JPH0526097A - Ignition device with misfire detector for gasoline engine - Google Patents

Abstract

PURPOSE:To provide an ignition device with a misfire detector the constitution of whose device and maintenance is simple and which can detect misfire accurately, in the case of a DLI(distributor less igniter) type ignition device. CONSTITUTION:In the case of a DLI type ignition device consisting of a power source 2, an ignition coil 1, a spark plug 3 and an ignition coil primary electric current intermittence means 4, an ignition device with a misfire detector is provided with a primary electric current rise-up delay circuit 5 at an ignition coil primary circuit. An ion electric current power source 6 consisting of a diode 64 and a condenser 61, and an ion electric current detecting circuit 7 are fitted to the secondary circuit of the ignition coil. Also, in the case of an ignition device with a flying spark mistake and misfire detector, a condenser 61 charging electric current and discharging electric current detecting circuit 8 is fitted in addition to the above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasoline engine using a distributorless igniter (hereinafter referred to as DLI) type ignition device for directly applying a secondary voltage of an ignition coil to a spark plug without passing through a distributor. Regarding misfire detection.

[0002]

2. Description of the Related Art In a gasoline engine such as an automobile engine, in order to purify exhaust gas and improve fuel efficiency, it is required to detect an ignition state of each cylinder and prevent misfire of all cylinders. Further, as a misfire detection device, conventionally, a method of making a hole in a cylinder block and mounting a combustion light sensor, mounting a pressure sensor on a mounting seat of a spark plug, and measuring an ionic current of an ignition circuit are known.

[0003]

The conventional misfire detection method has a drawback that the sensor mounting and maintenance are troublesome and the practicality thereof is poor. In the DLI type ignition device, a diode or series gap is inserted in the secondary circuit to prevent ignition due to spark discharge caused by the secondary voltage generated at the start of energization of the primary current, and an ion current is passed. I can't. The purpose of this invention is to
It is an object of the present invention to provide a misfire detection device for an I-type ignition device which has a configuration that can be easily mounted and maintained and which can accurately detect misfire. In addition to the above, it is an object of the present invention to provide an ignition device with a misfire and misfire detection device for a gasoline engine, which is capable of detecting a misfire with a spark plug.

[0004]

An ignition device with a misfire detection device for a gasoline engine according to the present invention comprises a power source, an ignition coil, a spark plug, and a primary current interrupting means for the ignition coil. In an ignition device that generates a secondary voltage in the secondary coil of the ignition coil by shutting off the primary current supplied to the primary coil and applies the secondary voltage directly to the spark plug, the primary current rises in the primary circuit of the ignition coil. A delay circuit was attached, an ion current power supply consisting of a diode and a capacitor was installed in the secondary circuit of the ignition coil, and a discharge current detection circuit for the capacitor was installed. An ignition device with a miss-fire and misfire detection device for a gasoline engine according to the present invention comprises a power source, an ignition coil, a spark plug, and a primary current interrupting means for the ignition coil, which is supplied from the power source to the primary coil of the ignition coil. In the ignition device in which a secondary voltage is generated in the secondary coil of the ignition coil by shutting off the primary current and the secondary voltage is directly applied to the spark plug, a primary current rising delay circuit is attached to the primary circuit of the ignition coil. The secondary circuit of the ignition coil was equipped with an ion current power source consisting of a diode and a capacitor, and a detection circuit for the charging current and discharging current of the capacitor was attached.

[0005]

According to the present invention, in the DLI type ignition device, a primary current rising delay circuit is attached to the primary circuit to lower the level of the secondary voltage generated at the start of energization of the primary current. At the same time, the secondary circuit is equipped with an ion current power source that charges the capacitor with a voltage of several hundred volts. This prevents spark discharge from being generated at the secondary voltage when the energization of the primary current is started. Ion current flows from the ion current power supply when the ignition and combustion are normally performed and the ions are present at a high density in the spark discharge gap. On the other hand, when a misfire occurs, fuel and air molecules remain in the spark discharge gap of the spark plug as they are, and the insulation resistance is large, so that no ionic current is generated. Therefore, the misfire can be detected from the presence or absence of the ion current. Further, the charging current to the capacitor at the time of spark discharge is detected, and when this current is equal to or higher than the set value, it is determined that the spark discharge has normally occurred. With this, a miss of flying fire is detected.

[0006]

According to the present invention, misfire can be discriminated by all electric circuits. Therefore, it is not necessary to mount sensors such as a combustion light sensor and a pressure sensor, and the structure is simple and the mountability to the engine is excellent. In addition, a high-voltage diode or series gap in the secondary circuit is not necessary, and a highly practical DLI ignition device with a misfire detection device can be obtained. Further, in the invention according to claim 2, the misfire detection device can be used almost as it is to detect a sparking mistake of the spark plug, and the operating state of the engine can be detected more accurately.

[0007]

FIG. 1 shows a primary coil L1 and a secondary coil L.
1 shows an ignition device 100 for an internal combustion engine, which includes an ignition coil 1 provided with 2, a power source 2 such as a battery, and a spark plug 3 mounted on a cylinder. To the primary circuit 11 of the ignition coil 1, the power supply 2, the primary current interrupting means 4, and the rising delay circuit 5 of the primary current are connected. The secondary circuit 12 of the ignition coil 1 is provided with an ion current power supply circuit 6 and an ion current detection circuit 7, and is connected to the spark plug 3.

The primary current interrupting means 4 is composed of a switching element 41 and a signal generator 42, detects the crank angle and throttle opening of the engine, and the spark discharge timing becomes an ignition advance angle adapted to the load and rotational speed of the engine. So that the primary current is intermittent.

The primary current rising delay circuit 5 comprises a capacitor 52 and a resistor 53 connected in parallel via a diode 51. The ion current power supply circuit 6 includes a capacitor 61.
And a Zener diode 62 are connected in parallel, and between the capacitor 61 and the ground, a resistor 63 forming a discharging circuit of the capacitor 61 and a diode 64 forming a charging circuit of the capacitor 61 are formed.

The operation of the misfire detection device of the present invention will be described with reference to the waveform chart shown in FIG. Signal generator 4
2 outputs a pulse signal a for interrupting the primary current, and the signal b that rises gently as in the switching element 41 is input. Switching element 41
By turning on and off, the secondary voltage shown in the ignition coil 1 of the secondary circuit 12 is generated. That is, the pulse wave a
The secondary voltage in the reverse direction generated at the start of is at a very low level, and is inserted into the secondary circuit 12 in the DLI igniter in order to prevent spark discharge from occurring in the spark plug 3 other than the ignition timing. A step-down diode for preventing backflow can be eliminated. At the end of the pulse wave a, a spark discharge is started by a high voltage p of 10 kilovolts or more, followed by a gentle voltage waveform q due to induction discharge of a level of several hundred volts. Further, the secondary voltage starts to be boosted before the end of the induction discharge, and further boosts after the end to show a gentle peak and then drop.

After the spark discharge is finished, the charge charged in the capacitor 61 (ion current power supply circuit 6) at the conduction voltage level of the Zener diode 62 is set to 1 megohm to adjust the time constant to a measurable time constant. As shown in FIG. 2, there is a difference in the current waveform between the case of normal ignition and the case of misfire by flowing through the discharge gap of 63 and the spark plug 3. That is, when ignited and burned, a gradual increase and decrease of the ionic current s is detected following the peak current r for charging the floating capacitance of the spark plug. Only r flows and no ionic current flows. Ion current detection circuit 7
Converts into a pulse indicating a current of a set level t or higher and outputs the pulse, and detects misfire based on the magnitude of this pulse width.

FIG. 3 shows an ignition circuit with a miss-fire and misfire detection device according to a second aspect of the present invention. In this embodiment, a resistor 65 is inserted between the diode 64 forming the charging circuit of the capacitor 61 and the ground, and in addition to the ion current (the discharging current of the capacitor 61) in the current detecting circuit 8, the discharge current during the spark discharge is increased. The charging current of the capacitor 61 due to the next voltage is also detected. As for the resistor 65, while the resistor 63 is a large resistor of about 1 megohm,
Use a resistor as small as 100 ohms.

As shown in FIG. 4, the charging current of the capacitor 61 has a waveform in which a high peak current of 20 to 30 milliamperes gradually decreases as the current waveform u when the spark discharge is normally performed by the spark plug 3. Becomes On the other hand, as shown in FIG. 5, when carbon C or the like adheres to the surface of the insulator 31 of the spark plug 3 and carbon sparks occur inside the spark plug 3 through the carbon C, a spark discharge S occurs. Is as follows.

For example, if the resistance of carbon C is 10 megohms and discharging through this resistance, the discharge voltage is 2
Even at 0 kilovolts, only 2 milliamperes of current will flow. Therefore, for example, 10 milliamperes is set as a reference level for determination, and when a current higher than this is set, normal spark discharge is performed, and when a current equal to or lower than the set level flows, it is determined that a flying miss has occurred.

Also, the disconnection of the ignition coil 1 and the primary circuit 11
Alternatively, when a spark discharge is not normally performed due to a faulty or degraded function of the ignition circuit such as a connection failure of the secondary circuit 12 or a voltage drop of the power supply 2, a so-called flying error occurs, or a secondary voltage does not occur or occurs. However, it is a low level. Therefore, the charging current of the capacitor 61 does not flow at all, or even if it flows, it has a low and gentle waveform as shown by the current waveform v.
When a secondary voltage of a level that does not allow dielectric breakdown of the spark plug 3 is generated in the secondary circuit 12, the current flowing to charge the floating capacitance of the spark plug 3 has a floating capacitance of 20 picofarads. If the secondary voltage is 20 kilovolts, it is 4 milliamps. Therefore, it is possible to discriminate the flying miss at the set level of 10 mA.

In this way, by measuring the level of the charging current to the capacitor 61 by the current detection circuit 8 and comparing it with the reference value obtained by the experiment or the calculation, it is possible to detect the missed spark in the spark plug 3. Therefore, by detecting the misfire in the spark plug 3 and then detecting the misfire, the cause of the misfire can be detected more accurately,
It can contribute to the improvement of the operation control of the gasoline engine.

[Brief description of drawings]

FIG. 1 is an ignition circuit diagram of a gasoline engine equipped with a misfire detection device of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the misfire detection device.

FIG. 3 is an ignition circuit diagram with a flying miss and misfire detection device of the present invention.

FIG. 4 is a waveform diagram for explaining the operation of the missed fire and misfire detection device.

FIG. 5 is a cross-sectional view of essential parts of the spark plug showing a smoldering state.

[Explanation of symbols]

1 ignition coil 2 power supplies 3 spark plugs 4 Primary current interruption means 5 Primary current rising delay circuit 6 Ion current power supply circuit 7 Ion current detection circuit 8 Current detection circuit 12 Secondary circuit 61 Capacitor 62 Zener diode

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location G01M 15/00 Z 7324-2G (72) Inventor Yasuo Ito 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Nippon Special Ceramics Co., Ltd.

Claims (2)

[Claims] 1. A secondary coil of an ignition coil, comprising a power source, an ignition coil, a spark plug, and a primary current interrupting means for the ignition coil, which is cut off by a primary current supplied from the power source to the primary coil of the ignition coil. Generate a secondary voltage,
In the ignition device for directly applying the secondary voltage to the spark plug, a primary current rising delay circuit is attached to the primary circuit of the ignition coil, and an ion current power source composed of a diode and a capacitor is provided in the secondary circuit of the ignition coil. An ignition device with a misfire detection device for a gasoline engine equipped with a capacitor discharge current detection circuit. 2. A secondary coil of the ignition coil, comprising a power source, an ignition coil, a spark plug, and a primary current interrupting means for the ignition coil, which is cut off by a primary current supplied from the power source to the primary coil of the ignition coil. Generate a secondary voltage,
In the ignition device for directly applying the secondary voltage to the spark plug, a primary current rising delay circuit is attached to the primary circuit of the ignition coil, and an ion current power source composed of a diode and a capacitor is provided in the secondary circuit of the ignition coil. An ignition device with a miss-fire and misfire detection device for gasoline engines equipped with a circuit for detecting the charging current and discharging current of a capacitor.