JP3213160B2 - Ignition system abnormality detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition system abnormality detecting method for detecting an abnormality in an ignition system mainly related to an ignition error or an ignition error in an automobile engine.

[0002]

2. Description of the Related Art Conventionally, in a multi-cylinder engine used for an automobile or the like, one of the cylinders may misfire and the rotation may become unstable. As a method for detecting such a misfire, a method for detecting an ignition error and a method for detecting an ignition error are known. In this case, the former can detect an abnormality in the ignition system, and the latter can detect an abnormality in the ignition system and the fuel system.

[0003] For example, in an electronically controlled ignition system that does not use a distributor, an ignition error is caused by an electronic control unit that controls a cam position sensor, an entire engine, and an ignition timing by a signal output from the cam position sensor. The primary signal is detected by monitoring the primary signal in an ignition primary system including an igniter that is connected to a control device and outputs a primary signal to an ignition coil.

A misfire is detected, for example, by detecting the presence or absence of engine speed fluctuations using a rotation speed signal or the like output from a cam position sensor.

[0005]

However, in the above-described method for detecting an ignition error, it is possible to detect an abnormality caused on the primary side of the ignition system, but to detect an abnormality on the secondary side thereof, for example, a high tension code. We cannot detect failures. Further, in determining the misfire based on the rotation fluctuation, it cannot be determined whether the rotation fluctuation has occurred due to abnormality in the fuel system or due to an ignition mistake. That is, it is difficult to detect an abnormality in the ignition system by any one of the methods, and if either one is used, only an insufficient abnormality can be detected.

An object of the present invention is to solve such a problem.

[0007]

In order to achieve the above object, the present invention takes the following measures. That is, the ignition system abnormality detection method according to the present invention applies a DC voltage sufficient to allow an ionic current to flow in the combustion chamber to the spark plug from almost the same time as the discharge in the spark plug, During the combustion period, at least the current flowing through the spark gap of the spark plug is observed by the DC voltage, and the state of the observed current is determined for each period during which the current flows, and the current determined during the combustion period is an ionic current. Yes, when it is determined that the current value of the ionic current is equal to or greater than a predetermined value set to a value that can determine the ionic current larger than during normal combustion, abnormality of the spark plug of the ignition system is detected. And

[0008]

With such a configuration, at least the current flowing through the spark gap of the spark plug due to the DC voltage flows during each period during discharge and during combustion. Judging considering
An abnormality in the ignition system is determined based on the state of the current, such as the magnitude and duration. That is, if a DC voltage is applied to the spark gap of the spark plug when the discharge is started at the same time as the ignition timing, if the ignition system is normal, the discharge is induced by the discharge and the DC voltage is applied to the ignition gap. Electric current flows. In addition, during normal combustion after the end of discharge, an ion current having a substantially constant magnitude flows into the combustion chamber according to the degree of combustion due to the DC voltage. As described above, if a DC voltage is applied to the spark plug approximately at the same time as the start of discharge, different currents flow during and after the discharge even if the ignition system is normal. If you judge in relation to the period,
An ignition error and an ignition error on the primary side and the secondary side of the ignition system can be easily distinguished and detected.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

An engine 100 schematically shown in FIG. 1 is a four-cylinder engine for an automobile, and its intake system 1 has a throttle valve 2 which opens and closes in response to an accelerator pedal (not shown).
, And a surge tank 3 is provided on the downstream side. A fuel injection valve 5 is further provided near one end communicating with the surge tank 3, and the electronic control unit 6 controls the opening of the fuel injection valve 5 based on a basic injection amount TP described later. ing. The spark plug 1 is located at a position corresponding to the ceiling of the combustion chamber 10.
8 is attached. An igniter 32 and an ignition coil 33 are electrically connected to the spark plug 18 via a diode 31. Spark plug 18,
The igniter 32 and the ignition coil 33 are typically an ignition system IGS, and may include diodes 23 and 33 for preventing current from flowing around.
Although only one cylinder ignition system IGS is shown in FIG. 1, the ignition system is actually provided for each cylinder except for the igniter 32. In the exhaust system 20, an O ₂ sensor 21 for measuring the oxygen concentration in the exhaust gas is provided with a three-way catalyst 2 disposed in a pipe leading to a muffler (not shown).
2 upstream. The engine 100 is not limited to a four-cylinder engine, but may be a three-cylinder engine.
It may be a cylinder or a 12 cylinder.

The electronic control unit 6 includes a central processing unit 7
, A storage device 8, an input interface 9, and an output interface 11. The input / output interface 9 includes a microcomputer for detecting a pressure in the surge tank 3. An intake pressure signal a output from the intake pressure sensor 13;
A cylinder discrimination signal G1, a crank angle reference position signal G2, and an engine speed signal b output from a cam position sensor 14 for detecting a rotation state of the engine 100, and a vehicle speed output from a vehicle speed sensor 15 for detecting a vehicle speed. A signal c, an LL signal d from an idle switch 16 for detecting the open / closed state of the throttle valve 2, a water temperature signal e from a water temperature sensor 17 for detecting the engine coolant temperature, and a current from the air-fuel ratio sensor 21 described above. The signal h and the like are input. On the other hand, the output interface 11 outputs a plurality of signals including a fuel injection signal f to the fuel injection valve 5 and a plurality of signals including an ignition signal IGt to the igniter 32. Although not shown, the electronic control unit 6 has an A / D converter for converting an analog signal into a digital signal.

The spark plug 18 is connected via a high voltage diode 23 to a bias power supply 24 for measuring an ion current and a circuit 25 for measuring an ion current. As the ion current measuring circuit 25 itself including the bias power supply 24, various circuits known in the art can be used, and the same number as the number of cylinders, that is, one for each cylinder is provided. Things.

The electronic control unit 6 includes an intake pressure signal a output from the intake pressure sensor 13 and a cam position sensor 14.
And the rotation speed signal b output from the main engine as main information, the basic injection time TP is corrected by various correction coefficients determined according to the engine state, and the fuel injection valve opening time, that is, the injector final energization time T is determined. A program for controlling the fuel injection valve 5 based on the determined energization time and injecting fuel corresponding to the engine load from the fuel injection valve 5 to the intake system 1 is stored. Further, in order to check the ignition system IGS, a DC voltage sufficient to allow an ionic current to flow through the spark plug 18 into the combustion chamber 10 is applied to the storage device 8 from about the same time as the discharge at the spark plug 18, In the discharge period including immediately after ignition and the subsequent combustion period, at least the current flowing through the spark gap 18a of the spark plug 18 is observed by the DC voltage, and the state of the observed current is determined for each period in which the current flows, When it is determined that the current determined during the combustion period is an ionic current and the current value of the ionic current is equal to or greater than a predetermined value set to a value that can determine an ionic current larger than that during normal combustion, the ignition system IGS The program for detecting the abnormality of the spark plug 18 is stored.

The outline of the ignition system abnormality detection program is as shown in FIG.

When a bias voltage is applied to the spark plug 18 from the bias power supply 24 immediately after the start of discharge, the ion current flows into the combustion chamber 10 at the time of combustion after discharge in accordance with the state of combustion. In the case of normal combustion, the ion current flows rapidly immediately after ignition, decreases before the top dead center TDC, increases again, and reaches a peak value where the value of the ion current becomes maximum near the crank angle where the combustion pressure becomes maximum. Become.

The ion current starts A / D conversion from top dead center TDC in an A / D conversion cycle (unit based on crank angle) set according to the engine speed NE, and converts an analog current value into digital data. The data number D is a certain conversion value, and the obtained conversion value is in ascending order from the top dead center TDC.
Tn is stored in the RAM of the storage device 8. Each time the stored conversion value is compared with the maximum value at that time,
The converted value having the maximum value is stored with a maximum value flag. The A / D conversion is performed for a predetermined time from the top dead center TDC, for example, 30 ° CA in terms of a crank angle.

In FIG. 2, first, in step S1, when the ignition signal IGt is input to the igniter 32 and a discharge period starts, it is determined whether or not the primary current of the ignition coil 33 has flowed. The process proceeds to step S2, and if not, the process proceeds to step S5. This determination may be made based on the fail-safe signal IGf output from the igniter 32. In step S2, when a high DC voltage is applied from the bias power supply 24 during the discharge period, it is determined whether or not a current has flowed into the spark gap 18a of the spark plug 18 via the diode 23,
If the current flows, the process proceeds to step S3; otherwise, the process proceeds to step S5. The discharge period may be set while the primary current is flowing. In step S3,
After the discharge is completed, the peak value of the ion current is compared with a predetermined value,
When the peak value is lower than the predetermined value, the process proceeds to step S4, and when the peak value is higher, the process proceeds to step S5. The predetermined value is set based on an average peak value in the case of normal combustion, and is set to a value that can determine an ion current having a large peak value when the spark plug 18 is wet or carbon is attached. It is. In step S4,
Based on the determination result in step S3, it is detected that the ignition system IGS is in a normal state in which no abnormality has occurred. In step S5, it is detected that an abnormality has occurred in the ignition system IGS based on the determination results in steps S1 to S3.

In such a configuration, if an abnormality occurs on the primary side of the ignition coil 33 of the ignition system IGS, for example, the ignition coil 33 and the igniter 32
If the connection is disconnected or the primary coil is disconnected, the primary current does not flow, and the control proceeds from step S1 to step S5 to detect an abnormality in the ignition system IGS. In this case, the fail-safe signal IGf is not input to the electronic control unit 6.

Next, if the primary current is flowing, but there is no current flowing due to the DC voltage from the bias power supply 24 during the discharge period, the control proceeds to steps S1, S2, S5, as described above. An abnormality in the ignition system IGS is detected. This is because when the ignition system IGS is normal, the DC voltage is supplied from the bias power source 24 during the discharge period to the spark plug 18.
When the voltage is applied to the bias power supply 24,
If the current cannot be detected, no discharge occurs in the spark gap 18a of the spark plug 18 and an abnormality on the secondary side, for example, a defect such as disconnection of the high tension cord occurs. Is to be detected. Similarly, if there is another defect on the secondary side and the spark plug 18 is smoldered or surplus fuel is applied, the smoldering or fogging causes a large ion current to flow, so the control is performed in steps S1 → S2 → S
Go to 3 → S5. Smoldering and fogging are caused by spark gap 18
This lowers the insulation resistance in the vicinity, and acts as a factor that causes the ionic current to leak. For this reason, the ionic current becomes larger than a normal current and exceeds a predetermined value.

On the other hand, the primary side of the ignition system IGS is also 2
If the secondary side is normal, that is, if the primary current is flowing, and a current other than the discharge current flows during the discharge period, and an ion current that is lower than a predetermined value flows during the combustion period after the discharge is completed, control is performed. Proceeds to steps S1, S2, S3, and S4 to detect that the ignition system IGS is normal. If the state of the ignition system IGS detected in this way can be recognized by the user using, for example, a display device or a light-emitting element, the cause of the malfunction of the engine 100 can be found quickly. In addition, since the abnormality of the ignition system IGS is detected separately for the primary side and the secondary side, the user can easily determine which part of the ignition system IGS is defective by devising a display method. The inspection work after the abnormality of the ignition system IGS is found can be facilitated.

The present invention is not limited to the embodiment described above. For example, although the ignition system IGS using the igniter 32 has been described in the above embodiment, a distributor may be used.

In addition, the configuration of each section is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0023]

As described in detail above, the present invention applies a DC voltage to a spark plug, determines whether a current flowing due to the DC voltage has been discharged, and in what period thereafter, the ignition system. Since the abnormality is detected, it is possible to detect whether the abnormality is on the primary side or the secondary side. Since the location of the abnormality can be detected separately, the subsequent inspection work can be facilitated.

[Brief description of the drawings]

FIG. 1 is a schematic configuration explanatory view showing one embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 5 ... Fuel injection valve 6 ... Electronic control unit 7 ... Central processing unit 8 ... Storage device 9 ... Input interface 10 ... Combustion chamber 11 ... Output interface 24 ... Power supply for bias 25 ... Circuit for ion current measurement

Continuation of front page (72) Inventor Toshio Yamamoto 2-1-1 Taoyuan, Ikeda-shi, Osaka Dai-Hatsu Industry Co., Ltd. (56) References JP-A-5-231293 (JP, A) JP-A-4-359131 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02P 17/12

Claims (1)

(57) [Claims] 1. A DC voltage sufficient to allow an ionic current to flow into a combustion chamber is applied to a spark plug from substantially the same time as a discharge in a spark plug, and the DC voltage is applied during a discharge period including immediately after ignition and a subsequent combustion period. At least the current flowing through the spark gap of the spark plug is observed, and the state of the observed current is determined for each period during which the current flows.The current determined during the combustion period is the ion current, and the current value of the ion current An ignition system abnormality detection method, comprising: detecting an abnormality in an ignition system spark plug when it is determined that the ignition current is greater than or equal to a predetermined value set to a value that can determine an ion current larger than that during normal combustion.