JPH0778379B2 - Knocking control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knocking control device for an internal combustion engine, which controls the ignition timing or the air-fuel ratio of the engine while detecting the knocking strength.

<Prior Art> As a conventional knocking control device for an internal combustion engine, for example, there are the following devices (see Japanese Patent Laid-Open Nos. 58-82074 and 56-20765).

That is, the knocking intensity of the engine is detected, the knocking intensity is compared with the slice level, and, for example, when the knocking intensity becomes equal to or higher than the slice level, the ignition timing is delayed, or the air-fuel ratio is made rich to avoid knocking. At the same time, the engine is operated at the knocking limit to improve output and fuel efficiency.

<Problems to be Solved by the Invention> By the way, in such a conventional knocking control device, the slice level of the knocking intensity is set according to the engine operating state (rotational speed, load, etc.). This is because the vibration level of the engine base changes according to the engine operating state, and knocking occurs at a level corresponding to the increase of the vibration level of the base.

However, in the conventional method in which the occurrence of knocking is physically detected and controlled according to only the engine operating state in this way, the vehicle speed becomes high, the road noise, the mechanical noise, etc. become loud, and the knocking noise can be heard. Even if there is no situation, the ignition timing will be retarded more than necessary and the output will deteriorate,
There is a problem that the air-fuel ratio is controlled to the rich side and the fuel efficiency deteriorates.

The present invention has been made in view of the above problems,
The purpose is to perform optimal knocking control according to the vehicle speed.

<Means for Solving the Problem> Therefore, the present invention, as shown in FIG. 1, includes a knocking strength detecting means for detecting the knocking strength of the internal combustion engine,
In a knocking control device for an internal combustion engine, which comprises a comparing means for comparing the detected knocking intensity with a slice level, and an engine control means for controlling engine operating conditions such as ignition timing or air-fuel ratio based on the comparison result, An engine operating state detecting means for detecting an operating state, a vehicle speed detecting means for detecting a vehicle speed, and a basic slice level set according to the engine operating state detected by the engine operating state detecting means, the vehicle speed detection Slice level setting means for correcting and setting according to the vehicle speed detected by the means.

<Operation> According to the above configuration, the slice level can be changed according to the vehicle speed.Therefore, at low vehicle speed, the slice level is reduced to reduce knocking noise, while at high vehicle speed, the slice level is increased. As a result, the output and the fuel consumption can be improved.

<Examples> Examples of the present invention will be described below.

FIG. 2 shows the system configuration of the electronically controlled ignition device.

A crank angle sensor 1 outputs a reference signal for each reference crank angle and a unit signal for each unit angle. The engine speed N is calculated from the cycle of the reference signal or the number of unit signals generated within a predetermined time. An air flow meter 2 outputs a voltage signal that relatively changes according to the intake air flow rate Q. A vehicle speed sensor 3 outputs a signal corresponding to the vehicle speed V from the rotation of the wheels.

Reference numeral 4 is a knocking sensor. This knocking sensor 4
For example, an in-cylinder pressure sensor using a piezoelectric ceramic that detects the pressure of combustion gas in the cylinder is used.
Then, in the signal processing circuit in the control unit 5, the signal from the knocking sensor 4 is converted into charge-voltage by the amplifier 6, and only the signal in the frequency band (for example, 6 to 19 KHz) corresponding to the knocking vibration is converted by the bandpass filter 7. It is passed, rectified by the rectifier 8, and integrated for a predetermined period for each combustion cycle of each cylinder by the integrator 9 to obtain a signal corresponding to the knocking intensity KN.

The central part of the control unit 5 is composed of a microcomputer, and is provided with a CPU 10, a ROM 11, a RAM 12, an input / output interface 13 and an A / D converter 14, and the various sensors 1
Based on the signals from 4 to 4, arithmetic processing is performed as described later, and an ignition signal is output to the ignition device 15 at the calculated ignition timing.

The ignition device 15 includes a power transistor 16 serving as a switching element, a power supply 17, an ignition coil 18, and a spark plug 19. When the power transistor 16 is cut off by the input of an ignition signal, the ignition device 15 is connected to the secondary side of the ignition coil 18. High voltage is generated,
At that time, the spark plug 19 operates to ignite.

The microcomputer in the control unit 5 controls the ignition timing while detecting knocking by performing arithmetic processing according to the flowchart of FIG.

In Stip 1 (indicated as S1 in the figure, and so on)
The knocking intensity KN detected by the knocking sensor 4 as the knocking intensity detecting means is read.

In step 2, the vehicle speed V detected by the vehicle speed sensor 3 as the vehicle speed detecting means is read.

In step 3, the vehicle speed V read in step 2 is compared with a predetermined vehicle speed V _0, and when V <V ₀ (low vehicle speed), the process proceeds to step 4, and the engine speed N and the intake air flow rate Q are compared. The slice level SL ₁ = f ₁ (N, Q) is calculated by the function f ₁ with the variable as a variable, SL ₁ is substituted for SL in step 5, and the process proceeds to step 8.

If V ≧ V ₀ (high vehicle speed) is compared in step 3, the process proceeds to step 6, and the slice level SL ₂ = f ₂ is calculated by another function f ₂ having the engine speed N and the intake air flow rate Q as variables. (N,
Q) is calculated, SL ₂ is substituted for SL in step 7, and the process proceeds to step 8.

Here, the function f ₁ and the function f ₂ are set so that the function f ₂ has a larger value, and SL ₁ <SL ₂ .

In step 8, knocking strength KN and slice level SL
When KN ≦ SL (knock is weak), the process proceeds to step 9, and the feedback correction amount FB for ignition timing correction is increased by a minute predetermined value δ ₁ minutes from the previous value for advance angle correction. Then, a new feedback correction amount FB = FB + δ ₁ is calculated and the process proceeds to step 11.

If KN> SL (strong knock) in the comparison in step 8, the process proceeds to step 10 and the feedback correction amount FB for ignition timing correction is set to a small predetermined value δ with respect to the previous value for retard correction.
Reduced by ₂ minutes, and new feedback correction amount FB = FB−
Calculate δ ₂ and proceed to step 11.

In step 11, the basic ignition timing ADV ₀ is added to the feedback correction amount FB obtained in step 9 or step 10 to calculate the final ignition timing (ignition advance angle) ADV = ADV ₀ + FB, and this routine is ended. .

The basic ignition timing ADV ₀ is set by another routine by searching a map in the ROM 11 from the engine speed N and the intake air flow rate Q.

In this way, when the ignition timing ADV is calculated, an ignition signal is output to the power transistor 16 at that timing, which causes the spark plug 19 to operate as described above.

Here, step 1 corresponds to the knocking strength detection means together with the knocking sensor 4, step 2 corresponds to the vehicle speed detection means together with the vehicle speed sensor 3, steps 3 to 7 correspond to the slice level setting means, and step 8 is compared. It corresponds to the means, and steps 9 to 11 correspond to the engine control means.

This makes it possible to compare the knocking strength with the slice level according to the vehicle speed, so at low vehicle speeds, the slice level is reduced to reduce knocking noise, while at high vehicle speeds knocking noise becomes a problem. Because it doesn't
The slice level can be increased to improve output and fuel efficiency.

Next, another embodiment will be described based on the flowchart of FIG.

In step 21, the knocking strength KN detected by the knocking sensor 4 is read.

In step 22, the vehicle speed V detected by the vehicle speed sensor 3
Read in.

In step 23, the slice level SL ₁ = f (N, Q) is calculated by the function f having the engine speed N and the intake air flow rate Q as variables.

In step 24, the vehicle speed V read in step 22 is compared with a predetermined vehicle speed V _0, and when V <V ₀ (low vehicle speed), the process proceeds to step 25, and SL ₁ is directly substituted into SL, Step 27
Proceed to.

When V ≧ V ₀ (high vehicle speed) is compared in step 24, the process proceeds to step 26, where SL ₁ obtained in step 23 is increased by a value k (V−V ₀ ) (k is proportional to vehicle speed V). The slice level SL = SL ₁ + k (V−V ₀ ) is calculated by adding (constant), and the process proceeds to step 27.

In step 27, knocking strength read in step 21
Compare KN with the slice level SL obtained in step 25 or step 26, and if KN ≤ SL (knock weak), proceed to step 28 and set the feedback correction amount FB for ignition timing correction for advance angle correction. Increase the value by a small amount δ _{1 from the} previous value to obtain a new feedback correction amount FB = FB + δ ₁
Is calculated and the process proceeds to step 30.

In the comparison of step 27, if KN> SL (knock strength), the process proceeds to step 29, and the feedback correction amount FB for ignition timing correction is set to a small predetermined value δ with respect to the previous value for retard correction.
Reduced by ₂ minutes, and new feedback correction amount FB = FB−
Calculate δ ₂ and proceed to step 30.

In step 30, the feedback correction amount FB obtained in step 28 or step 29 is added to the basic ignition timing ADV ₀ to calculate the final ignition timing ADV = ADV ₀ + FBB, and this routine ends.

Here, step 21 corresponds to the knocking strength detection means together with the knocking sensor 4, step 22 corresponds to the vehicle speed detection means together with the vehicle speed sensor 3, steps 23 to 26 correspond to the slice level setting means, and step 27 is compared. Steps 28 to 30 correspond to the engine control means, and means for detecting the engine speed N and the intake air flow rate Q used for calculating the slice level in step 23 serve as the engine operating state detecting means. Equivalent to.

The same effect can be obtained also by this. However, this embodiment simplifies the calculation as compared with the above-mentioned embodiment,
It requires less memory capacity.

<Effect of the Invention> As described above, according to the present invention, since the slice level setting means for correcting and setting the slice level according to the vehicle speed is provided, the slice level is reduced and the knocking sound is generated at a low vehicle speed. On the other hand, at the time of high vehicle speed where knocking noise is not a problem, the slice level can be increased to improve output and fuel efficiency.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention, FIG. 3 is a flowchart of the same embodiment, and FIG. 4 is a flowchart of another embodiment. Is. 1 ... Crank angle sensor, 2 ... Air flow meter, 3
…… Vehicle speed sensor, 4 …… Knocking sensor, 5 …… Control unit, 15 …… Ignition device, 19 …… Ignition plug

Claims (1)

[Claims] 1. A knocking strength detecting means for detecting a knocking strength of an internal combustion engine, a comparing means for comparing the detected knocking strength with a slice level, and an engine control means for controlling an engine operating condition based on the comparison value. In a knocking control device for an internal combustion engine, the engine operating state detecting means for detecting an operating state of the engine, the vehicle speed detecting means for detecting a vehicle speed, and the engine operating state detected by the engine operating state detecting means are set according to the engine operating state. And a slice level setting means for correcting and setting a basic slice level according to the vehicle speed detected by the vehicle speed detecting means.