JPH0826843B2 - Secondary voltage detector for spark ignition engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is a was generated by the ignition coil high voltage engine fire <br/> flower ignited electrically rather to the spark plug in the plug cable (engine), the secondary circuit of the ignition circuit detecting the formation to the secondary voltage waveform capacitance
The present invention relates to a secondary voltage detector for a spark ignition engine .

[0002]

2. Description of the Related Art In order to purify exhaust gas from an automobile engine and improve fuel efficiency, there is a demand for a device capable of detecting an ignition state of each cylinder of an engine and preventing 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]

However, in the conventional method, it is difficult to determine that the misfire has occurred during the ignition period of the spark stroke starting from the spark discharge of the spark plug, and the mounting is troublesome. However, when it is installed in all cylinders of all vehicles, there are drawbacks such as an increase in installation cost and time-consuming maintenance.

An object of the present invention is to provide a sensor capable of accurately detecting the waveform of the secondary voltage applied to all the spark plugs mounted on each cylinder with a simple structure.

[0005]

[Means for Solving the Problems] A secondary circuit of an ignition circuit is mounted.
And forms a capacitance between the secondary circuit and the secondary battery.
In the secondary voltage detector that detects the pressure waveform,
Insert the rubber or resin collar that has been fitted into the spark plug.
Cover the boot of the rubber cap that is fitted to the
And connect the lead wire to the metal tube to detect the secondary voltage waveform.
Put out.

The secondary circuit of the ignition circuit is attached to the secondary circuit.
Detects secondary voltage waveform by forming capacitance between circuits
When the secondary voltage detector is fixed to the engine,
Plural U-shaped grooves to fit and hold plug cables in
Equipped with a resin or rubber clamper installed side by side
Corresponding to the U-shaped groove near the U-shaped groove of the clamper
Embedding a strip-shaped metal plate having a U-shaped groove,
Connect the lead wire to the metal plate to detect the secondary voltage waveform.

[0007]

With respect to claim 1, the rubber or resin collar in which the metal cylinder is fitted is attached to the spa.
Rubber cap that fits into the high-voltage terminal of the
The secondary voltage detector is constructed by covering the gate part and connecting the lead wire for detecting the secondary voltage waveform to the metal cylinder.

Between the metal cylinder and the high voltage terminal of the ignition coil
The capacitive coupling causes a certain capacitance, which causes the metal cylinder to
The secondary voltage waveform is detected from the connected lead wire.

Incidentally, by analyzing the secondary voltage waveform, normal ignition,
Ignition mistakes and spark discharge mistakes are discriminated, and the discrimination results
Output to the engine control means that
It is possible to prevent deterioration of the catalyst and deterioration of the catalyst. Well
In addition, it can output to the display device to warn the driver.
It

(Claim 2) In the vicinity of the U-shaped groove of the clamper holding the plug cable
A strip-shaped metal having a U-shaped groove having a shape corresponding to the U-shaped groove
Embed the metal plate and strip the lead wire for detecting the secondary voltage waveform
It is connected to a metal plate to form a secondary voltage detector.

Between each plug cable and the strip-shaped metal plate
Is a band-shaped metal that produces a certain capacitance due to capacitive coupling.
The secondary voltage waveform is detected from the lead wire connected to the board.

Incidentally, by analyzing the secondary voltage waveform, normal ignition,
Ignition mistakes and spark discharge mistakes are discriminated, and the discrimination results
Output to the engine control means that
It is possible to prevent deterioration of the catalyst and deterioration of the catalyst. Well
In addition, it can output to the display device to warn the driver.
It

[0013]

Advantageous Effects of the Invention (Claim 1) The secondary voltage detector is fitted in the high voltage terminal of the spark plug.
A metal tube was fitted inside the boot of the rubber cap.
Cover the collar with rubber or resin and attach the lead wire to the metal tube.
It is a configuration to connect. Therefore, the configuration is simple and
A maintenance-free secondary voltage detector with excellent wearability
can get.

(Claim 2) The secondary voltage detector is a clamper for holding a plug cable.
Near the U-shaped groove of the U-shaped groove of a shape corresponding to the U-shaped groove
Embed a strip-shaped metal plate with grooves and connect the lead wires to the strip-shaped metal plate.
It is configured to connect to. Therefore, with a simple configuration,
Maintenance-free secondary voltage detector with excellent wearability
Is obtained.

[0015]

1 shows an ignition device 100 of an internal combustion engine equipped with an ignition coil 1, a distributor (distributor) 2 and a spark plug 3, and a high voltage cord 11 between the ignition coil 1 and the distributor 2 is shown. The secondary voltage detector 4 of the present invention is mounted on the. The secondary voltage detector 4 includes a sensor unit 40 including a conductor 41 mounted close to the high voltage cord 11 and a capacitor 42 connected between the conductor 41 and the ground, and a conductor 41. The voltage dividing detection circuit 5 is connected to the capacitor 42.

The conductor 41 has a structure in which a metal pipe having a length of about 2 cm is externally fitted to the high-voltage cord 11, has a capacitance of 5 pF, and is covered with an insulating and waterproof cover such as rubber.
Is it covered. The capacitor 42 is connected between the conductor 41 and the ground and has a capacitance of 10,000 pF.
In this embodiment, the capacitor 42 is connected to 500 k in parallel.
A resistor 43 of Ω is connected to form a discharge circuit for the capacitor 42.

The sensor unit 40 divides the secondary voltage generated by the high voltage cord 11 into 1/2000. As a result, the high voltage of about 20,000 V is lowered to the level of 10 V and is input to the voltage dividing detection circuit 5. The frequency of high voltage is 10
Since it is around kHz, the impedance of the sensor unit 40 is about 1.6 KΩ. Therefore, the connection of the parallel resistor 43 of 500 KΩ does not affect the voltage dividing ratio so much.

The voltage division detection circuit 5 includes an operation amplifier (operational amplifier) 51, a voltage division circuit 52 of its output, and an integration circuit 53 of the output of the operational amplifier 51.
And a comparator 54 that compares the divided voltage value of the voltage dividing circuit 52 with the integrated value of the integrating circuit 53.

Due to the voltage division of the conductor 41 and the capacitor 42, the voltage waveform at the intermediate point becomes a voltage waveform obtained by dividing the voltage waveform of the secondary circuit as it is, as shown in FIG. , And the subsequent inductive discharge component.

This inductive discharge component is spark-discharged by the spark plug 3 and ignites the fuel-air mixture in the cylinder of the engine, and spark-discharge is generated but is not ignited. Since the electric resistance of the spark discharge gap of 3 is different, the secondary voltage waveform is different.

When ignition is normally performed, the air-fuel mixture during combustion is ionized in the vicinity of the discharge gap immediately after ignition, and the electric resistance is reduced. Therefore, following a capacity discharge of about 100 nanoamperes for about 1 nanosecond, an induction discharge of about 50 milliamperes for about 1 millisecond is performed at a low voltage v ₁ , and the electric energy stored in the ignition coil 1 is almost It is done until it is completely released. Therefore, the increase of the secondary voltage after the induction discharge is small, a low peak waveform P ₁ is generated after the discharge, and the voltage waveform a ₁ is averaged.

When an ignition error occurs, the resistance of the discharge gap is large, so that the induced spark discharge following the capacity discharge ends in a short time, and a relatively large amount of electric energy remains in the ignition circuit (mainly the ignition coil). . Therefore, the discharge voltage waveform a
₂ has a sharply large peak waveform P ₂ following the low voltage v ₂ during the spark discharge due to the capacitive discharge and the subsequent inductive discharge.

Further, although ignition is caused by spark discharge, when the airflow in the cylinder is strong, sparks are caused to flow,
The length of discharge spark becomes longer, the discharge is interrupted, and dielectric breakdown may occur again between the spark plug gaps. For this reason, the secondary voltage waveform a ₃ becomes a ramp voltage v ₃ that gradually increases from a low level, or the capacity discharge occurs again, and after the spark discharge is stopped, the peak waveform P of an intermediate height is generated.
Having ₃ .

The sensor unit 40 secondary voltage waveform a of divided points by is amplified inverted by the operational amplifier 51 is divided further voltage dividing circuit 52 is one input of a comparator 54. The waveform diagram of the voltage dividing point is shown in b. The output of the operational amplifier 51 shows a voltage waveform c at the point where the capacitor C ₁ is charged via the resistor R ₁ of the integrating circuit 53.

The comparator 54 has the above-mentioned voltages b and c.
And outputs the pulse output d to the microcomputer or the pulse width discrimination circuit 55 at the output terminal. As shown in the figure, when ignition is normally performed, the level of the integrated waveform c ₁ is set to be lower than the level of the partial pressure b ₁ except during capacity discharge, and one short pulse d ₁ is output.

When an ignition error occurs, the integrated voltage waveform c ₂
In the case of the capacity discharge, the peak waveform P ₂ is the integrated voltage waveform c
Is set to exceed the _second level, long pulse D ₂ occurs with short pulses d ₂ to the output terminal.

Further, when ignition occurs but a spark in the discharge gap is flowed, the voltage level during the inductive discharge sharply rises as described above, and another capacitive discharge occurs. Therefore, the integrated voltage waveform c ₃ at the end of the induction discharge is at a high level, and the intermediate peak waveform P 3 after the spark discharge is completed.
_{Even if 3} occurs, it is possible to set so that the level of the integrated waveform is not exceeded. By setting in this way, a short pulse d ₃ or d _3
4 occurs.

Of the pulses generated at the output terminal in this way, the pulse d ₁ d ₂ d ₃ d ₄ due to capacitive discharge is extremely short in time with respect to the resonance cycle of the ignition coil, and is generated at the time of ignition failure. The pulse D ₂ for
Reach above The ignition failure is determined by, for example, determining that a misfire has occurred when a pulse of 1/4 or more of the resonance cycle of the ignition coil occurs at the output terminal.

FIG. 3 shows a first embodiment. In this embodiment, resin or rubber in which a metal cylinder 73 is fitted around a boot 72 of a plug cap 7 such as rubber for connecting to a high voltage terminal 71 of a spark plug 3 which is a secondary circuit of an ignition circuit . The conductor 41 is formed by covering the collar 74. The lead wire 64 is connected to the metal cylinder 73.
In addition, the microcomputer or pulse width discrimination
It is electrically connected to the circuit 55.

FIG. 4 shows a second embodiment. The conductor 41 is
Resin or rubber plug cable fixed to the engine
Utilizing the clamper 9 of 60, it is formed by embedding a metal band plate 93 U-shaped groove 92 is continuously provided in correspondence to the U-shaped groove 91 which plugs the cable 60 is fitted. This obi
The lead wire 64 is similarly connected to the metal plate 93, and
Connected to a black computer or pulse width discrimination circuit 55
Has been.

[Brief description of drawings]

FIG. 1 is an ignition circuit diagram of a spark ignition engine equipped with a secondary voltage detector of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the secondary voltage detector.

FIG. 3 is a cross-sectional view showing a first embodiment of a mounted state of a conductor of a sensor section of a secondary voltage detector.

FIG. 4 is a cross-sectional view showing a second embodiment in which a conductor of the sensor section of the secondary voltage detector is attached.

[Explanation of symbols]

1 Ignition coil 2 Distributor 3 Spark plug 4 Secondary voltage detector 7 Rubber cap 9 Clamper 40 Sensor part 41 Conductor 42 Capacitor 60 Plug cable 64 Lead wire 71 High voltage terminal 72 Boot part 73 Metal cylinder 74 Collar 91 U-shaped groove 92 U-shaped groove 93 Band-shaped metal plate

Claims (2)

[Claims] 1. A secondary circuit of an ignition circuit mounted on the secondary circuit.
Detects secondary voltage waveform by forming capacitance between the following circuits
In a secondary voltage detector, a rubber cap that fits a rubber or resin collar with a metal tube fitted inside the high-voltage terminal of the spark plug.
Cover the boot part of the and connect the lead wire to the metal tube to detect the secondary voltage waveform.
That secondary voltage detector of spark ignition engine. 2. A secondary circuit of an ignition circuit, which is mounted on the secondary circuit.
Detects secondary voltage waveform by forming capacitance between the following circuits
The secondary voltage detector is fixed to the engine and the plug cable is fitted.
Resin or rubber with multiple U-shaped grooves arranged side by side
It is equipped with a clamper made of steel , and corresponds to the U-shaped groove near the U-shaped groove of this clamper.
A strip-shaped metal plate having a U-shaped groove having a shape is embedded, and a lead wire is connected to the strip-shaped metal plate to detect a secondary voltage waveform.
Secondary voltage detector for spark ignition engine.