JPS60243368A - Ignition timing control device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To permit to detect knocking surely by a method wherein a reference signal upon diciding knocking is fixed to a specified value and the spark advance angle of a specified cylinder is advanced gradually with a specified timing to control the ignition timing to the lag angle side in accordance with the output of a knock deciding circuit. CONSTITUTION:The output signal of a knock detecting circuit 102 is inputted into a counter 104 and a comparater 109 while the counter 104 counts the output of the detecting circuit 102 of the specified cylinder, whose spark advance is advanced gradually. Generation of knocking is decided by comparing the value of previous count and the count value of this time in a comparator 107 while the reference signal of respective cylinders of a reference signal unit 108 are corrected upon deciding knocking. The comparator 109 compares the input signal thereof with the reference signal to output an ignition timing delaying signal upon generating knocking. According to this method, the knocking may be detected in any circumstance temperature surely and the engine may be restored correctly to the condition of the engine before generating the knocking.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to an ignition timing control device that corrects ignition timing to suppress knocking.

[Background of the invention]

Conventionally, methods such as lean mixture combustion and intake air supplementation have been implemented as measures to improve the fuel economy of automobiles or increase the output per unit volume.

However, the engine condition under these conditions tends to cause knocking, which may lead to adverse effects such as deterioration of driving performance, reduction of engine output, and even overheating.
It may also cause damage to the engine itself.

Therefore, an ignition timing control device has been put into practical use that electrically detects vibrations when knocking occurs using a noise control device, and uses this electrical signal to correct the ignition timing to the state before knocking occurs. Since the knock sensor output signal is half-wave rectified and detects whether or not knocking is occurring based on changes in the average value of vibration components, if the above average value increases fixedly for some reason, knocking is detected. There was a problem that it became impossible to detect.

As a measure for this purpose, as proposed in Japanese Patent Application No. 55-110999, there is a circuit configuration in which the amplification factor of the knocking signal amplifier is automatically controlled (hereinafter referred to as AGC controller). However, this configuration has the problem that the knocking detection sensitivity fluctuates depending on the environmental temperature, making it impossible to reliably detect knocking.

[Purpose of the invention]

An object of the present invention is to provide an ignition timing control device for an internal combustion engine that can reliably detect knocking under any environmental temperature and restore the engine state to the state before the knocking occurred.

[Summary of the invention]

The present invention provides the comparison signal as a predetermined value among the two signals input to the knock detection circuit, the knock signal and the comparison signal, through a DA converter, and adjusts the number of output pulses of the knock detection circuit in all engine ranges. The reference signal of the knock determination circuit is configured to be a specific value and to easily modify the reference signal of the knock determination circuit.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a conceptual diagram showing the gist of the invention, and shows the case where the number of pulses is used as a reference signal for knock detection.

In FIG. 1, lO3 is a function configured by software rewritten as a node, and includes a counter 104,
A counter 105 that holds the previous count value, a counter 106 that stores the current count value, a comparator 107 that compares the previous count value and the current count value, and a comparator 1
The comparator 109 is composed of a reference signal section 108 which inputs the output signal of 07 as a memory correction signal, and a comparator 109 which compares the signal of the detection circuit 102 and the signal of the reference signal 108.
outputs an ignition timing retard signal when knock occurs.

The output of the detection circuit 102 is sent to a counter 104 and a comparator 10.
9 is input. The other input of the ratio softener 109 is given a reference signal from the reference signal section 108, and the reference signal for each cylinder (in the case of 4 cylinders in the example of the first cause) and the output signal of the detection circuit 102 are A comparison is made, and an ignition timing retard signal is output when knock occurs. On the other hand, the counter 104 advances the angle of a specific cylinder and counts the signal from the detection circuit 102 of the cylinder that has been advanced. ) and compares the previous count value with the current count value to determine whether the specific cylinder that has been advanced is knocking, and if the current count value increases rapidly compared to the previous count value, It is determined that a knock has occurred in a specific cylinder whose angle has been advanced, and the reference signal (knock detection pulse number) of each cylinder in the reference signal section 108 is corrected. That is, the reference signal of the reference signal unit 1080 is rewritten by the count value of the specific cylinder that has been advanced.

FIG. 2 shows a specific configuration of an ignition timing control section of an internal combustion engine control device to which the present invention is applied. A central processing unit (hereinafter referred to as CPU) 12 performs digital calculation processing of various data including ignition timing of the internal combustion engine. El
, 0M14 store ignition timing control and other control programs and fixed data. The AM16 is a memory element that can be read and written. The backup RAM 17 retains memory even when the internal combustion engine is stopped.
It is AM. The CPU 12fi receives signals from various sensors (in this embodiment, a knocking detection device 30, a crank angle sensor 40, and a load sensor 50 are used) through the human output interface circuit 20, and based on these signals, outputs the signals to the LOM 14. It calculates the ignition timing according to the stored program and outputs the ignition signal IGN through 20 input/output interface circuits. Ignition signal IGN is amplifier 7
2 to the base of power transistor 740 to drive power transistor 74. By shutting off the power transistor 74, an ignition current is generated in the secondary coil of the ignition coil 76.

FIG. 3 shows a specific configuration of a portion of the input/output interface circuit 20 that contributes to ignition timing control. A position pulse signal (denoted as POS) from crank angle sensor 40 is applied to AND circuits 216 and 220. Further, the reference crank angle signal (R
EF) is applied to the reset terminal of the first counter register 210 and the I(, S flip-flop 2180 cent terminal.
8, the POS starts counting based on the rising of the EF and outputs the counted value to the comparator 206. The comparator 206 outputs the count value of the first counter register and the ignition timing data θ1. calculated by the CPU 12 and stored in the advance register 202. When the two match, a set pulse is output to the S7 flip-flop 214 and the RS flip-flop 218 is reset. When the set pulse is input to the RS control flop 214, the output is cut off, the power transistor 74 of the ignition system is cut off, and a radiation current is output to the secondary coil of the ignition coil 76.

Next, the timing of starting energization of the ignition coil will be explained. Second
The counter register 212 starts counting the position pulse PO8 via the AND circuit 220, and outputs the counted value to the comparator 208. . In the comparator 208,
This counting value is compared with the value calculated by the tcPU 12 and stored in the dwell register 204, and when the two match, a reset pulse is output to the S flip-flop 214 and the RS flip-flop 222 is reset. The S flip-flop 214 generates an output at the sub-terminal based on the reset pulse, turns on the power transistor 74k, and starts energizing the primary coil of the ignition coil 76.

Next, the introduction of the knocking signal KNCKP into the CPU 12 will be explained.

The output pulses KNCKP of the knocking detection device 30 are input to a counter register 234, and the number of KNCKPs is counted in proportion to the intensity of the knocking that has occurred. The CPU 12 is interrupted at the end of this counting, and the count value of the counter register 234 is taken into the CPU 12 via the bus 18, and at the same time, the count value of the counter register 234 is cleared by the reset register 238. Prepare for the next knocking occurrence.

The number of pulses NP input into the CPU 12 is data corresponding to the intensity of knocking, and is used for increasing the ignition timing correction amount.

FIG. 4 is a timing chart showing the operation of the circuit shown in FIG. 2 described above. In the figure, AH reference crank angle signal and B are position pulse signals. C indicates the counting status of the tenth counter register 210, and C1 is the setting value of the advance register 202. D indicates an output signal of the comparator 206, and indicates that an output is generated when the count value of the first counter register 210 reaches the set value of the advance register 202.

E indicates the counting status of the second counter register 212, and El is the set value of the dwell register 204. F is the output of comparator 208 and operates similarly to comparator 206. G is the comparator 206, 208
, that is, the Q output of the RS flip-flop 214 responsive to D and F. H indicates the current flowing through the ignition coil 66 in response to the Q output, and ■ indicates the ignition timing.

Next, FIG. 5 shows a block diagram of a knocking detection device 30 that responds to the occurrence of knocking and generates NCKP in a number of pulses depending on the intensity of the knocking. In the figure, a knocking sensor 401 is constituted by a piezoelectric element and converts a knocking motion of an engine cylinder into an electrical signal.

The output signal VIN of the knocking sensor 401 is input to a bandpass filter 403 via an input processing circuit 402. This bandpass filter 403 is provided to remove parasitic engine vibrations and efficiently extract the knocking signal, and its bandwidth is selected to match the frequency of the knocking signal. Band pass filter 40
The knocking signal that has passed through 3 is divided into two systems, one system can be input to the comparator 409 as a knock signal, and the remaining one system is half-wave rectified by a half-wave rectifier circuit 404, and further smoothed by a smoothing circuit 406. Rear input/output circuit (hereinafter referred to as l10) 4
10. On the other hand, a comparison signal for comparison with the knock signal is input from the l10410 to the comparator 409 through the D/A converter 412. In Hishuki 409 i)
The signal from the /A converter 404 and the knock signal from the bandpass filter 403 are compared, and a knock pulse is output to l10410.

FIG. 6 shows signal waveforms of each part in the block diagram shown in FIG. In FIG. 6, (1) is the output of the knocking sensor 401, (2) is the output of the input processing circuit 402, and (3) i, J are the output waveforms of the bandpass filter 403. /4'& exchanger 412
By comparing the output signals of , a knock pulse signal KNCP as shown in (6) is obtained. The bandpass filter output signal (3) is half-wave rectified to have the waveform (4), and after being further smoothed, it becomes the waveform (5), which is input to the l10410.

FIG. 7 shows the general flow of the ignition timing control device according to the second embodiment. In FIG. 7, interrupt request 6
When 00 occurs, the next step 602 is an interrupt request analysis process in which it is determined whether it is a knock (KNOCK), a reference (REB'), or a timer interrupt. If it is a timer interrupt (TIME interrupt), according to the instructions of the task scheduler 60'4, AD conversion of the input signal, input of the engine speed 606, calculation of ignition timing and energization time 608, digital input signal processing 610, and , correction processing 612.

Further, if the result of the interrupt request analysis process in step 602 is that the interrupt request is due to the occurrence of a knock, a knock signal processing routine is executed in step 615.

This knock signal processing routine is shown in detail in FIG. In FIG. 10, first in step 901, the content Np of the counter register 234 is fetched, and the number of pulses Np fetched at this time is calculated in step 901.
It is compared with the set pulse number NB at 02. As a result, if the value is greater than or equal to the set value (NP≧Ns), the process proceeds to step 903.
Conversely, if it is less than the set value (Np (Ns), step 904
Then, in steps 903 and 904, the pupil of Δθ is set.

Here, Np(I) and Ns(I) in step 902 are
It represents the intake pulse of the first cylinder and the setting pulse of the first cylinder.

Next, in step 905, the captured pulse Np(I
) is a pulse of a specific cylinder that is being advanced, and if it is a pulse of a specific cylinder, the process proceeds to step 907-\. In step 907, the number of pulses for the advanced cylinder is compared with the previous number of pulses for that cylinder. As a result of the comparison, if the number of pulses has increased rapidly, knocking has occurred in the advanced cylinder, and the difference ΔNs (increased number of pulses) between the number of pulses compared last time and this time is calculated in step 908. After calculating, in step 909, a knock pulse flag is set to report that knock has occurred in the specific cylinder in which the knock has been advanced.

On the other hand, if the result of the determination in step 602 in FIG. 7 is that the interrupt request is due to a reference signal, a rotation synchronization processing routine is executed in step 616.

In the routine of step 616, ignition timing data for one specific cylinder advance is set. In other words, θadw is added to the ignition timing θ(N, P) determined by the engine speed N and the engine load Tp. (Step 808 in FIG. 9).

FIG. 8 is a flowchart showing the ignition timing control routine. First, in step 701, the engine speed N
and the normal ignition timing θ (N, Tp) depending on the load Tp
is calculated. Next, in step 702, it is determined whether knock control is being performed. 1. If knock control is in progress. In step 703, knock correction (θ11←θ(N, Tp)+
θIN).

θKN was determined in step 903.

However, if knock control is not in progress, it is determined in step 704 whether the mode is for checking knock detection sensitivity. If it is in the check mode, the ignition timing of a specific cylinder can be gradually advanced in step 706 to cause a knock. When a knock occurs, the number of knock detection pulses increases rapidly. The knock detection pulses of other cylinders are corrected based on the number of pulses when knock occurs.

On the other hand, if it is not the check mode in step 704, the advance angle control for the specific cylinder is canceled and the number of knock detection pulses for each cylinder is not corrected.

Next, steps 704, 705, and 706 will be explained using FIG. If knock control is not in progress, it is determined in step 801 whether the operating state of the engine has suddenly changed. If it has changed, the check mode is canceled in step 811, the advance angle correction for knock occurrence of the specific cylinder is canceled in step 812, and the number of knock detection pulses for each cylinder, which determines the knock detection sensitivity, is not corrected in step 813. Set the previous one. On the other hand, if the engine condition has not suddenly changed, the process advances to step 802. Incidentally, the change in the operating state in step 801 is detected by signals from the load sensor 50 and load switch 80 shown in FIG.

In step 802, it is determined whether the mode is a check mode in which a specific cylinder is advanced. If it is not the check mode, the process proceeds to step 809 and it is determined whether the ignition timing of the advanced cylinder is the normal ignition timing θB20 (N, T?). If θB\θ(N, Tp), the specific cylinder that has been advanced has advanced, and the knock occurrence advance correction is canceled in step 812. In step 809, θB−〇(
N.

Tp), the specific cylinder is not advanced (
All cylinders are at the same ignition timing), and check mode is turned on to correct knock detection sensitivity.

If it is check mode in step 802, step 80
Proceed to step 3.

In step 803, the current engine speed N and load Tp are
It is determined whether or not to advance a specific cylinder. The advance angle determination rotation speed Nw and the advance angle determination load TP company in step 803 are specific values in this embodiment, but it is also possible to search using a map.

In step 803, engine speed N, load T, and Nw,
If Tw is not satisfied, the process proceeds to step 813 because control for modifying the knock detection sensitivity cannot be performed. Step 803
i. For example, the knock detection sensitivity is not modified in the idle state. In step 803, engine rotation speed N≧Nw.

If the load Tp≧Tpw is satisfied, the process advances to step 804 and a knock pulse is read. In step 804, the number of pulses for all cylinders before the advance angle in step 808 is stored. In step 805, it is determined whether the number of detected knock pulses has increased rapidly (i.e.,
A flag is used to determine whether or not a knock has occurred. In this case, the flag is set in step 9o9, and the flag is cleared in step 910. If the knock pulse flag is not 1'', no knock has occurred, so the ignition timing of the specific cylinder is gradually advanced, and θ8=θ(N, T
p) +θ mountain. Incidentally, the θ mountain is a specific value in this embodiment, but the engine rotation speed N1 engine load Tp
It is also possible to search for the value of the map. It can also be expressed as θadv−θadv(N, Tp).

On the other hand, if the knock pulse flag is "1" in step 805 (that is, when a knock occurs), the number of knock pulses in step 908 is corrected to the number of knock pulses for each cylinder (the number of knock pulses read in step 804). The corrected number of knock pulses is set as the number of knock detection pulses.This means that the knock pulse correction has been performed in step 806.

In step 807, since the knock pulse has been corrected, the check mode is turned off.

Next, the process of knock detection will be explained using FIG. 11 and FIG. 12. FIG. 11 (1) shows the cylinders, and the number (2) shows the number of cylinders. In other words, 1 is the first cylinder and 3 is the third cylinder.
Shows the cylinder. In this example, a specific cylinder is advanced; however,
FIG. 11 shows the case of a four-cylinder engine in which only the first cylinder is advanced.

11 and 13CDE represent the state before the first cylinder advance.

In other words, the numbers in Figure 11 (4) represent the number of knock pulses before the advance (knock does not occur); 4 in the 1st cylinder, 5 in the 3rd cylinder, and 3 in the 4th cylinder. Two shots were detected in the second cylinder. Details of the portion surrounded by the dashed line A in FIG. 11(3) and the number of pulses are shown in FIG. 11(5).

This number of pulses for each cylinder is read in step 804.

No knocking occurs in this state.

However, as shown in FIG. 12, if the difference between the previous count value (4 in the example) and the current count value (9 in the example) is large, it is determined that knock has occurred in the first cylinder.

Then, the difference between the number of pulses shown by ■ in Figure 12 (2) before the advance angle and the Norls number shown by [F] after the advance angle (in this example, 5
) becomes a correction signal for the knock detection noise, and the knock detection noise (number) of each cylinder is rewritten. Note that FIG. 12 (3) shows the output waveform of the DA converter.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the number of output pulses of the knock detection circuit becomes a specific value, and the reference number of pulses of the knock detection circuit can be easily corrected by advancing a specific cylinder. Even under certain conditions, knocking can be reliably detected and the ignition timing can be corrected to before the knocking occurs.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram showing the gist of the present invention, Fig. 2 is a specific configuration diagram of an ignition timing control section of an internal combustion engine to which the present invention is applied, and Fig. 3 is an input/output interface of the embodiment shown in Fig. 2. 4 is a timing chart showing the operation of the circuit in FIG. 3, FIG. 5 is a block diagram of the knocking detection device, and FIG. 6 is a block diagram of the block diagram in FIG. 5. Signal waveform diagrams of each part, Figure 7 is a general flowchart of ignition timing control, Figure 8 is a flowchart of the ignition timing control routine, Figure 9 is a flowchart showing the knock generation correction advance angle execution routine, Figure 10 is the knock occurrence correction advance angle execution routine. FIG. 11 and FIG. 12 are waveform diagrams for explaining the knock detection pulse number correction operation. 101...Sensor, 102...Detection circuit 1.104
~106...Counter, 107-109...Comparator, 108...Reference signal section, 30...Knocking control device, 401...Knocking sensor, 404...Half wave rectifier circuit 3 1? ↓Sumo 4 figure (8) REF ([3) PO5” For Tomoko J
1 for mutual use (1) The period of divination is also Caotu IRQ, 8 figures, light 9 figures, tank 10 figures TI, 11 figures rate, 121 bad eight BcDEF, 4 na'l-44Q

Claims (1)

[Claims] 1. Completely equipped with a knock sensor that detects vibrations when knocking occurs, and a knock judgment circuit that compares the output signal of this knock sensor with a reference signal and controls the ignition timing to be retarded according to the comparison result. 2 for ignition timing control device of internal combustion engine
The internal combustion engine is characterized in that the reference signal is fixed at a specific value, and the ignition timing is controlled to the retarded side in accordance with the output of the knock determination circuit by gradually advancing the ignition timing of a specific cylinder at a specific timing. Engine ignition timing control device.