JPS63159665A - Ignition timing controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve controllability and fuel consumption by holding MBT (minimum angular advance in maximum torque) correction amount immediately before shift to knock restraining process and starting MBT control when the period of maximum pressure in cylinder is smaller than a desired MBT control position even in restraining the knock. CONSTITUTION:A first calculating means d for calculating knock correction amount on the basis of the output of a knock detecting means a and a maximum period detecting means e for detecting a crank angle as that of maximum period in cylinder which has the maximum pressure detected by a pressure detecting means b in the cylinder of engine are provided. A second calculating means f calculates MBT correction amount on the basis of the output of the detecting means e, while holding a value of MBT correction amount immediately before shift to knock restraining process. And a basic ignition timing set by an ignition timing setting means g on the basis of the output of a running condition detecting means c is corrected according to both correction amounts to start MBT correction process when the maximum pressure period in the cylinder is smaller than a desired position even in restraining the knock.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention suppresses non-king in an automobile internal ring combustion engine while achieving M B T @! The present invention relates to an ignition timing control device for an internal combustion engine that improves drivability by performing I control. (Prior Art) In general, when considering the efficiency and fuel consumption of an engine, the minimum advance angle at maximum torque, so-called M B T (Minimum advance
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, knocking is detected by passing the in-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 with priority over MBT control. . Once knocking is suppressed, MBT control is applied to the ignition timing again to maximize engine torque. This is intended to suppress knocking while increasing the torque generated by the engine as much as possible, thereby improving driving performance. (Problems to be Solved by the Invention) However, in such a conventional ignition timing control device for an internal combustion engine, once knock suppression control is entered, the ignition timing of the MBT is changed, for example, in the latter half of the knock suppression control. However, even if the angle was retarded to the extent that knock would not occur, knock suppression control was given priority over MBT control during the knock suppression period, so the transition to MBT control was always due to knock control. This resulted in a decrease in responsiveness after the end of inhibitory control. Also, during the knock suppression period, MB
Since T control was not performed, it was not possible to improve fuel efficiency or power performance during this period. In addition to the above-mentioned problems, in conventional devices, M
There was a problem that the correction speed of the BTIII control was slow. In other words, in general, non-king avoidance control completely reduces the knock level.

Instead of setting it to [0], the control target is set near the critical trace knock where non-king occurs. This is because advancing the engine angle as much as possible while the knocking level is within a predetermined value contributes to improved output. In this case, from the point of view of the accuracy of knock control, a state in which about 10% of the detected knock data exceeds a predetermined value (hereinafter referred to as the knock suppression criterion) near the trace knock that is the control target is This condition is considered preferable and serves as a criterion for determining whether or not to suppress knocking (whether to retard the ignition timing). Therefore, when the detected non-king data exceeds the knock suppression criterion, the ignition timing is retarded, and when it falls below the knock suppression criterion, the MBT control is started. This means that among the actually detected knocking data, 1/10 of the knocking data exceeds the 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 knocking level is significantly lower after knocking has been suppressed, the ignition timing is subjected to 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 improved 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. (Objective of the Invention) Therefore, the present invention maintains the MBT correction amount immediately before the transition when transitioning to knock suppression processing, and even during knock suppression when the cylinder pressure maximum timing is smaller than the target position of MBT control. By starting MBT control, the response speed of MBT control at the time of recovery after knock suppression is increased, and MBT control is increased as much as possible without causing knock.
The purpose of this control is to improve engine drivability and fuel efficiency. (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 non-king 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 non-king 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. a maximum timing detection means e for detecting the angle as the maximum cylinder pressure timing, and calculating M and BT correction amounts for correcting the ignition timing so that the maximum cylinder pressure timing coincides with a target position where the generated torque of the engine is maximized; When transitioning to knock suppression processing, the MBTB immediately before this transition
A second calculation means f that holds the T correction amount and sets the basic ignition timing based on the operating state of the engine, corrects this according to the knock correction amount and the MBTBT correction amount, and also sets the basic ignition timing according to the knock correction amount and the MBTBT correction amount. The engine also includes ignition timing setting means g that starts MBT correction processing when the maximum cylinder pressure timing becomes smaller than the target position, and ignition means g that ignites the air-fuel mixture based on the output of the ignition timing setting means g. . (Function) In the present invention, when transitioning to knock suppression processing, the MBTBT correction amount immediately before transition is retained, and even during knock suppression, when the cylinder pressure maximum timing is smaller than the target position of MBT control, MBT control is performed. is started. Therefore, the response speed of the MBT*J control at the time of recovery after knock suppression is increased, and MBT control is performed as much as possible within a range that does not cause knocking, improving engine drivability and fuel efficiency. (Example) Hereinafter, the present invention will be explained based on the drawings. 2 to 11 are diagrams showing an 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 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 measures the explosion interval (120" crank angle for a 6-cylinder engine, 180" for a 4-cylinder engine).
Each time outputs the predetermined position in front of each cylinder compression point (TDC), for example, BTDC 70 ° (H) level pulse pulse, and the unit angle of the crank angle (for example, 2 °). A unit signal PO8, which becomes a (H) level pulse, is output every time. 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-i. 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 manually inputted to the 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 is output to the control unit 6 and the knocking 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 lO is the pressure signal Pa
(See Figure 4 (a)). It is clear that the high frequency component Pa' (
(See Figure 4 (b)).
The waveform shaping circuit 11 half-wave rectifies the high-frequency component Pa' and forms an envelope signal (envelope detection) from the half-wave rectified signal to generate a non-converting signal as shown in FIG. Knocking signal SN according to king level
It is output to the control unit 6 as . In addition, in this non-king 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 above-mentioned envelope (l) may be output as the non-king signal SN.Again. In FIG. 2, the control unit 6 has functions as a maximum timing detection means, a first calculation means, a second calculation means, and an ignition timing setting means, and includes a CPU 21, a ROM
22, a RAM 23, and an input/output control circuit 24 having built-in input/output interfaces, registers, counters, A/D converters, high frequency cut filters, and the like. CPU U21 is ROM2
It takes in necessary external data from the input/output control circuit 24 according to the program written in the RAM 23, and generates processing values necessary for knock avoidance control and MBTIJ control while exchanging data with the RAM 23. Arithmetic processing is performed and the processed data is sent to the input/output control circuit 2 as necessary.
Output to 4. Signals from the operating state detection means 1, pressure sensor 8, and knocking detection circuit 9 are input to the input/output control circuit 24, 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 26f, an ignition coil 27,
It is composed of a power supply 28, a distributor 29, and a power transistor Q. The ignition means 25 is a power transistor Q based on the ignition signal Sp. is ON/OFF 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 plug 26.
~26f to ignite 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. The value of these registers is compared with the count value of the position signal PO8, and when they match, the power transistor Q is turned on or off. 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 SN is A/D converted and stored in the RAM 23 as data X corresponding to the knocking level. Next, the non-king level data X stored in the RAM 23 in P2 is compared with a predetermined reference value XO, for example, a value that the knocking level detected during trace knocking exceeds at a frequency of about 10% to determine whether non-king has occurred. ,
Depending on the result of this determination, the knock correction amount β is determined using an arithmetic expression described later (see subroutine 5UB-1 in FIG. 8). P, the knock correction amount β is the advance angle limit value (0 in this example).
”), and when β = 0, MBT control is performed, so the MBT correction amount γ is determined by the calculation formula described later in P4 (see subroutine 5UB-2 in Fig. 9). Also, β≠ When it is O, it is determined that knock suppression control is in progress, and in P4, the cylinder pressure maximum timing θpmax at this time is compared with the target position of MBT control.Here, K is the target position of MBT control, and the engine The crank angle that maximizes the generated torque is set to a predetermined value, for example, in the range of ATDC 10° to 20'.When θpmax≦, the ignition timing is also corrected to the retarded side by MBT control, so knock suppression is achieved. It is determined that executing MBT control even during control is effective in terms of knock avoidance, and proceeds to step P to calculate the MBT correction amount for performing MBT control. On the other hand, θp
When max>K, if correction is performed using MBT control, the ignition timing will be corrected to the advanced side, so it is determined that processes other than knock suppression control may cause knocking, so MBT control is not performed and Ps is jumped. Then proceed to P6. Therefore, when the knock suppression control is in progress and θpmax > K, the original MBTIII? II has been canceled, but at this time, as will be described later, the MBT correction amount is held at the value immediately before shifting to the wave check process. At P6, the basic ignition timing ADVφ corresponding to the current operating condition is looked up from a table map as shown in FIG. 6, and at P1, the basic ignition timing ADVφ is corrected by the knock correction amount β and the MBT correction amount. , determine the final ignition timing ADV according to the following formula (■). ADV=ADV φ + β + r ---
・'-・■Finally, based on this ADv at P8 (70-
ADV) is output to the register in the input/output control circuit 24 as an ignition signal Sp 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 formed as follows and is output to the power transistor Q of the ignition means 25. That is, in the human 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 pos is input, the counter value is counted at the rise and fall of the unit angle signal pos. It's getting more and more popular. 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 Ql 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, which corresponds to step P2 described in FIG. 5 above. First, the non-king level and level data X of the pH is compared with the reference value Xo. When X>XO, it is determined that non-king has occurred and the ignition timing is retarded, so the current knock correction amount β7°8 is determined at Ptt according to the following equation (2). β, , w=β. , d-1° ・・・・・・■ However,
β. , 4 ; Previous value On the other hand, when X≦Xo, it is determined that non-king has been suppressed and the ignition timing is advanced, so β7°1 is determined in accordance with the following equation (2) at Pl3. β7゜0 = 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 units of 1゛CA, and the advance angle correction is performed more gently by 0.1'
This is done on a CA-by-CA basis. Next, at Pl4, the knock correction amount β
is the advance angle limit value [0°] and the retard angle limit value (for example, -10°).
), and if it is not within this range, the current β is limited to one of the respective limit values, and if it is within this range, that value is adopted as β. FIG. 9 is a flowchart showing a subroutine for MBT control, which corresponds to step P described in FIG. 5 above. First, in PZI, according to formula 0, the current MBT correction γ7
Find ゜1. However, γ. (4: Previous value M: To a constant greater than or equal to 1: Target position. Then, at Ptt, the MBT correction amount is regulated by the wave angle limit value (e.g. +10°) and the retardation limit value (e.g. -10°) Check whether it is within the range, and if it is not within this range, limit the current γ to one of the limit values, and if it is within this range, use that value as γ.In this way,
The MBT correction correction amount is calculated within a range of 10 degrees around the target position K, and so-called feedback control to follow the target is performed. Here, the maximum cylinder pressure timing θpmax is calculated as follows. The pressure signal Pa based on the pressure sensor 5 shown in FIG. P is A/D converted at the timing of the unit angle signal PoS. On the other hand, the unit angle signal PO3 (
(see (c) in the figure) is counted, and this counter is cleared every 360 counts by the cylinder discrimination signal REF-i (see (d) in the same figure). First, a certain interval in which the counter counts 60, for example 60 to 120.
The maximum value of the A/D converted pressure signal P is detected in the interval, and from this detected value, the lower limit value of a certain interval, for example 6
Let the value from which 0 is subtracted be α. Next, θ' pmax is calculated according to the following formula 〇, and the remaining 2 data after removing the maximum and minimum 2 data from the 4 latest data
The average value α obtained by averaging the data is detected as the crank angle θpmax with respect to the top dead center at the time of maximum cylinder pressure. θ' pmax=2α-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, and for example, θpmax detected at Tn is used to calculate the MBT correction amount T at the next 'ryt-+. The same holds true for the relationship between the knocking level data X and the knocking 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) and knock control is not performed, and based on the detection information of θpmax, M B T ? Feedback correction of ti control is performed (see section A), which causes θpma
Convergence control is performed so that x coincides with the target position. Note that the feedback correction at this time is performed within a range of +10° centered on the target position K, and the correction speed is 0.1°.
/ ignition, and this speed is the same as before. On the other hand, when the knocking level data X exceeds the reference value XO in section A, it is determined that non-king 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. Even during the knock suppression processing section, when the cylinder pressure maximum timing θpmax is less than the target position of MBT control (that is, when θρmax becomes smaller than K), M
BT control is immediately resumed (see section C). At this time, focusing on the MBT correction amount T, since the MBT control is temporarily stopped when the knock suppression process is in progress and θpmax > K, the MBT correction amount based on the sensor information of θpmax is
Calculation of the correction amount is not performed, and this point is the same as in the prior art. 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 position 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 position 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 the section date, and this held state remains until the end of section B or the start of section C. Continued. Additionally, since γ is not 0 from the end of section A to the start of section C, there is an MBT correction amount, but this value is not based on the θpmax detection information at that time, but is based on the target position. This means that it exists as a value that converges near . Then, the next time MBT control is restarted, the ignition timing is corrected based on this hold value γ. Since the MBT correction amount γ at the time of restart is a value converged near the target position, θpmax is immediately corrected to match the target position K regardless of the return from the interruption of MBT control. Therefore, M is significantly lower than before.
The responsiveness of BT control can be improved. That is, M
It is possible to increase the speed of convergence to the target position when BT control is restarted. In this way, in this embodiment, when the knock suppression process is shifted to, the MBT correction amount immediately before the shift is held, and even during knock suppression, when the cylinder pressure maximum timing is smaller than the target position of MBT control, the MBT correction amount is maintained. MBT control is started. Therefore, MBT as much as possible without causing knocking.
MBT at the time of return after knock suppression while realizing control
By increasing control response speed, fuel efficiency and power performance can be further improved. In this embodiment, an example is shown in which the present invention is applied to a mode in which the MBT correction amount is reduced in order to increase the response speed at the time of recovery after knock suppression, but of course the present invention is not limited to this. It goes without saying that the present invention can also be applied to devices that do not hold the MBT correction amount like conventional devices. (Effects) According to the present invention, when transitioning to knock control processing, the MBT correction amount immediately before transition is held, and even during knock suppression, when the cylinder pressure maximum timing is smaller than the target position of MBT control, MBT Since the control has been started, the response speed of the MBTitIIJ control at the time of recovery after knock suppression can be increased, and the MBT control can be performed as much as possible within the range that does not cause knock to improve engine drivability and fuel efficiency.

[Brief explanation of the drawing]

FIG. 1 is a basic conceptual diagram of the present invention, FIGS. 2 to 11 are diagrams showing an 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. is a block 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 flowchart showing the ignition timing control program, and FIG. 6 is a table of the basic ignition timing. A diagram showing an example of the 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 the subroutine for calculating the knock correction amount β, and FIG. 9 is the MBT correction. Figure 10 shows the subroutine for discharging the corrected amount of water, and the maximum cylinder pressure timing θ
Timing chart showing the effect of pmax detection, 1st
FIG. 1 is a timing chart showing the effect of the ignition timing control. l... 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) an MBT that corrects the ignition timing so that the maximum cylinder pressure timing coincides with a target position at which the engine generates the maximum torque;
After calculating the correction amount and transitioning to the knock suppression process, a second calculation means holds the value of the MBT correction amount immediately before this transition; ignition timing setting means that corrects according to the knock correction amount and MBT correction amount and starts MBT correction processing when the maximum cylinder pressure timing becomes smaller than the target position even during knock suppression processing; h) ignition timing setting means; An ignition timing control device for an internal combustion engine, comprising: ignition means for igniting an air-fuel mixture based on the output of the timing setting means.