JPH0416635B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device for an internal combustion engine, and in particular to a current interrupting capacity discharge device which is improved to control the energy during sustained discharge and have an ideal and efficient discharge characteristic. Regarding a 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. Historically, current interruption methods (capacitive discharge from secondary distributed capacitance and primary inductance A current-blocking capacitive discharge system that complements the characteristics of both the capacitive discharge method that utilizes the high voltage generated when the charge stored in the capacitor is discharged to the primary side of the ignition coil It has gradually evolved into a composite method.

With this combined method, almost ideal discharge characteristics can be obtained with the fast voltage rise characteristics of capacitive discharge and the long discharge duration of current cutoff method, but the discharge characteristics of conventional typical types are It was fixed.

In other words, when a vehicle equipped with an engine that is ignited by this composite ignition method is accelerating;
On the contrary, no measures have been taken to optimally control the discharge energy at certain times during deceleration or low-speed driving, and therefore, as is well known, the ignition energy must be increased to a certain extent during acceleration. Therefore, conventional combined ignition systems of the above-mentioned typical type are designed to always supply the maximum expected energy from the beginning.

This, of course, is inefficient and wastes energy by supplying maximum energy even when decelerating or running at low speeds, when maximum energy is not required.

Furthermore, there was basically no concept of clearly distinguishing between the acceleration of the vehicle and the acceleration of the engine.

For example, when the vehicle accelerates, the engine speed naturally goes into acceleration mode. However, conversely, just because the engine is in acceleration mode, it does not necessarily mean that the vehicle will also start accelerating.

To give a simple example, if the driver puts the transmission gear in neutral or depresses the accelerator with the clutch disengaged,
Let's consider the so-called blanking out of the engine.

At this time, originally there should be no need for high ignition energy. Nevertheless, conventional ignition devices with fixed ignition energy end up wasting energy even in such cases.

The fact that there was no idea to distinguish between the rotational state of the engine and the running state of the vehicle is an important problem.

This is because there have been attempts to control the ignition energy based only on the engine speed, although they are based on the current interruption method rather than the combined ignition method. A typical example can be found in JP-A-55-7921.

This conventional device attempts to supply high ignition energy when the engine rotational speed (not related to the running speed of the vehicle) is low, and low ignition energy when the engine rotation is high.

However, the first problem is that, as mentioned above, in this conventional example, the running speed of the vehicle is irrelevant, so energy control is performed even when the engine is revved up. .
However, in this conventional example, the higher the speed of the engine, the lower the supplied energy, so there may not be any inconvenience in intentionally supplying a large amount of energy when the engine is running dry, but it is not necessary. The irrationality of the control system operating to such an extent is a problem.

Secondly, there is some doubt about the conclusion that the faster the engine rotates, the more the ignition energy is reduced. As a result, if we look at the examples of circuits in this publication that actually achieve this problem, we find that the ignition energy is not only reduced at a constant rotational speed as mentioned above, but also during the process of increasing engine rotational speed. It has become a matter of decreasing the rate of increase.

This is practically unacceptable as an ignition system for an engine mounted on a vehicle. At least when the vehicle attempts to accelerate, the engine also enters a speed increase mode, and it is common sense that the ignition energy must be increased at such times. As a result, this conventional example clearly violates this common sense, and thus only results that are contradictory to each other can be obtained.

The present invention has been made in view of these conventional circumstances, and in order to make more effective use of energy in the above-mentioned current interrupting capacity discharge combined type ignition system, which is excellent in principle, Based on the vehicle speed detection information from the vehicle speed detection sensor, the ignition coil primary current is controlled to increase the ignition energy accordingly when the vehicle is accelerating, and to increase the ignition energy accordingly when the vehicle is traveling at low speed or decelerating. The aim is to keep the combined ignition energy supply to a relatively low level.

Before explaining the present invention based on embodiments, first, an example of a conventional composite type ignition device of this kind is shown in FIG. 1 as a representative, and its operation will be explained.

For example, when the interrupter 7 is closed as an ignition timing signal generator that equivalently turns on and off depending on the rotational position of the engine, the control transistor 8 is in an off state and no collector current flows, so the cutoff transistor 6 is in the on state, and the ignition coil primary current iP flows from the power supply battery 1 to the primary winding 5a of the ignition coil 5.
flows. At the same time, the energy storage capacitor 3 is charged by the DC high voltage power supply circuit 2 with the polarity shown in the drawing.

When the engine rotates and the interrupter 7 opens, a voltage is generated in the secondary winding 9b of the pulse transformer 9, and the base potential of the control transistor 8 becomes high, turning it on, and the interrupting transistor 6 turns off. The primary current of the ignition coil 5 is cut off. At this time, since the pulse generated in the pulse transformer primary winding 9a is connected to the gate of the thyristor 4 in the positive direction, the thyristor 4 is turned on, and the charge in the energy storage capacitor 3 is transferred to the primary winding of the ignition coil 5. Flows to 5a.

Since the voltage generated by discharging the capacitor and the voltage generated by cutting off the current are combined into the same phase as shown by the polarity in parentheses in the drawing, the secondary winding 5b of the ignition coil 5 A synergistic voltage is generated, which causes a spark to fly to the spark plug g, which then causes a sustained discharge due to current interruption.

In order to prevent the ignition coil primary side energy from flowing back to the power source, an impedance element (not shown) such as a choke coil may be interposed in series in the power line.

In contrast to the conventional configuration as described above, the present invention attempts to control the primary coil current iP depending on whether the vehicle is in an acceleration state, and the present invention is an improvement over the conventional configuration shown in Figure 1. If this is desired, the following embodiment may be applied to the portion 10 around the current cutoff transistor 6 in the figure.

FIG. 2 shows a first embodiment.
Only the portion 10 in the figure is extracted and shown. The remaining configuration may be the same as the conventional example shown in the first figure.

This embodiment is used as a circuit for bypassing the base current of the power transistor 6 in the circuit from the control transistor 8 (hereinafter abbreviated as driver) described above to the base of the NPN power transistor 6 as the current cutoff switching element 6. Insert the primary current control circuit. In the conventional basic configuration, if the constant base current flowing from driver 8 is iB, then
In this circuit, the sum of the base current ib to the power transistor 6 and the bypass current iby to the circuit corresponds to this current value (iB=ib+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 6,
By blocking this, a large discharge current can flow through the secondary side, or when that much discharge energy is not required, the bypass current iby can be increased, the base current ib can be decreased, and the primary current iP can be decreased.

For this purpose, first, as a bypass current path,
The collector-emitter of the npn transistor 11 is provided as a bypass with respect to the base of the power transistor 6, and the base of the transistor 11 receives a voltage from a current detection resistor 12 provided in series with the power transistor main current path. A pair of fixed resistors 1
A voltage divided by 3a, 13b and another fixed resistor 14 is applied.

The collector-emitter of an npn transistor 15 is connected to one end of the pair of fixed resistors 13a, 13b as a switching element 15 for selective short circuiting, and the vehicle speed detection sensor 1 is connected to the base of the npn transistor 15.
6's converted proportional voltage output V = (rpm) is inverted between the ground level and the power supply potential =
(rpm).

Then, when relatively low energy is required, for example during normal driving, the signal level is high, so the switching transistor 15 for selective shorting is turned on, and the resistor 13b is turned on.
is short-circuited, the base potential vb of the bypass transistor 11 is not so low with respect to the current conversion voltage v _s detected by the current detection resistor 12, and therefore the transistor 11 is at a potential that is easily turned on. placed in the environment.

Therefore, as the primary current iP increases, the bypass transistor 11 is turned on earlier, the bypass current iby increases, the base current ib to the power transistor 6 decreases, and the primary current iP is limited earlier, i.e. This is a limitation at low current levels. When the primary current iP temporarily decreases due to this restriction, the bypass transistor 11 is turned off, and the temporary current
The above operation is performed when iP starts to increase, resulting in an energy limit introduced in the time dimension. In any case, when the vehicle is not in an accelerating state and is running at low speed or decelerating, it is unnecessary to flow a large amount of primary current unnecessarily.

On the other hand, when the vehicle starts to accelerate and high energy is required, the switching transistor 15 is turned off as the signal level drops beyond a certain level, and the resistor 13b is inserted into the circuit, so that the base potential v _b is kept relatively lower than before,
Therefore, even when the primary current iP increases and the detection voltage _Vs increases, the bypass transistor 11 is placed in a situation where it is relatively difficult to turn on. In other words, unless the primary current iP becomes larger than before, it will not be limited by the turning on of this transistor 11, so when high energy is required, the primary current iP will be less limited, and the desired large secondary It can flow up to a value sufficient to obtain discharge energy.

Voltage V that makes the signal voltage proportional to the speed signal =
(rpm), as shown in the third diagram, the resistance 1, which was a fixed resistance value in the first embodiment,
4 is made variable, for example, two series resistors 14
A and 14b, and a switching element 15' for selective short circuiting may be placed at both ends of one of them. When low energy is required, the presence of the resistor 14b makes it easy to turn on the transistor 11, and when high energy is required, the switching transistor 15' is turned on and the resistor 14b is shorted, making it difficult to turn on the transistor 11. , the principle is the same as before.

Of course, by making the limit value of the primary current iP variable, it is possible to supply sufficient ignition energy depending on whether the vehicle is accelerating or not, especially when the vehicle is accelerating, but not when driving at low speeds. The present invention regulates the energy to a desired level during deceleration. Therefore, even if a current limiting circuit as shown in the illustrated embodiment is used, an electronic volume or other configuration (such as one using only transistors or a photocoupler) may be used. If desired, it may be possible to make the voltage continuously variable or multi-stage variable (combining a multi-stage threshold circuit and a plurality of series resistors) by using the following.

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

Furthermore, although the driver 8 may be a pnp transistor, this itself does not directly affect the present invention.

In any case, the present invention is excellent in principle, but because the output energy is unique,
This is a practical solution to the conventional current interrupting capacity discharge combined method ignition system, which had to always use the supplied power in accordance with the maximum required energy, or had to adjust the supplied power by focusing only on the engine speed. These ignition systems provide sufficient ignition energy to provide sufficient ignition energy when the vehicle is accelerating, and when the vehicle is equipped with an engine that is ignited by such an ignition system. Since it is possible to supply a reasonably reduced amount of energy when the power source is in a certain state, wasteful power consumption can be reasonably suppressed, and an extremely large effect can be produced.

[Brief explanation of drawings]

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 an energy storage capacitor for capacitive discharge, 4 is a first switching element for capacitive discharge, 5 is an ignition coil, 6 is a second switching element for current interruption, 9 is a second switching element control circuit, and 11 is a bypass circuit. , 12 is a current detection resistor, 13, 14
1 is a resistor, 15 is a switching element, and 16 is an engine operating state sensor.

Claims (1)

[Claims] 1. By releasing the accumulated charge stored in the energy storage capacitor to the primary side of the ignition coil and cutting off the primary current of the ignition coil,
A current interrupting capacitive discharge combined type ignition device for an internal combustion engine that obtains discharge energy consisting of a capacitive discharge portion and a subsequent inductive discharge portion on the secondary side of the ignition coil, the ignition being driven by the ignition device. A primary motor is provided with a sensor for detecting the running speed of a vehicle equipped with an engine, and is supplied to the ignition coil based on the output of the sensor, depending on whether the vehicle is in an accelerating state, a low speed running state, or a decelerating state. It has a circuit that can vary the current value limit, so that sufficient ignition energy is supplied when the vehicle is accelerating, and relatively less when the vehicle is running at low speed or decelerating. An ignition device for an internal combustion engine characterized by supplying low ignition energy.