JPS5912166A - Ignition device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the consumption of useless electric power by a method wherein a primary current limiting circuit, in which the limiting amount of the value of the primary current flowed to an ignition coil based on an operating condition signal can be changed, is provided in the compound electric current interrupting capacity and electric discharge type ignition device. CONSTITUTION:In the titled device, an interrupting transistor Tr6 is put ON or OFF by putting ON or OFF a control transistor (driver) which is put ON or OFF by a contact breaker and a high voltage is impressed to an ignition plug through the ignition coil by discharging a capacitor. In this case, the primary current limiting circuit 10 is interposed in a circuit from the driver to the base of said transistor Tr6. The circuit 10 is constituted so that a circuit between the collector and the emitter of a n-p-n Tr11 is provided as the side circuit with respect to the base of the power transistor 6 while the basic of the transistor 11 is provided with a voltage after dividing the voltage from a current detecting resistor 12 by a pair of fixed resistors 13a, 13b and the fixed resistor 14. The transistor Tr15 for selective short-circuit, whose base is connected with a speed detecting sensor 16, is connected to both terminals of the resistor 13b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition system for an internal combustion engine, and in particular, to an ignition system for an internal combustion engine, which has an improved current interrupting capacity to control energy during sustained discharge and provide ideal and efficient discharge characteristics. This invention relates to a combined discharge ignition device.

The spark discharge characteristics of 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 has an effect on the ignition performance of the fuel, The latter is said to be a factor that affects the combustion performance after ignition, and historically, the current interrupt method (capacitance from secondary distributed capacitance discharge and induced discharge from the primary inductance occur continuously),
The capacitive discharge method, which utilizes the high voltage generated when the charge stored in the capacitor is discharged to the primary side of the ignition coil, has gradually evolved into a current-blocking capacitive discharge composite method, which complements the characteristics of both.

This combined method provides almost ideal discharge characteristics, such as the fast voltage rise characteristic of the capacitive discharge method and the long discharge duration of the current cut-off method, but in the past, each characteristic was fixed and the engine operation Even if the required discharge characteristics change, such as between high-load low-speed operation and constant high-speed operation, or during acceleration and deceleration, the discharge t% can be adjusted accordingly.
The discharge energy could not be controlled, or -3- The design was designed to always reach the maximum discharge energy required, so it was inefficient, and even under operating conditions that did not require the maximum energy, the maximum discharge energy could not be controlled. Providing energy was a complete waste of energy.

The present invention has been made in consideration of this point, and in order to further utilize energy effectively in the above-mentioned M1 flow interrupting capacity discharge combined type ignition system which is excellent in principle, the present invention has been made in consideration of this point. The discharge characteristics are controlled by adjusting the ignition coil current so that the maximum energy is not supplied until the discharge energy is required.

Before explaining the present invention based on embodiments, first, an example of a conventional composite type ignition device of this type is shown in FIG.
Let me explain its operation.

For example, when the interrupter 7 is closed as an ignition timing signal generator that isometrically turned on and off according to the rotational position of the engine, the control transistor t is in the off state and no collector current flows, so the cutoff transistor t is in the on state, and the ignition coil secondary current iP flows from the power supply battery/to the primary winding jα of the ignition coil j. At the same time, the energy storage capacitor 3 is charged by the DC high voltage power supply circuit with the polarity shown in the drawing.

When the engine rotates and the interrupter 7 opens, a voltage is generated in the secondary winding 2b of the pulse transformer, and the base potential of the control transistor r becomes high, turning it on, and the cutoff transistor 6 turns off. As a result, the primary current of the ignition coil is cut off.

At this time, the pulse generated in the next winding α of the pulse transformer is connected to the gate of thyristor Hiro in a positive direction, so thyristor Hiro is turned on and the charge in the energy storage capacitor 3 is transferred to the ignition coil! The current flows through the primary winding Za.

The voltage generated by capacitor discharge and the voltage generated by current interruption are combined in the same phase as shown by the polarities in parentheses in the drawing, so the combined voltage is 1- This generates sparks to the spark plug 1, and thereafter causes a sustained discharge due to current interruption.

It should be noted that an impedance element (not shown) such as a choke coil may be interposed in series in the power supply line in order to prevent backflow of energy next to the ignition coil to the power supply.

In contrast to the conventional configuration as described above, the present invention attempts to control the primary coil current zp according to the engine operating conditions. , in the figure, the part 10 surrounding the current cutoff transistor
The following embodiments may be applied to.

FIG. 2 shows a first embodiment, in which only the portion 10 in FIG. 1 is shown.

The remaining structure may be the same as the conventional example shown in the first figure.

From the control transistor r (hereinafter abbreviated as driver) described above, current interrupting switching elements B and L (D npn
The primary current control circuit of this embodiment is inserted into the circuit leading to the base of the power transistor 6 as a circuit for bypassing the page current of the power transistor B. In the conventional basic configuration, if iB is the constant base current flowing from driver r, then in this circuit, the sum of base current ib to power transistor z and bypass current iby to this circuit corresponds to this current value ( sB=jb+iby).

Therefore, when high discharge energy is required, by reducing the bypass current iby, a large amount of primary current iP is allowed to flow through the power transistor t, and by blocking this, a large discharge current is allowed to flow through the secondary side. When a large amount of discharge energy is not required, the bypass current iby
The primary current iP can be reduced by increasing the base current ib and decreasing the base current ib.

For this purpose, first of all, npn (npn) as a bypass current path
A current detection resistor / is provided between the collector and emitter of the transistor // in a bypass manner with respect to the base of the power transistor t, and on the other hand, a current detection resistor / is provided in series with the main current path of the power transistor /l at the base of the transistor /l. , 2 to a pair of fixed resistors i3
A voltage divided by a, i3b and another fixed resistor /l is applied.

Then, an npn is connected to one end of the pair of fixed resistors /3α and /3b as a selective short circuit switching element /j.
) is connected between the collector emitter of the transistor l and the base is connected to the converting proportional voltage output V = f (rp
m') is input as an inversely proportional voltage v = fCrpm) inverted between the ground level and the power supply potential.

Then, when relatively low energy is required, for example during normal driving, the signal level V is high, so the switching transistor /j for selective shorting is turned on, and the resistor /3b is shorted. Therefore, the base potential υb of the bypass transistor // is not so low with respect to the current conversion voltage 'DB detected by the current detection resistor /λ, and therefore, the transistor /l is placed in a potential environment where it is easy to turn on. .

Therefore, as the negative current iP increases, the bypass transistor /l turns on earlier, and the bypass current ibv
As the base current ib to the power transistor increases, the base current ib to the power transistor decreases, and the current is limited earlier, that is, at a low current level. This restriction results in an energy restriction introduced in the time dimension in which the bypass transistor // is turned off when the primary current temporarily decreases, and the above operation is performed when the primary current begins to increase. In any case,
There is no need to wastefully flow a large amount of primary current when low energy is required.

On the other hand, when the situation accelerates and high energy is required, the switching transistor turns off as the signal level V drops more than enough, and the resistor 13b is inserted into the circuit. The potential υ) is kept at a relatively low value from the beginning, so even if the primary current iP increases and the detection voltage υ6 increases, the bypass transistor /l
is placed in a situation where it is relatively difficult to turn on. Unless the secondary current becomes larger in advance, it will not be subject to the restrictions associated with turning on this transistor, so in the end, the restriction on the secondary current will be relaxed when high energy is required. and can flow to a value sufficient to obtain the desired large secondary discharge energy.

If you want to handle the signal voltage as a voltage V = f (rpm) proportional to the speed signal, as shown in Figure 3, the resistance /g, which was a fixed resistance value in the first embodiment, should be made variable, for example. Two series resistors! ≠α, /llb, and a selective short circuit switching element /lb can be placed at both ends of one of them.When low energy is required, the resistor l≠
The presence of b makes it easier to turn on the transistor //,
When high energy is required, switching transistors/! ′
When turning on the resistor /ab, the short-circuiting of the resistor /ab creates a situation in which it is difficult to turn on the transistor l', and the principle is the same as before.

Of course, by making the limit value of the -order current iP variable,
Since the present invention is to regulate the energy to a desired level according to the speed and load (sensor/6 is of course a high-load sensor), it is not necessary to use a current limiting circuit such as the illustrated embodiment. However, if desired, it is possible to make it continuously variable or multi-stage variable (combining a multi-stage threshold circuit and multiple series resistors) by using a configuration with an electronic volume (some using only transistors, some including photocouplers, etc.). do not have.

Furthermore, the concept of variable limit value naturally includes a combination of unlimited and significant values.

Furthermore, although the driver r may be a pnp transistor, this itself does not directly affect the present invention.

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, making it possible to further extend its strengths9, and suppressing wasteful power consumption.

-/l-

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional composite type ignition system, FIG. 2 is a schematic diagram of a first embodiment of the present invention, and FIG. 3 is a schematic diagram of a second embodiment of the present invention. In the figure, 3 is the energy storage capacitor for capacitive discharge, ≠ is the first switching element for capacitive discharge, j is the ignition coil, B is the second switching element for current interruption, ri is the second switching element control circuit, // is the bypass circuit, /:t is a current detection resistor, /3. /≠ is a resistance, /j is a switching element,
/A is a machine rotation state sensor.

Claims (1)

[Scope of Claims] A current interrupting capacitive discharge combined type ignition device that generates an inductive discharge due to current interrupting following a capacitive discharge, wherein the limiting amount of the primary current value flowing through the ignition coil is variable based on an engine operating status signal. An ignition device for an internal combustion engine, characterized in that the ignition device has a primary current limiting circuit that controls the energy of the induced discharge portion.