JPS6056911B2 - Ignition system for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device for an internal combustion engine, and more particularly, to an ignition device for an internal combustion engine that is improved to control the energy during sustained discharge and have ideal and efficient discharge characteristics. This invention relates to a capacitive discharge composite ignition device.

The spark discharge characteristics in the ignition system of an internal combustion engine include the part where the spark starts flying (capacitive discharge) and the part where the spark continues to fly (inductive discharge).The former affects the ignition performance of the fuel, and the latter affects the combustion performance after ignition. It is said that these are factors that affect each of the ignition coils.
capacitive discharge from the secondary distributed capacitance and inductive discharge from the primary inductance), and capacitive discharge using the high voltage generated when the charge charged in the capacitor is released to the primary side of the ignition coil. This method has gradually evolved into a combined current and capacitance discharge method that complements the characteristics of both.

This combined method provides nearly ideal discharge characteristics, such as the fast voltage rise characteristics of the capacitive discharge method and the long discharge duration of the current and disconnection method, but conventionally, each characteristic was fixed and the engine Even if the required discharge characteristics change due to changes in the operating conditions, such as high load low speed operation and constant high speed operation, or acceleration and deceleration, it is not possible to control the three discharge characteristics to follow this change, Or, there was no such idea, and the design was designed to always provide the maximum discharge energy required, resulting in poor efficiency and the fact that the maximum energy was supplied even under operating conditions that did not require the maximum energy, resulting in a huge waste of energy. It was becoming.

The present invention has been made in view of this point, and in order to further utilize energy effectively in the above-mentioned electric current/interruption capacitance discharge combined ignition system which is excellent in principle, it is possible to The purpose is to control the discharge characteristics in order to avoid the mistake of supplying maximum discharge energy even when the maximum discharge energy is not required.

FIG. 1 shows a schematic configuration of an embodiment of the present invention. First, a known or conventional capacitive discharge type circuit portion and a current cut-off type circuit portion for the ignition coil 12 will be explained. When the ignition signal is not output from the signal generation circuit 13, the power transistor 7, which is generally used as a first switching element for cutting off current, is in the on state via the dwell control circuit amplifier circuit 5, and the ignition signal is not output. A primary current from a power source battery 14 flows through the primary winding of the coil 12 .

At the same time, an energy storage capacitor 3 is charged to the desired polarity (+, - in the figure) by a DC high voltage power source 1 such as a DC-DC converter, and a general thyristor is used as a second switching element for capacitance discharge. 2 is off. On the other hand, when the engine rotates and an ignition signal is generated from the ignition signal generation circuit 13, the power transistor 7 is turned off and the primary current of the ignition coil 12 is immediately cut off.

Further, the ignition signal turns on the thyristor 2, and the charge in the energy storage capacitor 3 flows to the primary winding of the ignition coil 12. In such an operation, due to current interruption. Since the generated voltage and the voltage generated by the discharge of the capacitor are combined in the same phase, a synergistic voltage is generated in the secondary winding of the ignition coil 12, and a spark flies to the ignition plug g.

The J configuration of the present invention added to such a conventional configuration will be explained below with reference to Figures 2 to 5.
A specific example of the discharge energy control circuit 20 in this embodiment is shown.

The output of the one-shot multipipulator or one-shot circuit 8, which takes its input from the primary terminal of the ignition coil 12, in this case the negative terminal, becomes a dogleg wave pulse synchronized with the discharge timing, as shown in the third diagram. .

Note that a known appropriate waveform shaping section 15 may be inserted into the one-shot circuit input. As shown from the left hand to the right hand in Figure 4, when the engine speed accelerates, the discharge interval gradually narrows during this transition period, so the one-shot output waveform interval also decreases in proportion to this. I'm going to pick it up.

Considering such a pulse train from an analog level concept, two first and second integrating circuits 9 with different time constants are used.
When integrating by 10, the output voltage change/rate of the smaller time constant, for example, the first integrating circuit 9, is larger, so at each time in this transient state, the output voltage change/rate of the first integrating circuit 9 is larger. A situation arises in which the output voltage of the second integrating circuit 10 is greater than the output voltage of the second integrating circuit 10.

This state is schematically shown in FIG.

For example, during the transition period from 1000r'Pm to 2000rpm, the output voltage of the first integrating circuit is high at any time t1. Therefore, comparator 1
By inputting the first integrating circuit output to the non-inverting or positive phase input of No. 1 and the second integrating circuit output to the inverting or negative phase input, the high level signal (2) is sent to the comparator 11 only during the transition period when the engine speed increases. It can be said that we get the output of

However, strictly speaking, if a sufficiently long time has passed in a steady state, the outputs of both circuits 9 and 10 will be the same in terms of potential regardless of the time constant, so the above requirement that only occurs during acceleration is met. In order to ensure that the following is satisfied, a level shift diode D1 is inserted on the positive phase side in order to obtain a low level of the comparator output in such a steady state.
It is preferable that the positive phase side potential is always lowered by the forward voltage of this diode D1. Even in this case, it is possible to create a condition that the output potential of the first integrating circuit 9 is higher in the previous transition period. In the above manner, for example, if an H signal is obtained as a detection signal to that effect during acceleration, the appropriate primary current limiting circuit 6 as a discharge energy control circuit is controlled to loosen the limitation. This allows large discharge energy to be obtained on the secondary side of the ignition coil.

An example of this circuit 6 is as shown in FIG. A current detection resistor 21 is inserted into the main current line of the power transistor 7, and the converted voltage output is connected to the voltage dividing resistor 24.
, 25a, 25b between 24 and 25a and input to the base of the bypass transistor 26.

The main current line or collector-emitter of the bypass transistor 26 is connected in parallel to the base current line of the power transistor 7.

Therefore, the base current 1 to this power transistor
If JB is the base current given at each ignition timing in a normal configuration without a bypass transistor, then b is the current JB minus the bypass amount due to the bypass transistor (1by) (Ib = IB - 1by).
.

On the other hand, if the resistor 25b is connected in parallel with the collector energizer of the Npn switching transistor 27 in this case, and the comparator output of the signal generation circuit 20 is applied to the base of the resistor 25b, the H level during acceleration ,
When the switching transistor 27 is turned on due to the current inflow, the bypass transistor base potential is relatively lowered due to the short circuit of the resistor 25b, thus creating a condition in which the bypass transistor is not turned on unless the primary current IP becomes considerably large. I can do it.

That is, since the bypass current 1by can be kept sufficiently small or made zero, the primary current 1P can be increased, and eventually the restriction is relaxed or lifted.
A large amount of secondary discharge energy is obtained when high energy is required, which is typically the case during acceleration. Conversely, as is already clear, when the comparator output becomes a low level (L), the switching transistor 27 is turned off, and the resistor 25b is inserted into the circuit. Therefore, even with a relatively small primary current of 1P, the transistor 26 becomes easy to turn on, and the primary current 1P is eventually limited by the bypass current 1by.

Even if the comparator is changed to output L level during acceleration, it is simply a problem with the usual method of logic level processing.
For example, if the resistors 25a and 25b are one fixed resistor 25,
By using two resistors as the resistor 24 and inserting the collector-emitter of the switching transistor in parallel with one of them, the basic current limiting operation and limit value switching mechanism can be achieved, with the only difference being on/off from the previous example. are similar.

In addition, as the energy control circuit 6, a circuit for changing the secondary side impedance or inductance of the ignition coil can be constructed using known techniques, and can be similarly driven by the present signal generation circuit 20. In any case, according to the present invention, although the present invention is excellent in principle, since the output energy is unique, the power supply design specifications must always be adjusted to the maximum required energy. This is a practical improvement to the type ignition system, allowing its advantages to be further extended and resulting in extremely large effects such as being able to suppress wasteful power consumption.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a basic embodiment of the ignition device of the present invention;
Fig. 2 is a schematic configuration diagram of an example of the main part of the first embodiment; Fig. 3;
4 and 5 are explanatory diagrams of the operation of the first embodiment, and FIG. 6 is a configuration diagram of an example of the current limiting circuit. In the figure, 2 is a switching element for capacitive discharge, 3 is an energy storage capacitor for capacitive discharge, 7 is a switching element for current cutoff, 6 is a current limiting circuit as an example of an energy control circuit, 12 is an ignition coil, and 20 is a There is a discharge energy control signal generation circuit.

Claims (1)

[Claims] 1 A current interrupting capacitive discharge combined type ignition device for an internal combustion engine that obtains discharge energy consisting of a capacitive discharge part and a subsequent inductive discharge part on the secondary side of the ignition coil, in which the discharge energy is generated at the primary side negative terminal of the ignition coil. A circuit that outputs a pulse train synchronized with the discharge interval; Two integrating circuits with different time constants that receive the pulse train; Comparing the outputs of the two integrating circuits in magnitude at an analog level, and comparing the outputs of the two integrating circuits when the engine is accelerating and when the engine is not accelerating. and a comparator for differentially detecting the time and outputting the result as an energy control signal, and the energy control signal controls discharge energy to the ignition coil during a transition period when the engine speed increases as the engine accelerates. An ignition device for an internal combustion engine, characterized in that a control circuit is brought into a control state suitable for supplying high energy.