JP2519574B2 - Internal combustion engine ignition device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for an internal combustion engine, and in particular, each ignition plug is provided with a dedicated ignition coil, and the secondary side of each ignition coil is provided. The present invention relates to an improvement effective for an ignition device of a type in which an output is directly connected to each spark plug.

[Prior Art] Recently, an ignition device that does not use a classical distributor but that provides a dedicated ignition coil to each ignition plug of each cylinder of an internal combustion engine as described above has begun to be favored. .

One of the reasons is that the long high-voltage wiring from the distributor to each spark plug, that is, the energy
It is sometimes desirable to eliminate long high-voltage wiring that causes loss and is also a noise source for electronic devices mounted on various vehicles. If each ignition coil is dedicated to each ignition plug, the dedicated ignition coil can be placed in the immediate vicinity of the corresponding ignition plug, or by devising the coil housing structure, etc., the secondary high voltage output part of each ignition coil Can also be directly fitted to the head of each corresponding spark plug.

On the other hand, looking at the conventional ignition device of this type for one spark plug, as far as the principle circuit structure is concerned, almost all of them can be represented by the circuit configuration shown in FIG.

The operation will be described below with reference to the operation waveforms of the main parts of each circuit shown in FIG. 4, and the ignition timing signal from an appropriate ignition timing sensor 11 that detects the ignition timing, such as a crank sensor, is a well-known existing ignition timing signal. Provided to a control unit 12 used in a kind of ignition device.

Now, when the ignition timing is not reached, as a preparation state for the next ignition, the input signal voltage V _i given from the control unit 12 to the input terminal 14 of the power switching circuit 13 is shown in FIG. As shown in the top row, the time
Suppose you stand up at t ₁ .

Then, in this conventional circuit, almost at the same time as the steep rise of the input signal voltage V _i , at the same time as the steep rise of the base current I of the bipolar power transistor Q ₁ included in the power switching circuit 13. _b
Which causes the transistor Q ₁ to turn on quickly.

That is, in this conventional circuit, the bipolar power
The input signal voltage V _i as a signal voltage for supplying the base current I _b to the transistor Q _1, between the base current I _b relates the rising, and has a little lag-free relationship.

However, when the transistor Q ₁ is suddenly turned off as described above, its collector-emitter voltage V
Also in _CE , since the collector is connected to the hot side of the vehicle-mounted battery 30 through the primary winding 21 of the ignition coil 20 in series, from the state where it was equal to the power supply voltage V _B of the battery 30 until then. , The collector of the transistor Q ₁
It sharply drops to the emitter saturation voltage V _{CE (sat)} , and accordingly, the primary winding 21 of the ignition coil 20 is shown in the second waveform from the bottom in FIG. As described above, the primary current I increasing from the battery 30 at a constant rising rate.
₂₁ will be supplied.

On the other hand, after that, when time t ₂ in FIG. 4 is reached and an ignition command signal (not shown) is given from the ignition timing sensor 11,
The input signal voltage (base current supply signal voltage) V _i given to the input terminal 14 of the power switching circuit 13 from the control unit 12 suddenly falls.

Then, as shown in FIG. 4 in which the waveform of the collector-emitter voltage V _CE sharply returns to the power supply voltage V _B , the bipolar power transistor Q ₁ immediately turns off, The primary current I ₂₁ of the ignition coil 20 is sharply cut off.

As a result, a high voltage V ₂₂ is induced in the secondary winding 22 of the ignition coil 20 in a predetermined polarity, in this case, in the negative direction, as shown in the bottom row in FIG. As a result, discharge sparks fly into the discharge gap of the spark plug 40 connected to both ends of the secondary winding 22.

[Problems to be Solved] However, the conventional ignition apparatus described above, in the in Figure 4 showing the operation waveforms, the ignition coil at time t ₁
At the beginning of supplying the primary current I ₂₁ to the primary winding 21 of 20, that is, at the steep rise of the signal voltage V _i for supplying the base current, in response to this, with respect to the base of the bipolar power transistor Q ₁ , However, the base current I _b is suddenly supplied.

Therefore, as also schematically shown from the time t _{1 in} FIG. 4, the primary current I ₂₁ depends on the mutual inductance between the primary and secondary windings of the ignition coil and the inter-winding stray capacitance. In some cases, a vibration component may be generated, and as a result, the secondary voltage V ₂₂ of the ignition coil 20 may also generate a vibration having a peak value of about 2 Kv.

But even so, if this is the type of ignition system that uses the classic distributor,
There is no particular problem. Since the discharge gap in the distribution bi Yuta portion to the discharge gap of the spark plug is also inserted in series, the discharge starting voltage can be set high, the ignition coil secondary winding when the sink beginning of the ignition coil primary current I ₂₁ as described above even the high voltage V ₂₂ of the line 22 extends to the front and rear 2Kv occurs, was not initially this by such erroneous ignition occurs in the spark plug.

However, as noted in this document, with an ignition device of the type in which the ignition coil secondary winding 22 is directly connected to the spark plug without using a distributor, it occurs when the ignition timing is not the predetermined time. Also, the ignition coil secondary voltage V _{22 of} around 2 Kv may cause the ignition plug to erroneously ignite.

Therefore, as shown by the phantom line in FIG. 3, in order to prevent such erroneous ignition in the conventional ignition device of this type, in the middle of the line from the ignition coil secondary winding 22 to the ignition plug 40, the erroneous error occurs. It was necessary to insert the high withstand voltage diode 41 in the direction opposite to the direction of the discharge current that causes ignition.

However, such a high breakdown voltage diode 41 is actually quite expensive and causes a failure, and also requires a complicated configuration when incorporated in the housing of the ignition coil.

The present invention has been made in view of such a conventional situation, and even when starting to supply the primary current to the ignition coil, the oscillation of the primary current unlike the conventional one does not occur, or at least it is suppressed to a sufficiently low level. It is an object of the present invention to provide an ignition device that can fundamentally solve the risk of erroneous ignition in a spark plug.

[Means for Solving the Problem] In order to achieve the above object, the present invention gradually increases the base current flowing into the base of a transistor after the rise of a signal voltage for supplying the base current to the bipolar power transistor. (A) a bipolar control transistor as a base current delay supply circuit for
(B) The main current line between the collector and the emitter of the bipolar control transistor is connected between the base and the emitter of the bipolar power transistor, and (c) the base of the bipolar power transistor and the signal voltage are applied. A series resistor is inserted between the terminal to which the signal voltage is applied and (d) a bipolar control transistor is rapidly connected between the terminal to which the signal voltage is applied and the base of the bipolar control transistor due to the rise of the signal voltage. We propose an ignition device for an internal combustion engine having a base current delay supply circuit in which a differential circuit for gradually shunting a current based on the application of a signal voltage is provided to the series resistor while turning on.

[Operation] According to the present invention, since the base current delay supply circuit is newly added, even if the signal voltage for base current supply rises sharply, the bipolar power transistor turns on rapidly. Since the electric conductivity can be gradually increased without causing the electric shock, a large vibration component does not occur in the primary current of the ignition coil.

Naturally, the induced voltage that can occur in the secondary winding of the ignition coil also
Compared to the conventional case, it can be kept sufficiently low, so even if the ignition plug is directly connected to the secondary winding of the ignition coil without going through the distributor, unexpected sparks will be generated when it is not the ignition timing. The risk of occurrence can be avoided.

[Examples] FIG. 1 shows a circuit configuration example of an internal combustion engine ignition device constructed according to the present invention, and FIG.
The operation waveforms of the main parts of the first illustrated circuit are shown.

In the figure, the components corresponding to the respective components or waveforms in the conventional example shown in the third and fourth illustrations are denoted by the same reference numerals,
Actually, in comparison with the circuit configuration in the conventional example shown in FIG.
The difference in the circuit shown in FIG. 1 because of the application of the invention is the base current delay supply circuit 50 incorporated in the power switching circuit 13.

The base current delay supply circuit 50 does not necessarily have to have the exact same circuit configuration as shown in the figure, and if the operation of the circuit 50 becomes clear through the following description, as long as it is a person skilled in the art, other configurations can be combined. However, in the case of the illustration, the primary winding 21 of the ignition coil 20 is connected to the base of the bipolar power transistor Q ₁ in which the main current line between the collector and the emitter is inserted in series and the ground. Between,
First, the collector-emitter line of the control transistor Q ₂ is connected.

On the other hand, as explained above, the control unit
A resistor R _c is provided between the input terminal 14 to which a signal voltage (input signal) V _i is applied in order to selectively apply a base current to the power transistor Q ₁ from 12 and the base of the power transistor Q _1. is inserted in series, it has been inserted the differential circuit 51 composed of a series circuit of a resistor R _o and the capacitor C _o between the input terminal 14 and the base of the control transistor Q _2, the base of the control transistor Q ₂ is also , Is grounded through a resistor R _b .

Since the base current delay supply circuit 50 having such a circuit configuration is provided, the ignition circuit shown in FIG. 1 operates as follows.

The explanation will be given with reference to the waveform diagram of each circuit in FIG. 2. The ignition timing signal from an appropriate ignition timing sensor 11 for detecting the ignition timing, such as a crank sensor, is also a known existing ignition timing signal. Is provided to the control unit 12 used in the ignition device of.

Now, when the ignition timing is not reached, as a preparation state for the next ignition, the input signal voltage V _i given from the control unit 12 to the input terminal 14 of the power switching circuit 13 is shown in FIG. As shown in the top row, the time
Suppose you stand up at t ₁ .

Then, in the circuit of this embodiment, unlike the case of the conventional example shown in FIG. 4, even if the input signal voltage V _i rises sharply, the bipolar power transistor included in the power switching circuit 13 The base current I _b flowing into the base of Q ₁ does not rise sharply.

Because, originally, even if the input signal voltage V _i that is the signal voltage for supplying the base current I _b rises sharply, the current flowing from the input terminal 14 into the power switching circuit 13 is initially the resistance R _o. This is because the differential circuit 51 including the capacitor C _o and the capacitor C _o flows rapidly toward the differential circuit 51, and the differential current thus causes the control transistor Q ₂ to turn on at a high speed. If the control transistor Q ₂ turns on, this will cause the base of the power transistor Q ₁ to be brought to a potential close to ground, so that the transistor Q ₁ cannot of course be turned on.

However, with the passage of time, according to a predetermined time constant determined by the specific values of the resistance R _o and the capacitor C _o , the current flowing toward the differentiating circuit 51 decreases, so that the power supply through the resistance R _c The base current I _b supplied to the base of the transistor Q ₁ gradually increases. FIG. 2 schematically shows this state with respect to the waveform of the increasing tendency of the base current I _b and the waveform of the decreasing tendency of the collector-emitter voltage V _CE of the power transistor Q ₁ .

In this way, since the power transistor Q ₁ gradually increases its conductivity from its active region to the saturation region, so to speak, compared to the conventional example in which the power transistor Q ₁ rapidly turns on from the OFF state to the saturation region, In the ignition circuit to which the present invention is applied, the primary side oscillating current is not generated or at least greatly suppressed by the mutual inductance and stray capacitance between the ignition coil primary winding 21 and the secondary winding 22.

Actually, according to the experiment by the applicant, as shown in FIG. 2 as well, when the circuit configuration of the conventional example is used,
As shown in FIG. 4, with the vibration component of the ignition coil primary current I _{21 at} the beginning of flow, a voltage of about 2 Kv is generated as the voltage V ₂₂ across the secondary winding 22 and is connected to the ignition coil secondary winding 22. Discharge sparks are blown to the spark plug 40, but in the ignition circuit employing the first illustrated base current delay supply circuit 50 according to the present invention, the oscillation of the primary current can be suppressed, and other parameters and circuit components are the same as those of the conventional example. However, the voltage V ₂₂ induced in the ignition coil secondary winding 22 can be kept at a value that does not reach 1 Kv even at the peak. No sparks were generated on the plug 40.

The operation at the ignition timing starting from time t 2 in FIG. ₂ is the same as that in the conventional example already described, and there is no disadvantage in adding the base current delay supply circuit 50 according to the present invention. .

As a precaution, if this ignition operation is also briefly mentioned, since the control transistor Q ₂ is already in the OFF state at this ignition timing, it does not have a significant effect, and the time t _{2 at which the} ignition should be started. Then, the ignition command signal (not shown) is given from the ignition timing sensor 11, and the input signal voltage (the signal voltage for supplying the base current) given to the input terminal 14 of the power switching circuit 13 from the control unit 12 is reached. When V _i falls sharply, the collector in FIG. 2 - as the waveform of the emitter voltage V _CE is indicated by being abruptly back to the supply voltage V _B, bipolar power transistors Q ₁ Immediately turns off as expected, and the primary current I ₂₁ of the ignition coil 20 is sharply cut off.

As a result, a high voltage V ₂₂ is induced in the secondary winding 22 of the ignition coil 20 in a predetermined polarity, in this case, in the negative direction, as shown at the bottom in FIG. As a result, discharge sparks fly into the discharge gap of the spark plug 40 connected to the secondary winding 22.

Although one embodiment of the present invention has been described in detail above, the illustrated base current delay supply circuit 50 is certainly simple and rational, but those skilled in the art can consider other circuit configurations.

[Effect] According to the present invention, it is possible to suppress a large induced voltage on the secondary winding side that tends to occur when starting to supply the primary current of the ignition coil, and prevent erroneous ignition of the spark plug at times other than ignition timing. can do.

Therefore, it is an extremely effective invention for an ignition device of the type in which the secondary winding of the ignition coil is directly connected to the ignition plug without interposing a distributor, and discharges a high withstand voltage diode for preventing misfiring as in the past. There is no need to insert it in series with the current line.

Therefore, it goes without saying that such an ignition device not only leads to lower costs, but also has a relatively shorter life compared to other electronic components,
The reliability of the high withstand voltage diode, which is liable to cause breakdown or breakdown, is reduced and reliability is increased, and a complicated structure for incorporating such a high withstand voltage diode in the casing structure of the ignition coil is not required.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a principle circuit portion in an ignition device of one embodiment configured according to the present invention, FIG. 2 is an explanatory diagram relating to operation waveforms of main parts of the first illustrated circuit, and FIG. FIG. 4 is a schematic configuration diagram of a principle circuit portion in the conventional ignition device targeted for improvement in FIG. 4, and FIG. 4 is an explanatory diagram relating to operation waveforms of main parts of the conventional circuit shown in FIG. In the figure, 11 is an ignition timing sensor, 12 is a control unit, 13 is a power switching circuit, 14 is an input terminal, 20
Is an ignition coil, 21 is a primary winding of the ignition coil, 22 is a secondary winding of the ignition coil, 30 is a battery, 40 is an ignition plug, 41 is a high voltage diode, 50 is a base current delay supply circuit, and 51 is a differentiation circuit. , Q ₁ is a bipolar power transistor, Q ₂
Is a control transistor, V _i is an input signal voltage or a signal voltage for supplying a base current, I _b is a base current, I ₂₁ is an ignition coil primary current, V ₂₂ is an ignition coil secondary voltage, and V _B is a battery power supply voltage. is there.

Claims (1)

(57) [Claims] 1. A bipolar current transistor having a base current delay supply circuit for gradually increasing the base current flowing into the base of the transistor after rising of a signal voltage for supplying the base current to the bipolar power transistor. Supplying a gradually increasing base current to the power transistor gradually turns on the transistor and gradually supplies the primary current to the ignition coil primary winding, while rapidly cutting off the base current to turn the transistor on. Abruptly turn off, abruptly interrupt the primary current of the ignition coil to obtain a high voltage in the secondary winding of the ignition coil,
An ignition device for an internal combustion engine, which discharges sparks to a spark plug connected to a secondary winding of the ignition coil by the high voltage; the base current delay supply circuit includes a bipolar control transistor; A main current line between the collector and the emitter of the transistor is connected between the base and the emitter of the bipolar power transistor; a series resistor is provided between the base of the bipolar power transistor and the terminal to which the signal voltage is applied. Is inserted between the terminal to which the signal voltage is applied and the base of the bipolar control transistor, while the bipolar control transistor is rapidly turned on by the rising of the signal voltage, and gradually. A differential circuit that divides the current based on the application of the signal voltage to the series resistor. An ignition device for an internal combustion engine, comprising: