JPH07243369A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce a turn ratio of an ignition coil while holding secondary voltage generated on a secondary winding at more than desired demanded secondary voltage. CONSTITUTION:An insulated gate bipolar transistor (IGBT) 4 is electrically switched on and off in accordance with an ignition signal from an ECU 1. A Zener diode 6 is provided to prevent overvoltage of primary voltage of an ignition coil 7. A collector terminal of the IGBT 4 is connected to one end of a primary winding 8, and a battery power source VB is connected to the other end of the primary winding 8. An ignition plug 12 for each cylinder is connected to a secondary winding 9 through a distributor 11. Zener voltage Vz of the Zener diode 6 is set so as to satisfy relation of Vz.a>Vr at the time when demanded secondary voltage on the secondary winding 9 of the ignition coil 7 is specified as Vr, the Zener voltage of the Zener diode 6 as VZ, and ratio of the number of turns N1 of the primary winding 8 and the number of turns N2 of the secondary winding 9 as (a).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for an internal combustion engine, and more specifically, by shutting off a primary current of an ignition coil,
The present invention relates to an induction discharge type non-contact internal combustion engine ignition device that performs a ignition operation by obtaining a desired secondary voltage on the engine side.

[0002]

2. Description of the Related Art As an ignition device for an internal combustion engine of this kind, for example, US Pat.
Japanese Patent No. 112630 is disclosed. FIG. 8 is a circuit diagram schematically showing a conventional ignition device, and a circuit similar to this is also described in the above publication. In FIG. 8, the igniter 20 has a Darlington transistor 21 for electrically connecting and disconnecting the primary current of the ignition coil 22. The Darlington transistor 21 is composed of two npn bipolar transistors.

The collector terminal of the Darlington transistor 21 is connected to the primary winding 23 of the ignition coil 22, and an ignition plug (not shown) is connected to the secondary winding 24. The Darlington transistor 21 includes a Zener diode 25 for preventing overvoltage of the transistor 21.
Are connected, and the breakdown voltage V _D of the element is determined by the Zener voltage V _Z of the Zener diode. From the characteristics of the effective operating breakdown voltage of the Darlington transistor 21, the Zener voltage V of the Zener diode 25 is
_Z (cut voltage) was set to about 350V.

In recent years, a system (hereinafter referred to as a DLI system) for directly supplying energy of an ignition coil to a spark plug without using a distributor has become widespread.
In the system, as shown in FIG.
A high breakdown voltage diode D1 is inserted between the next side. This is to prevent erroneous ignition of the spark plug due to the secondary on-voltage generated on the secondary side when the primary current of the ignition coil is started. The secondary ON voltage is greatly affected by the ignition coil turn ratio.

Even if the winding ratio is reduced and the high-voltage diode D1 is abolished, the secondary generated voltage cannot satisfy the required value at the current V _Z (350 V). On the other hand, in the ignition device of Japanese Patent Laid-Open No. 50-112630, the winding ratio (= secondary winding number / primary winding number) of the ignition coil 22 is set to 40 in order to increase the arc current by the spark plug and improve the ignition performance. It was set to ~ 60. US Patent No. 5,
In the ignition devices of Nos. 193 and 514, the turn ratio of the ignition coil 22 is set to 70 or less in order to induce a voltage of at least 6 kV between the electrodes of the spark plug. In other words, the turn ratio of the ignition coil 22 is generally about 90, whereas the turn ratio of the ignition coil used in the above publication is reduced. However, in these examples, no reference is made to the reduction of the secondary voltage of the ignition coil.

[0006]

The reduction of the winding ratio of 9 produces various merits, but when the required secondary voltage becomes high, it becomes difficult to reduce the winding ratio. That is,
The primary voltage V ₁ at the primary winding 23 is obtained from the secondary voltage V ₂ and the turn ratio a (V ₁ = V ₂ / a). Therefore, in order to obtain a predetermined secondary voltage V ₂ , lowering the turns ratio a causes an increase in the primary voltage V ₁ , and at this time, the primary voltage V ₁
Becomes equal to or higher than the Zener voltage V _Z (= 350 V), the primary voltage V ₁ is limited by the Zener voltage V _Z, and the secondary voltage V _{2 of the} next coil reaches the required secondary voltage V _r . There is a situation where you don't.

A more specific description will be given assuming that the winding ratio a = 70.
Then, the required secondary voltage V_rIs relatively low (eg V
_r= 15 kV) Primary voltage V₁= 15 kV / 70 = 21
It becomes 4V. At this time, V₁<V_Z(= 350V)
Primary voltage V₁Is the Zener voltage V_ZSubject to restrictions
First, the desired secondary voltage V desired_rCan be obtained. This
Against this, the required secondary voltage V_rIs high (eg V_r
= 30 kV) Primary voltage V₁= 30 kV / 70 = 428
Becomes V, V₁> V_Z(= 350V), 1
Next voltage V₁ W Zener voltage V_ZLimited by (= 350V)
It receives only 350V. As a result, the secondary power
Pressure V₂Is about 24.5kV (= 350V ₂To a large drop in
More likely to cause misfires and reduce drivability.
Cause problems. That is, for overvoltage protection of switching elements
The number of turns is reduced by the presence of the Zener diode of
That is, the secondary voltage does not rise further and the desired secondary
Voltage V_rWill not be able to get.

Further, the required secondary voltage V _r tends to increase with the lapse of time, which increases the possibility of inducing the above problem. Further, in recent years, the compression ratio of the internal combustion engine is increased to obtain the school output, and the air-fuel ratio is controlled on the lean side to improve the fuel consumption, which causes an increase in the required secondary voltage V _r , and 2 The above-mentioned problem that the secondary voltage is insufficient becomes remarkable.

The present invention has been made in view of the above problems, and its object is to keep the secondary voltage generated in the secondary winding at a desired required secondary voltage or more. At the same time, it is an object of the present invention to provide an ignition device for an internal combustion engine which can reduce the turn ratio of the ignition coil or can improve the secondary voltage of the ignition coil when the turn ratio is the same.

[0010]

In order to achieve the above object, an ignition device for an internal combustion engine according to a first aspect of the present invention comprises:
An ignition device for an internal combustion engine, comprising an ignition coil and a switching element for electrically interrupting a primary current of the ignition coil, wherein an element having a breakdown voltage of 450 V or higher is used, and the secondary winding of the ignition coil is used. Demand on the line 2
The next voltage is V _r , the breakdown voltage of the switching element is V _D , and the number of turns N ₁ and 2 of the primary winding of the ignition coil is
When the ratio (N ₂ / N ₁ ) to the number of turns N ₂ of the next winding is a, the relationship of V _D · a> V _r is satisfied and V _D is 450
The gist is that it is V or more.

[0011]

With the use of the switching element having a breakdown voltage of 450 V or higher, the breakdown voltage is improved, so that the breakdown of the switching element due to the voltage generated on the primary coil side when the secondary voltage is generated is effectively prevented.
Further, by setting the breakdown voltage V _D and the turns ratio a so as to satisfy the relationship of V _D · a> V _r , the secondary voltage in the secondary winding is maintained at a desired required secondary voltage V _r or higher. On the other hand, when the turns ratio a is reduced or the turns ratio is the same, an ignition system in which the secondary voltage of the ignition coil is improved can be obtained. In this case, the same requirement 2 due to the increase in the secondary voltage V _r required due to specifications (compression ratio or air-fuel ratio specification)
Even when the secondary voltage V _r rises, it is possible to secure a secondary voltage equal to or higher than the required secondary voltage V _r .

The present invention can be applied to either a system for distributing and supplying ignition energy to each spark plug by a distributor, or a system for directly supplying ignition energy to each spark plug without going through a distributor (DLI system). In any case, the above action can be obtained. Further, according to the present invention, request 2
Even when the secondary voltage V _r is increased and set to V _r = 30 kV, the secondary voltage equal to or higher than the required secondary voltage V _r can be ensured and the winding ratio a can be reduced. That is, as shown in FIG. 2, if V _Z = 350 V as in the conventional case, the required secondary voltage V _r = 30 kV cannot be obtained at the turns ratio a = 70, and the secondary side can obtain 30 kV. Requires at least a winding number ratio a = 90 or more. On the contrary,
According to this configuration, the winding ratio a = is set by using the swinging element having the breakdown voltage V _D of 450 V or more.
Also in the case of 70, the required secondary voltage V _r = 30 kV or more of the secondary voltage V ₂ can be obtained (for example, see the characteristic line of V _Z = 467 V in FIG. 2).

According to the second aspect of the invention, it is possible to obtain an ignition device for an internal combustion engine which has good ignition performance and has an appropriate turn ratio capable of ensuring an appropriate secondary voltage. Also,
According to the invention of claim 3, it is possible to obtain an ignition device for an internal combustion engine which can be mounted in a plug hole of an engine. Further, according to the invention of claim 4, it is possible to obtain a small-sized ignition device for an internal combustion engine with a simple configuration.

Further, according to the invention of claim 5, in addition to the operation of claim 1, the DL is reduced by decreasing the winding ratio a.
The following actions specific to the I system are obtained. That is, DLI
In the system, when power is supplied to the primary winding, 2
In the secondary winding, a so-called secondary-side ON voltage is generated, and if the secondary-side ON voltage is equal to or higher than a predetermined level, the main hall is generated and premature ignition occurs. However, according to this configuration, the turn-on ratio a of the ignition coil is reduced, so that the secondary-side ON voltage is lowered, and premature ignition is prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an ignition control device of a spark ignition type four-cylinder internal combustion engine (hereinafter referred to as an engine). In FIG. 1, an electronic control unit (hereinafter referred to as “ECU”) 1 is mainly composed of a microcomputer.
It includes a / D converter and a waveform shaping circuit. ECU
A rotation angle sensor 2 is connected to 1, and a rotation detection signal from the sensor 2 is input. The rotation angle sensor 2 includes a rotor 2a that rotates according to the rotation of the engine and a pickup coil 2b that detects passage of teeth provided on the rotor 2a.
It consists of and.

The igniter 3 includes an IGBT (insulated gate bipolar transistor) 4, a pair of zener diodes 5 and 6 connected in series in opposite directions, and a constant current control circuit 13. The IGBT 4 is shown by an equivalent circuit. It is electrically interrupted (ON / OFF) based on the gate terminal of the IGBT 4. Incidentally, the Zener diode is built in the IGBT so that the circuit is miniaturized.

One Zener diode 5 between the gate and collector of the IGBT 4 is provided to regulate the voltage when the gate terminal has a high voltage and the collector and the emitter have a low voltage. The other Zener diode 6 is provided to prevent the overvoltage of the primary voltage of the ignition coil 7, which will be described later. Constant current control circuit 1
3 is connected to the emitter terminal of the IGBT 4, and the primary current of the ignition coil 7 is set to a constant value (6, 5 in this embodiment).
Control to A).

The ignition coil 7 includes a primary winding 8 and a secondary winding 9
And an iron core 10. The collector terminal of the IGBT 4 is connected to one side of the primary winding 8, and the battery power source V _B is connected to the other side. In the secondary winding 9,
A spark plug 12 for each cylinder is connected through a distributor 11. Ignition coil 7 has a predetermined winding ratio a consisting a ratio of windings N ₁ of the primary winding and the winding N ₂ of the secondary winding (N ₂ / N _1).

In the ignition device configured as described above, the electric signal (ignition signal) from the ECU 1 causes the I
When a voltage is applied to the gate terminal of the GBT 4, the IGBT 4 turns on as the gate voltage is applied, and
The primary current flows through the secondary winding 8. The constant current control circuit 13 holds this primary current at a predetermined current value (6, 5 A). Then, by turning off the IGBT 4 at a predetermined timing, the primary current is cut off and a high voltage is induced in the secondary winding 9 of the ignition coil 7. At this time, a voltage is applied to the spark plug 12 via the distributor 11, and if the secondary voltage in the secondary winding 9 is equal to or higher than a preset required secondary voltage, the spark plug 12 is discharged.

[0020] In this embodiment, the Zener voltage of the Zener diode 6 has determined breakdown voltage V _D of the IGBT 4, (shown below V _Z) to be V _D = V _Z is the conventional this V _Z It is set higher than that of the Darlington transistor, specifically, V _Z = 467V
I am trying. Here, the conventional bipolar transistor has a characteristic in which the effective withstand voltage and the current amplification factor h _FE contradict each other. Therefore, when a predetermined current amplification factor h _FE is required, it is difficult to increase the effective operating breakdown voltage, but if the IGBT 4 is used as in this embodiment, the current amplification factor h _{FE is} increased.
It has no characteristics, the effective operating breakdown voltage can be easily improved, and the Zener voltage V _Z can be set high.

Further, the secondary voltage V induced in the secondary winding 9
₂ is determined from the designed primary energy W ₁ , the secondary capacitance C 2 and the conversion efficiency η (V ₂ = √ (2 · W ₁ / C
2) ・ η). At this time, the primary energy W ₁ is determined by the primary inductance L ₁ and the primary current I ₁ (W ₁ =
^{_{L 1 · I 1 2/2}} ). Further, the primary voltage V ₁ reflected on the primary winding 8 is obtained from the secondary voltage V ₂ and the winding ratio a (V ₁ = V ₂ / a).

At this time, the high voltage V induced in the secondary winding 9
₂ , the counter electromotive force V ₁ is also generated in the primary winding 8. Two
As the voltage V ₂ induced in the secondary winding 9 is higher, the counter electromotive force V ₁ = V ₂ / a inversely proportional to the winding ratio a is also generated on the primary winding 8 side.

When V ₁ is small, the current flowing through the Zener diode 6 is 0, Then, a current flows through the Zener diode 6, so that a current flows through the primary winding 8, which reduces V ₂ .

In the present embodiment, the Zener voltage is set high so that the relationship of V _Z · a> V _r is established, so that even if the required voltage V _r is generated in the secondary winding, the Zener voltage is applied to the primary winding 8. The secondary voltage can be maintained high without the current flowing. Further, in the present embodiment, the Zener voltage V ₂ is set to be high, so that the above condition (V _r <
V _Z · a) is satisfied and for this reason the winding ratio a = 70
And

Further, in order to avoid mounting restrictions of the ignition coil,
In an ignition coil having a cylindrical outer shape that can be mounted in a plug hole provided from the upper part of the engine body to the mounting hole of the ignition plug, the physique is important.
For example, if the plug hole diameter of the engine as shown in FIG. 11 is 31 mm, the outer diameter of the tubular portion of the ignition coil body needs to be 30 mm or less.

Therefore, in the specification in which the required primary energy of the ignition coil is secured at a constant value and the primary current I ₁ is maintained at a predetermined value, when the winding ratio a = 90, The outer diameter is 30.5 mm, and the outer diameter when a = 80 is 29.6 mm.
Therefore, it is necessary to set the ratio of the number of turns on the physique to a = 80 or less. That is, the required primary energy W ₁ = L ₁ · I ₁ ²
In the specification in which / 2 is maintained at a constant value and the primary voltage I is maintained at a predetermined value, the primary inductance L ₁ is constant, that is, the primary winding number N ₁ is constant, so the winding ratio a should be reduced. Reduces the number of secondary turns N _2, and the size of the ignition coil can be reduced. In this embodiment, the outer diameter can be reduced.

In this ignition coil, the number of windings is reduced and the open magnetic circuit type shown in the drawing is used to further reduce the size and facilitate the mounting in the plug hole. The operation and effect when the required secondary voltage V _r = 30 kV is described below with reference to FIGS. 2 to 4. FIG. 2 shows the magnitude of the secondary voltage V ₂ borne by the turn ratio a of the ignition coil 7 for each zener voltage V _Z (V _Z = 350, 412, 467, 63).
7,875 V). In FIG. 2, the secondary voltage V ₂ increases as the zener voltage V _Z and the turns ratio a increase. That is, in the conventional ignition device configured by the Darlington transistor, since the Zener voltage V _Z = 350 V, the winding ratio a> about 90 is required to obtain the desired required secondary voltage V _r (= 30 kV). there were. On the other hand, in the case of using the IGET4 and setting the Zener voltage V _Z = 467V, the secondary voltage V ₂ = about 32k with the turns ratio a = 70.
V is generated, and good discharge can be obtained.

The required secondary voltage is lower than the above V _r = 2
When the IGBT 4 is used and the Zener voltage is V _Z = 467 V, the action and effect when the winding ratio is 8 kV is
= 70 can be reduced to a = 65. In other words, request 2
When the secondary voltage V _r = 28 kV, the zener voltage V _Z = 647 is set at the turns ratio a = 70, so that the conventional secondary voltage V ₂ = 24.5 kV at V _Z = 350 V is V It becomes possible to improve _Z = 32 kV.

FIG. 12 shows a method of measuring the secondary voltage V ₂ in FIG. This measuring method is called the SAE method, and V _B
= 14 V, C = 50 pF, and i = 6.5 A, the value of V ₂ is measured. On the other hand, FIG. 3 shows the relationship between the arc current I ₂ and the arter duration T when the primary current is cut off for each winding ratio a. Here, the arc current I ₂ and the arc duration T are defined as shown in FIG. 4, and the stationary state shows the secondary current waveform and the secondary voltage waveform when the spark plug 12 is discharged. . FIG. 3 shows that the arc duration T becomes longer as the turn ratio a increases, and in the case of the present embodiment (turn ratio a = 70), the arc duration = about 1.2 msec.

Then, in FIG. 3, in order to guarantee a good ignition performance, the arc duration T ≧ 0.8 mse is normally set.
c is required. Therefore, in this embodiment, that condition is satisfied, and good ignition can be obtained. Further, according to FIG. 3, at least about 40 turns ratio a is required to satisfy the arter duration T ≧ 0.8 Amsec, and in order to obtain the required secondary voltage V _r = 30 kV at the turns ratio a = 40. Indicates that the upper limit of the Zener voltage V _Z is 750 V (= 30 kV /
40).

It should be noted that the actual secondary voltage V ₂ on the secondary side requires some margin for the required secondary voltage V _r = 30 kV. Therefore, assuming a realistic margin of 3 kV, the target value when the required secondary voltage V _r = 30 kV is the secondary voltage V ₂ = 33 kV. Further, when obtaining the secondary voltage V ₂ = 33 kV, if the winding ratio a = 40 is indispensable from the arc characteristics of FIG. 3, the upper limit of the Zener voltage V _Z is set to 825 V (= 33 kV / 40).

As described above, according to the configuration of this embodiment, the IGBT
By using 4 to electrically connect and disconnect the primary current of the ignition coil 7, the effective operating breakdown voltage can be improved.
Therefore, the Zener voltage V _Z can be set high, and at this time, by satisfying V _Z · a> V _r , the winding ratio a can be lowered without lowering the secondary voltage V ₂ of the ignition coil 7. it can. The primary winding number of the ignition coil 7 is determined by the designed primary energy.
The decrease in the turns ratio a results in a decrease in the secondary turns, and the ignition coil 7
Can be downsized. Further, smoldering of the spark plug 12 can be prevented by the reduction of the winding number ratio a, and a good driver stability can be obtained.

In addition, specification changes (compression ratio increase, air-fuel ratio
Required secondary voltage V due to_rRises
Even if the secondary voltage V₂The desired request secondary power
Pressure V _rWhile maintaining the above, the turn ratio a of the ignition coil 7 is lowered.
Can be reduced. That is, the required secondary voltage V_r3
0kV, the actual target secondary voltage V₂To 33 kV
If the zener voltage value V_ZIs 450-825V
It should be set within the range, in this case, the ignition coil is always
7 can be miniaturized, as well as good ignition performance
Can be demonstrated.

Although the igniter 3 is constructed by using the IGBT 4 in the above-mentioned embodiment, the igniter 3 can be constructed by using MOSFET. M in FIG.
A circuit diagram using the OSFET 15 is shown. Even in this case, the withstand voltage of the MOSFET 15 can be easily made higher than that of the bipolar transistor, so that the Zener voltage V _Z of the Zener diode 6 can be set to 450 V or higher (preferably 450 to 825 V), thereby achieving the object of the present invention. be able to. Further, also in this example, the Zener diode 6 is built in the MOSFET, so that the circuit is miniaturized.

Furthermore, the present invention is applied to a system for directly supplying the ignition energy from the ignition coil 7 to the ignition plug 12 of each cylinder without passing through the distributor 11, that is, a so-called KLI (Distributer Less Ignition) system. The following actions and effects can be obtained. FIG. 6 shows the relationship between the primary-side terminal voltage (battery power supply V _B ) in the primary winding number 8 and the voltage (so-called secondary-side ON voltage) generated in the secondary winding 9 at each moment, in the winding ratio. It is shown for each a. This secondary-side on-voltage is
This voltage is generated when the primary side is energized based on the ignition signal from the ECU 1. If this voltage level exceeds a predetermined level, careless discharge is generated by the spark plug 12 and it causes premature ignition. . FIG. 7 shows the primary side terminal voltage V ₁₀
And a secondary winding ON voltage V ₂₀ showing a circuit diagram of the primary winding 2
7 shows an ignition coil 26 including a secondary winding 28.

In FIG. 6, it is known that, for example, when the spark plug gap = 0.7 mm, if the secondary side on-voltage exceeds 1.85 kV, discharge may occur and premature ignition may occur. Therefore, if the secondary side on-voltage is suppressed to less than 1.85 kV, pre-ignition is prevented, and in the case of the winding ratio a = 70 as in the present embodiment, the vehicle-mounted device that is normally used is mounted. Maximum value in battery (primary side terminal voltage = 14.
5V) always on the primary side, spark plug gap = 1.0m
When the secondary side ON voltage exceeds 2.20 kV, pre-ignition may occur, but if the turns ratio a = 70, the secondary side ON voltage will always be less than 2.20 kV. However, it does not cause premature ignition.

On the other hand, in the ignition coil used in the DLI system, a high voltage diode is usually connected in series with the secondary winding in order to prevent pre-ignition due to the secondary side ON voltage (FIG. 10). . However, this high-voltage diode can be eliminated and cost reduction can be realized. Although the example using the IGBT as the switching element has been described above, other elements such as a MOSFET and a bipolar transistor may be used.

However, since the current capability per unit area of the MOSFET and the bipolar transistor is inferior to that of the IGBT, it is necessary to enlarge the element size, which is disadvantageous when the device needs to be downsized. Further, in the bipolar transistor, there is a trade-off relationship between the effective operation breakdown voltage and the current amplification factor, and it is necessary to further increase the element size and secure the current capability in order to make the breakdown voltage 450 V or higher. The element size at that time is IG
This is 2.6 times the element size of BT (area ratio).

[0039]

According to the present invention, with the above-mentioned structure, the following excellent effects can be obtained. According to the invention of claim 1, it is possible to reduce the turn ratio of the ignition coil while maintaining the secondary voltage generated in the secondary winding at a desired required secondary voltage or higher. In this case, it is possible to cope with a rise in the required secondary voltage.

According to the invention of claim 2, good ignition performance can be obtained. Further, according to the invention of claim 3, it is possible to obtain a small-sized ignition device for an internal combustion engine which is easily mounted on an engine. According to the invention of claim 4, an ignition device for an internal combustion engine having a simple structure can be obtained. Also, claim 5
According to the invention of (1), not only the above effect can be obtained, but also the secondary side on-voltage in the DLI system can be reduced and premature ignition can be prevented by discharge.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an internal combustion engine ignition device according to an embodiment.

FIG. 2 is a diagram showing, for each Zener voltage, a magnitude of a secondary voltage with respect to a turn ratio of an ignition coil.

FIG. 3 is a diagram showing the relationship between the arc current and the arc duration when the primary current is cut off, for each turn ratio.

FIG. 4 is a waveform diagram showing a secondary current and a secondary voltage when the spark plug is discharged.

FIG. 5 is a circuit diagram of an ignition device according to another embodiment.

FIG. 6 is a diagram showing a relationship between a primary-side terminal voltage and a secondary-side on-voltage for each turn ratio.

FIG. 7 is a circuit diagram showing an ignition coil.

FIG. 8 is a waveform diagram for explaining a secondary-side on voltage.

FIG. 9 is a circuit diagram of an ignition device in the related art.

FIG. 10 is a circuit diagram of an ignition coil used in a DLI system.

FIG. 11 is a cross-sectional view of an ignition coil mounted in a plug hole.

FIG. 12 is a circuit diagram showing a method of measuring the secondary voltage V ₂ .

[Explanation of symbols]

 3 Igniter 4 IGBT (Insulated Gate Bipolar Transistor) 6 Zener diode 7 Ignition coil 8 Primary winding 12 Spark plug 15 MOSFET

Claims (15)

[Claims] 1. An ignition device for an internal combustion engine, comprising an ignition coil and a switching element for electrically interrupting a primary current of the ignition coil, wherein a required voltage in a secondary winding of the ignition coil is V _r , The breakdown voltage of the switching element is V _D , the number of turns N ₁ of the primary winding and the number of turns N _{2 of the} secondary winding of the ignition coil
When the ratio (N ₂ / N ₁ ) of the above is the winding number ratio a, the following relationship is satisfied: V _D · a> V _r , and V _{D is set} to 450 V or more. 2. The ignition device for an internal combustion engine according to claim 1, wherein the turn ratio a is 40 or more and 80 or less. 3. The ignition device for an internal combustion engine according to claim 2, wherein the ignition device is mounted in a plug hole of the engine, and the outer diameter of the tubular portion of the ignition coil body is 30 mm or less. 4. The ignition device for an internal combustion engine according to claim 3, wherein the ignition coil is an open magnetic circuit type ignition coil. 5. The ignition device for an internal combustion engine according to claim 2, wherein the ignition device is used in a system for directly supplying ignition energy from an ignition coil to an ignition plug of each cylinder. . 6. The ignition device for an internal combustion engine according to claim 2, wherein the secondary voltage is 28 KV or more. 7. The ignition device for an internal combustion engine according to claim 1, wherein an IGBT is used for the switching element. 8. The internal combustion engine according to claim 7, wherein a zener diode for preventing overvoltage is connected to the IGBT, and the breakdown voltage V _D of the IGBT is determined by the breakdown voltage V _Z of the zener diode. Ignition system for engines. 9. The ignition device for an internal combustion engine according to claim 8, wherein the Zener diode is incorporated in an IGBT. 10. The switching element is a MOSFET
The ignition device for an internal combustion engine according to claim 1, wherein the ignition device is used. 11. The Zener diode for preventing overvoltage is connected to the MOSFET, and the breakdown voltage V _D of the MOSFET is determined by the breakdown voltage V _Z of the Zener diode. Ignition device for internal combustion engine. 12. The Zener diode is a MOSFET
The ignition device for an internal combustion engine according to claim 11, which is incorporated in the internal combustion engine. 13. The ignition device for an internal combustion engine according to claim 1, wherein a bipolar transistor is used as the switching element. 14. A zener diode for preventing overvoltage is connected to the bipolar transistor, and the breakdown voltage V _D of the bipolar transistor is determined by the breakdown voltage V _Z of the zener diode. An ignition device for an internal combustion engine as described. 15. The ignition device for an internal combustion engine according to claim 14, wherein the Zener diode is incorporated in a bipolar transistor.