JPH10274142A - Ignition device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use an ignition device for an internal combustion engine without causing any fault even under a severe environment and the like, by setting to a specific value or more, the maximum energy determined by the primary inductance of an ignition coil the primary current and applied to a switching element when the primary current of the ignition coil is shut off. SOLUTION: Regarding Es/b maximum energy, in the case that only the primary side (pure inductance) of an ignition coil 3 is supposed, (1/2)×L1 ×I2 (mJ) is applied to a switching element 2 every ignition time (every time primary current is shut off). In the case that the whole ignition energy ignition misfired is applied to the switching element 2, the maximum energy becomes 1/3, and in a worst case, becomes 1/2, in comparison with a case that the pure inductance is supposed. Therefore, the Es/b maximum energy of the switching element 2 is set to about 200 mJ more, the primary inductance of the ignition coil 3 becomes about 8 mH or more when shut off current is set to about 10A, thus, most primary inductance of the ignition coil 3 whose present primary inductance is mainly 2-4 mH can be covered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device in which an igniter is built in an ignition coil, and more particularly to an intelligent power chip in which a control circuit is integrated in a switching element.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 2-171904 discloses a technique in which an insulated gate bipolar transistor (hereinafter referred to as "IGBT") is used for an ignition device for an internal combustion engine and has a protection function. The purpose of the present invention is to optimize the circuit and to cope with an increase in current by the IGBT, and does not describe the performance and withstand capability required for the ignition device as in the present invention.

[0003]

In the above prior art, I
The purpose of the present invention is to add a current limiting circuit as a protection function of the GBT to improve the accuracy of the current limiting characteristics, but does not mention the original performance and tolerance of the ignition device. To use it as an ignition device,
There are various restrictions depending on the usage, environment, and the like, and unless these are satisfied, the igniter cannot be used. In the present invention, the immunity of a one-chip igniter in which a control circuit is integrated into an IGBT chip, a withstand voltage, and the like required for practical use as an ignition device are quantified in terms of combinations and usage.

[0004]

Means for Solving the Problems To solve the above problems, the Es / b withstand voltage, continuous withstand voltage, primary voltage clamp voltage, V _CE (sat), and the like are quantified and specified, so that they can be practically used as ignition devices. Provide a one-chip igniter.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.
1, 2 and 3 show the circuit configuration when the primary current of the ignition coil is cut off by the switching element, the primary current I _c ,
It shows the primary voltage V ₁ and the energy ∫ (I _c × V ₁ ) dt applied to the switching element. FIG. 1 shows a normal ignition state, in which the switching element 2 is turned on and off by an ignition signal 1. When energized, primary current flows I _c to the switching element 2 from the primary side of the ignition coil 3. This primary current I _c
There primary voltage V ₁ is generated in the collector of the switching element when the blocking. Induced by the primary voltage V ₁ , a high voltage is generated on the secondary side of the ignition coil 3, and a spark is generated on the ignition plug 4. When a spark is generated in the spark plug, the ignition coil 3
The switching element because the energy will be released, the energy at the time of interruption of the primary current I _c is hardly applied (however, minute energy generated by the leakage inductance generated during interruption of the primary current I _c is applied .). As shown in FIG. 3, assuming that only the primary side of the ignition coil (pure inductance) is assumed, the energy required for (1/2) × L ₁ × I ₂ (mJ) is applied to the switching element. (Interruption of primary current). For example, if L ₁ = 5 mH and I (breaking current) = 10 A, then E = 250 mJ. However, the actual ignition coil has a secondary coil as shown in FIG. However, even if all of the ignition energy of the ignition coil is applied to the switching element due to a mistake, the energy is usually 1/3 of the energy obtained by the above-described calculation formula assuming the pure inductance of FIG. Therefore, by setting the Es / b resistance of the switching element to 200 mJ or more, when the breaking current is 10 A, the primary inductance of the ignition coil can be 8 mH or more. Can cover most of

The continuous withstand voltage will be described with reference to FIGS. 4 and 5. FIG. In FIG. 4, an ignition signal V _IN output from the ECU 10 is input to a one-chip igniter 11, and controls the gate of the IGBT 2 via a control circuit 12 having a current limiting circuit. The IGBT 2 is a primary current I of the ignition coil 3.
Energizes and de-energizes _c to generate a high voltage on its secondary side.
In the present invention, the stall energization tolerance is defined because the stall detection time in the ECU is 1.5 seconds or less. FIG. 5 shows the operation timing. Ignition signal V
_IN is turned on is controlled by the normal operation ECU, and outputs an OFF signal, I _c is energized in response to the ignition signal V _IN, IGB
An on-voltage V _CE is generated between the collector and the emitter 2 of T2. At this time, the power consumed by the IGBT is ∫ (I _c ×
V _CE ) dt. When the current limit is applied, IG
Since V _{CE of} BT2 rises to limit I _c , power consumption P _w
Increases rapidly. Time t when ECU detects engine stall
_{During 1} (1.5 sec), a HIGH ignition signal is output from the ECU, and the ignition device is continuously energized. At this time,
The power applied to the switching element of the ignition device is I
It is determined by _c × V _CE . By the operation of the current limiting circuit provided in the ignition device, V _CE during continuous energization is V _CE = V _B -I _c ×
(R ₁ + R _x ). Here, the primary resistance R ₁ is an ignition coil, R _x is the resistance between V _B to GND except R _1.
According to this formula, I _c × V _CE is usually 80 W or less, but it is necessary to consider up to 100 W by increasing the current for increasing the output and reducing the resistance of R ₁ . Further, it is necessary to assume the worst temperature condition to which the switching element of the ignition device is exposed, and to set the standard at Tj = 150 ° C.

The threshold voltage of the igniter will be described with reference to FIG. The threshold voltage of the igniter needs to be determined in consideration of the potential difference between GND-a of the ECU and GND-b of the igniter. (LOW voltage of igniter) + Ｇ (GND-b)
− (GND-a)｝ <(igniter threshold voltage) The igniter is energized even though the ignition signal is LOW, resulting in a continuous energized state.
It can lead to destruction. In many cases, the pull-up power supply _Vcc of the ignition signal output unit of the ECU 10 is based on 5 V.
The voltage needs to be determined. In FIG. 6, resistors 13 and 14
Voltage drop V _a, V _b and at, ECU 10 a voltage that the voltage obtained by adding such as a voltage drop V _c by the connection resistance was subtracted from V _cc between the igniter 11, the threshold voltage MAX igniter. Thus, the threshold voltage is set to 0.5 to 3.5V.

In the IGBT section of the igniter, a bidirectional Zener diode 15 of polysilicon is provided between the gate and the collector as shown in FIG. The Zener MAX voltage is a value necessary to protect the IGBT section,
Since it is determined based on the withstand voltage of the crystal of the wafer, it is set according to the withstand voltage of the crystal. MIN is determined by the required output voltage of the ignition coil. The output voltage V _2, the primary winding N ₁ and the secondary winding N ₂ of the ignition coil, obtained by the conversion efficiency k of the primary voltage V ₁ (here = Zener voltage V _z) and primary and secondary voltage, V ₂ = K × V _z × (N ₂ / N ₁ ). Here, for example, the required value of V ₂ is 30 kV, and k =
When 1, by a V _z ≧ 410V (N ₂ /
N ₁ ) can be achieved at 75 or more.

Next, the ON voltage of the igniter switching element will be described with reference to FIG. The one-chip igniter 11 of the present invention using the IGBT 2 has an input voltage V since the collector current is controlled by the gate voltage.
It is necessary to define the _IN and the collector current I _c. Further, the flow collector current I _c, the primary resistance R in the ignition coil 3
_Since a voltage of ₁ × I _c is consumed, the on-voltage between the collector and the emitter of the IGBT 2 must be less than V _B −I _c × (R ₁ + R _x ) (where R _x is not R ₁ resistance between -GND V _B). For example, when a typical ignition coil is used and the primary resistance R ₁ = 0.7Ω ± 10%,
When a primary current I _c = 8 A flows through R ₁ MAX at 50 ° C., the voltage drop at the primary resistance R ₁ of the ignition coil becomes 9 V, and when V _B = 12 V, the ON voltage of the IGBT 2 (V
_CE (sat)) must be equal to or less than 3.0 V, unless the primary current I _c =
8A cannot be driven.

Next, FIG. 8 shows an example of a package configuration of the one-chip igniter of the present invention. 1-chip igniter of the present invention, V _B for driving only the ignition signal from the ECU
It is possible to configure the three terminals of the signal terminal, the collector terminal, and the GND as external output terminals without the need for the terminal. FIG.
In the package structure shown in FIG. 1, a one-chip igniter 11 is bonded to a base 22 of a metal lead integrated with a bonding material 23 such as solder.
And the metal lead 21 and Al or A
This is a standard package structure of a semiconductor power element called TO-220 or TO-3P, which is connected by ultrasonic bonding with a wire 20 such as u, and is individually sealed with 24 epoxy resins. In the one-chip igniter of the present invention, since the control circuit unit is integrated on the same chip as the switching element, it can be incorporated in a standard package of a normal power semiconductor, and cost reduction including equipment can be achieved.

Next, when used as an ignition device, it is necessary to consider that various surges are applied to each terminal. In particular, since the igniter of the present invention has a control circuit, it is necessary to protect the input terminal section, and the input terminal is provided with a zener diode for surge protection. As shown in FIG. 9, the ignition signal output unit of the ECU 10 is pulled up from _Vcc of 5 V. Some ECUs perform OPEN detection diagnosis of the signal line using this output stage. The Zener voltage of the protective Zener diode 31 is set to 6 V or more in the present invention, since the OPEN detection may be erroneously diagnosed unless the Zener voltage is set to this V _CC or more.

[0012]

According to the present invention, it is possible to use a one-chip igniter in which a control circuit is integrated in an IGBT without causing a problem even in a special and severe usage such as an automobile ignition device or an environment. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a normal ignition state using the present invention.

FIG. 2 is a waveform chart at the time of silent discharge using the present invention.

FIG. 3 is a waveform chart with pure inductance using the present invention.

FIG. 4 is an explanatory diagram of an ignition system configuration using the present invention.

FIG. 5 is an operation timing chart.

FIG. 6 is an explanatory diagram of an ignition system using the present invention.

FIG. 7 is an explanatory diagram of a switching element.

FIG. 8 is an explanatory view of a package structure of the present invention.

FIG. 9 is an explanatory diagram of an ignition system configuration using the present invention.

[Explanation of symbols]

1 ... ignition signal, 2 ... switching device, 3 ... ignition coil, 4 ... spark plug, 5 ... net inductance, I _c ... primary current, V _B ... battery voltage, V ₁ ... primary voltage, 10 ...
ECU, 11: one-chip igniter, 12: control circuit unit, V _IN : input signal voltage, V _CE : collector-emitter voltage, R _x : wiring resistance, P _w : power consumption by switching elements, 13, 14 ... Resistance, _Vcc ... ECU reference voltage,
V _a ... drop voltage of the resistor 13, V _b ... drop voltage of the resistor 14, V _c ... ECU and 1 drop voltage of a connection portion between the chip igniter, the GND-a ... ECU output stage GN
D, GND-b: GND of igniter, 15: Primary voltage clamp Zener diode, C: Collector, G: Gate, E: Emitter, 20: Wire, 21: Metal lead, 22: Lead integrated base, 23: Connection material , 24 ...
Epoxy resin for solid sealing, 31 ... Zener diode for input protection.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yuichi Kashimura 2520 Oji Takaba, Hitachinaka City, Ibaraki Prefecture Inside the Automotive Equipment Division, Hitachi, Ltd. (72) Inventor Noboru Sugiura, Hitachi, Ibaraki Pref.

Claims (8)

[Claims] 1. An igniter for controlling the supply and cutoff of a primary current flowing through an ignition coil in accordance with an ignition signal output from an ECU and generating a high voltage on a secondary side thereof, wherein a switching circuit portion is constituted by a vertical IGBT. A one-chip type igniter in which a current limiting circuit as a protection function is integrated in the IGBT chip, wherein a primary inductance and a primary current of the ignition coil are applied to the switching element when the primary current of the ignition coil is cut off. An ignition device for an internal combustion engine, wherein the energy tolerance determined by the above is set to 200 mJ or more. 2. An ignition device for an internal combustion engine according to claim 1, wherein said igniter has a withstand capacity which is not destroyed by continuous application of power for 1.5 seconds or more when a power of 80 to 100 W is applied at a junction temperature Tj = 150 ° C. 3. The igniter according to claim 1, wherein the igniter is the ECU.
An ignition device for an internal combustion engine having a threshold voltage for controlling energization / interruption with an input signal of 0.5 V to 3.5 V from the company. 4. The igniter according to claim 1, wherein
An ignition device for an internal combustion engine in which a Zener diode for clamping a primary voltage is formed of a bidirectional polysilicon diode between a collector and a gate of T and has a clamp voltage of 410 V or more in a range of Tj = -40 ° C. to 150 ° C. . 5. The igniter according to claim 1, wherein when the input voltage is 3 to 3.5 V and the collector voltage is 8 A, the on-voltage V _CE (sat) between the collector and the emitter is 3.0 V or less. Engine ignition device. 6. The igniter according to claim 1, wherein
An ignition device for an internal combustion engine having three terminals as a terminal for external connection, a signal terminal for receiving an ignition signal from the controller, a collector terminal connected to the primary side of the ignition coil, and a GND terminal. 7. The igniter according to claim 1, wherein the igniter is TO-220.
Or, an ignition device for an internal combustion engine that is housed in a TO-3P standard package and does not use a dedicated package structure as an igniter. 8. The igniter according to claim 1, further comprising an input protection Zener diode between the input terminal and GND, wherein the Zener diode is formed of either diffusion or polysilicon, or both, and And an ignition device for an internal combustion engine having a voltage of 6 V or more.