JP3213161B2 - Ion current detection 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 abnormality in an ion current detection system for detecting an abnormality in an ion current control system in a control using an ion current in an automobile engine.
It relates to a detection method.

[0002]

2. Description of the Related Art Conventionally, in an engine used in an automobile or the like, a high voltage is applied to a spark plug during combustion to generate an ionic current in a combustion gas, and the characteristics of the ionic current are measured. For example, there is known a fuel injection type engine which controls the injection amount of a fuel injection type engine (for example, Japanese Patent Application Laid-Open No. 58-75).
No. 36). Normally, the elements measured as the characteristics of the ionic current include a maximum current value that almost coincides and becomes maximum when the combustion pressure becomes maximum, a time until the maximum current value is reached, and an integrated value of the current value. Etc.

[0003]

However, the characteristics of the ion current are not always accurately measured, and if the control is performed based on erroneous measurement, the engine may stop. . For example, when the cooling water temperature of the engine is equal to or higher than a predetermined water temperature, and a normal value is also detected for the engine speed and the air-fuel ratio, an ion current having a characteristic predicted from such an operating state of the engine is generated. Even if it cannot be detected, if the engine control is performed by measuring the characteristics of the detected ion current, the engine operation will be erroneous because it is different from the actual operation state of the engine.

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

[0005]

In order to achieve the above object, the present invention takes the following measures. That is, the ion current detection system abnormality detection method according to the present invention employs an ion current detection method for detecting an ion current generated in a combustion chamber.
Equipped with an ion current detection system.
In a control system that controls the engine using the characteristics of the output ion current , the peak value of the ion current is detected, and the detected peak value of the ion current is equal to or greater than a predetermined value.
It is determined that the ion current detection system is abnormal, and the peak value of the detected ion current is equal to or greater than a predetermined value, and the starting amount is increased.
If it is time, determine that the ion current detection system is abnormal
It is characterized by not doing.

[0006]

[Function] With such a configuration, the detected ion
If the peak value of the ion current is
Is used to detect abnormalities in the output system.
Make sure that the peak value of the flow is
If it is time, determine that the ion current detection system is abnormal
Therefore, a normal operation state can be maintained.

[0007]

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

The 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.
This ignition system IGS except for the igniter 32 is shown in FIG.
Although only the system is shown, one cylinder is used for each cylinder.
They are connected system by system. The exhaust system 20 includes
O ₂ sensor 21 for measuring oxygen concentration in exhaust gas
Is mounted at a position upstream of a three-way catalyst 22 provided in a pipe leading to a muffler (not shown). In addition,
The engine 100 is not limited to a four-cylinder engine, but may be a three-cylinder or twelve-cylinder engine.

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 an ion current measuring circuit 25 to form an ion current detection system IDL. Various circuits known in the art can be used as the ion current measuring circuit 25 itself including the bias power supply 24.
The same number as the number of cylinders, that is, one ion current detection system IDL is provided for one cylinder.

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. In the control system that detects the ion current generated in the combustion chamber and controls the engine 100 using the characteristics of the ion current, the storage device 8 stores the ion current in the operating state where the ion current can be normally generated. Detecting the current, determining the characteristic of the detected ion current, and prohibiting control of the engine 100 using the characteristic of the ion current when the determined characteristic is different from the characteristic of the ion current predicted in the operating state. Program is stored. In this program,
If the detected characteristics differ from the expected characteristics,
Engine control based on the characteristics of the ionic current
Not done. In other words, operation where ion current can be generated normally
In the state, it is usually possible to predict the characteristics of the ion current.
The detected ion current characteristics differ from the predicted characteristics.
Indicates that an abnormality has occurred in the ion current detection system.
It means you did. Therefore, in such a case
Of Engine Based on Characteristics of Ion Current Detected
Is executed, the control is not suitable for the actual operation state.
Therefore, erroneous control can be performed by prohibiting this.
Is prevented. This program also includes ion current
And the peak value of the detected ion current is
If the value is equal to or greater than the predetermined value, it is determined that the ion current detection system is abnormal,
If the peak value of the detected ion current is equal to or
If it is time to increase the operating time,
Includes steps that are not determined to be out of line abnormalities.

[0012] This engine erroneous control prohibition and ion current detection
The outline of the outgoing system abnormality detection program is as shown in FIG.

In step S1, it is determined whether or not the engine 100 is in a normal operation, that is, an operation state in which an ion current can be generated normally. If the operation is normal, the process proceeds to step S2. Transition. The normal operation refers to, for example, a case in which conditions (predetermined values) such as a cooling water temperature, an engine speed, and an engine load are set, and the operation state satisfies the conditions. Specifically, the cooling water temperature is 270 ° C. or more, the engine speed is 500 rpm or more, and the intake pressure (load) is −450 m.
Hg above may be set feedback control execution moderate conditions based on the signal of the O ₂ sensor 21. Step S2
Then, it is determined whether or not an ion current is detected. If detected, the process proceeds to step S3, and if not, the process proceeds to step S4. In this embodiment, it is assumed that a peak value as one of the characteristics of the ion current is detected. In step S3, it is determined whether or not the ion current has an abnormal characteristic, that is, an abnormal peak value. If the ion current is not an abnormal peak value, the program is terminated. If the ion current is abnormal, the process proceeds to step S4. Normally, the peak value of the ion current during normal combustion increases only to a substantially constant level with the upper limit of the state where the throttle valve 2 is fully opened as an upper limit. Therefore, the peak value of the detected ion current may be compared with a predetermined value (upper limit value), and if it is larger than the predetermined value, it may be determined that the peak value is abnormal. In step S4, it is detected that the ion current detection system IDL is in an abnormal state.

In step S5, similarly to step S3, it is determined whether or not the ion current has an abnormal peak value. If the ion current has an abnormal peak value, the process proceeds to step S6. Move to step S8. In step S6, it is determined whether or not it is at the time of starting,
If it is at the time of starting, the process proceeds to step S7; otherwise, the process proceeds to step S4. In step S7, start-up control such as correcting the basic injection amount TP with a start-up increase correction coefficient is performed. In step S8, normal control according to the operation state at that time is performed.

Normally, 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 to the combustion chamber 10 at the time of combustion after discharge according to 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 this way, if the converted value is given the data number DTn, the position at which the converted value becomes the maximum value (in terms of crank angle)
Can be easily specified. For example, the control of the ignition timing can be executed using the data indicating the position of the maximum value.

In such a configuration, the engine 100
If the ion current is not detected despite the normal operation, that is, as shown in FIG. 3, if the ion current is instantaneously observed after ignition, but the ion current is large even if combustion proceeds, If no peak occurs, the control proceeds from step S1 to S2 to S4 to detect an abnormal state of the ion current detection system IDL and prohibit engine control based on the ion current. Further, in a normal operation state and in a state where the ion current is also detected, when the peak value of the ion current indicates an abnormal value as shown in FIG. 4, that is, the peak value is equal to the upper limit value. If it exceeds, the control proceeds to steps S1 → S2 →
The process proceeds from S3 to S4, and the control of the engine is similarly prohibited.

On the other hand, if the engine 100 is not operating normally and there is no abnormality in the ion current, the control
The process proceeds from step S1 to S5 to S8, and normal control is performed. If the operation is not normal and the peak value of the ion current also indicates an abnormal value and the operation is not the operation at the time of starting, the control is performed in steps S1 → S5 → S
Proceeding from 6 to S4, the control of the engine based on the ion current is prohibited. On the contrary, if the engine is not in the normal operation state and the abnormal ion current peak value is measured, but the start time is the start time, especially when the engine is in the cold state, the control proceeds to step S1 → S5 → S6 → S7,
The control at the time of starting is performed without detecting abnormality of the ion current detection system IDL. That is, at the time of starting, a leak occurs due to smoldering or fogging of the spark plug 18 and the peak value of the ion current exceeds a normal value, but a causal relationship between the abnormal value and the operation is apparent. Therefore, there is no problem with the ion current detection system IDL.
Is not detected as an abnormality.

As described above, the characteristic of the ion current is determined in consideration of the operation state of the engine, and the abnormal state of the ion current detection system IDL is determined based on the result to prohibit the control. It can be effectively prevented, and a normal operating state can be maintained. If the abnormal state of the ion current detection system IDL 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, when such a display device is used, an abnormality other than at the time of starting the ion current detection system IDL is displayed because the abnormality is caused by the detection system IDL itself. That is, since the ionic current indicates an abnormal value due to smoldering, fogging, or the like, the display may not be performed. By displaying the abnormality, the user can appropriately perform the subsequent processing.

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.

[0022]

According to the present invention, as described in detail above, detection
When the peak value of the ion current is higher than
If it is time to increase the volume, use the ion current detection system.
Operation is not considered abnormal.
Can be. In addition, the characteristic of the ion current is determined, and when the characteristic is different from the expected characteristic, the control of the engine based on the characteristic of the detected ion current is prohibited. In addition, erroneous control of controlling the engine based on erroneous information due to the characteristics of the ion current can be prevented.

[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.

FIG. 3 is a waveform chart showing a waveform of an abnormal ion current of the embodiment.

FIG. 4 is a waveform chart showing a waveform of an abnormal ion current 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 the front page (72) Inventor Toshio Yamamoto 2-1-1 Taoyuan, Ikeda-shi, Osaka Dai-Hatsu Kogyo Co., Ltd. (56) References JP-A-7-119533 (JP, A) JP-A-5-26093 (JP, A) JP-A-5-215059 (JP, A) JP-A-58-7536 (JP, A) JP-A-4-148077 (JP, A) JP-A-4-259671 (JP, A) JP-A-5-223002 (JP, A) JP-A-5-187306 (JP, A) JP-A-5-149230 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 45 / 00 345 F02P 17/12

Claims (1)

(57) [Claims] An ion current generated in a combustion chamber is detected .
An ion current detection system is provided.
Ri in the control system by utilizing the characteristics of the detected ion current for controlling the engine, it detects <br/> the peak value of the ionic current, i when the peak value of the detected ion current is greater than a predetermined value
It is determined that the ON current detection system is abnormal, and the peak value of the detected ion current
If it is time to increase the operating time,
Ion current detection characterized by not judging that the output system is abnormal
Output system abnormality detection method.