JP2523248B2 - Secondary voltage waveform detector for gasoline engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary voltage waveform detecting device for detecting a secondary voltage waveform generated in a secondary circuit of an ignition circuit in a gasoline engine.

[0002]

2. Description of the Related Art In order to purify exhaust gas from automobile engines and improve fuel efficiency, there is a demand for an apparatus capable of detecting ignition and combustion states of each cylinder of an engine and preventing misfire of all cylinders. As a method of detecting the combustion state of each cylinder, the present inventor mainly analyzes the decay characteristic of the electric charge (secondary voltage) charged in the electrostatic stray capacitance of the spark plug to determine the combustion characteristics of each cylinder. It was found that misfire can be detected accurately.

[0003] high voltage cord for supplying secondary voltage to the spark plug is typically on the engine cylinder head, instrumentation to so that the same surface clamped at substantially equal intervals
It is worn .

[0004]

This secondary voltage waveform detection
As a device , close to all high voltage cords installed in parallel 1
The structure in which one conductive plate is arranged is the simplest and the cost is low, and it is not necessary to make a special change to the conventional high-voltage cord mounting .

However, when the high voltage cords are arranged at substantially equal intervals in parallel with one conductive plate, the electrostatic capacitance generated between the high voltage cords arranged at both ends and the conductive plate is arranged inside. The capacitance becomes smaller than the capacitance between the high-voltage cord and the conductive plate, and there is a drawback that the detection accuracy varies.

An object of this invention is approximately equal intervals Ru can Ichika equalizing the electrostatic capacitance generated between the parallel to all high voltage cord and the conductive plates arranged in, gasoline engine secondary voltage waveform detecting device Is provided.

[0007]

The present invention has the following constitution.
Used. (1) Each spark plug installed in a multi-cylinder gasoline engine
High voltage coil that supplies the secondary voltage generated by the ignition coil to the
A conductor is arranged close to the cord, and the conductor is
In the secondary voltage waveform detection device that forms capacitance between the
The conductors are high-voltage cords arranged in parallel at substantially equal intervals.
It is made of a conductive plate that is arranged in parallel with
On the outer side of the conductive plate corresponding to the high voltage cord,
The inner side of the conductive plate corresponding to the high voltage cord located
A capacitance adjusting means for increasing the capacitance is provided.

(2) The high pressure coil having the structure of (1) above.
The conductor is a conductive plate in which arc-shaped grooves corresponding to the
And the outer plate portion of the conductive plate is higher in voltage than the inner plate portion.
The capacitance can be increased by forming it so that it becomes longer in the direction
Configured the adjusting means.

(3) The conductor having the configuration of (1) above,
Is formed of a rectangular flat conductive plate, and the electrostatic
By forming a communication hole for capacitance adjustment, the capacitance adjustment
Configured the steps.

(4) High-voltage cord and conductive plate located outside
Is the distance between the inner high voltage cord and the conductive plate.
Fold both ends of the rectangular flat conductive plate so that it is shorter than the separation.
The capacitance is adjusted by forming the conductor with a bent one.
Configured the node means.

(5) It has the structure of (1) above and is located outside.
A rectangular flat conductive plate that surrounds the high-voltage cord
The conductor should be formed by bending both ends of
Then, the capacitance adjusting means is configured.

[0012]

(Operation and effect of the invention) (Claim 1) Outer side portion of the conductive plate corresponding to the high-voltage cord located outside
The inside of the conductive plate corresponding to the high voltage cord located inside
It is subjected to electrostatic capacitance adjusting hand stage to increase the capacitance from the side.

As a result, the high-voltage cord located outside
The capacitance generated between the conductive plate and the
The capacitance between the high voltage cord and the conductive plate
Become

Therefore, the secondary voltage waveform generated in each cylinder is detected.
The output level is constant (when the combustion state of each cylinder is the same).
Therefore, the combustion state of each cylinder of the engine can be accurately detected.

(Claim 2) Outside of a conductive plate in which arcuate grooves corresponding to a high-voltage cord are arranged in parallel.
The plate part should be longer than the inner plate part in the high-voltage cord placement direction.
Is formed. This ensures that the high pressure coat located outside
Capacitance between the cable and the conductive plate increases,
The capacitance generated between the high voltage cord and the conductive plate
Become equal.

Therefore, the secondary voltage waveform generated in each cylinder is detected.
The output level is constant (when the combustion state of each cylinder is the same).
Therefore, the combustion state of each cylinder of the engine can be accurately detected.

(Claim 3) The conductor is formed of a rectangular flat plate-shaped conductive plate.
A communication hole for adjusting capacitance is formed in the center. By this
Between the high voltage cord located inside and the conductive plate
High-voltage cord and conductive plate located outside, with reduced capacitance
And becomes substantially equal to the electrostatic capacitance generated between.

Therefore, the secondary voltage waveform generated in each cylinder is detected.
The output level is constant (when the combustion state of each cylinder is the same).
Therefore, the combustion state of each cylinder of the engine can be accurately detected.

(Claim 4) The distance between the high-voltage cord located outside and the conductive plate is inward.
The conductor is formed by bending a rectangular flat plate-like conductive plate so that it is shorter than the distance between the high-voltage cord and the conductive plate.

As a result, the high-voltage cord located outside
The capacitance generated between the conductive plate and the
The capacitance between the high voltage cord and the conductive plate
Become

Therefore, the secondary voltage waveform generated in each cylinder is detected.
The output level is constant (when the combustion state of each cylinder is the same).
Therefore, the combustion state of each cylinder of the engine can be accurately detected.

(Claim 5) A rectangular flat plate is arranged so as to surround a high-voltage cord located outside.
The conductor is formed by bending both ends of a rectangular conductive plate.
I have.

As a result, the high-voltage cord located outside
The capacitance generated between the conductive plate and the
The capacitance between the high voltage cord and the conductive plate
Become

Therefore, the secondary voltage waveform generated in each cylinder is detected.
The output level is constant (when the combustion state of each cylinder is the same).
Therefore, the combustion state of each cylinder of the engine can be accurately detected.

[0025]

EXAMPLE A first example of the present invention (corresponding to claims 1 and 2)
Will be described with reference to FIGS. FIG. 1 shows a secondary voltage waveform detecting device 1 of the present invention, which comprises a body 2 having a substantially rectangular plate shape made of electrically insulating rubber or plastic, and a conductive plate 3 embedded in the body 2.

The body 2 also serves as a class <br/> pump attaching preparative high voltage cord 41 to 44 for applying a secondary voltage generated by the ignition coil of a gasoline engine the spark plug on the cylinder head, the upper surface Grooves 21 to 24 each having a semicircular cross section are arranged in parallel at equal intervals to form fitting grooves for the high-voltage cords 41 to 44.

The conductive plate 3 is embedded in the body 2 almost all over the surface thereof in parallel with the high voltage cords 41 to 44, and a predetermined electrostatic capacitance is generated between each of the high voltage cords.

In this embodiment, the conductive plate 3 has the above-mentioned grooves 2
Corrugated plate-shaped metal plate 30 in which grooves 31 to 34 (substantially semicircular in cross section) corresponding to 1 to 24 are arranged in parallel (substantially H-shaped when viewed from above and below)
Is formed by. A lead wire 35 is soldered to the corner of the metal plate 30 and taken out to the outside, and a connector is connected to the tip of the lead wire 35. The metal plate 30, outside
Outer end 3A corresponding to one of the high pressure cords 41, 44
But among corresponding to high voltage cord 42, 43 located on the inner side
It is formed longer than the other end 3B in the wiring direction of the high-voltage cord.

As a result, assuming that the metal plate 30 is rectangular, the high-voltage cords 41 and 44 at both ends and the metal plate 30 are arranged.
Electrostatic capacitance generated between the can, prevents the phenomenon is smaller than the electrostatic capacitance generated between the high voltage cord 42, 43 and the metal plate 30 located on the inner side, all high voltage cord 41 to
It is possible to make the capacitance generated between the metal plate 44 and the metal plate 30 uniform.

As shown in FIG. 2, the grooves 21 to 2 of the body are formed.
The high-voltage cords 41 to 44 connecting the distributor D of the engine E and the spark plug P are fitted in the connector 4, and the fitting surface is filled with a waterproof adhesive. In this state, the secondary voltage waveform detection device 1 is operated by the distributor D
The high pressure cords 41 to 44 connected from the above are collected, clamped on the cylinder head of the engine, and guided to the spark plug P.

FIG. 3 shows an ignition circuit of a gasoline engine equipped with the secondary voltage waveform detecting device 1 of the present invention. The secondary voltage waveform detection device 1 constitutes a secondary voltage divider 5 with a capacitor C connected to the ground, the divider 5 is connected to a secondary voltage waveform detection circuit 6, and the detection circuit 6 is a microcircuit. It is connected to a discrimination circuit 7 such as a computer.

The ignition coil T has a primary circuit L1 connected to the on-vehicle power supply V and the signal generator SG, and a secondary circuit L2 connected to the distributor D and the spark plug P. The secondary voltage waveform detection device 1 holds a capacitance of 1 pF with the high voltage cord 4 of each cylinder. The capacitor C has a capacity of 3000 pF, and a resistor R of 3 MΩ is connected in parallel to form a discharge circuit.

The voltage divider 5 divides the secondary voltage generated in the secondary circuit L2 into 1/3000. As a result, the discharge time constant of the RC circuit becomes about 9 milliseconds, and the relatively slow voltage change of the secondary circuit L2 can be measured. The secondary voltage waveform detection circuit 6 detects the secondary voltage waveform divided by the voltage divider 5.

When the voltage waveform of the secondary voltage waveform detecting device 1 and the capacitor C is a voltage waveform obtained by dividing the voltage waveform of the spark plug P almost as it is, when the fuel-air mixture in the cylinder of the engine E is ignited. Between the electrodes of the spark plug P , when spark discharge occurs but ignition is not performed, smoldering of the spark plug P , performance degradation of the ignition coil T, voltage drop of the power supply V, and the like cause a flying mistake. Among the secondary voltage waveforms applied to, the attenuation characteristics of the secondary voltage waveform charged in the electrostatic stray capacitance of the spark plug P after spark discharge are different. By analyzing the attenuation characteristic of this secondary voltage waveform, it becomes possible to determine the state of a gasoline engine such as a missed flight, misfire, or normal ignition.

For example, when a misfire occurs in a cylinder, fuel ions are not present in the spark discharge gap of the spark plug P, so that the secondary voltage slowly decays, and when ignition occurs, fuel ions are present. Decays faster.

The discriminating circuit 7 compares the characteristic of the divided voltage waveform analyzed by the secondary voltage waveform detecting circuit 6 with the data obtained in advance by experiment or calculation, and outputs a predetermined output to the main computer for controlling the gasoline engine. Alternatively, the control signal is directly output to the control means for controlling the fuel injection amount or the ignition timing.

A second embodiment of the present invention (corresponding to claims 1 and 3)
4 ) is shown in FIG. In this embodiment, the conductive plate 3 embedded in the body 2 is composed of a rectangular flat metal plate 8, and a communication hole 81 for capacitance adjustment is formed in the center of the inner side of the metal plate 8. Are formed.

The capacitance adjusting means is as shown in FIG.
, High-voltage cords 41, 44 located outside and rectangular flat plate shape
The distance L 1 from the conductive plate 3 to the inner high voltage cords 42, 4
3 is made shorter than the distance L 2 between the conductive plate 3 and the conductive plate 3.
Good {third embodiment (corresponding to claims 1 and 4)}.

The capacitance adjusting means is shown in FIG.
As shown in FIG.
Each end of the rectangular flat conductive plate 3 may be bent in a circular manner.
{Fourth embodiment (corresponding to claims 1 and 5)}.

[Brief description of drawings]

FIG. 1 is a perspective view of a secondary voltage waveform detection device of the present invention.

FIG. 2 is a diagram showing how the secondary voltage waveform detection device of the present invention is mounted on an engine.

FIG. 3 is an ignition circuit diagram of a gasoline engine using a secondary voltage waveform detection device.

FIG. 4 is an assembled perspective view of a secondary voltage waveform detection device according to a second embodiment.

FIG. 5 is a sectional view of a secondary voltage waveform detection device of a third embodiment.

FIG. 6 is a sectional view of a secondary voltage waveform detection device according to a fourth embodiment.

[Explanation of symbols]

1 Secondary voltage waveform detector ( secondary voltage waveform of gasoline engine
Shape detection device) 3 Conductive plates 31 to 34 Grooves (arc-shaped grooves) 41 to 44 High-voltage cord 81 Communication hole 3A end (outer side) 3B end (inner side)

Claims (5)

(57) [Claims] 1. A conductor is disposed in the vicinity of a high voltage cord for supplying a secondary voltage generated by an ignition coil to each spark plug mounted on a multi-cylinder gasoline engine, and each conductor is
In the secondary voltage waveform detecting device for forming an electrostatic capacitance between the high voltage cord, the conductor has been made of a conductive plate disposed in parallel with each high voltage cord in parallel at substantially equal intervals, outwardly <br /> outward side portion of the conductive plate corresponding to the high voltage cord positioned, capacitance adjusting means for increasing the inner lateral side by Risei capacitance of the conductive plate corresponding to the high voltage cord located on the inner side A secondary voltage waveform detection device for a gasoline engine, characterized by being provided with. 2. An arc-shaped groove corresponding to the high-voltage cord is arranged in parallel.
Forming the conductor with the conductive plate provided, How to place the high voltage cord from the outer plate of the conductive plate to the inner plate
By forming it so that it becomes longer,
The secondary voltage waveform detection of the gasoline engine according to claim 1, which is configured.
Output device. 3. The conductor is formed of a rectangular flat conductive plate.
Then To form a communication hole for capacitance adjustment in the center of the conductive plate
The gaso according to claim 1, wherein the capacitance adjusting means is constituted by
Secondary voltage waveform detector for phosphorus engine. 4. A high voltage cord and a conductive plate located outside.
The distance is the distance between the high voltage cord located inside and the conductive plate.
Bend both ends of the rectangular flat conductive plate so that
By forming the conductor with
The secondary voltage wave of the gasoline engine according to claim 1, which is configured as a stage.
Shape detector. 5. Circulating around a high-voltage cord located outside
Like a rectangular flat conductive plate with both ends bent in an arc shape
The capacitance adjusting means is constructed by forming the conductor with
The secondary voltage waveform detection of the gasoline engine according to claim 1
apparatus.