpmax is not performed, and this is the same as the conventional case. However, as described above, the MBT responsiveness after completion of the knock suppression process is inferior as it is. This is because the ignition timing is continuously corrected by the knock suppression process, but this correction is only for knock suppression, and may be largely deviated from the target value K from the viewpoint of MBT control. In such a case, it is easily inferred that even if the MBT control is restarted at a slow speed of 0.1 ° / every ignition, it takes a long time to approach the target value K. On the other hand, in the present embodiment, the value of the MBT correction amount γ which has converged to the vicinity of the target value K is held as it is at the transition to the section B, and this hold state is continued until the end of the section B. In addition, γ = 0 in the section B.
Therefore, the MBT correction amount γ itself exists, but this value is not based on the θpmax detection information at that time,
That is, it exists as a value that converges near the target value K. Then, when the MBT control is restarted next time, the ignition timing is corrected based on the hold value γ. Since the MBT correction amount γ at the time of this restart is a value that converges in the vicinity of the target value K, it is immediately corrected so that θpmax matches the target value K regardless of the return from the interruption of the MBT control. As a result, the responsiveness of MBT control can be significantly improved compared to the conventional case. That is, it is possible to increase the speed of convergence to the target value K when the MBT control is restarted. In the above-described first embodiment, the MBT correction amount γ is held at the value immediately before the shift to the knock suppression control, and this held state is continued during the knock suppression control. Next, as the second embodiment, the knock suppression is performed. A case where an appropriate correction is added to the MBT correction amount γ held during processing will be described. FIG. 12 is a diagram showing a second embodiment of the present invention. This figure shows
It is a flowchart showing a program for correcting the MBT correction amount γ during knocking suppression control, and this program is a fifth step.
Although not shown in the main routine shown in the figure, β ≠ 0
Is a subroutine that is executed when. First, at P ₃₁ , the knocking level data X is compared with the reference value Xo, and when X> Xo, it is determined that knocking has occurred, and at P ₃₂ , the current MBT correction amount γ _new is calculated according to the following equation. On the other hand, when X ≦ Xo, it is determined that the knock suppression process has ended, and the current MBT correction amount γ _new is calculated in P ₃₃ according to the following equation. _{γ new = γ old -Δγ 1 ......} γ new = γ old -Δγ 2 ...... However, Δγ _1> Δγ ₂ where, [Delta] [gamma] ₁ and [Delta] [gamma] ₂ is a preset value by experiments or the like. Then, MBT correction amount γ is advance-angle limit value at P ₃₄ (e.g., + 10 °) and retard limit value (e.g., -10 °) to check whether the range is restricted by a, in the range If this is not the case, γ this time is limited to one of the respective limit values, and if it is in this range, that value is adopted as γ. As described above, in the second embodiment, the MBT correction amount γ is corrected according to the knocking level data X during the knock suppression process, so the MBT correction amount γ approaches the target value K more. Therefore, the speed of convergence to the target value K can be further increased when the MBT control is restarted. FIG. 13 is a diagram showing a third embodiment of the present invention. This figure is a flow chart showing a program for correcting the MBT correction amount γ during the knock suppression process. This program is omitted in the main routine shown in FIG. 5, but is a subroutine executed when β ≠ 0. Is. First, in P ₄₁ , it is determined whether or not the knock correction amount β is decreasing, and when it is decreasing, it is determined that the retard correction is being performed, and in P ₄₂ , the MBT correction amount γ of this time is calculated according to the following equation. . On the other hand, MBT correction amount of time according to the following equation by P ₄₃ determines the advance of correction when in increased γ
Ask for. _{γ new = γ old -Δγ 1 ......} γ new = γ old + Δγ 2 ...... However, Δγ _1> Δγ ₂ where, [Delta] [gamma] ₁ and [Delta] [gamma] ₂ is a preset value by experiments or the like. Then, MBT correction amount γ is advance-angle limit value at P ₄₄ (e.g., + 10 °) and retard limit value (e.g., -10 °) to check whether the range is restricted out with, in the range If this is not the case, γ this time is limited to one of the respective limit values, and if it is in this range, that value is adopted as γ. As described above, in the third embodiment, the MBT correction amount γ is calculated according to the mode of the knock suppression control during the knock suppression processing, and this value is used for the ignition timing setting during the knock suppression processing.
The knock correction speed is increased, and knock suppression is completed in a shorter time. (Effect) According to the present invention, when the process shifts to the knock control process, the MBT correction amount immediately before the shift is held (or variable according to the knock situation), and after the knock suppression is finished, the MBT control is performed based on the held value. As described above, the response speed of MBT control at the time of recovery after knock suppression can be increased, and the drivability of the engine can be improved.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram of the present invention, FIGS. 2 to 11 are diagrams showing a first embodiment of an ignition timing control device for an internal combustion engine according to the present invention, and FIG. 2 is its overall configuration diagram, FIG. FIG. 4 is a configuration diagram of the knocking detection circuit, FIG. 4 is a diagram showing the operation of the knocking detection circuit of FIG. 3, FIG. 5 is a flow chart showing a program for ignition timing control, and FIG. FIG. 7 is a diagram showing an example of a table map, FIG. 7 is a timing chart showing the operation of the counter in the input / output control circuit, FIG. 8 is a diagram showing a subroutine for calculating the knock correction amount β, and FIG. 9 is its MBT. FIG. 10 shows a subroutine for calculating the correction amount γ, and FIG. 10 shows the maximum cylinder pressure timing θpmax.
11 is a timing chart showing the operation of detecting the ignition timing, FIG. 11 is a timing chart showing the operation of the ignition timing control thereof, and FIG. 12 is a second embodiment of the ignition timing control apparatus for an internal combustion engine according to the present invention, the MBT correction amount thereof. FIG. 13 is a flowchart showing a subroutine for calculating γ, and FIG. 13 is a flowchart showing a subroutine for calculating the MBT correction amount γ showing the third embodiment of the ignition timing control device for the internal combustion engine according to the present invention. 1 ... Operating state detecting means, 6 ... Control unit (maximum time detecting means, first
Computing means, second computing means, ignition timing setting means), 7 ... knock detecting means, 8 ... pressure sensor (pressure detecting means), 25 ... ignition means.

Claims (1)

[Claims] 1. A knock detecting means for detecting knocking occurring in an engine; b) a pressure detecting means for detecting an in-cylinder pressure of the engine; and c) an operating state detecting means for detecting an operating state of the engine. d) first calculation means for calculating a knock correction amount for correcting the ignition timing so as to suppress knocking based on the output of the knock detection means; and e) maximum in-cylinder pressure based on the output of the pressure detection means. Maximum timing detecting means for detecting the crank angle as the maximum cylinder pressure timing, and f) calculating an MBT correction amount for correcting the ignition timing so that the maximum cylinder pressure timing coincides with a predetermined position where the torque generated by the engine is maximum, When the process shifts to knock suppression processing, the value of the MBT correction amount immediately before this transition is held, or the held value is changed according to the change in the knock correction amount or the knocking level. Second computing means, and g) setting a basic ignition timing based on the operating state of the engine, correcting the basic ignition timing according to the knock correction amount and the MBT correction amount, and holding the MBT correction amount when the knock suppression process ends. Ignition timing control of an internal combustion engine, comprising: ignition timing setting means for starting the MBT correction process based on the value; and h) ignition means for igniting the air-fuel mixture based on the output of the ignition timing setting means. apparatus.