JP3192074B2 - Ignition device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ignition device for a one-chip type internal combustion engine.

[0002]

2. Description of the Related Art Conventional techniques include, for example, Japanese Patent Application Laid-Open No.
There is the one described in No. 3. In this method, the current limiting circuit is constituted by a bipolar transistor amplifying circuit or a bipolar transistor differential circuit, and the detection unit detects only the potential difference by the resistance element.

[0003]

In the above prior art,
Since the current limiting circuit is composed of a bipolar transistor amplifier circuit or bipolar transistor differential circuit,
In order to integrate the IGBT with the IGBT on one chip, an isolation or junction type structure is required, and the manufacturing process becomes complicated due to an increase in the element area and the number of masks, which is disadvantageous. In addition, since the detection unit detects only the potential difference by the resistance element, no consideration is given to the influence of the temperature on the detection level.

An object of the present invention is to provide a compact and high productivity.
And an ignition device for an internal combustion engine.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an engine for an internal combustion engine.
Ignition according to the ignition control signal output from the electronic control unit
A switch that controls the energization / cutoff of the primary current flowing through the coil
Current flowing through the switching element and the switching element
A current limiting circuit for controlling the switching element.
Internal combustion engine composed of edge-gate bipolar transistors
In the Seki igniter, the current limiting circuit is a self-separating type.
An N-MOS transistor, the insulated gate type
Bipolar transistor and the self-isolating N-MOS transistor
Transistor and one chip formed on a common semiconductor substrate
Is achieved by

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A current limiting circuit is a self-isolation type NM
By using an OS transistor circuit, the IGBT
Easy to build in a chip, compact
It is possible to supply a simple ignition device. In addition, by providing a diode in the current limiting circuit, the temperature dependency of the detection circuit can be reduced, so that a highly reliable ignition device can be achieved. Highly accurate and reliable current limiting function
IGBT igniter with a single chip is possible.

[0007]

FIG . 1 shows a configuration example of a normal ignition system. 1 denotes an ECU, 2 denotes an ignition device, 3 denotes an ignition coil, and 4 denotes an ignition plug. The output stage of the ECU 1 includes a PNP transistor 9, an NPN transistor 10, and a resistor 11, and turns on and off the transistors 9, 10 at an appropriate ignition timing calculated by the CPU 8, and outputs HIGH and LOW pulses to the ignition device. I do. The ignition device 2
It comprises a power transistor 5, a current detection load 6, a current control circuit 7, and an input resistor 12 mounted on the hybrid IC 13, and the output signal of the ECU 1 is LOW →
When HIGH, the power transistor 5 starts energizing, and HI
By cutting off from GH to LOW, a high voltage of 300 to 400 V is generated at the collector of the power transistor 5.

FIG. 2 shows an internal equivalent circuit representing the configuration of the one-chip ignition device of the present invention. 14 is an ignition coil, 15
Is a main IGBT constituting a main circuit for energizing and interrupting the primary current flowing through the primary coil of the ignition coil 14, and 16 is a current detecting sub-IGBT for detecting the primary current.
17 is a current detection circuit for detecting a primary current, 17 is a current detection circuit, 18 is a current limiting circuit for controlling a gate voltage to limit the primary current to a set value, and 19 is an input resistor. 20
Is an IC in which the main IGBT 15, the sub IGBT 16, the current detecting circuit 17, the current limiting circuit 18, and the input resistor 19 are integrated into one chip. The power transistor, the current detection load, and the current control circuit in the normal system shown in FIG. 1 are constituted by integrated circuits on the same one chip.

FIG. 3 shows the configuration of an ignition system according to an embodiment of the present invention.

An input resistor 26 is provided at the input stage of the ignition device. The power transistor 21 is an IGBT combining an enhancement type n-channel MOS gate transistor and a PNP bipolar transistor,
It is composed of a main IGBT constituting a main circuit and a sub-IGBT for current detection for detecting a primary current, and the main IGBT and the sub-IGBT are separated at a ratio of 1000: 1 to 10000: 1. The current detection load element 22 is a sub-IGBT
Are provided between the emitter and the GND, and are formed in one chip by a diffusion resistor. For example, if the ratio is 100
In the case of 0: 1, when 8A flows through the main IGBT, the sub I
A current of 8 mA flows through the GBT. Assuming that the detection voltage is 0.8 V, 0.8 (V) /0.008 (A) = 100 (Ω)
Therefore, the diffusion resistance is set to 100Ω. Further, under the same conditions, when the ratio of the main and the sub is 10000: 1, the diffusion resistance may be set to 1 kΩ. The ratio and the resistance value can be set arbitrarily. FIG. 7 shows an example of the diffusion resistor 57 formed in the IGBT 55.

A bias voltage is applied to an input stage of the current control circuit by a forward voltage of diodes 28 and 29 pulled up by a resistor 27. By setting the temperature coefficient of the forward voltage of the diode to be zero with respect to the gate threshold voltage of the N-MOS transistor 23 and the temperature coefficient of the load element 22 for current detection, the relationship between the current and the detected voltage is always constant. The current detection is constant and does not have a temperature coefficient.

As an example, the diffusion resistance is generally 20
Because it has a positive temperature coefficient of 00-3000 ppm,
For example, assuming that the temperature coefficient of the resistor is 2500 ppm and the detection level is 0.8 ± 0.2 V (0.6 to 1.0 V), when the temperature of the current detection circuit rises by 100 ° C., the resistance value changes by 25%. The detection voltage corresponding to the current is 1.
It becomes 0V and rises by + 0.2V. In contrast, diodes generally have a negative temperature coefficient of -2 mV / ° C, so that a temperature change of 100 ° C will
mV × 100 = −0.2 V, and the temperature coefficient of the resistance can be canceled. In this example, the diodes 28 and 29 are configured in two lines in consideration of the temperature characteristics of the threshold voltage of the N-MOS transistor. The diode is made of polysilicon, and FIG. 8 shows an example of a polysilicon diode 59 formed on the IGBT 58.

In a conventional bipolar transistor, a mirror integration circuit or the like is provided after current detection to reduce the loop transfer gain so as to suppress the oscillation phenomenon at the time of non-saturation. FIG. 5 shows an example in which a Miller integration circuit is provided in an IGBT igniter. A current limiting circuit composed of a MOS differential amplifier and a Miller integrating circuit are composed of the resistor 43 and the capacitor 44. However, MOS configured in IGBT
In the transistor amplifier circuit and the MOS differential amplifier circuit, it is possible to reduce the oscillation phenomenon at the time of non-saturation by emphasizing giving the phase margin of the loop transmission loop gain by configuring an amplifier circuit having a low gain. . FIG.
Shows an example of a waveform representing the IGBT operation. When an ignition signal is input to the IGBT and the IGBT is turned on and a collector current flows, the collector-emitter voltage of the IGBT rises. When the collector current reaches the current limit value, the IGBT
Becomes unsaturated, and the current is controlled to be constant. In this current control, due to the relationship between the secondary delay due to the primary inductance of the ignition coil and the amplification factor of the IGBT, the current may oscillate when the unsaturated control is performed. It is important to make sure you can afford it. FIG. 10 shows an example of the phase / gain frequency response of the loop transmission with one end of the feedback loop released.

The condition under which oscillation occurs is that the gain is 0d
In the case where the phase is delayed by 180 ° above B, the N-
If the MOS current limiting circuit is configured as a Miller integrating circuit, the delay increases and the margin for oscillation is reduced, so that the configuration of FIG. 4 is more advantageous for one-chip implementation.

Since the current control circuit section is constituted by the self-isolation type N-MOS transistor 23, it can be easily formed in the PNPN semiconductor structure forming the IGBT. FIG. 6 shows the structure. The IGBT 50 has a four-layer structure of semiconductor PNPN. A positive voltage of a power supply is connected to a collector 51, a negative voltage of a power supply is connected to an emitter 52, and a sufficient positive voltage is applied to a gate 53 insulated by an oxide film to form an N channel in a depletion layer. Current flows through Self-isolation type N-MOS
The transistor 49 has a structure in which an N layer is formed in a P base layer of an IGBT, source and drain terminals are drawn therefrom, and a gate terminal insulated with an oxide film is provided therebetween. The N-MOS transistor described here assumes both an enhancement type and a depletion type.

FIG. 7 shows a case where a transistor is formed by a junction separation type. A P-substrate 56 is provided to form a transistor, and a PNP or NP is provided therein.
In this structure, an N transistor is formed.
Since it is far from the basic structure of the GBT, not only the number of masks increases but also the P / N structure has four or more layers, so that there are many problems in manufacturing and functions.

FIG. 4 shows another embodiment. Similarly to the above-described embodiment, the power transistor 30 is an IGBT, and includes a main IGBT constituting a main circuit and a sub-IGBT for detecting a primary current, and a load element 31 for detecting current is connected to an emitter of the sub-IGBT. It is provided between GND. The load element is constituted by a diffusion resistor in one chip.

The current control circuit has a differential circuit configuration composed of N-MOS transistors 32 and 33 and resistors 34, 35 and 36. Since the N-MOS transistor of the present embodiment is also of the self-isolation type, as in the first embodiment, it is fabricated in the PNPN semiconductor structure constituting the IGBT. A differential reference voltage is set by resistors 37 and 38, and a bias voltage is applied to the input stage of the current control circuit by a forward voltage of a diode 40 pulled up by a resistor 39. By setting the temperature coefficient of the forward voltage of the diode to be zero with respect to the differential circuit reference voltage and the temperature coefficient of the current detection load element 22, the voltage drop due to the load element 22 is always constant and the temperature coefficient is reduced. This enables uninterrupted current detection. The principle of operation is as described in the example of claim 1, but since the current limiting circuit is constituted by a differential circuit, N-M
Since the temperature characteristics of the threshold voltage of the OS transistor are not affected, the temperature coefficient can be canceled by one diode 40.

[0020]

According to the present invention, compact and productive
A good internal combustion engine ignition device can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration of a normal ignition device.

FIG. 2 is an internal equivalent circuit showing the gist of the present invention.

FIG. 3 shows an embodiment of a circuit according to claim 1 of the present invention.

FIG. 4 shows an embodiment of a circuit according to claim 2;

FIG. 5 is an example in which a Miller integrating circuit is provided in a current limiting circuit.

FIG. 6 shows an embodiment of a self-isolation type N-MOS transistor integrated in an IGBT.

FIG. 7 shows an embodiment of a junction isolation transistor integrated in an IGBT.

FIG. 8 shows an embodiment of a diffusion resistor and a polysilicon diode integrated in the IGBT.

FIG. 9 is a waveform example for explaining a current limiting operation.

FIG. 10 is an example of a loop frequency response characteristic.

[Description of Signs] 1 ... ECU, 2 ... Ignition device, 3,14 ... Ignition coil, 4
... Spark plug, 5 ... Power transistor, 6,22,3
1 ... Current detection load, 7, 18 ... Current limiting circuit, 8 ... C
PU, 9: PNP transistor, 10: NPN transistor, 11, 12, 19, 26, 27, 34, 35, 3
6, 37, 38, 39, 43, 47: resistor, 13: hybrid IC board, 15: main IGBT, 16: sub
IGBT, 17: current detection circuit, 20: one-chip igniter, 21, 30, 48, 50, 55, 59: IGBT,
23, 32, 33, 42, 49 ... Self-isolation type N-MOS
Transistors, 28, 29, 40 ... diodes, 44 ...
Capacitor, 51: Collector terminal, 52: Gate terminal,
53 ... emitter terminal, 54 ... junction separated type transistor,
56 ... P-substrate, 57 ... Diffusion resistor, 59 ... Polysilicon diode.

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Noboru Sugiura 2520 Takahiro, Hitachinaka-shi, Ibaraki Pref. Hitachi, Ltd. Automotive Equipment Division (56) References JP-A-5-164031 (JP, A) JP-A Heisei 2-136563 (JP, A) JP-A-52-114833 (JP, A) JP-A-4-143458 (JP, A) JP-A-3-500673 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02P 3/04 301 H01F 38/12

Claims (3)

(57) [Claims] A switching element for controlling the supply and cutoff of a primary current flowing through an ignition coil according to an ignition control signal output from an electronic control unit for an internal combustion engine; and a current limiting circuit for limiting a current flowing through the switching element. wherein the switching element is an insulated gate type bipolar Trang
In the ignition device for an internal combustion engine including a resistor , the current limiting circuit includes a self-isolation type N-MOS transistor, and the insulated gate bipolar transistor and the self-isolation type N-MOS transistor are provided on a common semiconductor substrate. An ignition device for an internal combustion engine , which is formed and integrated into one chip . 2. The current detecting load according to claim 1, wherein said current detecting load is provided between said current detecting load and said self-isolating N-MOS transistor, and said current detecting load is provided for detecting a current flowing through said insulated gate bipolar transistor. A diode having a temperature coefficient opposite to that of the load for detection .
Ignition device for an internal combustion engine that. 3. The current limiting circuit according to claim 2, wherein said current limiting circuit is a self-isolating N-MOS.
An ignition device for an internal combustion engine, comprising a differential amplifier circuit.