JPH03267548A - Knocking detecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To detect the knocking by calculating the integration division of the output signals of a vibration detecting means as the time division from a standard signal, in an internal combustion engine in time control system using a crank angle sensor which outputs only the standard signal. CONSTITUTION:The time ADVTN1 from the generation of standard signal REF on the basis of the standard signal REF to the start of integration and the time ADVTN2 from the generation of the standard signal REF to the completion of integration are estimation-calculated according to a calculation equation, and time is counted from the generation of the standard signal REF by a timer, and integration is carried out through the lapse of the calculated time. Accordingly, the function of a time division estimation means is achieved by a control unit 9, and the time(t) from the generation of the standard signal REF is estimation-calculated so that the time division ADVTN1<=t<=ADVTN2 is the integration time division, and the output signals of a knocking sensor are integration-calculated only in the time division. The obtained value is compared with a prescribed signal, and knocking is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application> The present invention provides a method for processing signals from means for detecting vibrations of an internal combustion engine comprising a crank angle sensor that generates a reference signal at a predetermined crank angle position of the engine. The present invention relates to a knocking detection device that detects the occurrence of knocking.

<Conventional technology> Conventionally, electronically controlled ignition control devices for internal combustion engines set the ignition timing (crank angle position) according to the engine operating state, and perform ignition by outputting an ignition signal at this timing. For this purpose, a reference signal is generated at a predetermined crank angle position of each cylinder, and a reference signal is generated at a crank angle of 1.
Using a crank angle sensor that generates unit signals every ° or 2 degrees, ignition is performed at the set ignition timing by measuring the number of unit signals generated after the reference signal for each cylinder is generated and determining the crank angle position. It is common to have the

However, crank angle sensors that have a unit signal generation function require high accuracy and are expensive.

Therefore, using a crank angle sensor that generates only a reference signal and a cylinder discrimination signal, when the reference signal is generated, the generation cycle of the reference signal (time since the previous reference signal) is calculated, and based on this cycle, the generation cycle of the reference signal is calculated. A time control system has been proposed that estimates and calculates the time until the ignition timing and outputs an ignition signal when this time elapses to cause ignition. Incidentally, Japanese Unexamined Patent Publication No. 61-286584 discloses a time control system, although it is intended for fail-safe purposes.

In addition, using the above-mentioned crank angle sensor, in addition to the generation cycle of the reference signal, the rate of change in the generation cycle (deviation between the latest generation cycle and the previous generation cycle) is calculated, and these order cycles and the rate of change are calculated. Attempts have also been made to perform ignition timing control by more accurately estimating and calculating changes in crank angular velocity.

On the other hand, conventional knocking detection is performed as described below, for example (see Japanese Unexamined Patent Publication No. 59-49369, etc.)
.

In other words, a specific frequency component corresponding to the knocking level is extracted from the output signal of a knocking sensor installed in the engine to detect vibration, and is subjected to integral processing over a specific section where knocking occurs, and then integrated for each cylinder according to the cylinder discrimination signal. The presence or absence of knocking is determined by comparing it with the averaged signal.

Based on this determination, the basic ignition timing, which is set according to the engine speed and load, is gradually advanced in the direction of the engine if knocking does not occur, and is retarded by a relatively large amount if knocking occurs. The knocking level is controlled appropriately by repeating the control.

<Problems to be Solved by the Invention> Here, in the above-mentioned knocking detection, when a specific frequency component corresponding to the knocking level is extracted from the output signal of the knocking sensor and a specific interval integration process is performed to generate knocking. Since the integration interval is set by the crank angle interval, conventionally, a crank angle sensor that generates a reference signal and a unit signal is used to measure the number of unit signals generated after the reference signal is generated. Knowing the crank angle position, I was able to determine the early integration interval.

However, in the above-mentioned time control type control device using a crank angle sensor that outputs only a reference signal, it is not possible to set an integral interval based on the crank angle.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a knocking detection device for a time-controlled internal combustion engine using a crank angle sensor that outputs only a reference signal.

<Means for Solving the Problems> For this reason, the present invention, as shown in FIG. vibration detecting means for outputting vibration; time interval estimating means for estimating and calculating a predetermined interval in which knocking occurs frequently as a time interval from the time when the reference signal is generated based on at least a calculated value of the generation cycle of the reference signal; an integrating means for integrating the output signal from the vibration detecting means only in the time interval calculated by the interval estimating means; and a knocking determining means for comparing the output signal of the integrating means with a predetermined signal to determine the presence or absence of knocking. It was composed of

Effects> In the above configuration, the period in which the output signal from the vibration detection means is integrated is calculated as the period of time from the reference signal calculated based on the generation period of the reference signal.

Then, the output signal from the vibration detection means is integrated only in the time period, and is compared with a predetermined signal to detect knocking.

<Example) Embodiments of the present invention will be described below based on the drawings.

In FIG. 2 showing the configuration of an embodiment, an internal combustion engine 1 includes an air cleaner 2. Intake duct 3. Air is drawn in via the throttle chamber 4 and the intake manifold 5.

An air flow meter 6 is provided in the intake duct 3 to detect the intake air flow rate Q. Throttle chamber 4
is provided with a throttle valve 7 that operates in conjunction with an accelerator pedal (not shown) to control the intake air flow rate Q. A throttle sensor 15 is attached to the throttle valve 7 to detect its opening degree TVO using a potentiometer.

The intake manifold 5 is provided with an electromagnetic fuel injection valve 8 for each cylinder, and injects fuel into the intake manifold 5 that is pressure-fed from a fuel pump (not shown) and controlled to a predetermined pressure by a pressure regulator.

The fuel injection amount is controlled by a control unit 9 with a built-in microcomputer based on the intake air flow rate Q detected by the air flow meter 6 and the distributor 1.
The basic fuel injection amount T,
By calculating this basic fuel injection amount T, and correcting it based on the cooling water temperature, etc., the final fuel injection amount TIf is subtracted by 4-shi, and a drive pulse with a pulse width corresponding to this fuel injection amount T is obtained. By outputting a signal to the fuel injection valve 8 in synchronization with engine rotation, the required amount of fuel is injected and supplied to the engine 1.

Here, the crank angle sensor 10 outputs a reference signal REF that rises at a position of 75 degrees before the compression top dead center of each cylinder and falls at a position of 5 degrees before the compression top dead center of each cylinder, as shown in FIG. , outputs a small pulse cylinder discrimination signal close to a specific reference signal.

The detection of the engine rotational speed is calculated as the reciprocal of the generation cycle of the reference signal REF position (time from the previous generation of the reference signal REF).

Further, each cylinder of the engine 1 is provided with an ignition plug 11, to which a voltage generated by an ignition coil 12 is constantly applied via a distributor 13, thereby igniting a spark and creating an air-fuel mixture. ignite and burn. here,
The ignition coil 12 has an attached power transistor 12
The timing at which high voltage is generated is controlled via a. Therefore, the ignition timing (ignition advance value) ADVT is controlled by controlling the OFF timing of the power transistor 12a using the ignition timing control from the control unit 9. In this case, the crank angle sensor 10
Based on the reference signal REF from the time of generation of the reference signal REF, the ignition timing A
The time until DV ADVT is estimated using a formula described later, and an ignition signal (OFF signal of the power transistor 12a) is output when the calculated time elapses by counting the time from the generation of the reference signal REF with a timer.

ADVT=TREFLX (75-ADV)/110
-KX (TREFO-TREF)
)/180 (1) Here, the first term on the right side of equation (1) above is the proportional control value, and the second term is the expected control value.

On the other hand, knocking detection is performed by a device as shown in FIG.

The cylinder head 21 of the engine 1 is equipped with a knocking sensor 22 as a vibration detection means that detects the vibration of the cylinder head wall and outputs it as a voltage, and the signal from the knocking sensor 22 corresponds to a knocking signal. Only high frequency components are extracted by bandpass filter 23.

Next, the rectifying and integrating circuit 24 converts the bandpass filter 2
The signal from No. 3 is integrated only in a predetermined section (described later) where knocking occurs frequently, and is output to the A/D converter 25 at the next stage without being integrated in other sections.

Then, in the knocking determination section 26, the A/D converter 2
The signal directly input from 5 is compared with the signal obtained by averaging this signal for each cylinder according to the cylinder discrimination signal, and if the one-minute value of the signal in the integration interval exceeds the averaged value. In all other cases, it is determined that there is knocking, and in all other cases, it is determined that there is no knocking.

That is, the rectifying and integrating circuit 24 corresponds to an integrating means, and the A/D converter 25 and the knocking determination section 26 correspond to a knocking determining means.

Based on this determination, the ignition timing calculating section 27 in the control unit 9 performs advance/delay correction of the basic ignition timing set according to the rotational speed and load of the engine 1 to appropriately control the knocking level.

Here, as a configuration according to the present invention, the knocking sensor 22
The crank angle interval in which the output signal of is integrated is calculated as the time interval from the reference signal calculated based on the generation cycle of the reference signal REF generated by the crank angle sensor 10.

That is, in the present invention, where the integration interval is from a predetermined position a after compression top dead center of each cylinder to a position b degrees after compression top dead center, the crank angle sensor 10 is as shown in FIG. Since the reference signal REF as shown in FIG. Estimation is performed using an arithmetic expression, and the integration is performed at the elapse of the calculated time from the generation of the reference signal REF by a timer.

ADVTNI-TREFH/70X a---(
2) ADVTN2-TRBFH/70X b --
-(3) However, THEFH is the time from the current rise of the reference signal REF to the current fall of the reference signal REF.

Therefore, the control unit 9 performs the function of time interval estimating means.

With such a configuration, it is estimated that a time interval in which the time t from the generation of the reference signal REF satisfies ADVTNI≦t≦ADVTN2 is an integration interval, and the output signal of the knocking sensor 22 is integrated only during this time interval.

Incidentally, the above equations (2) and (3) were calculated by estimating the integral interval using a value proportional to the generation cycle of the reference signal REF, that is, a proportional control value, but in order to further improve the control characteristics, , (4) and (5), the reference signal REF
An expected control value based on the rate of change in the occurrence period may be added.

ADVTNI-TREFH/70 X aK x (
TREF-TREFI)/180X a...(4)A
DVTN2 = TREFH/70 x b-K x
(TREF-TREFI)/180x b...(5) However, TREF, current cycle TREFI related to the rise of the reference signal REF; current cycle K related to the fall of the reference signal REF; expected value gain (effect of the invention) As explained above, according to the present invention, in a time-controlled internal combustion engine using a crank angle sensor that outputs only a reference signal, the integral interval of the output signal of the vibration detection means is calculated as the time interval from the reference signal. I decided to do this, so
It has become possible to provide a knocking detection device for a time-controlled internal combustion engine.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 3 shows the integration time based on the signal from the crank angle sensor used in this embodiment. FIG. 4 is a timing chart for estimating and calculating the knocking detection device.

Claims (1)

[Claims] A crank angle sensor that generates a reference signal at a predetermined crank angle position of an engine; a vibration detection means that detects vibrations occurring in the engine and outputs them as a voltage signal; time interval estimating means for estimating and calculating the interval as a time interval from the time of generation of the reference signal based on at least a calculated value of the generation period of the reference signal; and only the time interval calculated by the time interval estimating means is outputted by the vibration detecting means. A knocking detection device for an internal combustion engine, comprising: an integrating means for integrating a signal; and a knocking determining means for comparing an output signal of the integrating means with a predetermined signal to determine whether knocking is present.