JPS6172877A - Knocking controller - Google Patents

Abstract

PURPOSE:To perform knocking control in a proper manner, by delaying the ignition timing in time of detecting a knocking vibration and, when the knocking vibration fails to reduce even if the delay timing advance exceeds a comparative delay timing advance, regarding the cylinder in a combustion stroke as a noise cylinder. CONSTITUTION:There are provided with a knock vibration detecting device (b) inputting an output signal out of a knock sensor (a) and each of engine running state and crank angle detecting devices (d) and (c). A timing advance value is set according to a running state by a timing advance value setting device (e), and when a compensation signal to be mentioned later is inputted, the timing advance value is compensated to the delayed timing advance side according to a knocking vibration. And, in a cylinder discriminating device (f), in the case where a variation in the knocking vibration is below the specified value when the timing advance value is compensated to the delayed timing advance side as much as the comparative delay timing advance, the cylinder in a combustion stroke at that time is discriminated as a noise cylinder. And, when the cylinder in the combustion stroke is not the said noise cylinder, a compensation signal is emitted out of a compensation signal generating device (g) whereby an ignition signal is generated according to the compensated timing advance value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a knocking control device, and more particularly to a device that controls ignition timing to suppress knocking occurring in an engine.

(Prior technology) Knocking is mainly caused by compression ignition of unburned gas, and if it occurs violently, it can cause loss of energy (lower output), shock to various parts of the engine, and lower fuel efficiency, so it cannot be avoided. desirable.

Conventional devices to suppress such knocking include:
For example, there is a device using the "knocking detection device" described in Japanese Utility Model Application Publication No. 59-6734. This device uses a knock sensor attached to the engine body (cylinder block) to detect the vibration of the engine body, and analyzes this vibration component through a filter or by Fourier transformation to determine its frequency and amplitude. The occurrence of knocking is determined by When it is determined that knocking has occurred, the ignition timing is controlled (for example, delayed) in accordance with the intensity of knocking to suppress knocking.

However, such conventional knocking control devices are configured to analyze the frequency and vibration of the vibration component detected by the knock sensor to determine whether knocking has occurred, and if it is determined that knocking has occurred, delay the ignition timing. Therefore, mechanical vibrations caused by moving parts of the engine such as valves and pistons (this becomes mechanical noise).

Hereinafter, this will be abbreviated as mechanical noise.

) has the same frequency and amplitude as the vibration caused by knocking (which becomes a regular knocking signal. Hereinafter referred to as regular knocking), it is not possible to distinguish between the two, and the mechanical vibration is called knocking. It is considered as vibration due to In other words, mechanical noise is regarded as a regular knock.

If the ignition timing is controlled due to this erroneous determination that knocking has occurred, the ignition timing will be controlled to be more retarded than necessary even though there is no knocking, resulting in a decrease in output.
There has been a problem in that it causes deterioration in fuel efficiency, deterioration in exhaust composition, etc. (hereinafter referred to as deterioration in driving performance).

(Object of the Invention) Therefore, the present invention aims to delay the ignition timing up to the maximum retardation amount when a predetermined knocking vibration is detected, and to
If the knocking vibration does not reduce even if the retardation amount exceeds the comparative retardation amount, the cylinder in the combustion stroke is regarded as a noise cylinder and this is learned sequentially, and the next time the knocking vibration is detected, based on this learning result. By controlling the ignition timing, it is possible to accurately distinguish between mechanical noise and regular knocking, and to appropriately control the ignition timing to suppress knocking (avoiding excessive delays in ignition timing), thereby avoiding deterioration in driving performance. It is an object.

(Structure of the invention) FIG. 1 is an overall configuration diagram for clearly explaining the present invention.

Knock sensor a detects vibrations in the engine body,
The knock vibration detection means determines the output of the knock sensor a to detect a predetermined knock vibration. The operating state detection means d detects the operating state of the engine, and the advance angle value setting means e sets the advance angle value based on the operating state, and when a correction signal is input, the advance angle value is set to the knocking vibration. Correct the angle to the retard side up to the maximum retard amount according to the amount. On the other hand, the crank angle detection means C detects the crank angle of the engine, and the cylinder discrimination means f detects whether the change in knocking vibration is less than a predetermined value when the advance value is corrected to the retard side by the comparative retard amount. For example, the cylinder in the combustion stroke at that time is determined as a noise cylinder based on the crank angle of the engine, and this is learned and stored as corresponding to the operating state at that time. When a predetermined knocking vibration occurs, the correction signal generating means g reads a noise cylinder corresponding to the operating state at that time from the cylinder determining means f, and outputs the correction signal if this does not match the cylinder in the combustion stroke,
The ignition signal generating means outputs an ignition signal at a timing corresponding to the advance angle value determined by the advance angle value setting means e.

The ignition means i ignites the air-fuel mixture based on the ignition signal, thereby accurately distinguishing between mechanical noise and regular knock, and preventing the ignition timing from being delayed too much.

(Example) Hereinafter, the present invention will be explained based on the drawings.

2 to 5 are diagrams showing an embodiment of the present invention.

First, the configuration will be explained. In FIG. 2, reference numeral 1 denotes a four-cylinder engine, in which intake air is supplied from an air cleaner 2 to each cylinder through an intake pipe 3, and fuel is injected by an injector 4 based on an injection signal S+. Each cylinder is equipped with an ignition plug 5, and the ignition plug 5 receives a high-voltage pulse P from an ignition coil 7 via a distributor 6.
i is supplied. The spark plug 5, the distributor 6, and the ignition coil 7 constitute an ignition means 8 that ignites the air-fuel mixture, and the ignition means 8 generates and discharges a high-voltage pulse P1 based on the ignition signal Sp. Then, the air-fuel mixture in the cylinder is ignited and exploded by the discharge of the high-pressure pulse Pi, and is discharged through the exhaust pipe 9 as exhaust gas. The intake air flow rate Qa is detected by the air flow meter 10,
It is controlled by a throttle valve 11 in the intake pipe 3. engine 1
The vibration Ve of the main body is detected by a knock sensor 12, and the output of the knock sensor 12 is input to a knock vibration detection means 13. The knocking vibration detection means 13 compares the frequency and amplitude of the vibration Ve with predetermined reference values to detect a predetermined knocking vibration Vn. For example, a vibration Ve having a frequency of about 7 kHz and higher than a predetermined vibration level is detected as a knocking vibration Vn. Further, the crank angle (piston position) of the engine 1 is detected by a crank angle sensor (crank angle detecting means) 14, and the crank angle sensor 14 is built into the distributor 6 and has a predetermined rotor plate 15. As shown in Figure 3, the rotor plate eye 5 has each ring for reference signals and angle signals.
15a and 15b are formed, and their formation position is 1° on the outer periphery.
Four reference signal slits 15b are provided at intervals of 90° (distributor angle) inside the reference signal slits 15b.

Regarding the reference signal slits, the slit (#1) corresponding to the first cylinder is formed wider than the other slits and is used as a discrimination signal for the first cylinder. Note that this reference signal slit 15b is inserted at every 60° for a 6-cylinder engine, and at 45° for an 8-cylinder engine in the case of an engine other than 4 cylinders.
provided for each The crank angle sensor 4 transmits light from, for example, a light emitting diode through these slits 15a.
, 15b, and the light receiving diode receives this light and converts it into a voltage ON-OFF signal (pulse) and outputs it. Therefore, the crank angle sensor 4 outputs a reference signal Ci every 180 degrees of crank angle, and an angle signal C every 2 degrees.
, is output. The reference signal C1 is set to be output when each piston is at a position of 70° before compression top dead center (BTDC70°). This is because ignition timing control is performed at a timing before top dead center, and necessarily requires a reference signal before top dead center. Also, the reference signal C
By detecting the input timing and order of i, it is possible to determine which cylinder is in the combustion stroke. Furthermore, by counting the angle signal C8, the rotation speed N of the engine 1 can be calculated. Air flow meter 1 above
0 and crank angle sensor 14 are operating state detection means 16
The signals from the operating state detection means 16 and the knock vibration detection means 13 are transmitted to the control unit 17.
is input.

The control unit 17 has functions as advance angle value setting means, cylinder discrimination means, correction signal generation means, and ignition signal generation means, and includes a CPU 21, a ROM 22, and a RAM 22.
23 and an I/'O boat 24. C.P.
U21 takes in necessary external data from the I10 boat 24 according to the program written in the ROM 22, performs arithmetic processing while exchanging data with the RAM 23, and transfers the processed data to the I10 as necessary. Output to boat 24. A signal from the operating state detection means 16 is input to the I10 port 24, and an injection signal Si and an ignition signal Sp are output from the I10 boat 24. The ROM 22 stores a program that controls the CPU 21, and the RAM 23 is composed of, for example, a non-volatile memory and stores data used in calculations in the form of a map, and the stored contents are stored in the engine 1.
Retains even after stopping.

Next, the effect will be explained.

Generally, ignition timing control is performed as one method to avoid knocking. This aims to avoid knocking as much as possible and optimally control the combustion state by advancing the ignition timing when no knocking occurs, and retarding the ignition timing when knocking occurs. However, if the occurrence of knocking is incorrectly determined, the effect of ignition timing control cannot be obtained, and on the contrary, the combustion state may deteriorate. Conventionally, under certain conditions, the occurrence of knocking is incorrectly determined, resulting in the above-mentioned problem.

Focusing on the fact that normal knocking is caused by the ignition and explosion of the air-fuel mixture, if this timing is also used as one of the judgment parameters, it is possible to make a more accurate judgment on the occurrence of knocking. . On the other hand, in a multi-cylinder engine, at a crank angle at which knocking is expected to occur in one predetermined cylinder, the intake/exhaust timing is often set in one of the other cylinders.

In such an engine, large vibrations similar to knocking vibrations Vn occur when a valve mechanism that opens and closes intake and exhaust ports operates. Therefore, it may be difficult to determine whether knocking is normal or not by simply using the occurrence timing as one of the determination parameters. In other words, in order to accurately detect knocking in an engine that inherently vibrates a lot, an important point is how to separate the signal and mechanical noise.

Therefore, in this embodiment, we focused on the fact that when the ignition timing is shifted, if the cylinder is not at the ignition timing, the noise vibration Vn will not change, but if the cylinder is at the ignition timing, the noise vibration Vn will change. When vibration Vn occurs, the ignition timing is delayed up to the maximum retardation amount K L M, and when the ignition timing is delayed to the noise threshold value βn, it is determined whether or not there is a change in the knocking vibration Vn, thereby accurately distinguishing mechanical noise from normal knock. In addition to learning this result one by one according to the driving condition and using this learning result in the next knocking judgment, the knocking judgment can be made accurately and quickly and the knocking suppression control can be performed appropriately. On the other hand, by limiting the ignition timing retard amount β to the maximum retard amount (KLM) mentioned above, problems associated with retard control for determining knocking (due to too much retardation) can be avoided. (deterioration of driving performance) is avoided.

Figure 4.5 is a flowchart showing the knocking control program written in the ROM 22, and in the figure P
, ~P31 indicate each step of the program.

FIG. 4 is a flowchart showing a knocking determination program, and this program is executed once every 180 degrees of crank angle in synchronization with engine rotation. For models other than 4 cylinders, for example, every 120° for 6 cylinders, and 9° for 8 cylinders.
It will be executed once every 0°.

First, at P, it is determined which cylinder is in the combustion stroke, and at P2, it is determined whether or not a predetermined knocking vibration Vn is occurring. This knocking vibration Vn includes not only regular knocking but also mechanical noise having the same vibration components as regular knocking, and it cannot be determined from this alone that it is regular knocking. If knocking vibration is not occurring, end the current program, and if knocking vibration is occurring, go to P3 to create a noise cylinder map (for example, a two-dimensional table map with intake air amount Qa and rotational speed N as parameters). ) from the noise cylinder Ni corresponding to the operating condition at that time.
Look up the number of and use P4 to set the knock position cylinder Np (
A cylinder that is in the combustion process. The same applies hereafter) is compared with the number of this noise 1viNi. And Np=
When it is Ni, it is determined that the noise is mechanical noise caused by the noise cylinder, and the current program is terminated. Therefore, in this case, it is possible to immediately determine that it is mechanical noise without performing knock suppression control, which will be described later, and it is possible to optimally maintain the combustion state without retarding the ignition timing. This is because the noise cylinder map is always rewritten with the latest data by the noise learning flow NGF described later, and if it was previously determined to be mechanical noise, it can be immediately determined to be mechanical noise in the same operating state thereafter. It is. On the other hand, when Np≠Ni, the process shifts to the noise learning flow NGF in order to determine whether the current knocking vibration Vn is a regular knock or a new mechanical noise (not stored in the previous noise cylinder map). . Note that the noise learning flow NGF is based on the premise that the ignition timing is retarded under predetermined conditions by executing the ignition timing control program, which will be described later, every 10 m5.

In the noise learning flow NGF, first, at P, the noise threshold (comparative retardation amount) βn of the retardation amount β corresponding to the current operating state is determined.
is looked up from a predetermined threshold map. The noise threshold βn is a reference value for distinguishing between mechanical noise and regular knock, and if the ignition timing is delayed by this βn, the knocking vibration Vn will not be reduced if it is mechanical noise, but it will be reduced if it is regular knock. The value is set so that the amount of reduction can be quantitatively understood. Different values are adopted for this noise threshold βn depending on the operating state, and the optimum value is stored on a two-dimensional table map consisting of Qa and N, for example. Next, in P6, the current retard amount β is compared with the noise threshold value βn, and when β≦βn, it is determined that the retard amount β is still insufficient for knocking determination, and the knock determination timer is activated in P7. The time measurement value tn is reset to tn=Q, and the knock discrimination counter provided for each cylinder is reset to set the count value C'n to Cn=o, and the process proceeds to P8. On the other hand, β〉
When βn, it is determined that knocking can be detected, and
First, in P9, the count value Cn of the knock discrimination counter is set to [1].
] and Pl. It is determined whether or not the time measurement value tn is tn=Q. This time measurement value tn represents the duration of the knocking vibration Vn after β>βn. When t n = Q (for example, the first routine after β<βn), start the knock discrimination timer with pH, and
When n≠0 (routine after the first time), the time measurement value tn is compared with the discrimination reference value to at Pl2. When tn≧to, it is already t.

It is determined that a certain period of time has elapsed, the knock discrimination timer and the knock discrimination counter are reset at pH, and the process proceeds to pH. In addition, when tn<to, count value Cn is set at Pl4.
is compared with the discrimination reference value co, and if Cn=Co, knocking vibration Vn occurs frequently within a certain period of time despite executing knock suppression control, so it is determined that it is mechanical noise and the current Knock position cylinder Np to noise cylinder Ni
In P6, the number of the cylinder Np is written in a predetermined noise cylinder map.

On the other hand, if Cn≠Co, it is determined that it is a regular knock, and in P8, [1] is added to the counter value KNCT (hereinafter referred to as knock counter value) of the knock counter that counts the number of knocks, and the current program ends. do. In this way, in the noise learning flow NGF, the noise threshold βn
Knocking vibration V when the ignition timing is retarded beyond
Mechanical noise and regular noise can be clearly distinguished from the change in n. Each time such noise learning is performed, the data in the noise learning map is always updated to the latest value. Therefore, in the operating range where noise learning was performed, if knocking vibration Vn is detected in the next routine and the corresponding cylinder matches the noise cylinder Ni, it can be immediately determined that it is mechanical noise.

Therefore, unnecessary retard control can be omitted, which leads to avoidance of deterioration in driving performance due to too much delay in ignition timing, as pointed out in the conventional example.

FIG. 5 is a flowchart showing an ignition timing control program, and this program is executed once every 10 m5.

First, P2. Read the knock count value KNCT with
P7. It is determined whether the value of the lever is zero (that is, whether or not knocking vibration Vn is occurring). KN
When CT=0, it is determined that knocking vibration Vn has not occurred and the process proceeds to PX3, and when KNCT≠0, the process proceeds to the retard correction flow THF. In the retard angle correction flow THF, P2J+ subtracts [l] from the knock count value KNCT, and P bar corrects the advance angle value θ to the retard side (delays).
The retardation correction amount Dr per one knock is added to the retardation amount β, and the process proceeds to Pz&. PA determines whether the knock count value KNCT is zero or not, and if KNCT≠0, P is set again.
-P store-PzIl loop is executed, and when KNCT=0, P2. Proceed to. That is, in the retard angle correction flow THF, the retard amount β is determined according to the number of knock occurrences. Therefore, the larger the number of knock occurrences, the larger the retard amount β becomes.

Next, PX3 compares the retard amount β with a predetermined maximum retard amount KLM, and if β≦KLM, the advance angle correction flow 5 is performed.
) (Move to F, and when β>K LM, use PX7 to convert β-K
As LM (that is, β is limited to KLM), the advance angle correction flow SHF is entered. The value of the maximum retardation amount KLM is set to a value that suppresses the knocking vibration Vn in the case of regular knocking. Therefore, the amount of retardation β for suppressing knocking is limited to a value equal to or less than the maximum retardation angle 1iKLM, and even in the case of mechanical noise, for example, it is possible to avoid deterioration in driving performance due to too much delay in the ignition timing. Incidentally, conventionally, when a predetermined knocking vibration Vn is detected regardless of mechanical noise or regular knock, the retard amount β is increased to suppress the vibration Vn, and in particular, in the case of mechanical noise, the effect of retard control is This only resulted in the above problem.

In the advance angle correction flow SHF, the advance angle correction amount Da is subtracted from the retard amount β at P, 8, and the process proceeds to P29.

The advance angle correction amount Da is an advance angle amount per fixed time, and in this program, it is an advance angle amount every 10 m5. did .

Once, while executing the above-mentioned retard control, the ignition timing is advanced by the advance angle correction amount Da every 10 ms. Next, it is determined whether the retard amount β has become a negative value at P,9,
When β〈0, proceed to Pal as β-0 in Pio, and β
If ≧0, proceed directly to PSl. The state β=0 means that no retard control is performed and the ignition timing is equal to the optimum advance value. In PSl, the final advance angle value FADV is calculated according to the following equation (2).

FADV=θ−β −1−−−■However, θ:
Advance angle value In formula (2), the advance angle value θ is determined by looking up the optimum value corresponding to the current operating state from a two-dimensional table map using, for example, the intake air amount Qa and the rotational speed N as parameters. The final advance value FADV is 7 before the top dead center of each cylinder.
This is advance angle data that indicates at what degree counting from 0° the ignition is to be performed, and is determined by correcting the advance angle value θ corresponding to the driving state at that time with the retard amount β. Then, the air-fuel mixture is ignited at a timing corresponding to this final advance value FADV.

To summarize the above, when knocking vibration Vn does not occur, and even if knocking vibration occurs but is immediately determined to be mechanical noise based on previous learning results, the ignition timing is not retarded and becomes FADV-θ, which is always optimal. Maintains a good combustion condition.

On the other hand, when a regular knock occurs or when mechanical noise that is not included in the previous learning results occurs, the knock count value K
The ignition timing is retarded according to the NCT, and knocking is suppressed or mechanical noise is determined. In this retard control process, the retard amount β is prohibited from exceeding the maximum retard amount KLM, so it is possible to prevent the ignition timing from being delayed too much in the case of mechanical noise, and to avoid deterioration in driving performance. can. This effect is particularly noticeable in engines that tend to generate mechanical noise due to their lighter weight.

(Effects) According to the present invention, knocking can be appropriately suppressed by accurately distinguishing between regular knocking and mechanical noise, and it is also possible to prevent the ignition timing from being delayed too much to suppress knocking, resulting in a decrease in driving performance. can be avoided.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the present invention, FIGS. 2 to 5 are diagrams showing an embodiment of the present invention, FIG. 2 is a schematic configuration diagram thereof, and FIG.
The figure is a plan view of the rotor plate of the crank angle sensor.
FIG. 4 is a flowchart showing the knocking determination program, and FIG. 5 is a flowchart showing the ignition timing control program. 8-----1 ignition means, 12-----knock sensor, 13-----knock vibration detection means, 14--1-.
- Crank angle detection means, 16 - - Operating state detection means, 17 - Control unit (advance value setting means, cylinder discrimination means, correction signal generation means, ignition signal generation means).

Claims (1)

[Scope of Claims] a) a knock sensor that detects vibrations of the engine body; b) knock vibration detection means that determines the output of the knock sensor and detects predetermined knock vibration; and c) detects the crank angle of the engine. d) operating state detecting means for detecting the operating state of the engine; and e) setting an advance angle value based on the operating state and knocking the advance angle value when a correction signal is input. a lead angle value setting means for correcting to the retard side up to a maximum retard amount according to the vibration; If the cylinder angle is below, the cylinder in the combustion stroke at that time is determined as a noise cylinder based on the crank angle of the engine, and the cylinder determination means learns and stores this as corresponding to the operating state at that time; g) a predetermined value; h) correction signal generation means for reading out a noise cylinder corresponding to the operating state at that time from the cylinder discrimination means when knocking vibration occurs, and outputting the correction signal if the noise cylinder does not match the cylinder in the combustion stroke; An ignition signal generating means for outputting an ignition signal at a timing corresponding to the advance angle value determined by the angle value setting means; and i) an ignition means for igniting the air-fuel mixture based on the ignition signal. Knocking control device.