JPH01216058A - Knocking control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve responsiveness especially at the time of transitive operation by providing two renewal means to renew knock determining levels for all the cylinders and for each cylinder respectively, and selecting the renewal means corresponding to the engine operation condition to adjust knock control factors. CONSTITUTION:A renewal means M4 for renewing a knock determining level for every ignition at all the cylinders without identifying each cylinder, and a renewal means M5 for renewing a knock determining level for each cylinder are provided to which a knock sensor signal is inputted from a knock sensor M2 respectively. Among these renewal means M4, M5, the renewal means M4 is selected when it is determined that the engine operation is in transitive condition based on an output from an operation condition detecting means M6, and the renewal means M5 is selected when it is determined that it is in steady operation condition by means of a selecting means M7 respectively. The selected and renewed knock determining level is compared with the knock sensor signal at a determining means M8, and knock control factors are adjusted by an adjusting means M3 based on the result of the comparison.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a knock control device (knock control system) that detects knock occurring in an internal combustion engine and controls knock control factors such as ignition timing and air-fuel ratio. It is something.

[Prior Art] In the knock control 5 of a multi-cylinder engine, an example of a method for creating a knock determination level is shown in (a) in FIG.
), (b), the knock sensor signals corresponding to each cylinder are averaged for each cylinder during a predetermined knock determination period to obtain a background value LBG, and that value LBG is multiplied by a constant to determine the knock determination level l. −.

This cylinder-specific knock detection level l- is based on the optimal background value (cylinder-specific background value) LBG for each cylinder, so when the engine is in a steady state, a reliable knock detection can be made. When the engine is in a transient state where the engine signal suddenly changes, the cylinder-specific background value LBG for each cylinder can only be created and changed every time that cylinder ignites (every 4 ignitions in the case of a 4-cylinder engine), so the required back-up is The problem was the delay in response to the ground value LBG.

For this reason, Japanese Patent Laid-Open No. 60-256539 discloses a method for avoiding this problem. This is calculated by calculating the average value of the knock sensor signals of the gold cylinder and the average value of the knock sensor signals for each cylinder, and calculating the difference between the average value of the knock sensor signals of each cylinder and the average value of the knock sensor signals of the gold cylinder. The ratio is calculated, a knock determination level for each cylinder is determined according to this difference or ratio, and knock is determined from this knock determination level and the knock sensor signal.

[Problems to be Solved by the Invention] However, in the disclosed knock control device for an internal combustion engine, the difference or ratio of the average value of the knock sensor signal of each cylinder to the average value of the knock sensor signal of the gold cylinder is calculated. Since the knock detection level for each cylinder is created according to this difference or ratio, reliable knock detection when the engine is in a steady state and perfect response when the engine is in a transient state are possible. It would be hard to say that I was satisfied. Furthermore, the processing becomes very complicated because it is necessary to calculate the difference or ratio of the average value of the knock sensor signals of each cylinder to the average value of the knock sensor signals of the gold cylinders.

An object of the present invention is to ensure controllability of a multi-cylinder internal combustion engine in a steady state and responsiveness of a multi-cylinder internal combustion engine in a transient state;
Another object of the present invention is to provide a knock control device for an internal combustion engine that can set a knock determination level through simple processing.

[Means for Solving the Problems] In order to achieve the above object, the present invention, as shown in FIG. In a knock control device for an internal combustion engine, the knock control device for an internal combustion engine is equipped with an adjusting means M3 for adjusting knock control factors according to a knock judgment result obtained by inputting a knock sensor signal and adjusting a knock judgment level every time a golden cylinder is ignited, regardless of the cylinder. a bell updating means M4 for updating the knock determination level for each cylinder; a cylinder-by-cylinder determination level updating means M5 for inputting a knock sensor signal and updating the knock determination level for each cylinder; When the internal combustion engine M1 is in a transient state, the operating state detecting means M6 detects the operating state, and when the internal combustion engine M1 is in a transient state, the all-cylinder ignition-per-ignition determination level updating means M4 selects the update of the knock determination level for each all-cylinder ignition, and the internal combustion When the engine M1 is in a steady state, the cylinder-specific determination level updating means M5
a selection means M7 for selecting an update of the knock determination level for each cylinder according to the method, and a knock determination level selected and updated by the selection means M7 and the knock sensor signal, and the comparison result is sent to the adjustment means M3. The gist of the present invention is a knock control device for an internal combustion engine, which is provided with a knock determination means M8 that outputs a knock.

[Operation] The operating state detecting means M6 detects the operating state of the multi-cylinder internal combustion engine M1, and the operating state detecting means M6 detects the operating state of the multi-cylinder internal combustion engine M1.
1 is in a transient state, the selection means M7 selects the update of the knock determination level for each all cylinder ignition by the all cylinder ignition determination level update means M4, and when the internal combustion engine M1 is in a steady state, the determination level for each cylinder update means M5 The knock determination means M8 selects the update of the knock determination level for each cylinder by
compares the selected and updated knock determination level with the knock sensor signal, and outputs the comparison result to the adjustment means M3. Then, the adjusting means M3 adjusts the knock control factor according to the determination result.

[Example] An example embodying the present invention will be described below with reference to the drawings.

As shown in Fig. 2, the knock sensor 1 is installed in the cylinder block of a multi-cylinder engine (a four-cylinder engine is used in this embodiment) EQ, and detects the knock of the multi-cylinder engine Eg by detecting the vibration of the cylinder block. To detect. An input processing circuit 2 is connected to this knock sensor 1, and the input processing circuit 2 is adapted to extract only a signal unique to knocking. A microcomputer (hereinafter referred to as MPU) 3 serving as a determination level updating means for every cylinder ignition, a determination level updating means for each cylinder, an operating state detection means, and a selection means is an RO.
A control program stored in a read-only memory (M) 4 executes various arithmetic processes, and the results of the various processes are temporarily stored in a random access memory (RAM) 5. This MPtJ3 inputs the output signal of the knock sensor 1 via the input processing circuit 2, and generates a knock judgment level Lk for each cylinder.
It has a function to update the information every time all cylinders are ignited, regardless of the cylinder, and to update it for each cylinder.

This knock judgment level is created using 4-ignition annealing. That is, when the average value of the knock sensor signal in the current knock judgment period is l-i, and the background value of the knock sensor signal updated last time is LBG*-1, the current background value LBGi is calculated using the following formula. I'm looking for it.

Then, the knock determination level Lk is calculated by multiplying this background value 1BGi by a constant.

An engine rotation speed sensor 6 constituting a driving state detection means detects the engine rotation speed and outputs a detection signal thereof to the MPU 3. MPLI3 calculates the change in the engine speed per unit time, and when the rate of change in the engine speed is greater than a predetermined value, it determines that the operating state of the engine EQ is in a transient state, and also calculates the engine speed. When the rate of change of is smaller than a predetermined number of times, it is determined that the operating state of the engine EQ is in a steady state. That is, for example, 500r
If pm/S e C or higher, there is a transient state and 500 p
If it is less than pm/sec, it is determined to be in a steady state.

One input terminal of the comparator 7 constituting the knock determination means is connected to the MPU 3, and the other input terminal is connected to the input processing circuit 2, and the output terminal of the comparator 7 constitutes the knock determination means. It is connected to the knock determination circuit 8. The comparator 7 compares the knock determination level Lk output by the MPLJ 3 with the knock sensor signal from the input processing circuit 2, and outputs a pulse signal when the knock sensor signal is greater than the knock determination level Lk.

A knock determination circuit 8 adds the number of pulse signals from the comparator 7, and when the added value exceeds a predetermined value, outputs a knock determination signal to an ignition timing control device 9 serving as an adjusting means.

When the ignition timing control device 9 receives a knock determination signal from the knock determination circuit 8, it retards the ignition timing by 0.degree. 25.degree. CA for each knock (input of a knock determination signal).

Next, the operation of the knock control device for an internal combustion engine configured as described above will be explained based on FIG. 3.

First, vibration of the multi-cylinder engine Eq is detected by the knock sensor 1, and a signal of "1" from the knock sensor is inputted to the MPU 3 via the input processing circuit 2.

The MPU 3 updates the background value LBG (LBGi) of the knock sensor signal for each cylinder each time the cylinder is ignited, regardless of the cylinder, using equation (1) above, or updates the background value LBG (LBGi) for each cylinder using equation (1) above. Background I for each cylinder of the knock sensor signal for each different ignition (in the case of 4 cylinders, every 4 ignitions)
The background value BG (LBGi) for each cylinder is determined by updating the LBG (LBGi), and the knock determination level Lk is calculated by multiplying the value 1-BG (LBGi) by a constant.

In addition, the MPU 3 constantly detects changes in the engine speed based on signals from the engine speed sensor 4 and no 6, and
By determining whether the rate of change is greater than or equal to a predetermined value or less than a predetermined value, it is determined whether the engine EQ is in a transient state or a steady state (step 1). When the MPU 3 determines that it is in a transient state, it selects to update the knock determination level lk based on the knock sensor signal every time all cylinders are ignited, regardless of the cylinder, and uses the updated level lk for each cylinder to the comparator. 7 (step 2). Further, when the MPU 3 determines in step 1 that the multi-cylinder engine EQ is in a steady state, it selects updating of the knock determination level Lk based on the knock sensor signal for each cylinder, and updates the updated level Lk for each cylinder accordingly.
is output to the comparator 7 (step 3).

Then, as shown in FIG. 6(b), the comparator 7 compares the knock sensor signal with the cylinder-specific knock determination level Lk of the MPU 3, and the knock sensor signal
3, a pulse signal is output to the knock determination circuit 8. Zarani, 6th
As shown in FIG. 1C, the pulse signals are added in the knock determination circuit 8, and when the added value exceeds a predetermined value Qo, a knock determination signal is output to the ignition timing control device 9.

Then, as shown in FIG. 6(d), the ignition timing control device 9 retards the ignition timing by a predetermined amount based on this knock determination signal.

In this way, when updating the knock detection level for each ignition of all cylinders or updating the knock detection level for each cylinder is calculated and selected depending on the operating state (transient state, steady state) of the multi-cylinder engine EQ, as shown in Fig. 4. In the transient state, in the figure, the required true value (background value) l-BGI
In contrast, in the conventional case, the background value LBO2 is created and updated only once every four ignitions for each cylinder, resulting in a delay and a possibility of misjudgment of knock. In this state, the background value LBO2 updated every time all cylinders are ignited is selectively used, and the knock determination level is created and updated every time ignition occurs, resulting in excellent responsiveness. Roughly speaking, during steady operation, the background value LBO2 for each cylinder provides excellent controllability. In FIG. 4, the conventional background value LBO2 for each cylinder and the background value LBO2 for each cylinder selected during steady state according to the present invention represent one of the four cylinders.

In this way, in the internal combustion engine knock control device of this embodiment, the engine rotation speed sensor 6 distinguishes the operating state of the engine Eg between the transient state and the steady state, and when the operating state is in the transient state, the knock judgment level is set for each ignition of all cylinders. Also, in the steady state, the knock judgment level is updated only for each cylinder, so in the already disclosed knock control device, the knock judgment level for each cylinder is updated for the average value of the knock sensor signal of the gold cylinder. In order to create a knock judgment level for each cylinder based on the difference or ratio of the average values of knock sensor signals, the responsiveness during a transient state of engine Eg and engine EQ are calculated.
Although the controllability in the steady state was not completely satisfied, this does not occur, and it is possible to achieve excellent responsiveness in the transient state and excellent controllability in the steady state. In addition, unlike the conventional AM, there is no need to calculate the difference or ratio of the average value of the knock sensor signals of each cylinder to the average value of the knock sensor signals of the gold cylinders, so the overall processing can be simplified. .

Note that the present invention is not limited to the above embodiment, and in the above embodiment, the knock judgment level Lk uses the so-called 4-ignition annealing shown in equation (1). As shown in the figure, the average value LGB4 of the knock sensor signal during the current knock judgment period is compared with the comparison level LGBS, and if the comparison level LGB5 is larger than the average value LGa4, the comparison level LBO5 is increased by a predetermined amount at the next update. When the comparison level L BO5 is smaller than the average value L Ga4, the comparison level L BO5 is updated by increasing ΔL by a predetermined amount.
The knock determination level Lk may be calculated by multiplying 5 by a constant.

In the above embodiment, the engine speed sensor 6 determines whether the operating state of the engine EQ is a transient state or a steady state. It may be determined whether the state is a transient state or a steady state by detecting whether or not the state is present.

Roughly speaking, in the above embodiment, either the knock determination level is updated each time a cylinder is ignited or the knock determination level is updated for each cylinder, depending on the operating state (transient state, steady state) of the multi-cylinder engine Eg. I tried to select it, but it always says MPL.
Using I3, the knock determination level Lk based on the knock sensor signal of the gold cylinder is updated every time the gold cylinder is ignited, regardless of the cylinder, using the formula (1) above, and the knock determination level Lk based on the knock sensor signal of each cylinder is calculated for each cylinder. The operating state (transient state,
The knock determination level for the golden cylinder or the knock determination level for each cylinder may be selected depending on the steady state).

Furthermore, although the above embodiment describes the case where the ignition timing is controlled by knock detection, other knock control factors such as the air-fuel ratio may be controlled.

[Effects of the Invention] As detailed above, according to the present invention, the controllability of a multi-cylinder internal combustion engine in a steady state and the responsiveness of a multi-cylinder internal combustion engine in a transient state can be ensured, and the controllability of the multi-cylinder internal combustion engine can be ensured with simple processing. It has an excellent effect of being able to set the knock judgment level.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is an electric circuit diagram of a knock control device for an internal combustion engine according to an embodiment, Fig. 3 is a flowchart for explaining the operation, and Fig. 4 shows the operating state. FIG. 5 is a time chart for explaining background values accompanying changes, FIG. 5 is a time chart for explaining abrasion, and FIG. 6 is a time chart for explaining knock determination processing. Ml is a multi-cylinder internal combustion engine, M2 is a knock sensor 4, M3 is an adjusting means, M4 is a judgment level updating means for every cylinder ignition, M
5 is a determination level updating means for each cylinder, M6 is an operating state detection means, Ml is a selection means, and M8 is a knock determination means. Patent applicant Nippondenso Co., Ltd. Agent Patent attorney

Claims (1)

[Claims] 1. A knock sensor for detecting knock occurring in a multi-cylinder internal combustion engine, and an adjusting means for adjusting knock control factors according to a knock determination result based on the knock sensor signal. A knock control device for an internal combustion engine, comprising: inputting a knock sensor signal to update a knock determination level every time all cylinders are ignited, regardless of the cylinder; determination level updating means for each cylinder for separately updating a knock determination level; operating state detection means for detecting the operating state of the internal combustion engine; and determination for every ignition of all cylinders when the internal combustion engine is in a transient state according to the operating state detection means. Selection means for selecting updating of the knock determination level for each cylinder ignition by the level updating means, and selecting updating of the knock determination level for each cylinder by the cylinder-by-cylinder determination level updating means when the internal combustion engine is in a steady state; A knock control device for an internal combustion engine, comprising: knock determination means that compares the knock determination level selected and updated by the selection means with a knock sensor signal, and outputs the comparison result to the adjustment means. .