JPS63100273A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve operability of an engine, by a method wherein, when an engine is migrated to knock suppresion processing, a correction amount of MBT (Minimum advance for Best Torque) right before migration is held or is varied according to a knock state, and after completion of knock, based on a hold valve, MBT control is started. CONSTITUTION:When an engine is migrated to knock suppression processing, a value of an MBT correction amount right before migration is held, and by means of a second computing means (f), a hold value is varied according to a change in a knock correction amount and a knocking level. Based on the running state of an engine, a fundamental ignition timing is set, a knock correction amount is corrected according to a knock correction amount or the MBT correction amount. Upon collection of knock suppresion processing, based on the hold value of the MBT correction amount, MBT correction processing is started by means of an ignition timing set means (g), and based on an output, an air-fuel mixture is ignited by means of an ignition means (h). This constitution increases the response speed of MBT control during restoration after suppresion of knock, and improves operability of the engine.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an ignition timing control device for an internal combustion engine, which suppresses knocking in an automobile internal combustion engine and performs MBT control to improve drivability. (Prior art) -i is the minimum advance angle at maximum torque, so-called M B T (Minimum advance angle), considering the efficiency and fuel consumption of the engine.
It is known that it is best to ignite the engine near the MBT, but under certain operating conditions of the engine, knocking may occur before the MBT and stable operation may not be possible. Therefore, a system has been developed in which so-called knock control, in which the ignition timing is controlled depending on the presence or absence of knocking, is used in combination with the above MBT control. There are things listed. This device detects the pressure inside the combustion chamber (hereinafter referred to as cylinder pressure) and sets the crank angle at which the pressure is maximum (hereinafter referred to as cylinder pressure maximum timing) θpmax to a predetermined position that maximizes the torque generated by the engine. The ignition timing is controlled by MBT so that the At the same time, non-king is detected by passing the cylinder pressure detection signal through a signal processing circuit, and when the knocking level exceeds a predetermined value, the ignition timing is retarded in order to suppress non-king, giving priority over MBT control. . When the non-king is suppressed, the ignition timing is controlled by MBT again to maximize the torque generated by the engine. This is intended to improve driving performance by increasing the torque generated by the engine as much as possible while suppressing knocking. (Problem to be Solved by the Invention) However, in such a conventional ignition timing control device for an internal combustion engine, MBT control is performed while the detected non-king level is smaller than a predetermined value, and the maximum torque is The ignition timing is corrected until the ignition timing is obtained, and knock suppression control is performed in priority over MBT control only when the detected knocking level exceeds a predetermined value.
If the knocking level is below a predetermined value (specifically when the return angle is advanced after knock avoidance) for the following reasons,
MBT? 1. There was a problem that the correction speed of IJ control was slow. In other words, in general, non-king avoidance control completely reduces the knock level.

Rather than setting it to [0], the control target is set near the trace knock, which is near the critical point where knocking occurs. This is because advancing the angle as much as possible while the non-king level is within a predetermined value contributes to improved output. In this case, the accuracy of knock control is determined by a state in which about 10% of the detected non-king data exceeds a predetermined value (hereinafter referred to as the knock suppression criterion) in the vicinity of trace knock, which is the control target. This state is considered preferable because of this, and serves as a criterion for determining whether or not to suppress non-king (whether or not to retard the ignition timing). Therefore, when the detected knocking data exceeds the knock suppression criterion, the ignition timing is retarded, and when the detected knocking data falls below the knocking criterion, the engine shifts to MBT control. This means that 1/10 of the actually detected knocking data exceeds the above-mentioned predetermined value, which means that the non-king is not completely zero. On the other hand, if it is below the knock suppression criterion, the ignition timing is corrected by MBT control, but since the knock suppression mode is adopted as described above, the advance angle correction amount by MBT control is a delay for knock suppression per combustion cycle. Angle correction amount l
/10 or so. Therefore, for example, even if the actual non-king level is significantly lower after knocking has been suppressed, the ignition timing may be controlled by MBT control at a relatively slow advance speed for fear of inducing knocking.
In such a case, the response speed of MBT control decreases, and there is room for improvement in terms of improving drivability. That is, there is a specific relationship between the respective correction speeds of the knock correction amount and the MBT correction amount from one aspect of knock suppression, and this does not necessarily fully meet the MBT control side's request of the response speed of the MBT control. (Object of the Invention) Therefore, the present invention maintains the MBT correction amount immediately before the transition (or changes it depending on the knock situation) when transitioning to the knock suppression process, and performs MBT control based on this retained value after the knock suppression process is completed. The purpose of this is to increase the response speed of MBT control at the time of recovery after knock suppression, thereby improving engine drivability. (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 knock detection system that detects knocking occurring in the engine, as shown in FIG. means a
and a pressure detection means for detecting the cylinder pressure of the engine,
Operating state detection means C for detecting the operating state of the engine;
a first calculating means d for calculating a knock correction amount for correcting the ignition timing to suppress knocking based on the output of the knock detecting means a; and a crank whose cylinder pressure is maximized based on the output of the pressure detecting means S. Knock suppression is achieved by calculating the maximum timing detection means e that detects the maximum timing of the cylinder pressure as the timing of the maximum cylinder pressure, and the MBT correction amount that corrects the ignition timing so that the maximum cylinder pressure timing coincides with a predetermined position where the engine generates the maximum torque. When proceeding to the process, a second process is performed in which the value of the MBT correction amount immediately before this transition is held, or the held value is changed depending on the change in the knock correction amount, or the non-king level.
A basic ignition timing is set based on the calculation means f and the operating state of the engine, and this is set based on the knock correction amount and M B
The ignition timing setting means g performs correction according to the T correction amount and also starts the MBT correction process based on the held value of the MBT correction amount when the knock suppression process ends, and the air-fuel mixture is adjusted based on the output of the ignition timing setting means g. an ignition means for igniting the
It is equipped with (Function) In the present invention, when transitioning to knock suppression processing, M
The BT correction amount is held (or it is variable depending on the knocking situation), and after the knock suppression ends, MBT control is started based on this held value. Therefore, the response speed of MBT control at the time of recovery after knock suppression is increased, and engine drivability is improved. (Example) Hereinafter, the present invention will be explained based on the drawings. 2 to 11 are diagrams showing a first embodiment of the present invention. First, the configuration will be explained. 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 that detect various parameters related to the operating state of the engine. That is, the operating state B detection means 1 is composed of a crank angle sensor 2, an air flow meter 3, a throttle valve opening sensor 4, and a cylinder discrimination sensor 5. The crank angle sensor 2 is set at a predetermined position before compression top dead center (TDC) of each cylinder at every explosion interval (120° crank angle for a 6-cylinder engine, 180° for a 4-cylinder engine), for example, at a (H) level at 70° BTDC. It outputs a reference position signal REF that becomes a pulse of (H) level, and also outputs a unit signal P OS that becomes a pulse of (H) level for every unit angle (for example, 2 degrees) of the crank angle. Note that by counting the pulses of the signal REF, the engine rotation speed Ne can be determined, and this processing is performed by a control unit, which will be described later. The air flow meter 3 detects the intake air amount Qa to the engine, and the throttle valve opening sensor 4 detects the throttle valve opening Cv. Note that since the throttle valve opening sensor 4 is a sensor for detecting the load of the engine, it is not limited to a sensor that detects the throttle valve opening Cv, but may be a sensor that detects, for example, intake negative pressure. Furthermore, the cylinder discrimination sensor 5 detects a specific cylinder (for example, the first
cylinder), and determines the specified crank angle position before compression top dead center of a specific cylinder (for example, 80° BTDC of the first cylinder).
) outputs the cylinder discrimination signal REF-4. therefore,
This cylinder discrimination signal REF-1 is output once every two revolutions of the crankshaft. The output of the driving state detection means 1 is inputted to a control unit 6, and a signal from the knock detection means 7 is further inputted to the control unit 6. 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 built into a cylinder gasket between the cylinder head and the cylinder block, and sends a pressure signal Pa corresponding to the combustion chamber pressure (in-cylinder pressure) of the engine via a charge amplifier (not shown). and outputs it to the control unit 6 and the non-king detection circuit 9. As shown in FIG. 3, the knocking detection circuit 9 is composed of a bandpass filter (BPF) 10 and a waveform shaping circuit 11. The bandpass filter 10 is a pressure signal Pa
(See Figure 4 (A)), only the high frequency component Pa' of, for example, 6 to 15 kHz (see Figure 4 (B)), which is particularly abundant when knocking occurs, is passed through and output to the waveform shaping circuit 11, and the waveform is shaped. The circuit 11 half-wave rectifies the high frequency component Pa' and forms an envelope signal from the half-wave rectified signal (envelope detection) to generate a knocking signal according to the knocking level as shown in FIG. 4(c). It is output to the control unit 6 as SN. In addition, in this knocking detection circuit 9, the pressure signal P
A 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 described above may be output as the non-king signal SN. Referring again to FIG. 2, the control unit 6 has the functions of maximum timing detection means, first calculation means, second calculation means, and ignition timing setting means, and includes a CPU 21, a ROM 2,
2. It is constituted by a microcomputer consisting of a RAM 23 and an input/output control circuit 24 containing an input/output interface, a register, a counter, an A/D converter, a high frequency cut filter, etc. The CPU 21 controls the input/output control circuit 2 according to the program written in the ROM 22.
You can import the external data you need from 4, or use R.
While exchanging data with AM23, it calculates the processing values necessary for knock avoidance control and MBT control,
The processed data is output to the input/output control circuit 24 as necessary. The input/output control circuit 24 includes an operating state detection means 1,
Signals from the pressure sensor 8 and the non-king detection circuit 9 are input, and an ignition signal Sp is output from the input/output control circuit 24. The ignition signal Sp is input to the ignition means 25, and the ignition means 25 includes spark plugs 26a to 26f1, an ignition coil 27,
The ignition means 25, which is composed of a power source 28, a distributor 29, and a power transistor Q, fires the power transistor Q based on the ignition signal Sp. 0N10FFIII is controlled to generate high voltage Pi on the secondary side of the ignition coil 27, and this high voltage Pi is distributed by the distributor 29 to the spark plugs 26 to 26.
26f and ignites the air-fuel mixture. Note that this ignition timing control (0N10FF control of the power transistor Q) is performed by setting a value (advance value) corresponding to the determined ignition timing in an advance value (ADV) register (not shown) provided inside the input/output control circuit 24. ), compare the values of these registers with the count value of the position signal PO8, and when they match, turn the power transistor Q1 on or off.
Set to FF state. Next, the effect will be explained. FIG. 5 is a flowchart showing an ignition timing control program, and this program is started every time the reference position signal REF is input from the crank angle sensor 2. First, P.
The knocking signal S8 is A/D converted and stored in the RAM 23 as data X corresponding to the non-king level. Next, in P2, the knocking level data X stored in RAM10 is set to a predetermined reference value Xo, for example, IN where the non-king level detected at the time of trace knock is about 10%.
The presence or absence of knocking is determined by comparing it with the value that exceeds the value of 100 degrees, and based on the determination result, the knock correction amount β is calculated using the calculation formula described later (see subroutine 5UB-1 in Fig. 8).
. At P, it is determined whether the knock correction amount β is equal to the advance angle limit value (O” in this embodiment), and when β=0, the MBT
In order to perform control, the MBT correction amount is set using the calculation formula described later in P4 (see subroutine 5UB-2 in Figure 9).
. On the other hand, when β≠O, it is determined that knock suppression control is in progress, and P4 is jumped to proceed to P%. Therefore, while the knock suppression control is in progress, the original MBT control is stopped, but at this time, the MBT correction amount is held at the value immediately before shifting to the knock process, as will be described later. Ps looks up the basic ignition timing ADVφ corresponding to the current operating condition from a table map as shown in FIG. 6, P& corrects the basic ignition timing ADVφ based on the knock correction amount β and the MBT correction amount, The following formula■
The final ignition timing ADV is determined according to the following. ADV=ADVφ+β+r ・'−・・■Finally, P
, a value (70-ADV) is set in a register in the input/output control circuit 24 based on the ADV of the lever, and an ignition signal Sp is output at a predetermined ignition timing. Specifically, the output processing of the ignition signal Sp is performed as follows. The value obtained by subtracting the final ignition timing ADV from 70°CA (7
0°-ADV) to the register of the input/output control circuit 24, and then the processing of this processing program is temporarily terminated. Then, each time the above processing is performed, (70-AD
When the value V) is written into the register of the input/output control circuit 24, the ignition signal Sp is generated as follows and is output to the power transistor Ql of the ignition means 25. That is, in the input/output control circuit 24, for example,
As shown in (c), when the reference position signal REF is input from the crank angle sensor 2, the counter value is reset to zero, and after that, every time the unit angle signal PO8 is input, the counter value is counted at the rise and fall of the unit angle signal PO8. Therefore, this counter value increases by 1 every 1° CA. On the other hand, (70-ADV) is written in the register at a predetermined timing as described above, and a comparator compares the value of this register with the value of the counter described above, and when the two match, the ignition is started. The signal sp is output to the power transistor Q1 of the ignition means 25. And the above ignition signal S
When p is output to the power transistor Q, this power transistor Q is turned from on to off, and the high voltage generated on the secondary side of the ignition coil 28 is passed through the distributor 30 to the ignition plug ( 26a
~27f) for ignition. FIG. 8 is a flowchart showing a knock control subroutine. First, the knocking level data X is compared with the reference value Xo at Pl+. When X>XO, it is determined that non-king has occurred and the ignition timing is retarded, so the current knock correction amount βnow is determined using p+z according to the following equation (2). β・・−１βota 1°・・・・・・■However, β. , 4 : Previous value On the other hand, when X≦Xo, it is determined that knocking has been suppressed and the ignition timing is advanced, so the PI3 calculates β, , , w according to the following formula (■). β00w=β. ta + 0.1°... ■In this way, the ignition timing is corrected depending on whether or not non-king occurs. At this time, the retard angle correction is performed in 1° CA units, and the advance angle correction is performed more gently in 0.1" CA units. Next, in PI4, the knock correction amount β is set to the advance angle limit value [0° ] and the retard limit value (for example, -10"). If it is not within this range, limit the current β to one of the respective limit values, and set it within this range. If so, use that value as β. FIG. 9 is a flowchart showing a subroutine for MBT control. First, the current MBT correction T new is determined using pz+ according to equation 0. However, γ. , 4: Previous value M: Constant greater than or equal to 1 Here, K is the target value for MBT control, and is the crank angle that maximizes the torque generated by the engine, for example, ATDCIO.
0, which is set to a predetermined value in the range of "~20", then pz
MBT correction correction amount eye angle limit value (for example, +10°) in z
Check whether it is within the range regulated by The value is adopted as T. In this way, the MBT correction amount is calculated within a range of 10" before and after the target position K, and so-called feedback control that follows the target is performed. Here, the cylinder pressure maximum timing θpmax is calculated as follows. The high frequency component is removed from the pressure signal Pa based on the pressure sensor 5 shown in FIG. , this pressure signal P is A/D converted at the timing of the unit angle signal PO8.On the other hand, a counter in the input/output control circuit ll converts the unit angle signal pos.
<Refer to (c) in the same figure)) is counted, and this counter is cleared every 360 counts by the cylinder discrimination signal REF-i (refer to (d) in the same figure). First, the maximum value of the A/D-converted pressure signal P is detected in a certain interval in which the counter counts 60, for example, in the interval from 60 to 120, and from this detected value, the lower limit value of the certain interval, for example, 60
Let the value from which is subtracted be α. Next, according to the following formula 〇, θ
' pmax is calculated, and the average value α obtained by averaging the remaining 2 data after removing the maximum and minimum 2 data from the 4 latest data is the crank angle θpn + ax with respect to the top dead center at the time of maximum cylinder pressure. Detected as . θ'pmax-'lα-70 . . . ■ FIG. 11 is a timing chart showing the operation of this embodiment. Calculation of each correction amount is based on data one ignition before. For example, θpmax detected at Tn is -1 at the next T.
It is used for calculating the MBT correction amount T in . This also applies to the relationship between the non-king level data X and the knock correction amount β. When the non-king level data X continues to be below the reference value xO, the knock correction amount β is

[0] (advance angle limit value), knock control is not performed, and feedback correction of MBT control is performed based on the detection information of θpmax (see section A). As a result, convergence control is performed so that θpmax matches the target value. Note that the feedback correction at this time is performed within a range of ±10'' centering on the target value K, and the correction speed is 0.1°/every ignition.
This speed is the same as before. On the other hand, if the knocking level data X exceeds the reference value XO in 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) to move to. At this time, focusing on the MBT correction fir, since the MBT control is temporarily stopped during the knock suppression process, θpma
The calculation of the <MBT correction amount is not performed based on the sensor information of x, and this point is the same as the conventional method. However, as described above, if this continues, the MBT responsiveness after the knock suppression process will be inferior. This is because the ignition timing continues to be corrected by the knock suppression process, but this correction is only for knock suppression, and from the viewpoint of MBT control, there may be cases where the ignition timing deviates significantly from the target value K. In such a case, even if the MBT control is restarted at a slow rate of 0.1°/every ignition, it can be easily inferred that it will take a long time to approach the target value K. On the other hand, in this embodiment, the MBT correction amount that has converged close to the target value is held as it is at the same time as the transition to section B, and this hold state is continued until the end of section B. To add, in section B, r=
Since it is not o, the MBT correction amount T itself exists, but
This value is not based on the θpaeax detection information at that time, but exists as a value that converges close to the target value. Then, the next time MBT control is restarted, the ignition timing is corrected based on this hold value T. Since this value has converged near the MBT correction amount target value at the time of restart, θpI118x is immediately corrected to match the target value K regardless of the return from the interruption of MBT control. As a result, the MBT control window performance can be greatly improved compared to the conventional method. In other words, it is possible to speed up the convergence speed to the target value when restarting MBT control. In the first embodiment described above, the MBT correction amount T is held at the value immediately before shifting to knock suppression control, and knock suppression control is performed. In the middle, this held state was continued, but next, as a second embodiment, a case will be described in which an appropriate correction is made to the MBT correction Mar held during the knock suppression process. 2 is a diagram showing a second embodiment. This figure is a flowchart showing a program for correcting the MBT correction amount T during non-king suppression control, and although this program is omitted in the main routine shown in FIG. , this is a subroutine that is executed when β≠0.First, in P31, the knocking level data X is compared with the reference value XO, and when X>Xo, it is determined that knocking has occurred, and the
The current MBT correction amount γ7°1 is determined using the following equation 〇 using g. On the other hand, when X≦XO, it is determined that the knock suppression process has ended, and the current MBT correction amount T7°8 is determined in accordance with the following equation (0) in P33. TIIIW=γ. 3. −Δγ1 ・・・・・・■
γnew = Tota +ΔT2 ・・・・・・■
However, ΔT>Δγ, where Δγ1 and ΔT2 are values set in advance through experiments or the like. Next, in P34, the MBT correction amount γ is set to the advance angle limit value (for example, +10") and the retard angle limit value (for example, -
If it is not within this range, the current γ is limited to one of the respective limit values, and if it is within this range, that value is adopted as γ. In this way, in the second embodiment, the MBT correction amount γ is corrected according to the knocking level data X during the knock suppression process, so that the MBT correction amount approaches the upward target value K. Therefore, the speed of convergence to the target value when the MBT control amount is restarted can be further accelerated. FIG. 13 is a diagram showing a third embodiment of the present invention. This figure is a flowchart showing a program for correcting the MBT correction amount during the knock suppression process. Although this program is omitted in the main routine shown in FIG.
This is a subroutine that is executed when ≠00. First, P4
In step 1, it is determined whether or not the knock correction amount β is decreasing, and if it is decreasing, it is determined that the retard angle correction is in progress, and in step P4□, the current MBT correction amount γ is determined according to the following equation (■). On the other hand, if it is increasing, it is determined that the advance angle is being corrected, and the current MBT correction amount γ is determined at Pd2 according to the following equation (2). r 11ew thousand T0,4-Δγ1 ・・・・・・■γ
7.1=γ. , 4+Δγ2 ・・・・・・■ However, Δ
γ1>ΔT2 Here, Δγ and Δγ2 are values set in advance through experiments or the like. Next, in p4n, the MBT correction amount upper angle limit value (for example, +10°) and the retard angle limit value (for example, -
If it is not within this range, the current γ is limited to one of the respective limit values, and if it is within this range, that value is adopted as γ. In this way, in the third embodiment, the MBT correction amount is increased during the knock suppression process according to the aspect of the knock suppression control, and this value is used for setting the ignition timing during the knock suppression process, so that the knock correction speed is increased. speeds up, and the suppression of non-king ends in a shorter time. (Effects) According to the present invention, when transitioning to knock control processing, the MBT correction amount immediately before transition is held (or this is varied according to the knock situation), and after knock suppression ends, MBT control is performed based on this retained value. Therefore, the response speed of MBT control at the time of recovery after knock suppression can be increased, and engine drivability can be improved.

[Brief explanation of the drawing]

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, FIG. 2 is an overall configuration diagram thereof, and FIG. Figure 4 is a diagram showing the configuration of the knocking detection circuit, Figure 4 is a diagram showing the operation of the knocking detection circuit in Figure 3, Figure 5 is a flowchart showing the ignition timing control program, and Figure 6 is the basic ignition timing control. A diagram showing an example of a table map, FIG. 7 is a timing chart showing the action 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 a diagram showing the MBT. FIG. 10 is a timing chart showing the operation of detecting the maximum cylinder pressure timing θp+*ax;
FIG. 11 is a timing chart showing the action of the ignition timing control, and FIG. 12 is a flowchart showing a subroutine for outputting the MBT correction amount, showing a second embodiment of the ignition timing control device for an internal combustion engine according to the present invention. FIG. 13 is a flowchart showing a subroutine for calculating the MBT correction amount γ, showing a third embodiment of the ignition timing control device for an internal combustion engine according to the present invention. 1... Operating state detection means, 6... Control unit (maximum timing detection means, first calculation means, second calculation means, ignition timing setting means), 7... Knock detection means, 8... Pressure sensor (pressure detection means), 25...
...Ignition means.

Claims (1)

[Scope of Claims] a) Knock detection means for detecting knocking occurring in the engine; b) Pressure detection means for detecting the cylinder pressure of the engine; c) Operating state detection means for detecting the operating state of the engine. d) a first calculation means for calculating a knock correction amount for correcting the ignition timing to suppress knocking based on the output of the knock detection means; and e) a first calculation means for calculating a knock correction amount for correcting the ignition timing to suppress knocking based on the output of the pressure detection means; f) a maximum timing detection means for detecting a crank angle at which the cylinder pressure is maximum as the timing of maximum cylinder pressure;
A second calculating means that calculates the correction amount and, when moving to knock suppression processing, holds the value of the MBT correction amount immediately before this transition, or changes the held value according to a change in the knock correction amount or a knocking level. and g) Setting the basic ignition timing based on the operating state of the engine, correcting it according to the knock correction amount and the MBT correction amount, and setting the MB when the knock suppression process is completed.
An internal combustion engine characterized by comprising: ignition timing setting means for starting MBT correction processing based on the held value of the T correction amount; and h) ignition means for igniting the air-fuel mixture based on the output of the ignition timing setting means. Engine ignition timing control device.