JPS5912169A - Ignition device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the consumption of useless electric power by a method wherein an electric discharge energy control circuit is controlled by a control signal generated in accordance with the transitional change of the pulse train interval of pulse signals synchronized with the interval of electric discharge, in the compound electric current interrupting capacity and electric discharge type ignition device. CONSTITUTION:An ignition coil 12 is provided with a primary current by putting a thyristor 2 ON by an ignition signal from an ignition signal generating circuit 13 to discharge a capacitor 3 while the primary current of the ignition coil 12 is interrupted by putting a power transistor Tr7 OFF by the ignition signal. The ignition device of such type is provided with the electric discharge energy control signal generating circuit 20. The circuit 20 is constituted by a one shot circuit 8, converting a signal taken out of the primary terminal of the ignition coil 12 into a rectangular wave pulse synchronizing with the timing of electric discharge, two sets of integrating circuits 9, 10, integrating the output of one shot circuit 8 and having respective different time constants, and a comparating circuit 11, comparing the outputs of the circuits 9, 10 and controlling a current control circuit 6 in accordance with the result of the comparation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device for an internal combustion engine, and more particularly, to
The present invention relates to a current-interrupting capacity-discharge composite ignition device that has been improved to have ideal and λ-efficient discharge characteristics by controlling the energy of the current.

The characteristics of spark discharge 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 flying (inductive discharge).The former affects the ignition performance of the fuel, and the latter affects the combustion after ignition. It is said that these factors each affect the performance, and the history is a current cutoff method (which utilizes the high voltage generated when the primary current of the ignition coil is cut off).
A capacitive discharge method that utilizes the high voltage generated when the charge charged in the capacitor is released to the primary side of the ignition coil (capacitive discharge from the secondary distributed capacitance and inductive discharge from the primary inductance occur continuously) From, the current breaking capacity number that complements the characteristics of both! It has gradually evolved into a composite method.

This combined method provides nearly ideal discharge characteristics, such as the fast voltage rise υ characteristic of the capacitive discharge method and the long discharge duration of the current cutoff method, but in the past, each characteristic was fixed and the engine Operation-3- Even if the required discharge characteristics change, such as between high-load low-speed operation and constant high-speed operation, or between acceleration and deceleration, the discharge characteristics can be controlled to follow these changes. However, since the idea was designed to always provide the maximum discharge energy required, it was inefficient and it was impossible to provide the maximum energy even under operating conditions that did not require the maximum energy. It had become a waste of money.

The present invention has been made in view of this point, and in order to further utilize energy effectively in the above-mentioned current interrupting capacity discharge combined type ignition device which is excellent in principle, the maximum discharge The purpose is to control the discharge characteristics in order to avoid the mistake of supplying maximum energy even when no energy is 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 cutoff type circuit portion for an ignition coil saw will be explained. When the ignition signal is not output from circuit 3, the power transistor 7, which is commonly used as the first switching element for current interruption, is in the on state through the dwell control circuit and the amplifier circuit, and the ignition coil saw is turned on. A primary current from the power supply battery flows through the primary winding.

At the same time, the energy storage capacitor 3 is charged to the desired polarity (+, - in the figure) by a DC high-voltage power supply such as a DC-DC converter, and a general thyristor is used as the second switching element for capacitance discharge. is turned 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 2 is cut off. In addition, the ignition signal controller turns on, and the charge in the energy storage capacitor 3 flows to the primary winding of the ignition coil.

In this type of operation, the voltage generated by current interruption and the voltage generated by capacitor discharge are combined into the same phase, so a synergistic voltage is generated in the secondary winding of ignition coil 1-2. Then, a spark flies to the spark plug t.

The configuration of the present invention added to such a conventional configuration will be explained below with reference to FIGS. 2 to 5. FIG. 2 shows a specific example of this embodiment of the discharge energy control circuit 20. It shows.

The output of the one-shot multivibrator or one-shot circuit which takes the input from the primary terminal of the ignition coil saw, in this case the negative terminal, becomes a rectangular wave pulse synchronized with the discharge timing as shown in FIG. Note that a known appropriate waveform shaping section /j may be inserted into the one-shot circuit input.

As shown from the left hand side to the right hand side of the fourth figure, when the engine speed accelerates, the discharge interval gradually narrows during this transition period, and the one-shot output waveform interval also decreases. It gets clogged in proportion to this.

Understanding such a pulse train from an analog level concept,
Two first and second integrating circuits with different time constants, 1
When integrating at 0, the output voltage change rate of the one with a smaller time constant, for example, the first integrating circuit 2, is larger, so at each time in this transient state, the output voltage change rate of the first integrating circuit 2 is larger. A situation arises in which the output voltage of the second integrating circuit/θ is larger than the output voltage of the second integrating circuit/θ.

This state is schematically shown in FIG. For example 110
In the transition period from 00rp to 'H3O0r'l)m, the output voltage of the first integrating circuit is high at any time ti.

Therefore, if the first integrating circuit output is input to the non-inverting or positive phase input of the comparator/l, and the second integrating circuit output is input to the inverting or negative phase input, a high level signal (H ) can be obtained at the output of the comparator l/.

However, strictly speaking, if a sufficiently long time has passed in a steady state, the outputs of both circuits y and /θ will be the same potential regardless of the time constant, so In order to ensure a good harvest, in order to obtain a low level of comparator output in such a steady state,
It is better to insert a level shift diode on the positive phase side and make sure that the positive phase side potential is lower by the forward voltage of this diode.

Even in this case, it is possible to create a condition that the output potential of the first integrating circuit 7 is higher in the previous transition period.

As described above, if an H signal is obtained as a detection signal to that effect during acceleration, for example, the current limiting circuit B as the discharge energy control circuit is controlled as appropriate to limit the current. By loosening the ignition coil, large discharge energy can be obtained on the secondary side of the ignition coil. An example of this circuit B is as shown in FIG. 6, for example.

A current detection resistor 2/ is connected to the main current line of the power transistor 7.
is inserted, and the converted voltage output is taken out from between the voltage dividing resistor 2ja and the corb wholesaler 2ja, and input to the base of the bypass transistor.

The main current line to the collector-emitter of the bypass transistor 2B is connected in parallel to the base current line of the power transistor 7.

Therefore, if the base current given to each ignition timing in a normal configuration of bypass transistors is jB, then the base current ib to this power transistor is calculated from this current zB by the bypass portion ib caused by the bypass transistor.
y is subtracted (ib = jB −ib
V).

On the other hand, if the collector-emitter of an npn switching transistor (7) is connected in parallel to the resistor 2jb, and the comparator output of the signal generation circuit KO is given to the base, the H level,
When the switching transistor 27 is turned on due to current inflow, the p1 resistance and tsb are short-circuited, and the bypass transistor base potential is relatively lowered, so that the primary current i
Unless P becomes considerably large, a condition can be created in which the bypass transistor does not turn on.

That is, since the bypass current ibv can be suppressed sufficiently small or made zero, the negative current iP can be increased, and eventually the restriction is relaxed or lifted, and a large secondary side discharge energy is generated in the second acceleration. This can be achieved when high energy demands are typically required.

Conversely, as is already clear, when the comparator output becomes a low level (L), the switching transistor 7 is turned off, causing the resistance 2! b is inserted into the circuit, so even a relatively small primary current iP does not easily turn on the transistor roller, and the primary current zP is ultimately limited by the bypass current 1b11.

Even if the comparator is changed to output L level during acceleration, it is simply a matter of conventional logic level processing; for example, if the resistor 2ja, is replaced with one fixed resistor, and the resistor 2≠ is replaced with two resistors. If you insert the collector-emitter of a switching transistor in parallel with one of them, it will turn on.

The only difference from the previous example is OFF, but the principle fishing force current limiting operation and limit value switching mechanism are the same.

In addition, as the energy control circuit t, a circuit for changing the impedance or inductance on the secondary side of the ignition coil can also be assembled using known techniques, and can be similarly driven by the present signal generation circuit -0.

In any case, according to the present invention, the current interrupting capacity discharge combined type ignition system was excellent in principle, but because the output energy was unique, the power supply design specifications had to be always adjusted to the maximum required energy. This will bring about extremely great effects, such as making practical improvements to the device, allowing it to further extend its strengths, and reducing 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. 5;
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, C is a switching element for capacitive discharge, 3 is an energy storage capacitor for capacitive discharge, 7 is a switching element for current interruption, B is a current limiting circuit as an example of an energy control circuit, / is an ignition coil, and -〇 is a discharge This is an energy control signal generation circuit. Fig. 3 Flute 4 Fig. 1i5 figure 6 Trowel

Claims (1)

[Claims] A current-interrupting capacitive discharge and composite ignition device that generates an inductive discharge due to current interrupting following the capacitance number -4, comprising: a pulse signal synchronized with the discharge interval generated at the ignition coil-next negative terminal; An energy control signal generation circuit is provided which generates an energy control signal according to the engine rotational state in response to a transient change in the interval of the pulse train, and the discharge energy control circuit is activated by the energy control signal during the transitional period when the engine rotational speed increases. An ignition system for an internal combustion engine whose main feature is to bring the ignition system into a control state suitable for supplying high energy.