JPH0552173A - Trouble diagnostic device for ignition device in internal combustion engine - Google Patents

Abstract

PURPOSE:To diagnose a trouble in a spark plug and a secondary coil by detecting voltage of a primary coil of an ignition coil to compare a voltage waveform of the detected voltage with a voltage waveform of the other cylinder. CONSTITUTION:A power transistor 3 is connected as a switching means to a primary coil 2 to connect a spark plug 5 to a secondary coil 4 of an ignition coil 1. These coils are connected to a diagnostic device 11 through a diode 10. A voltage waveform means is constituted of the diagnostic device 11 and the diode 10 to constitute a memory means (RAM), voltage waveform comparator means and a trouble discriminating means by the diagnostic device 11. In the diagnostic device 11, by detecting a voltage waveform, applied to the primary coil, through comparison with a voltage waveform of the other cylinder, abnormality of the spark plug 5 and the secondary coil 4 is decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure diagnostic device for an ignition device in an internal combustion engine.

[0002]

2. Description of the Related Art The following is a conventional example of a failure diagnosis device for an ignition device (Japanese Patent Laid-Open No. 1-130060).
(See the official gazette). That is, a power transistor is connected in series to the primary coil of the ignition coil, and the power transistor is operated so that the ignition plug connected to the secondary coil of the ignition coil is ignited. Further, the back electromotive voltage generated in the primary coil of the ignition coil is detected, and the failure of the ignition device is diagnosed based on the back electromotive voltage.

[0003]

However, in such a conventional failure diagnosing device for an ignition device, the failure is diagnosed from the counter electromotive voltage generated in the primary coil of the ignition device. When an abnormality (for example, an electrode cap abnormality or electrode damage) or a secondary abnormality of the ignition coil occurs, a counter electromotive voltage is generated in the primary coil, and it may be difficult to detect the occurrence of such an abnormality. There is a problem that there is.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a failure diagnosing device capable of determining an abnormality such as an ignition plug.

[0005]

Therefore, according to the present invention, as shown in FIG. 1, the primary coil B of the ignition coil A and the switching means C are connected in series, and the switching means C is connected.
In which the ignition plug E connected to the secondary coil D of the ignition coil A is ignited by driving a voltage detector for detecting the voltage applied to the primary coil B of the ignition coil A. Means F, voltage waveform storage means G for storing the waveform of the detected voltage for each cylinder, voltage waveform comparison means H for comparing the stored voltage waveform with the voltage waveforms of other cylinders, and the voltage waveform comparison means. Failure determination means I for determining a failure of the ignition device based on the comparison result of H;
I was prepared.

[0006]

In this way, by comparing the waveform of the voltage applied to the primary coil with the voltage waveforms of other cylinders,
The failure of the igniter was judged, and it was possible to diagnose even when the spark plug and the secondary coil side were abnormal.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the ignition coil, the power transistor, and the like will be described only for a specific cylinder, and the other cylinders will be denoted by the same reference numerals and description thereof will be omitted. 2 to 6 show a first embodiment of the present invention.

In FIG. 2, a power transistor 3 as a switching means is provided in the primary coil 2 of the ignition coil 1.
Are connected in series, and a spark plug 5 is connected in series to the secondary coil 4. A predetermined voltage is applied to the base terminal of the power transistor 3 from the drive circuit 7 in the control device 6, respectively. The controller 6 includes a water temperature sensor, an idle switch,
Detection signals are input from various sensors 8 such as a crank angle sensor and an air flow meter, and the control device 6 sets the ignition timing based on various information and outputs the ignition timing signal to the drive circuit 7. Further, the control device 6 drives and controls various actuators 9 such as fuel injection valves.

The degree harness connecting the primary coil 2 of the ignition coil 1 and the power transistor 3 is connected to the diagnostic device 11 via the diode 10. The diagnostic device 11 comprises I / O, a CPU, a ROM, and a RAM, and diagnoses a failure of the ignition device as described later. Further, a display device 12 for displaying work instructions and a diagnosis result to a service person is provided, and the display device 12 is driven by the diagnosis device 11. In addition, the input device 1 including a keyboard or a touch screen, etc.
3 is provided, and the input device 13 inputs a work result to the diagnostic device 11 according to an instruction of the diagnostic device 11 or
To operate. The display device 12 and the input device 13
And may be combined.

The diagnostic device 11 and the control device 6 are connected to each other by a mutual communication line, and the control device 6 connects the diagnostic device 1 to the diagnostic device 1.
1, the detection values and calculated values of various sensors are output, and conversely, the diagnostic device 11 outputs an actuator operation command and a sensor detection value to the control device 6. Control device 6
Is preferentially followed by the command from the diagnostic device 11.

Here, the voltage waveform of each part is formed as shown in the time chart of FIG. That is, the signal waveform of A in FIG. 3 is an ignition signal (collector voltage) input from the control device 6 to the power transistor 3 and is formed in a rectangular shape (see FIG. 2), and the signal waveform of B in FIG. 3 is a voltage waveform of the primary coil 2 and a signal waveform of C in FIG. 3 is a voltage waveform of the primary coil 2 input to the diagnostic device 6 via the diode 10.

Here, the diagnostic device 11 and the diode 10 are used.
And constitute the voltage waveform detecting means, and the diagnostic device 11 constitutes the voltage waveform storing means (RAM), the voltage waveform comparing means, and the failure determining means. Next, the operation will be described with reference to the flowcharts of FIGS. The routine shown in the flowchart of FIG. 4 is a routine for storing the voltage waveform on the primary coil 2 side for each cylinder, and the same steps are performed for each cylinder. Therefore, in this routine, the # 1 cylinder and the # 2 cylinder will be described.

In S1, it is determined whether or not the voltage waveform on the primary coil 2 side of the # 1 cylinder is stored in the memory. If NO, the routine proceeds to 2, and if YES, the routine proceeds to S4. In S2, it is determined whether or not the energization of the spark plug 1 of the # 1 cylinder is started. If YES, the process proceeds to S3, and if NO, the routine ends. Here, the start of energization is the time when the ignition signal of the # 1 cylinder changes from LOW to HIGH.
A signal is input from the control device 6 to the diagnostic device 11 via the mutual communication line.

In S3, the voltage sampling value for 10 msec from the start of energization is stored in the # 1 cylinder memory.
In S4, it is determined whether or not the voltage waveform on the primary coil 2 side of the # 2 cylinder is stored in the memory. If NO, the process proceeds to S5, and if YES, the process proceeds to S7. In S5, it is determined whether or not power supply to the spark plug 1 of the # 2 cylinder is started, and YES
If NO, the process proceeds to S6, and if NO, the routine ends.

In S6, the voltage sampling value for 10 msec from the start of energization is stored in the # 2 cylinder memory.
Further, in S7 to S10, it is determined whether or not the voltage waveform is stored in each of the # 3 cylinder to the # 6 cylinder, and the voltage waveform is stored in the memory for each cylinder in a step not illustrated.

Next, the failure determination routine will be described with reference to the flowchart of FIG. In S11, the maximum value VMAX1 of the voltage waveform is obtained from the voltage waveform of the primary coil 2 of the # 1 cylinder stored in the memory for the first cylinder, and the average voltage value VHOLD1 when the voltage value is 18 V or more is obtained. Furthermore, the time during which the voltage of 18 V or higher continues is TH
Calculated as OLD1.

Here, the maximum value VMAX1 is the discharge start voltage, VHOLD1 is the voltage during discharge, and THOLD.
D1 is the discharge time. Further, in S12 to S16, similarly to S11, the maximum values VMAX2 to VMAX6 of the voltage waveform and the average voltage value VHO in the # 2 cylinder to # 6 cylinder.
LD2-VHOLD6, continuous time THOLD2-THO
LD6 is calculated respectively.

In S17, the maximum value V calculated for each cylinder
The average value VMAXAV is calculated by averaging MAX1 to VMAX6. Specifically, the average value of four values of VMAX1 to VMAX6 excluding the minimum and maximum is taken. In S18, the average voltage value V calculated for each cylinder
The average value VHOLDAV of HOLD1 to VHOLD6 is S
It is calculated in the same manner as 17.

In S19, the average value THOLDAV of the durations THOLD1 to THOLD6 calculated for each cylinder is calculated in the same manner as in S17. The average values VMAXAV, VHOLDAV and THOLDAV thus obtained are shown in FIG. In S20, the calculated average value VMAX
The difference between AV and the maximum value VMAX1 to 6 is calculated for each cylinder, and it is determined whether or not the difference (VMAXAV-VMAXN) is less than or equal to a set value VMAXM (for example, 80V), and YE
If S, the process proceeds to S21, and if NO, it is determined that the ignition device of the cylinder has an abnormality, and the process proceeds to S25. Where V
In a cylinder in which MAXAV-VMAXN is larger than VMAXM, it is shown that the discharge start voltage is lower than that in other cylinders, and it is considered that there is no discharge, an abnormality in the electrode interval of the spark plug, an abnormality such as stain.

At S21, the calculated average value VHO is calculated.
The difference between LDAV and the average voltage value VHOLD1 to 6 is calculated for each cylinder, and the difference (VHOLDAV-VHOLD
It is determined for each cylinder whether DN) is larger than a set value VHOLDM (for example, 5V). If YES, the process proceeds to S22, and if NO, it is determined that the ignition device of the cylinder is abnormal, and the process proceeds to S25. Where (VHOLDAV-VHO
In a cylinder whose LDN) is smaller than VHOLDM, it is shown that the discharge voltage is higher than that in the other cylinders, and it is conceivable that there are abnormalities such as an increase in the electrode interval of the spark plug and an increase in the resistance value of the secondary coil 4 system.

In S22, the calculated THOLDA is calculated.
The difference between V and THOLD1 to 6 of each cylinder is calculated for each cylinder, and it is determined for each cylinder whether or not the difference (TOLDAV-THOLDN) is larger than the minimum set value TOLDDML (for example, -1.0 msec), and YES When is S
If NO in step 23, it is determined that the ignition device of the cylinder has an abnormality, and the flow advances to step S25. Where (THOLDAV
-THOLDN) is smaller than THOLDML, the discharge time is longer than that of other cylinders.
Abnormalities such as earth leakage in the secondary coil 4 system are considered.

In S23, the difference (T
HOLDAV-THOLDN) is the maximum set value THOLD
It is determined for each cylinder whether it is smaller than MH (for example, 1.0 msec). If YES, the process proceeds to S24, and if NO, it is determined that the ignition device of the cylinder has an abnormality, and the process proceeds to S25. Where (THOLDAV-THOLDN) is TH
In the cylinders larger than OLDMH, the discharge time is shorter than that in the other cylinders, and it is conceivable that there is an abnormality such as an increase in the electrode interval of the spark plug and an increase in the resistance value of the secondary coil 4 system.

While the ignition device is determined to be normal in S24, it is determined that a failure has occurred in the ignition device in S25.
As described above, the voltage waveform on the primary coil 2 side is detected, and the maximum value of this voltage waveform, the discharge start voltage, and the discharge time are compared with the average value with other cylinders to determine that the ignition device has failed. Therefore, the abnormality of the spark plug 5 and the abnormality of the secondary coil 4 can be determined in the same manner as the abnormality determination of the primary coil 2. Further, since the voltage on the primary coil 2 side is detected, it is very difficult to detect the voltage of the secondary coil because the ignition coil and the spark plug are directly connected as in the low voltage electronic distribution system. This is advantageous and has the effect that it is not necessary to mount a high-voltage measuring probe, and the diagnostic work of a service person can be greatly improved.

FIG. 7 is a flow chart showing the second embodiment of the present invention. In the present embodiment, in order to improve the accuracy of failure determination, the determination is performed in a predetermined engine load operating state in which the secondary ignition request voltage becomes high. That is, S
At 31, the basic injection amount T calculated by the control device 6 is calculated.
P is the second from the first predetermined value TPL (for example, 3.0 msec)
It is determined whether or not it is within a range up to a predetermined value TPH (for example, 3.5 msec). If YES, the process proceeds to S32, and if NO, the routine ends.

In S32, the detected engine speed N is changed from the first predetermined value NL (for example, 800 rpm) to the second predetermined value NH.
(For example, 1200 rpm) is determined, and if YES, the process proceeds to S33, and if NO, the routine ends. Here, the driving state determined in S31 and S32 is a driving state that is established for a predetermined time when the vehicle transmission is idling in the neutral state and the driving is performed.

In S33, the routine shown in the flow charts of FIGS. 4 and 5 of the first embodiment is executed to diagnose the failure of the ignition device.

[0027]

As described above, the present invention detects the voltage of the primary coil of the ignition coil and compares the voltage waveform with the voltage waveforms of the other cylinders to diagnose the failure of the ignition device. Therefore, it is possible to diagnose the failure of the spark plug and the secondary coil, and it is possible to greatly improve the diagnostic workability.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the present invention.

FIG. 2 is a configuration diagram showing a first embodiment of the present invention.

FIG. 3 is a signal waveform diagram of each part of the above.

FIG. 4 is a flowchart of the above.

FIG. 5 is another flowchart of the above.

FIG. 6 is a view for explaining the operation of the above.

FIG. 7 is a flowchart showing a second embodiment of the present invention.

[Explanation of symbols]

 1 ... Ignition coil 2 ... Primary coil 3 ... Power transistor 5 ... Spark plug 6 ... Control device 11 ... Diagnostic device

Claims (1)

[Claims] 1. An ignition device in which a primary coil of an ignition coil and a switching means are connected in series and the switching means is driven to ignite a spark plug connected to a secondary coil of the coil. A voltage detecting means for detecting a voltage applied to the primary coil of the ignition coil; a voltage waveform storing means for storing a waveform of the detected voltage for each cylinder; and a stored voltage waveform for other cylinders. A failure diagnosis device for an ignition device in an internal combustion engine, comprising: a voltage waveform comparison means for comparing with the voltage waveform comparison means; and a failure determination means for determining a failure of the ignition device based on a comparison result of the voltage waveform comparison means.