JPS5936108B2 - Ignition system for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved structure of an ignition system for an internal combustion engine, and particularly to an ignition system that controls the maximum current value between the ignition coil and the next winding to a predetermined value. By adding a circuit that controls the ignition coil-subwinding current with a control width, the spark arc time (spark plug energy) of the ignition plug can be controlled to a predetermined value.

In conventional ignition devices for internal combustion engines, the maximum current value flowing through the primary winding of the ignition coil is controlled to be constant regardless of battery voltage, engine speed, and spark plug current of the internal combustion engine.

In conventional ignition systems for internal combustion engines, the maximum current flowing through the primary winding of the ignition coil is controlled to a constant value regardless of the arc current flowing through the ignition plug, so there is no need to exceed or shorten the ignition energy required by the internal combustion engine. It has the disadvantage that it can bring about

In order to solve the above-mentioned drawbacks, the present invention measures the arc current value and arc time by detecting the secondary current flowing through the spark plug, that is, the secondary winding current of the ignition coil, using a current detection resistor. (It is also possible to estimate the arc energy consumed by the spark plug if the arc voltage does not change much.) Based on this detection output, it is possible to estimate the arc energy consumed by the spark plug.
An object of the present invention is to provide an ignition device for an internal combustion engine that can obtain the optimum ignition energy required by the internal combustion engine by providing a feedback circuit that controls the next winding current only within a certain predetermined control range. It is something to do.

The present invention will be described below with reference to embodiments shown in the drawings.

In FIG. 1, reference numeral 1 denotes a known ignition signal generating device, one example of which is an ignition timing detecting device using an electromagnetic pickup.

2 is a known ignition signal shaping circuit that amplifies the signal from the ignition signal generator 1, shapes the waveform, and controls the time during which the primary winding current flows through the ignition coil 41 of the ignition circuit 4; 3 is the ignition coil-next winding; A power transistor that controls the line current intermittently (
This is an amplifier circuit that supplies the base current of the Darlington power transistor (Darlington power transistor) 46.

6 is a control circuit that has a function of controlling the base current of the amplifier circuit 3; 7 is a control circuit that detects the primary winding current of the ignition coil 41; a potential difference corresponding to the primary winding current generated in the current detection resistor 45 is set to a predetermined potential difference; This is a comparison circuit for comparison, and the above configuration forms a main feedback loop that controls the ignition coil-next winding maximum current to a predetermined constant value, and the control circuit 6 and comparison circuit 7 in this main feedback loop control the current. Configure the control circuit.

Furthermore, in order to control the arcing time of the spark plug 42 to a predetermined value, the arithmetic circuit 8 uses a current detection resistor 43 that detects the secondary winding current of the ignition coil 41 to control the arcing time of the spark plug 42 to a predetermined value. In order to eliminate fluctuations, the arcing time of the spark plug 42 (arc (energy) is controlled to a constant value.

Note that 5 is a power source battery, 41a and 42b are the primary and secondary coils of the ignition coil 41, and 44 is a Zener diode for protecting the power transistor 46.

Next, the circuit shown in FIG. 1 will be explained in detail with reference to FIG.

The amplifier circuit 3 consists of resistors 31, 32, 33, 35 and a transistor 34.

The control circuit 6 includes a capacitor 61, a resistor 62, and a transistor 63.

Comparison circuit 7 includes resistors 71a, 71b, and 72a. 72b, 7
4, 75a, 75b, 77, transistor 73a 7
3b and a Zener diode 76.

The operational circuit 8 includes an operational amplifier 81, a comparator 82, a capacitor 83, 88, a thyristor 84, resistors 85a to 85m, a transistor 86, a diode 87, and a thyristor 84.
It consists of a gate signal generation circuit 89 for applying a signal to the gate of the gate.

As shown in FIG. 3, this gate signal generation circuit 89 includes inverters 89a, 89b, and a NAND circuit 89d.
89e and a capacitor 89f for determining pulse width, and the input terminal B connected to the input side of the inverter 89a is connected to the output side of the ignition signal shaping circuit 2, and the inverter 89
The output terminals C connected to the output side of the thyristor 84 are connected to the gates of the thyristors 84, respectively.

In the circuit shown in FIG. 3, the power supply positive terminal A and the power supply negative terminal A in the circuit shown in FIG. 1 are omitted.

Next, the operation of the apparatus of the present invention having the above structure will be explained.

An ignition signal generator 1 generates an ignition signal in response to the rotation of the internal combustion engine, and this ignition signal is sent to an ignition signal shaping circuit 2.
The power transistor 46 of the ignition circuit 4 is turned on and off according to the output of the amplifier circuit 3, and the primary winding current of the ignition coil 41 is controlled as shown in FIG. 4a. A high voltage is generated in the secondary winding 41b at 8 points shown in FIG. 4, which are the points at which the primary current is cut off, and an ignition spark is generated in the ignition plug 42.

Here, when an ignition spark is generated in the ignition plug 42, a secondary winding current flows as shown in FIG. voltage is generated.

This voltage is applied to the comparator 82 and compared with the v level shown in FIG.
When the voltage is turned on, the output of the comparator 82 goes to the lOl'' level and the transistor 86 becomes conductive.

Further, at the point in time when the output of the ignition signal shaping circuit 2 becomes lower than the high level as shown in FIG. 4d, the gate signal generating circuit 89
Then, a pulse output as shown in FIG. 4e is generated, making the thyristor 84 conductive and instantly discharging the charge in the capacitor 83.

The resistance value of the resistor 85b and the capacitance of the capacitor 83 are determined so that when the charge in the capacitor 83 is discharged, even when the transistor 86 is conductive, only a current less than the holding current flows through the cyrisk 84. Thyristor 84 shuts off.

Then, the capacitor 83 is only connected to the capacitor 83 during the T1 period during which the transistor 86 is conductive after the thyristor 84 is cut off.
is charged as shown in FIG. 4C.

That is, the charging voltage of this capacitor 83 is
The longer the time that 6 is conductive, the higher the value becomes.

Then, when the transistor 86 is cut off, the capacitor 83
holds its charging voltage, and this charging voltage is compared with level 2 shown in FIG. 4C by operational amplifier 81 to control the primary current for the next cycle.

When the charging voltage of the capacitor 83 is higher than the v2 level, the output level of the operational amplifier 81 becomes high, increasing the bias level of the comparator circuit 7, and increasing the output voltage of the comparator circuit 7.

As a result, the base current of the transistor 3 increases, the conductivity of the transistor 3 increases, the conductivity of the transistor 34 when conductive is decreased, the conductivity of the power transistor 46 when conductive is decreased, and the primary current decrease.

Conversely, when the charging voltage of the capacitor 83 is lower than level 2, the output level of the operational amplifier 81 is lowered, and the bias level of the comparator circuit 7 is lowered.
lower the output voltage.

This reduces the base current of transistor 63, reducing the conductivity of transistor 63, increasing the conductivity of transistor 34 when conducting, increasing the conductivity of power transistor 46 when conducting, and increasing the primary current. increase.

This allows the arc current and arc time to be made uniform.

In addition, since the primary current is detected by the current detection resistor 45 and applied to the comparator circuit 7, when the primary current is large, the output voltage of the comparator circuit 7 increases, reducing the degree of conduction of the power transistor 46 when conductive. When the primary current is small, the output voltage of the comparator circuit 7 becomes small, increasing the degree of conductivity of the power transistor 46 when conducting, increasing the primary current, and constantly constant ignition energy. Control what you get.

In the above-described embodiment, only the arcing time of the spark may be detected by setting the rubel (1) shown in FIG. 4 to the O level.

Further, in the above-described embodiment, the capacitor 83 is discharged at each ignition timing, and the bias level of the comparator circuit 7 is corrected according to the secondary current each time. The bias level of the comparator circuit 7 can be corrected according to the average secondary current per two revolutions of the internal combustion engine by dividing the frequency and discharging the capacitor every - for the number of cylinders. Comparison circuit 7
The bias level may be modified.

As described above, in the device of the present invention, the primary current is feedback-controlled by the feedback circuit in order to control the arc energy to a predetermined value according to the secondary current detected by the current detection resistor connected to the secondary side of the ignition coil. Therefore, the primary current of the ignition coil is feedback-controlled to an optimal value in response to the spark arc of the spark plug, and the most suitable ignition spark can be supplied to the internal combustion engine.
This has an excellent effect in that the usable life of the spark plug can be significantly extended by preventing a decrease or increase in ignition energy due to consumption of the spark plug.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the device of the present invention, and FIG.
The figure is a detailed electric circuit diagram of the device shown in FIG. 1, FIG. 3 is an electric circuit diagram showing a specific circuit of the gate signal generation circuit 89 applied to the device of the present invention shown in FIG. 2, and FIG. 4 is a detailed electric circuit diagram of the device shown in FIG. It is a signal waveform diagram of each part used for explaining the operation of the device. 1...Ignition signal generator, 6,7...
A control circuit and a comparison circuit constituting the current control circuit, 8...
...Arithmetic circuit, 41...Ignition coil, 43,
45... Current detection resistor, 46... Power transistor.

Claims (1)

[Scope of Claims] 1. An ignition signal generator that generates an ignition signal that determines ignition timing, and a power transistor that is turned on and off in response to the ignition signal that is generated in this ignition signal generation device. an ignition coil that is intermittent, a spark plug that is connected to the secondary side of the ignition coil and that generates an ignition spark by the high voltage generated on the secondary side, and a current detector that is connected to the secondary side of the ignition coil. For an internal combustion engine, comprising a resistor and a feedback circuit that performs feedback control of the primary current to control the arc energy to a predetermined value in accordance with the secondary current detected by the current detection resistor connected to the secondary side. Ignition device. 2. The feedback circuit includes a current detection resistor connected to the primary side of the ignition coil, and the power transistor to control the primary current to a predetermined value according to the primary current detected by the current detection resistor connected to the primary side. A patent comprising: a current control circuit that controls a base current of the circuit; and an arithmetic circuit that corrects a primary current control value by the current control circuit in accordance with a secondary current detected by a current detection resistor connected to the secondary side. An ignition device for an internal combustion engine according to claim 1.