JPS62131976A - Device for controlling ignition timing for spark ignition engine - Google Patents

Abstract

PURPOSE:To prevent knocking with good response while improving fuel consumption and output by detecting combustion light to monitor the condition of combustion, and controlling ignition timing to be a condition that self-ignition takes place without being brought to knocking. CONSTITUTION:A combustion light signal is inputted into an optical filter 5 by means of an optical fiber 4 installed in a combustion chamber 3, and components peculiar to self-ignition and knocking combustion are selected, which are transduced into electric signals by a photo-detector 6. Among these signals, only components peculiar to knocking and self-ignition are sent to a knocking judging circuit 12 and a self-ignition judging circuit 13 through filters 10 and 11 respectively, from which components which are greater their respective reference voltages, are inputted into a control circuit 14 as a knocking or a self-ignition signal. The control circuit 14 carries out the lead angle of ignition timing until a self-ignition existing condition is detected. On the other hand, this lead angle control is stopped if a signal of knocking is inputted, immediately carrying out a lag angle by a certain quantity on the contrary.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an ignition timing control device for a spark ignition engine.

(Prior art) In spark ignition engines such as gasoline engines, 1,1
．． An ignition timing control device has been adopted which aims to improve fuel efficiency and output while avoiding knocking by optimally controlling the v-ignition timing according to the operating state of the engine.

As disclosed in Japanese Unexamined Patent Publication No. 57-79262, the ignition timing is set in advance to the flame timing required according to the operating condition of the engine, and at the same time the combustion condition of the engine is adjusted to the combustion chamber. The ion probe detects the ion concentration in the combustion chamber, and if the ion density in the combustion chamber is detected, which increases unreasonably during engine knocking, the ignition timing is retarded by a certain crank angle to ensure combustion while avoiding knocking. The aim is to maintain good sound and output.

(Problem to be solved by the invention) However, if the ignition timing is retarded by a certain value when knocking is detected in this way, even if knocking can be avoided, it is not necessarily possible to achieve the best fuel efficiency and maximum output. It could not be said that the ignition timing was controlled to the required level.

This means that even if knocking can be avoided by retarding the ignition timing when knocking occurs, the ignition timing will not necessarily be controlled to the optimal ignition timing when knocking is not occurring, including after 11+j. This is because, although the ignition timing is set to the optimum value in advance according to the operating conditions, due to engine variations, changes over time, etc. This is because the lead angle may fluctuate from the set lead angle value, and control is not necessarily performed accurately and responsively as requested. This point can be better understood if we consider the avoidance of knocking. Even if the ignition timing is set in advance to the maximum advance value that can avoid knocking, the fluctuation
In other words, unless knocking occurs and combustion is performed with the best combustion efficiency, unless proper monitoring is performed, it will not be possible to avoid knocking. It would be great if the ignition timing was controlled to the optimum condition for actual combustion.

General Knocking is more likely to occur under favorable combustion conditions, where sufficient fuel and air are taken into the combustion chamber and the temperature is high. Immediately after ignition, the ignition flame propagates due to the sudden rise in pressure and temperature within the combustion chamber. This refers to the current situation where the fuel self-ignites from the corners of the combustion chamber before the combustion occurs, and the combustion rapidly spreads. Therefore, the condition of +'+tf in which the engine causes knocking, that is, the condition in which self-ignition occurs but does not result in knocking, is actually an extremely good combustion condition and is preferable for improving fuel efficiency and output.

The present invention addresses these problems and improves combustion efficiency by monitoring actual combustion and controlling ignition timing so that self-ignition combustion, which does not lead to knocking but is a precursor to knocking, is achieved. The aim is to maintain a high level of

(Means for solving the problem) Therefore, as shown in FIG. 1, the present invention detects the optical signal of the engine combustion chamber. A means for determining self-ignition combustion from this optical signal, a means for similarly determining knocking combustion, and a means for advancing the ignition timing until self-ignition occurs according to the result of the determination, and adjusting the ignition timing when knocking occurs. and ignition timing control means for retarding the ignition timing.

(Function) Therefore, when the ignition timing is controlled in this manner, although self-ignition occurs during combustion in the engine, the reaction is gradual and the combustion is maintained in a state of high combustion efficiency that does not result in knocking. Therefore, knocking can be reliably and responsively avoided, while fuel efficiency and output can be further improved.

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

Figure 2 [Here, 1 is the 4-cylinder engine body, 2 is the person installed in the combustion chamber 3 of each cylinder. It is an optical fiber for transmission. 5 is an optical filter that extracts only components (such as frequencies) characteristic of self-ignition combustion and knocking combustion from the optical signal transmitted from the optical fiber 4; 6 is a photodetector that converts this optical signal into an electrical signal; be. This electrical signal is input to a filter (bypass filter) 1 ( ) that selects only components specific to knocking, and
It is also input to a filter (low-pass filter) 11 that selects only components specific to self-ignition combustion. The peak value of the output of the filter 10 is compared with a reference voltage value in a knocking determination circuit 12 to determine whether or not knocking is occurring or not and its magnitude.

Similarly, the output of the filter 11 is compared with a reference voltage value in a self-ignition determination circuit 13 to determine whether or not self-ignition occurs in each combustion cycle.

The ignition timing control circuit 14 includes these knocking determination circuits 12.
Based on the output of self-ignition determination circuit 1: (), when there is no self-ignition, the ignition timing is advanced until self-ignition occurs, and when knocking is detected, the ignition timing is retarded by a certain amount. Note that each of these circuits can also be configured by a microcomputer.

15 is an ignition coil that generates high-voltage ignition pulses in response to an ignition signal from the ignition timing control circuit 14; 16 is a distributor that distributes the high-voltage ignition pulses to the spark plugs 2 of each cylinder in accordance with the alpha firing order. Further, numeral 7 in the figure indicates a power supply for each of the circuits.

The system is constructed as described above, and its operation will now be described with reference to FIG.

The combustion light signal generated during the combustion process by the dangerous fiber 1 attached to the combustion chamber 3 of each cylinder is input to the optical filter 5, and only the components peculiar to self-ignition combustion and knocking combustion are selected from this light signal. , these are converted into electrical signals by the photodetector 6.

As shown in FIG. 3, of this electrical signal, only the component specific to non-king (however, there is knocking in M3 Figure 8, and there is no knocking in B) is sent through the filter 10 to the knocking discrimination circuit 12, where it is sent to the knocking determination circuit 12, where it is It is compared with a reference voltage value. A component larger than this reference voltage value is input to the control circuit 14 as a knocking signal.

-h, the filter 11 removes the components specific to self-ignition combustion from the electrical signal (Fig. C shows self-ignition,
D (no self-ignition) is selected and similarly compared with the reference voltage value by the self-ignition discrimination circuit 13, and a component larger than the reference voltage value is inputted to the control circuit 14 as a self-ignition signal.

The control circuit 14 advances the ignition timing when there is no self-ignition, and this advance is continued until the state of self-ignition is detected, and when self-ignition occurs, the ignition RJtll is held in that state. -Hl If a signal indicating knocking occurs manually during this advanced angle system 1, it is stopped and the ignition timing is immediately retarded by a certain amount.

When a no-knocking signal is input, the ignition timing is advanced based on the ignition and self-ignition signal.

Based on the ignition controlled in this manner (1), the ignition coil 15 outputs a high-voltage ignition pulse, and power is distributed to each spark plug 21 via the distributor 16.

As a result, the ignition timing is maintained at the highest combustion efficiency state, where combustion in the engine self-ignites, but the reaction is gradual and does not cause knocking, resulting in improved fuel efficiency and
In addition to further improving output, the ignition advance is controlled just before knocking occurs, so even if combustion conditions fluctuate, the ignition timing is retarded by a certain amount even if knocking occurs. This makes it possible to immediately avoid knocking.

(Effects of the Invention) As described above, the present invention monitors the combustion state by detecting combustion light, and distinguishes between components specific to self-ignition combustion and components specific to knocking combustion. Since the ignition timing is controlled so that the reaction is gradual and does not result in knocking, the engine's fuel efficiency and output are improved, while knocking can be avoided with a good response. be hit.

[Brief explanation of drawings]

Figure 1 is a diagram corresponding to claims of the present invention, Figure 2 is a schematic configuration diagram of an embodiment of the present invention, and Figure tjS3 is a signal waveform diagram showing control operations. DESCRIPTION OF SYMBOLS 1... Engine body, 2... Spark plug, 3... Combustion chamber, 4... Optical 7 eyeball, 5... Optical filter, 6...
...Photodetector, 10.11...Filter, 12...
Knocking discrimination circuit, 13... Self-ignition discrimination circuit, 1
4... Ignition timing control circuit, 15... Spark plug, 1
6...Distributor.

Claims (1)

[Claims] means for detecting an optical signal in the engine combustion chamber; means for determining self-ignition combustion from the optical signal; means for similarly determining knocking combustion; and advancing the ignition timing until self-ignition occurs in accordance with the determination result. An ignition timing control device for a spark ignition engine, comprising ignition timing control means for retarding ignition timing when knocking occurs.