JPH08261122A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE: To cause an ignition device for an internal combustion engine arc of high energy and long conducting period and also reduce its cost. CONSTITUTION: A first condenser C1 is connected between a secondary side coil 2b of a DC-DC converter 2 and a primary side coil 1a of an ignition coil 1 and selectively grounded node of the secondary side coil 2b and the primary side condenser C1 to mount a diode D2 for providing current from the primary side coil 1a to the first condenser C1 through a grounding line and a second thyriser SCR2 for providing charging current to the first condenser when charging is connected in parallel with the primary side coil 1a. Accidental arc may be prevented by providing the charging current to the second thyrister and also AC arc is caused by resonance phenomena between the primary side coil of an ignition coil and the first condenser to produce the arc of high energy and long conducting period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine ignition device, and more particularly to an internal combustion engine ignition device using DC-CDI.

[0002]

2. Description of the Related Art Conventionally, in an ignition device for an internal combustion engine of a two-wheeled vehicle, for example, an AC-CDI that generates an AC arc in which positive and negative voltages alternately appear in the discharge of a plug and a DC arc that has only one voltage are used. There is DC-CDI that occurs. The discharge time of AC-CDI is about twice as long as that of DC-CDI, and the discharge energy may be increased by about 30%. Therefore, regarding the ignition performance, AC arc is more DC
It can be said that it is superior to the arc. However, AC
In the case of -CDI, the exciter coil provided in the generator is relatively expensive, and in AC-CDI, the generated voltage of the primary coil becomes low not only at low rotation but also at high rotation.

On the other hand, in DC-CDI, A
It can be configured without providing an expensive exciter such as C-CDI. For example, the basic circuit shown in FIG. 3 is shown below. DC-CDI1 is provided between the positive terminal of the on-vehicle battery BT and the primary coil 1a of the ignition coil 1.
1 is provided. In this DC-CDI 11, the primary side coil 2a of the DC-DC converter 2 is connected to the positive terminal of the battery BT, and between the secondary side coil 2b and the primary side coil 1a of the ignition coil 1. , Forward diode D1 and first capacitor C1
And are connected in series in this order. A plug 3 is connected to the secondary coil 1b of the ignition coil 1.

The diode D1 and the first capacitor C
A thyristor SCR1 for flowing a current toward the ground side is connected to the node 1 and the control signal of the charging / ignition control circuit 4 is input to its gate. A diode D3 is connected to the node between the first capacitor C1 and the primary coil 1a of the ignition coil 1 so that a current flows to the ground side.

A conventional DC-C constructed in this way
In the DI 11, when the thyristor SCR1 is turned off, the first capacitor C1 is charged, and when the thyristor SCR1 is turned on by the input of the control signal from the charging / ignition control circuit 4 output at the ignition timing, the first capacitor C1 is turned on. A discharge current flows through the thyristor SCR1 from the primary coil 1a, and the plug 3 is discharged by the high voltage of the secondary coil 1b boosted by the voltage generated by the primary coil. When the thyristor SCR1 is turned off, the first capacitor C1 is charged again, and the first capacitor C1 is charged / discharged as the thyristor SCR1 is turned on / off.

In such a conventional DC-CDI 11,
Since it does not require an exciter like AC-CDI,
Although it is inexpensive, the generated voltage of the DC-DC converter is constant regardless of the engine speed, and there is an advantage that a high voltage can be obtained in the low rotation range and the high rotation range. When the capacitor C1 is charged at a high frequency of about 20 to 100 kHz, a counter electromotive voltage of about 100 V is generated by the inductance of the primary coil 1a when the charging current flows through the primary coil 1a of the ignition coil, and Will be hindered. For this reason, it takes time to charge the capacitor C1 to a predetermined voltage, which not only reduces the efficiency of the entire apparatus, but also may cause a state in which charging is not in time when the engine rotates at high speed.

Further, an undesired high voltage is generated in the secondary coil 1b due to the voltage generated in the primary coil 1a of the ignition coil 1, and an arc may be generated in the plug 3 at a timing that is not a proper timing. There is. Therefore, as shown in FIG. 3, the diode D3 is provided in parallel with the primary coil 1a so that the charging current is reduced to the primary coil 1a.
It does not flow to a. Therefore, at the time of discharging, only the current in one direction flows, and a DC arc is generated.

[0008]

The conventional AC-CDI and DC-CDI have both merits and demerits as described above, but they are inexpensive as an ignition device and can be used in a low rotation range. It is desirable that the voltage is always high up to a high rotation range, the discharge time is long, and an arc having a large discharge energy is generated.

In view of the problems of the prior art and the findings of the present inventors, the main object of the present invention is to generate an arc with high energy and a long discharge time and to reduce the cost, and an ignition device for an internal combustion engine. To provide.

[0010]

According to the present invention, there is provided a first capacitor connected between a DC power source and a primary coil of an ignition coil, and charging of the first capacitor. And a first switching element for selectively grounding a node of the DC power source and the first capacitor by a control signal according to an engine rotation cycle so as to discharge the primary coil. Resonance generating means connected to the node of the DC power supply and the first capacitor for causing resonance between the first capacitor and the primary coil when the capacitor is discharged, and to the first capacitor. And a second switching element connected in parallel with the primary side coil so as to allow a charging current to flow while avoiding the primary side coil during charging. Combustion engine ignition device, or, DC
A first capacitor connected between a power source and a primary coil of the ignition coil; the DC power source and the first capacitor for charging the first capacitor and discharging the primary coil; First selectively grounds the node of the node by a control signal according to the engine rotation cycle
Resonance element connected to the node of the DC power supply and the first capacitor so as to cause resonance between the switching element and the first capacitor when the first capacitor is discharged. It is achieved by providing an ignition device for an internal combustion engine, characterized in that it has means and a second capacitor connected in parallel with the primary coil.

[0011]

With this configuration, when the first capacitor is charged by the first switching element, the charging current flows through the second switching element, so that the charging current flows through the primary side coil and an erroneous arc occurs. This can be prevented, and at the time of discharge, the second switching element can be turned off to cause a discharge current to flow in the primary coil of the ignition coil, thereby generating an arc in the plug. Further, by causing a current to flow from the primary side coil to the first capacitor by the resonance generating means, a resonance phenomenon can be generated by the primary side coil and the first capacitor, and an AC arc can be generated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic circuit diagram of an ignition device for an internal combustion engine of a motorcycle to which the present invention is applied. The same parts as those shown in FIG. 3 shown in the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted. In the ignition voltage generating circuit 5, the secondary coil 2b of the DC-DC converter 2
The diode D1 and the first capacitor C1 between the primary coil 1a of the ignition coil 1 and the first coil 1a, and the first thyristor SCR1 connected to the nodes of both of them are connected in the same manner as in the conventional example.

At a node between the diode D1 and the first capacitor C1, a diode D2 as resonance generating means is provided.
Is connected in parallel with the first thyristor SCR1 in a direction in which a current flows toward the node of the diode D1 and the first capacitor C1. By providing the diode D2 in this way, the discharge current of the first capacitor C1 is
As shown by an arrow A in FIG. 1, the first capacitor C1 once flows toward the primary coil 1a through the first thyristor SCR1 and the ground line, and then the first capacitor C1.
When the current is about to flow in the direction shown by the arrow B opposite to the arrow A due to the resonance between the primary coil 1a and the coil 1,
It can flow through the diode D2. Therefore,
A resonance phenomenon may occur due to the first capacitor C1 and the primary coil 1a. The same operation can be performed by connecting the cathode of the diode D2 to the anode of the diode D1.

Further, at the node between the first capacitor C1 and the primary coil 1a, the diode D3 shown in the conventional example is provided.
A second thyristor SCR2 as a second switching element, which is used instead of, is connected in a direction in which a current flows from the node toward the ground side. At the time of charging the first capacitor C1, the second thyristor SCR2 is turned on, and the charging current flows through the second thyristor SCR2 as shown by the arrow C in the figure, so that the charging current flows through the primary coil 1a. Can be suppressed.

A control signal based on the cycle of the engine speed from the charging / ignition circuit 4 and considering the advance angle is input to each gate of both thyristors SCR1 and SCR2. When the arc is blown to the plug 3, the first thyristor SCR1 is controlled to be turned on and the second thyristor SCR2 is controlled to be turned off. When the charging current is passed to the first capacitor C1, the first thyristor SCR1 is turned off, The second thyristor SCR2 is controlled to be turned on.

In the present ignition circuit thus constructed, the first thyristor SCR1 is turned off and the second thyristor SCR2 is turned on, so that the charging current flows as indicated by the arrow C and the first thyristor SCR2 is turned on. The capacitor C1 is charged. At this time, as described above, the charging current flows into the second thyristor SCR2 and hardly flows into the primary coil 1a of the ignition coil 1, so the DC-DC converter is miniaturized and charged at a frequency of about 20 to 200 kHz. At this time, there is no possibility that the charging capacity is reduced or an erroneous arc is generated due to the counter electromotive voltage generated in the primary coil 1a.

When the arc is blown to the plug 3, the first thyristor SCR1 is turned on and the second thyristor SCR is turned on.
When 2 is turned off, a current flows as indicated by an arrow A by discharging the first capacitor C1. This time,
A current flows only in the direction of arrow A through the first thyristor SCR1, but a diode D flows in the opposite direction of arrow B.
As described above, the resonance phenomenon may occur due to the primary coil 1a and the first capacitor. Therefore, since AC arcs in which positive and negative voltages are alternately generated are generated in the plug 3, large discharge energy and long discharge time can be obtained.

Although the thyristor is used as the second switching element in this embodiment, the thyristor is not limited to the thyristor and may be any one that can be turned on / off by a control signal to selectively flow the charging current. For example, a transistor capable of high-speed switching or the like can be applied.

Next, FIG. 2 shows a second embodiment according to the present invention. The same parts as those in the above-mentioned embodiment are designated by the same reference numerals and their detailed description will be omitted. In the second embodiment, the second thyristor SCR2 provided in the above embodiment is used.
A second capacitor is provided instead of Even in this case, the same effect as that of the above-described embodiment can be obtained.

That is, in order to charge the first capacitor C1, 20 to 20 supplied from the DC-DC converter is charged.
An intermittent current of 100 kHz is applied to the ignition coil 1 1
A second capacitor C2 connected in parallel with the secondary coil 1a
By-passing as the charging current of 1, the occurrence of a counter electromotive voltage in the ignition coil 1 is prevented. The electric charge charged in the capacitor C2 is the primary coil 1a of the ignition coil 1 when the intermittent current generated by the DC-DC converter is "interrupted", that is, not flowing.
Is slowly discharged (arrow B). In other words, by smoothing the current flowing through the primary coil 1a of the ignition coil 1 by the second capacitor C2, the counter electromotive voltage generated by the inductance of the ignition coil 1 is prevented.

According to the present invention, the second thyristor SCR2 and the second capacitor C2, which are separately provided in each of the embodiments, can be provided in parallel. Even in this case, the same action and effect as those of the above-described embodiment can be more effectively achieved without causing any inconvenience. In this case, the capacitance of the second capacitor C2 or the second thyristor SC
It is also possible to reduce the current allowance of R2.

[0023]

As described above, according to the present invention, the DC-CD
The structure of I is configured to generate a high voltage arc in a low rotation range and a high rotation range, and a charging current for the first capacitor for generating the voltage is caused to flow through the second switching element. As a result, it is possible to prevent a back electromotive voltage from being generated in the primary coil of the ignition coil and to prevent deterioration of the charging performance of the capacitor and an erroneous arc, and a resonance phenomenon is caused by the first capacitor and the primary coil to cause an AC arc. Since a large discharge energy and a long discharge time can be obtained without using an exciter, the cost of the device can be reduced. Also, the same effect can be obtained by using a second capacitor instead of the second switching element.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a main part showing an ignition device for an internal combustion engine to which the present invention is applied.

FIG. 2 is a view similar to FIG. 1 showing a second embodiment.

FIG. 3 is a main part circuit diagram showing an internal combustion engine ignition device using a conventional DC-CDI.

[Explanation of symbols]

 1 Ignition coil 1a Primary coil 1b Secondary coil 2 DC-DC converter 2a Primary coil 2b Secondary coil 3 Plug 4 Charging / ignition control circuit 5 Ignition voltage generation circuit 11 DC-CDI

Claims (2)

[Claims] 1. A first capacitor connected between a DC power supply and a primary coil of an ignition coil; and the DC power supply for charging the first capacitor and discharging the primary coil. A first switching element for selectively grounding a node with the first capacitor by a control signal according to an engine rotation cycle; and a first switching element for connecting the first capacitor and the primary coil when the first capacitor is discharged. Resonance generating means connected to the node of the DC power source and the first capacitor to cause resonance between the DC power source and the first capacitor, and a charging current to flow while avoiding the primary coil when charging the first capacitor. An ignition device for an internal combustion engine, comprising: the primary coil and a second switching element connected in parallel. 2. A first capacitor connected between a DC power supply and a primary coil of an ignition coil; and the DC power supply for charging the first capacitor and discharging the primary coil. A first switching element for selectively grounding a node with the first capacitor by a control signal according to an engine rotation cycle; and a first switching element for connecting the first capacitor and the primary coil when the first capacitor is discharged. A resonance generating means connected to a node of the DC power supply and the first capacitor to cause resonance between the first power source and the second capacitor, and a second capacitor connected in parallel with the primary coil. Ignition device for internal combustion engine.