JPS5891369A - Knocking control device - Google Patents

Abstract

PURPOSE:To avoid the knocking promptly by a method wherein a decision level for knocking the amount of step retard, the speed of spark-advance and the amount of maximum retard are varied in accordance with the operating condition of an engine in the system in which an ignition timing is controlled in accordance with the intensity of the knocking of the internal-combustion engine. CONSTITUTION:A knock signal detecting unit 25 detects only the frequency element of knocking by a bandpass filter and compares it with a different knocking decision level in accordance with the operating condition obtained by an operating condition measuring unit 24 to obtain a knocking signal. A delay angle control unit 27 varies the control gain (the amount of step retard) upon controlling the delay angle and the control gain (the speed of spark-advance) upon controlling the spark-advance so as to correspond to the operating condition of the internal-combustion engine. According to this method, the knocking may be avoided promptly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device that controls ignition timing by detecting knocking in an internal combustion engine with a knock sensor to avoid knocking.

When severe knocking occurs in an internal combustion engine, the unburned air-fuel mixture in the combustion chamber combusts instantaneously, causing a sudden rise in pressure and temperature, which also induces pressure vibrations. Most of this energy is dissipated from the inner wall of the piston and cylinder head as wasteful heat and vibration, resulting in a decrease in output. Also,
The impact at that time affects the connecting rods, crank bearings, etc., deteriorating their durability, and also having a negative impact on the pulp, pistons, etc. Therefore, ignition timing calculation means that avoids such knocking have been developed.

FIG. 7 shows seven examples of this type of knock avoidance device, in which knock sensors are installed at positions where the knock signal values from each cylinder can be obtained as uniformly as possible. This knock sensor converts the power transmission into an electrical signal and extracts it. Engine/-2 constantly vibrates during operation, so these vibrations are output as a signal regardless of whether knocking occurs or not. The vibration frequency of knocking is 6 to t KHz, and since the Senna/single body has a characteristic of a resonance point of about t KHz, when knocking occurs, a large output signal is obtained by resonating the senna. It is configured so that

3 is a knock control unit, which includes a knock vibration detection section 3A, a knock intensity determination section JB, and a retardation control section 3C.
It consists of Here, the knock vibration detection section 3A detects only the knocking signal with a frequency of about 7 kHz among these signals, since the electrical signal from the knock sensor also includes signals caused by mechanical vibrations other than knocking. To detect.

When knocking occurs in the combustion chamber, the vibrations are transmitted to the knock sensor via the cylinder tabs j, and output from the knock sensor l.

The electric signal is supplied to the knock vibration detection section J of the knock control unit J. The knock vibration detection unit 3 extracts only the knocking signal and sends it to the next knock intensity determination unit 3.
The determination unit JB determines the knocking intensity every seven ignitions from the obtained knocking signal.

When the knocking intensity is higher than a predetermined knocking intensity reference level, knocking is determined for the first time, and the knocking intensity is determined based on the degree of the intensity. The retard control unit 3C is a device that delays the ignition timing according to the intensity of knocking, and when the knock vibration detection unit 3C determines that knocking has occurred, a retard signal is supplied to the igniter unit of the distributor 6. be done. If it is determined that knocking is still occurring in the next ignition combustion, the ignition timing is delayed to the east, and if it is determined that knocking has occurred and there is no °C, the advance angle signal is It is supplied to the igniter unit 7.

That is, by controlling the ignition timing according to the degree of knocking in this way, knocking can always be suppressed to a minute level, and fuel efficiency can be improved.

Figure 1 shows the configuration of the HIC igniter unit 7 used in this example and the parts related to it.
is a hybrid inverter circuit (HIC) that determines the ignition timing according to the magnitude of the phase control signal voltage supplied from the knock control unit J via the terminal D, and the input torque obtained from the terminal D is pickup coil i
The pace current of the power transistor/no is cut off with a delay from the reference ignition # period caused by o. This allows the ignition timing to be delayed. Note that the relationship between the retard angle (angle at the distributor base) and the input voltage (V) from the terminal D is as shown in figure In2, as the input voltage increases, the retard angle also increases.

Next, the I# details of the advance angle signal, that is, the phase control signal voltage obtained by the retard control section JC will be explained.

When the knocking signal is supplied to the retard control section 3c, the retard control section JC generates a voltage corresponding to a retardation of approximately 0.4 degrees for every 1 knock, that is, a phase control voltage, as shown in Figure 3. occurs. However, the maximum retard angle is always constant at 2.0 degrees regardless of the operating conditions, and the control gain is also always constant, and the control gain (step retard t) during retard control is 0.3! There is a V/l knock. However, the maximum retard violet is always held down by Tei and ##V.

In addition, when the knocking signal supplied to the retard control section 3C becomes low level under the operating condition where the engine speed is /200 ryn or less, the engine operating state Jk in FIG.
C> and (ljd@g/g to 1 as shown in column
The control gain corresponding to the advance angle speed of +ee is 0, tV/-・C
Then, the engine is /ko again. If the knocking signal supply similarly goes to low level under the operating condition of 0 rpm or higher, (C
) and (as shown in column (r)) co, ra@g/
Control gain corresponding to advance angle speed of m*e is 0, core V/s@
In other words, the control gain at the time of advance angle is selected to one of the above values only depending on whether the engine speed is less than or more than θθrpm. There is. In the knock intensity determination 83B, knocking is determined if the difference between the knocking signal and the background signal for each ignition is a constant value, and this knocking determination criterion also depends on the operating conditions of the engine.
It is considered to be constant regardless of the situation.

Referring to FIG. 2, in the knocking control device configured as described above, if knocking occurs in the combustion chamber of the engine, a phase control voltage is supplied to the HICt via the knocking control unit 3. Therefore, HICf delays the retard angle according to the input voltage, cuts off the pace voltage /B of the power transistor l/, and cuts off the primary current of the ignition coil /co. Therefore, in the spark plug /J (@ /see diagram) /
With each knock, the ignition timing is delayed. Furthermore, when knocking ceases, the ignition timing is advanced at a constant advance speed determined by the operating state of the engine, and the ignition timing is advanced. In FIG. 1, /41 is a key switch, and /4 is a button switch.

However, in such conventional knocking control devices for internal combustion engines, the control gain for detecting knocking and retarding the ignition timing, the control gain for advancing the ignition timing, and the knocking criterion are determined depending on the operating conditions of the engine. Therefore, under bulk rotation and high load conditions, when knocking occurs, the control gain for each knock is small, and the retardation speed cannot catch up with the knocking control, causing discomfort to the driver. In addition, when the knocking signal disappears under such operating conditions and the angle is advanced, the control gain is determined by Class II depending only on the engine speed, so
The advance angle speed may be too fast, and in this case it will be blown away. King tends to reoccur, causing similar discomfort to the driver.

The object of the present invention is to eliminate the above-mentioned drawbacks and to adapt to the operating conditions of the engine: 1. Knock control that changes the control gain, maximum retard value, and knock judgment level in the case of retard and advance angles to strict values, thereby quickly avoiding knocking regardless of driving conditions. The goal is to provide equipment.

The present invention will be described in detail below based on the drawings.

In the following, the explanation will be continued using the same reference numerals for FIG. 1 and the same parts as shown in FIG.

, FIG. 5 shows an embodiment of the present invention, in which knocking is determined using a microcomputer and the ignition timing is thereby controlled to avoid knocking. Here, 〃 is the crank angle sensor,
Disc A and pickup B 41, which are installed coaxially with the engine crankshaft, generate crank angle signals each time the crankshaft rotates by λ degrees and every time the crankshaft rotates by 10 degrees. . - indicates intake passage n
This is an air flow meter installed in the engine, which detects the intake air amount of the engine. The operating condition measuring section J calculates the engine speed based on the crank angle signal from the crank angle sensor, and also calculates the basic fuel injection amount (WK), which indicates the engine load, based on the intake air amount and engine speed from the air flow meter. Calculate the quotient divided by the popular engine speed.

Further, in the knock signal detection section, 4 KHK to t KH is set in the same manner as in the case of the knock vibration detection section 3A shown in FIG.
Only the knock frequency component of z is detected by a band pass filter and is supplied to the knock intensity determination section as a knock signal. As shown in FIG. 1, the knock intensity determination section determines the presence or absence of knocking based on different knocking determination levels corresponding to the operating conditions obtained from the operating condition measurement section 2, and obtains a knocking signal. .

That is, FIG. 6 shows the basic fuel injection m determined in accordance with the engine speed <r, pm) and the load of the internal combustion engine.
1 (-) indicates a predetermined knock judgment level, and when the voltage vL obtained by subtracting the background level Va from the knocking signal voltage 7 section obtained by the knock signal detection section is greater than the knock judgment level. Get a knock signal.

- is a retard angle control section which calculates a retard angle based on the knocking signal from the knocking strength determination line and the engine operating state. In this case, the control gain during retard angle control (step retard t) and the control gain during advance angle control (advance angle speed) are made to correspond to the operating state of the internal combustion engine, as shown in Figs. change. Furthermore, the maximum retard t(V) is similarly changed as shown in the figure.

In other words, Figs. The step retard amount (V/knock: control gain during retard angle control), the advance angle speed (V/s@c: control gain during knee advance control) and the maximum retard amount are shown, respectively.
Based on the knock presence/absence signal obtained from the knock intensity determination section and the operating conditions obtained from the operating condition evaluation section, the step retard amount (V/) shown in FIG. 7, the advance angle speed ( V/s@a) or the maximum retard amount (v) shown in the figure is determined.

Based on these values, the retard control section core calculates a knock control ignition timing signal.

This knock control ignition timing signal is converted to the ignition timing calculation circuit r2.
supply The basic ignition timing signal obtained from the evaluation by the operating condition measuring section is also supplied to this arithmetic circuit, and the knock control ignition timing signal and the basic ignition timing signal are added together to determine the ignition timing. The ignition timing signal obtained by this arithmetic circuit energizes the power transistor λq (corresponding to the transistor l/ in Figure 1) to ignite the engine. The following is an example of the case where the basic fuel injection amount is LO (ms), the value obtained by subtracting the background level v from the knocking signal is t, O (V). Detail the operation.

First, the knock intensity determination section KORO determines that there is knocking, and supplies a knocking signal to the retard control section-2. On the other hand, the engine speed and the basic fuel injection lid are supplied to the retard control section from the operating condition measurement section. At this time, the step retard amount (V/knock), advance angle speed (V
/s@e) and the large eel retard t(V) are shown in Figure 7~
From the figure, '0. Jco (V/knock), θ, k (V
/see ) and da, zt(V). A knock control ignition timing signal is calculated from each of these values and is supplied to an ignition timing calculation circuit. As a result, in the calculation cycle W & Co, the knock ff1lj' control ignition timing is added to the basic ignition timing to find the ignition timing appropriate for the operating conditions of the internal combustion engine, and the power transformer tap is driven to cut off the primary current of the coil l. ignite at ℃.

As explained above, according to the present FJAVC, the knocking determination level and step retard amount during knocking control are determined according to the operating conditions of the engine.

By changing the advance angle speed and maximum retard amount, the optimal control amount is always obtained.The responsiveness of ignition timing adjustment is improved, and knocking can be quickly avoided, making it easier for drivers to 11 degrees of discomfort can be reduced.

[Brief explanation of drawings]

#! / Figure is a configuration diagram showing an example of a conventional knocking control device, #f&- Figure is a circuit diagram showing the configuration of a 70 HrC igniter unit, Figure 3 is a 70 HIC igniter, - retard angle and input terminal in the unit A graph showing the relationship with the voltage, Fig.
The figure is a block diagram showing an example of the configuration of the knocking control device of the present invention together with a partially cutaway diagram of the engine. FIG. 6 is a diagram showing the maximum retard amount. l...knock sensor, co...engine, 3...
・Knock control unit, 3mm...Knock-
motion detection section, 3B...knock intensity determination section, 3C...retard angle control section, da...combustion chamber, j...
Cylinder block, 6...distributor, ? ...Igniter unit, t...HIC, 9...Terminal, 10...Pickup coil, //...Power transistor, /λ...Ignition coil, /9...Spark plug, /4I...Key switch, 1
5...battery, thing...crankshaft, lie...
・Air 70-meter, S3...Make air passage, J...Operating condition measurement section, O...Knock signal detection section, M...Knock intensity determination section, -7...Retard angle control Part, Ko... Ignition timing calculation circuit 1.2? ...Power transistor. Applicant: Nissan Motor Co., Ltd. Figure 1 Figure 2 Figure 3 Terminal wo no heka 1 (V) Figure 4 Figure 8 (V/jec) Figure 9 [v]

Claims (1)

[Claims] A knocking control device that detects knocking occurring in an internal combustion engine and changes ignition timing based on the detection signal to prevent knocking, comprising: a knocking detection means; and an operating state for detecting an operating state of the internal combustion engine. a detection means, a retard control means for calculating a retard value or an advance value by changing a control gain of retard control or advance control according to the operating state obtained by the operating state detecting means; The present invention is characterized in that it has an ignition timing calculation means for calculating the ignition timing from the retard value or the advance value obtained by the control means, and ignition is performed by the ignition signal obtained by the ignition timing calculation means. Knocking control device.