JPS61250366A - Sensing system for combustion condition - Google Patents

Abstract

PURPOSE:To enable a system to simultaneously detect pressure and knocking, by providing a means, which individually detects a combustion condition in spaces different from each other in a cylinder, while a means which detects a change of pressure in the cylinder on the basis of a change of time difference between individual signals output from said former means. CONSTITUTION:A system provides a combustion condition detecting means, which individually detects a combustion condition in mutually different spaces in a cylinder 1, for instance, a plurality of sensor 2, 3 for detecting a physical quantity (ion, light, temperature, etc.) generated when combustion is performed. While the system provides a time difference detecting device 6 receiving an output signal from said each sensor 2, 3 and outputting a time difference signal between the maximum output signals of a signal change. Further the system provides an inflection point detecting device 7 receiving an output signal from said device 6 to detect an inflection point of the signal change and outputting a corresponding signal. In this way, the system, in which the output signal from said each sensor 2, 3 corresponds to a change in the advance direction of a combustion wave at normal time 5a and abnormal time 5b, can obtain a point of time corresponding to the maximum value of pressure in the cylinder 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sensing method for detecting combustion and conditions within a cylinder.More specifically, it uses a plurality of sensors to detect the maximum value of cylinder internal pressure. The present invention relates to a combustion state sensor that can simultaneously detect combustion abnormalities such as knocking and knocking.

(Prior Art) In order to establish an internal combustion engine electric control system, a sensor is required to accurately grasp the combustion state of the engine.

Pressure,
In particular, a sensor that detects the maximum value of cylinder internal pressure and a knock sensor are important in engine control. For this purpose, concentration sensors, pressure sensors. A wide variety of sensors are used, such as optical sensors, acceleration sensors, ion sensors, and acoustic sensors.

Conventional pressure sensors and knock sensors will be briefly explained.

Conventional pressure sensors include a capacitive type, a semiconductor piezoresistive type, and a surface elastic wave type, but most of them are equipped with a diaphragm, etc., and the pressure is converted into strain by the diaphragm, which is then extracted as an electrical signal. Many FEI knock sensors detect cylinder pressure, engine block vibration, combustion noise, etc.

(Problems to be solved) The above conventional pressure sensors and knock sensors that detect mechanical changes have a high background noise level, and especially in the case of multiple cylinders, it is difficult to avoid mixing noise generated from other cylinders. Therefore, a means for selecting the target signal is required, which causes problems in terms of complexity and signal-to-noise ratio.

In addition, since pressure and knocking are detected at separate locations, there is a problem in that they are often complicated and expensive.

The present invention was made to improve the above problems,
The purpose of the present invention is to provide a combustion state sensing method that can detect pressure and knocking simultaneously, improves durability, ease of installation, and other problems, and improves responsiveness and accuracy.

(Means for solving the IpH1!i point) The combustion state sensing method according to the present invention includes a combustion state detection means that individually detects the combustion states of different spaces in the cylinder, and The pressure time difference detection means detects the time point corresponding to the maximum value of the cylinder internal pressure based on the time difference change of the individual signals output from the detection means, and the pressure time difference detection means detects the time difference of the individual signals and the change in relative value. The system is designed to detect abnormal combustion such as knocking based on differences in the

[Effect]

By determining the combustion state within the cylinder by processing the combustion state detection signals of multiple individual spaces, it is possible to simultaneously detect the maximum pressure corresponding angle and abnormal combustion such as knocking, and improve the signal-to-noise ratio. and the resulting reliability for combustion detection.

It is possible to output combustion data that improves responsiveness and enables calculation of the optimal ignition angle.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration block diagram for explaining the present invention in detail.

In the figure, 1 is a schematically drawn cylinder of an internal combustion engine, and 2
,3 is the first and second sensor! ! Physics that occurs during smoking I
(ions, light, t!A degree, etc.).

4 is the ignition spark generated by the spark plug 11, 5a, 5
b is an arrow indicating the propagation direction of the flame generated by ignition;
5a indicates the direction of flame propagation during normal combustion, and 5b indicates the direction of flame propagation during abnormal combustion.

6 is a time difference detection device, and the first sensor 2. In response to the signal output from the second sensor 3, the maximum output signal l! of the signal change is received! Outputs the time difference signal between.

Reference numeral 7 denotes an inflection point detection device that receives the detection signal output from the time difference detection device 6, detects an inflection point of signal change, and outputs a corresponding signal.

8 is an ignition timing variable device, and a time difference detection device 6. It receives the detection signal output from the inflection point detection device 7 and outputs a signal for obtaining the optimum ignition timing.

9 is a high pressure system, and a spark plug 1 installed in the cylinder 1.
A high-voltage power supply for generating spark discharge at 1.

A power distribution system 10 distributes the high voltage output from the high voltage system 9 to each cylinder.

Reference numeral 11 denotes a spark plug, which forms an ignition spark 48.

FIG. 2 is a diagram showing changes in the output of the first sensor with respect to the crank angle.

The actual test in the figure shows the change in the amount of light received inside the cylinder in the direction of flame propagation during normal combustion when a single optical sensor is used as a sensor.In other words, the movement of combustion is It is detected by a light beam at the location where the sensor is attached, and as combustion progresses and the light beam approaches the sensor, the output increases to a peak. I understand that. Furthermore, as the combustion cycle progresses, depending on changes in combustion conditions, when the ignition spark 4 is generated again by the ignition plug 11, abnormal combustion such as knocking may occur within the cylinder. In the case of knocking, ignition of combustion often starts not only from the ignition spark 4 but also from the outer periphery inside the cylinder. Therefore, as shown by the broken line in the figure, a peak is output in the latter half of the combustion cycle.

By using this fact and further using a plurality of sensors to detect the light rays inside the cylinder during combustion, it becomes possible to detect the flame propagation direction and the pressure change inside the cylinder.

That is, the signal outputs from the plurality of sensors correspond to changes in the traveling direction of the combustion waves of normal combustion and abnormal combustion. Therefore, by determining the change in time difference and the point of inflection, the traveling direction of the combustion wave and the time it takes to pass through the sensor can be determined.If the interrelationship between pressure and combustion wave transmission is set in advance, the maximum cylinder pressure can be determined. The time point corresponding to can be found.

Furthermore, the same signal from each sensor can be canceled out as a noise signal of the same magnitude and opposite directions.

Note that although the flame propagation has been described above by detecting light rays during combustion, the present invention is not limited to light rays, and detection using ionic current, 1 degree, etc. is also possible.

3 and 4 are explanatory diagrams of a first embodiment in which the combustion state sensing method of the present invention is applied to a general ignition phase adjustment device using an optical sensor.

In the figures, the same reference numerals or symbols as those described above represent the same parts or equivalent parts, and their explanation will be omitted.

FIG. 3 shows an enlarged view of the integrated first and second sensors, which are essential parts of the present invention. In the figure, 12.12- is the light receiving part, 1
3.13' is a light guide material such as a quartz rod. 14
15. 15' is a screw for attaching to the cylinder 16.

Light receiving portions 12, 12- are fixed to the tips of the rods 13, 13' so that light beams generated during combustion within the cylinder can be easily guided to the rods 13, 13'.

The rod 13° 13' to which the light receiving portion 12.12= is fixed is fixed via both surfaces 114, and has directivity in the direction of flame propagation.

Therefore, the light beam generated during combustion is transmitted to the first sensor 2,
The second sensor 3 captures the light, the phototransistor 17.17 detects the light, and the axle motion amplifier 18 outputs the light to detect the direction of travel.

FIG. 4 is a block diagram of a first embodiment of the present invention including the sensor of FIG. 3.

In the figure, a waveform shaping circuit 19 shapes the waveform output from the differential amplifier 18 to generate pulses corresponding to inflection points.

20 is a coil for forming a high-voltage power supply; 21 is a distributor for distributing the high voltage output from the coil 20 to each plug; 22 is an ignition phase detection circuit; the spark plug 11 is discharged from the distributor 21; The ignition phase is detected by receiving the ignition signal.

A crank angle detection sensor 23 detects the crank angle.

An ignition phase adjustment circuit 24 receives the output of the waveform shaping circuit 19, the ignition phase signal of the ignition phase detection circuit 16, and the detection signal of the crank angle sensor, and calculates and outputs the optimum ignition timing.

According to the above configuration, the combustion state is detected by the time difference between the outputs of each sensor due to the directivity of the integrated sensor 2.3, and the flame is integrated when the output of the differential amplifier 18 passes the zero point. It is known when the sensor passes through the sensors 2 and 3 provided at a specific position, and from this the corresponding maximum pressure corresponding time can be obtained.

Note that the noise generated due to the adhesion of engine oil to the light receiving section can be canceled out as the same noise changes in the outputs of the individual sensors.

Figure 5 shows the applicant's application (Japanese Patent Application No. 59-156229).
FIG. 2 is a configuration block explanatory diagram showing a second embodiment in which the combustion state sensing method of the present invention is applied to a cumulative ignition timing control device such as the above, by using an ion sensor. In the drawings, the same reference numerals or the same numbers as those described above represent the same parts or equivalent parts, and their explanation will be omitted.

First sensor 2. The second sensor 3 is a sensor that detects the ionic current generated during combustion, and has a pair of detection rods facing each other with a common electrode interposed therebetween.

A differential amplifier 25 compares the signals detected by the sensor 2.3 and outputs a signal proportional to the differential voltage.

26 is a normality/abnormality determination circuit that determines whether the flame propagation direction of the combustion direction is normal or abnormal.

Reference numeral 27 denotes an inflection point determination circuit which detects an inflection point based on the signal output from the differential amplifier 25 and determines the point in time when the cylinder internal pressure corresponds to a local maximum value.

The microcomputer μCOM is connected to an input interface 28, and includes a CPLJ 29 that performs predictive calculations according to input according to a built-in program, and a ROM 30 that stores fixed values such as calculation conditions and constants to be supplied to the calculations of the CPU 29. A RAM 31 that stores parameters that change from time to time depending on input signals from each sensor, a timer circuit 32 that uses a crystal starter to generate reference clock pulses necessary for the operation of the entire microcomputer μCOM, and a CP
A lecture on outputting the results of LJ29 prediction calculations! and an output interface 33 having one function.

The conduction angle signal output of the output interface 33 is connected to the input of the igniter 31, and the signal output of the igniter 31 causes the high voltage circuit 32 to generate a high voltage, and since this is a distributor, 1i! ! ! Through 33, spark plug 1
By outputting the signal to 1, ignition can be obtained in the cylinder 1.

The ignition timing prediction cumulative control device according to the second embodiment includes a crank angle sensor 23 that detects a first angle corresponding to the upper fulcrum of the piston of the internal combustion engine, and a second angle that sets the second angle that provides optimal power timing for the engine. ROM 30, a sensing portion that detects a third angle corresponding to the maximum cylinder internal pressure value of the engine, and a first ROM 30; Second. R to remember the third angle
AM 31 and means such as a CPU 29 that predicts and calculates the next ignition angle based on at least one of the first and second angles and the third angle according to the rotation of the engine, and calculates the calculated ignition angle. By repeatedly adjusting the subsequent ignition timing depending on the angle, the third angle is configured to gradually approach the power timing.

Here, the third angle that brings about the maximum value of the cylinder internal pressure of the engine is detected by determining the combustion state within the cylinder from the output of the ion sensor.

That is, as the combustion wave progresses, the point of maximum cylinder internal pressure is output from the inflection point determination circuit 27 due to the time difference change of a plurality of signals corresponding to the progress of combustion, which are output by changes in the ion current flowing through the electrodes of the sensor 2.3. On the other hand, the occurrence of knocking is detected by the normality/abnormality determination circuit 26 based on the time difference and change in relative value of a plurality of signals.

〔effect〕

The combustion state sensing method of the present invention determines the normal combustion state of the combustion state in the cylinder and the maximum fIIFR period of the cylinder internal pressure by comparing a plurality of physical quantities generated during combustion and detecting the traveling direction and passing time. I can do it.

In addition, the noise screening means can be omitted and a pressure sensor and a knock sensor are not required separately, which not only improves accuracy and response but also simplifies the configuration and reduces costs.

In each of the embodiments, a plurality of sensors are integrated and arranged, but it goes without saying that the same effect can be obtained even if the sensors are arranged at different positions.

[Brief explanation of drawings]

FIG. 1 is a detailed explanation of the present invention;
The diagram shows the relationship between the crank angle and the output of the first sensor, and FIG. 3 shows the first sensor included in the 40th sensor. -1° An enlarged view of the second sensor. FIG. 4 is a block diagram of the overall configuration of the first embodiment of the present invention. FIG. 5 is a block diagram of the overall configuration of the second embodiment of the present invention. 1... Cylinder, 2.3... Combustion state detection means, 6...
Pressure time difference detection means. Applicant NEC Home Electronics Co., Ltd. Agent Patent Attorney Masu 1) Takeo No. I Figure 2m No. 3m

Claims (2)

[Claims] 1. Combustion state detection means for individually detecting combustion states in different spaces within the cylinder; and detecting changes in cylinder internal pressure based on time difference changes in individual signals output from the combustion state detection means as the combustion state progresses. A combustion state sensing method characterized by comprising pressure time difference detection means. 2. 2. The combustion state sensing method according to claim 1, wherein the pressure time difference detection means detects abnormal combustion such as knocking based on differences in time differences and changes in relative values of individual signals.