JP3184466B2 - Ignition device for internal combustion engine provided with ion current detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an internal combustion engine for a vehicle, which is provided with an ion current detecting device capable of applying a voltage to a spark plug to flow an ion current when an air-fuel mixture is burning. The present invention relates to an ignition device for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in a vehicle engine, a lean burn control (hereinafter, referred to as a lean burn control) in which an operation is controlled by setting an air-fuel ratio higher than a stoichiometric air-fuel ratio in order to improve fuel efficiency and reduce emissions. (For example, JP-A-6-34491). In such lean burn control, for example, an ion current is passed through the combustion chamber,
In some cases, the ion current is detected to detect combustion fluctuation, and feedback control is performed in lean burn control.
In this case, in order to detect an ion current, an ion current detection device that applies a detection voltage to a plug gap of a spark plug is connected to a secondary coil of an ignition coil of the ignition device.

In an ignition device having such an ion current detecting device, an ion current is generated by applying a detection voltage to the plug gap after the discharge is completed in the plug gap by an ignition signal. . Normally, this ion current is weak, and when knocking occurs, the current corresponding to the knock frequency is superimposed. By detecting the knock frequency component, a more stable combustion state according to the operating conditions is obtained. Can be controlled.

[0004]

By the way, when the knock frequency component fnc is detected, for example, as shown in FIG.
2 connected to the low voltage side of the secondary coil 92c (93 in the figure, a spark plug, 94 is a switching transistor), in a high rotation region, a knock frequency component fnc and a damped oscillation current Ipd. And the noise current component fns due to the knock frequency component fn
It may be difficult to detect c. This is because the mutual induction of the ignition coil 92 causes the energy remaining in the primary coil 92p to attenuate the oscillating current Ip.
However, as shown in FIG. 5, at low rotation, the knock frequency component fnc can be detected with a time interval from the damped oscillation current Ipd by passing through the band-pass filter BPF as shown in FIG.

However, as the rotation speed increases, the time between the damped oscillation current Ipd and the knock frequency component fnc decreases, and in some cases, the knock frequency component fnc completely overlaps the noise current component fns, and It becomes difficult to extract knock frequency component fnc even through filter BPF. As a result, in the operating state where knocking should be detected most, knocking may not be properly controlled.

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

[0007]

In order to achieve the above object, the present invention takes the following measures. That is, the ignition device of the internal combustion engine provided with the ion current detection device according to the present invention, the vibration current component generated by the mutual induction action of the ignition coil, the vibration absorption circuit in the primary coil of the ignition coil of the primary coil
In this configuration, the current is cut off and connected in parallel to absorb the current . With such a configuration, the residual energy generated by the mutual induction in the ignition coil is consumed by the vibration absorbing circuit, and the oscillating current component superimposed on the detected ionic current can be suppressed. As a result, even when the knock component is superimposed on the ion current, it is possible to reliably detect the oscillating current component due to the residual energy because the oscillating current component is suppressed. Therefore, highly accurate knock control can be performed.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition coil for applying a discharge voltage to a spark plug connected to a secondary coil to generate a spark in a plug gap by interrupting a current to a primary coil. When an air-fuel mixture burns, an ion current is generated by applying an ion current detection voltage to the spark plug via the secondary coil
Is allowed to be provided with an ion current detecting device for detecting an ion current, the primary coil of the ignition coil, a vibration absorbing circuit for absorbing a vibration current component superposed on the ionic current after the discharge voltage application, current in the primary coil After shutting off , connect in parallel and detect the ion current with the knock frequency component superimposed.
An ignition device for an internal combustion engine provided with an ion current detecting device, characterized in that the output.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. The ignition device 100 in FIG. 1 is for an internal combustion engine for a vehicle, that is, an engine, and shows a configuration for one cylinder in an engine having a plurality of cylinders such as three cylinders. The ignition device 100 of this embodiment is a so-called full transistor type, and may basically have a configuration known in the art, and includes an ignition coil having a primary coil 1p and a secondary coil 1c. 1, a switching transistor 2 connected to the low voltage side of the primary coil 1p of the ignition coil 1, and a vibration absorbing circuit 3 for absorbing a vibration current component ff superimposed on the ion current Ii after application of a discharge voltage. A current detection device 4 is provided. The high voltage side of the primary coil 1p is connected to the positive electrode of a battery (not shown), and the high voltage side of the secondary coil 1c is connected to the high voltage side of the primary coil 1p via a diode D1. A spark plug 5 is connected between the low voltage side of the secondary coil 1c and the ground G. The switching transistor 2
The illustration of the igniter for driving is omitted.

The vibration absorbing circuit 3 is selectively connected in parallel to the primary coil 1p of the ignition coil 1, and has a configuration in which a resistor 31 and a switching element 32 are connected in series. The resistance 31 preferably has a resistance value smaller than about 100Ω, for example.
Is preferably a bidirectional three-terminal thyristor (hereinafter referred to as a triac). A control voltage Vg is applied to the gate of the triac 32 from the control circuit 6, and the triac 32 is turned on for a predetermined period at a predetermined timing. The timing at which the triac 32 is turned on is a point in time when the discharge ends, and is controlled so that the on state is maintained until the oscillating current component ff generated by the mutual induction action of the ignition coil 1 is attenuated (FIG. 2). . In the case of this embodiment, the triac 32
Is set to turn on from the end of discharge until the next ignition signal SIg rises. Therefore, the control circuit 6
In order to detect the end of the discharge, a primary current Ip flowing through the primary coil 1p of the ignition coil 1 is detected, and it is detected that the primary current Ip has become equal to or less than a preset threshold level THL after ignition. A current measurement and comparison circuit is built-in. The control circuit 6
May be built in an ECU comprising a microcomputer system for controlling the air-fuel ratio of the engine and the like.

The ion current detecting device 4 includes a diode D2
A charge amplifier 41 and a bias power source 42 are connected to the high voltage side of the secondary coil 1c of the ignition coil 1 via the power supply. The bias power supply 42 applies a high bias voltage to the spark plug 5 via a diode after the discharge is completed, that is, immediately after ignition. The charge amplifier 41 amplifies a weak ion current output from the spark plug 5 after the application of the high bias voltage. In order to detect knocking, the ion current detection device 4
Then, a knock detection device including a band-pass filter that filters only the knock frequency component fn superimposed on the ion current Ii at the time of knocking may be connected.

In such a configuration, when the switching transistor 2 is turned on by the ignition signal SIg from the igniter and then turned off, a back electromotive force is generated by the primary current Ip flowing through the primary coil 1p, thereby generating a secondary voltage. A discharge voltage Vd is generated in the secondary coil 1c. And
By applying the discharge voltage Vd to the spark plug 5, a spark discharge occurs in the plug gap of the spark plug 5, and combustion starts. On the other hand, the ignition signal SIg
A high bias voltage is applied to the spark plug 5 from the bias power supply 42 at the time when the discharge is completed, that is, at the time when the discharge ends, to generate the ion current Ii in the combustion chamber. The triac 32 is turned on at substantially the same timing as when the high bias voltage is applied.

When the triac 32 is turned on,
The primary side coil 1p of the ignition coil 1 has a resistor 3
1 will be connected in parallel. By connecting the resistor 31 in parallel with the primary coil 1p, the resistance of the resistor 31 and the primary coil 1p consumes residual energy in the primary coil 1p when the discharge voltage Vd is applied. Therefore, the mutual induction due to the residual energy is suppressed in the secondary coil 1c, and as a result, the oscillating current component f
f (shown by a dotted line in FIG. 2) is absorbed by the resistor 31. By absorbing the oscillating current component ff, the number of large and small peaks generated when the ion current Ii starts to flow is reduced.

Therefore, as shown in FIG. 2, when the knock frequency component fn is superimposed on the ion current Ii at high rotation, the knock frequency component fn overlaps the above-mentioned peak in the signal passed through the band-pass filter. Can be avoided, and knocking can be reliably detected. Further, the period in which the resistor 31 is connected in parallel with the primary coil 1p is from the end of the discharge to the rising of the next ignition signal SIg, so that it is possible to prevent the discharge voltage from lowering. For this reason, reliable ignition can be performed. If the end of the period in which the resistors 31 are connected in parallel is, for example, a predetermined crank angle from the top dead center, the knock frequency component fn superimposed on the ion current Ii
Is a state in which the resistor 31 is not connected in parallel.
Thus, the knocking can be more reliably detected.

The present invention is not limited to the embodiment described above. For example, the ion current detection device 1
04 may be connected to the low voltage side of the secondary coil 1c of the ignition coil 1 as shown in FIG. In this case, the ion current detecting device 104 secures a voltage necessary for generating the ion current Ii therein by charging the secondary coil 1c of the ignition coil 1 when a discharge voltage is generated. And a charge amplifier having the following. That is, the charge amplifier charges while the ignition device 100 is applying a discharge voltage to the spark plug 5, and after the discharge in the spark plug 5 is completed, the charge voltage obtained by charging, that is, the ion current detection voltage, is applied to the spark plug 5. 5, a band-pass filter that amplifies a weak ion current Ii generated by the ion current detection voltage and filters only a knock frequency component fn superimposed on the ion current Ii when knocking occurs (see FIG. No).

Instead of the triac 32, a mechanical switch element such as a relay may be used. In addition, the configuration of each unit is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0017]

As described above, according to the present invention, the vibration absorbing circuit for absorbing the oscillating current component superimposed on the ionic current after the application of the discharge voltage is connected to the primary coil of the ignition coil and the current of the primary coil is cut off. After connecting in parallel , knock
By detecting the ionic current on which the frequency component is superimposed, it is possible to prevent the oscillating current component and the knock frequency component from overlapping. Therefore, a knock frequency component can be detected accurately up to a high rotation range without lowering the ignition performance of the ignition coil.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing one embodiment of the present invention.

FIG. 2 is a waveform chart for explaining the operation of the embodiment.

FIG. 3 is an electric circuit diagram showing another embodiment of the present invention.

FIG. 4 is an electric circuit diagram of a conventional example.

FIG. 5 is a waveform chart for explaining the operation of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ignition coil 1p ... Primary side coil 1c ... Secondary side coil 3 ... Vibration absorption circuit 4 ... Ion current detection device 5 ... Spark plug

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuhiko Okamura 1-115-27 Tsukamoto, Yodogawa-ku, Osaka Die Inside Diamond Electric Co., Ltd. (72) Inventor Yoshiyuki Fukumura 1-15-27 Tsukamoto, Yodogawa-ku, Osaka Die (56) References JP-A-62-48962 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02P 17/00

Claims (1)

(57) [Claims] An ignition coil for applying a discharge voltage to a spark plug connected to a secondary coil by generating a spark in a plug gap by interrupting a current to a primary coil, and when the air-fuel mixture is burned by the spark. And apply an ion current detection voltage to the spark plug via the secondary coil to generate an ion current
And an ion current detection device for detecting, and a vibration absorption circuit that absorbs a vibration current component superimposed on the ion current after applying a discharge voltage to the primary coil of the ignition coil is connected in parallel after the current of the primary coil is cut off Then knock around
An ignition device for an internal combustion engine, comprising: an ion current detection device that detects an ion current on which a wave number component is superimposed .