JPH09228937A - Ignition device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the reliability of contact between terminals and enable the detection of disconnection by setting input impedance of an ignition device in such a manner that a current which flows into the ignition device from an electronic controller for internal combustion engine is 1mA or more. SOLUTION: An output step of an electronic controller for internal combustion engine ECU 1 is connected with an NPN transistor 7 through a resistance 6 from a reference power supply Vcc and is connected with an ignition device 2 through a resistance 8. The transistor 7 is turned ON and OFF at proper ignition timing and outputs HIGH and LOW ignition signals to its collector part to drive the ignition device 2. Input impedance of the ignition device 2 is set in such a manner that a terminal current becomes 1mA or more in accordance with values of Vcc of ECU 1, resistance 6, and resistance 7. In this way, since a secure connection current with ECU can be ensured in the ignition device, it is possible to obtain the reliability of secure connection even if inexpensive Sn plating is used at a connection terminal. Moreover, it is possible to detect disconnection of a connection part in ECU.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ignition device for an internal combustion engine using an IGBT.

[0002]

2. Description of the Related Art As a conventional technique, there is one described in Japanese Patent Laid-Open No. 2-136563, which states that a current limiting circuit is composed of a bipolar transistor amplifier circuit or a bipolar transistor differential circuit. However, nothing is mentioned about the connection reliability due to the contact current of the input terminal portion becoming too small due to the voltage driving of the IGBT. Further, nothing is mentioned about the feasibility of functions such as disconnection detection as an ignition system combined with an ECU.

[0003]

In the ignition device that directly drives the IGBT by the ignition control signal from the ECU, the ignition from the ECU is performed because the IGBT is a voltage-driven type switching element formed of an insulated gate type. Requires almost no current for control signals. Also,
Even if a current limiting circuit is provided, if the current is not limited, almost no current is required.
Only a small current of the order of μA flows through the connection terminal between the ignition device and the ignition device. At this time, it is necessary to obtain reliable contact reliability between the terminals.

Further, a normal ECU detects the disconnection between the ECU and the ignition device at the output part thereof. However, when the above ignition device is used, since almost no current flows from the ECU to the ignition device, there is almost no difference between the presence and absence of the disconnection, and therefore the disconnection detection by the ECU becomes impossible.

An object of the present invention is to provide an ignition device for an internal combustion engine capable of detecting disconnection of a connection at an ECU output section.

[0006]

In order to solve the above problems, in the prior art, the connection terminals were plated with Au to prevent oxidation of the terminal portions to ensure the reliability of the connection.
If u plating is used, there is a problem that it becomes expensive.

In the present invention, an inexpensive Sn-plated terminal can be used by setting the input impedance of the ignition device so that the current flowing from the ECU into the ignition device is 1 mA or more and ensuring the contact current of the connection terminal portion.

Further, when there is a disconnection due to a circuit impedance that causes a current of 1 mA or more to flow from the ECU to the ignition device, the voltage at the ECU output stage changes, so the detection of the disconnection between the ignition device in a normal ECU. Is possible.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an ignition system. Reference numeral 1 is an ECU, 2 is an ignition device, 3 is an ignition coil, 4 is an ignition plug, and 5 is a battery. The output stage of the ECU 1 is connected to the collector terminal of the NPN transistor 7 and the resistor 8 via the resistor 6 from the reference power source Vcc configured in the ECU 1, and is connected to the ignition device 2 via the resistor 8. The transistor 7 turns on at an appropriate ignition timing,
The ignition device is turned off, and a HIGH and LOW ignition signal is output to the collector portion to drive the ignition device 2. The ignition device 2 is I
The GBT 9 and the hybrid IC 10 include a current detection load 11, a current limiting circuit 12, and an input resistor 13. When the output signal of the ECU 1 is LOW → HIGH, the IGBT 9 starts energization, and when it is HIGH → LOW to cut off the current, a high voltage of about 400 V is generated in the collector portion of the IGBT 9.

Normally, an ignition device using this IGBT is
Since the gate voltage of the IGBT 9 is directly controlled by the output signal from the ECU 1, a large current is caused to flow between the collector and the emitter by the voltage control which is a characteristic of the IGBT.
Gate of BT, that is, connection terminal 1 of ECU 1 and ignition device 2
Almost no current flows through No. 4. Further, the current limiting circuit consumes almost no current during normal operation in which no current limiting is applied. For this reason, since only a current of the order of μA flows through the connection terminal 14, the connection reliability between the terminals becomes unstable. The connection terminal 14 is usually Sn-plated, but if the contact current between the terminals is small as described above, the terminals may be oxidized and contact failure may occur.
Therefore, when the contact current between terminals is small (less than about 1 mA), expensive Au plating is used for plating the connection terminals to prevent oxidation of the terminals and ensure connection reliability. In the present invention, in order to solve this problem, the input impedance of the ignition device 2 (impedance viewed from the ignition signal input portion from the ECU 1) is intentionally set, and the terminal current flowing through the connection terminal 14 is set to 1 mA or more, and the connection terminal 14 Even when the plating of Sn is Sn plating, sufficient connection reliability is obtained. The input impedance is set as the circuit configuration of the ignition device 2, or is set by the resistor 15 (bleeder resistor) provided between the input terminal and GND for current adjustment. This input impedance is set by Vcc of ECU 1, resistance 6,
The terminal current is set to 1 mA or more according to the value of the resistor 7. FIG. 2 shows an example in which the present invention is applied to a one-chip igniter. One-chip igniter 16 is IGBT
It comprises a current limiting circuit 17, a current limiting circuit 18, and an input resistor 19. The IGBT 17 is composed of a main 20 and a sub 21, and the main: sub is divided at a ratio of 1000: 1 to 10000: 1. The current detection load 22 is provided between the emitter of the sub IGBT 21 and the GND. Further, between the gate and collector of the IGBT 17, a phase direction Zener diode 23 for clamping the primary voltage at about 400 V is formed of polysilicon. A protective phase-direction Zener diode 24 and a resistor 25 are formed between the gate and the emitter. The resistor 26 provided between the input and GND is the bleeder resistor for controlling the terminal current according to the present invention. Of course, it is also an example of the present invention that the impedance of the circuit is adjusted without using the bleeder resistance to secure the terminal current of 1 mA or more.
As shown in FIG. 7, the bleeder resistance inserted between the input and GND according to the present invention is configured as a diffusion resistance 27 in the PNPN semiconductor structure forming the IGBT, or is formed of polysilicon 28 as shown in FIG. It Reference numerals 29 and 30 denote IGBT main body portions. Detection of disconnection in the connection between the ECU and the ignition device using the bipolar transistor in the ignition system will be described with reference to FIGS. 3 and 4. When the ECU 1 has a disconnection detection unit 31 and the connection unit 32 is opened due to a disconnection or the like, a signal such as A is usually generated in the disconnection detection unit 31 as shown in FIG. The signal becomes as shown by B. This is because when the normal HIGH signal is output, the HIGH signal is input from Vcc of the ECU 1 to the ignition device via the resistors 33 and 34. Then, the current flows from the base of the resistor 35 and the bipolar transistor 36 to the GND via the emitter and the current detection load 37. As a result, the voltage of A in FIG.
− (V _{BE of} bipolar transistor 36)] × [(resistor 34 + resistor 35) ÷ (resistor 33 + resistor 34 + resistor 3)
5)] + Ic × resistance 37. Indicates that the current is limited and Ic becomes constant. In contrast,
When the connecting part 32 is broken, it becomes like B, and is Vcc
Shows the value of At this time, the reference voltage of is set, and when it exceeds this, it is judged as a disconnection. However, normal IGBT
In the ignition device using, the signal as shown in FIG. 5 is output to the disconnection detection unit. C indicates normal operation, and D indicated by dotted line indicates disconnection. As described above, since the IGBT requires almost no current, the current is not limited and the voltage is almost the same as the voltage at the time of disconnection. Therefore, it is difficult to set the reference voltage for disconnection detection, and conventional disconnection detection cannot be performed. When the present invention is used, the impedance of the ignition device or the voltage due to the bleeder resistance can be controlled, so that the reference voltage for disconnection detection can be set in the same manner as the conventional disconnection detection method because it can be made different from the voltage at the time of disconnection. Yes, disconnection can be detected.

[0011]

According to the present invention, a reliable connection current with an ECU can be secured in an ignition device using an IGBT, so that reliable connection reliability can be obtained even if inexpensive Sn plating is used for the connection terminal. . Further, it becomes possible for the ECU to detect disconnection of the connecting portion.

[Brief description of drawings]

FIG. 1 is an embodiment of the present invention (using a hybrid IC).

FIG. 2 is an embodiment of the present invention (one-chip igniter).

FIG. 3 is a configuration for detecting disconnection in an ECU.

FIG. 4 shows an operation waveform when a disconnection is detected (when a bipolar transistor is used).

FIG. 5 shows an operation waveform when a disconnection is detected (normal IGBT ignition device).

FIG. 6 is an operation waveform when a disconnection is detected (IGB using the present invention.
T ignition device).

FIG. 7 is a vertical structure in which a resistor is formed in the IGBT chip.

FIG. 8 is a vertical structure in which a resistance is formed in the IGBT chip.

[Explanation of symbols]

1 ... ECU, 2 ... Ignition device, 3 ... Ignition coil, 4 ... Ignition plug, 5 ... Battery, 6, 8, 33, 34, 35 ... Resistor, 7 ... NPN transistor, 9, 17 ... IGBT, 10 ...
Hybrid ICs 11, 22, 37 ... Current detection load, 12, 18, 37 ... Current limiting circuit, 13, 19 ... Input resistance, 14 ... Connection terminal, 15, 26 ... Resistance (bleeder resistance), 16 ... One chip Igniter, 20 ... Main I
GBT, 21 ... Sub-IGBT, 23 ... Phase direction polysilicon Zener diode, 24 ... Phase direction Zener diode, 25 ... Protection resistor, 27 ... Diffusion resistance, 28 ... Polysilicon, 29, 30 ... IGBT body, 31 ... Disconnection detection Part, 32 ... connection part, 36 ... bipolar transistor,
, Detection voltage, detection voltage (when current is limited),
Disconnection detection voltage, ... disconnection detection reference voltage, ... IGBT
Detection voltage when using the ignition device, ... Break detection unit reference voltage,
… Detection voltage (at the time of disconnection),… disconnection detection reference voltage, A…
Disconnection detection voltage using bipolar transistor (normal), B ... Disconnection detection voltage using bipolar transistor (when disconnection), C ... Disconnection detection voltage using IGBT (normal), D ... IGBT The voltage of the broken wire detector (when broken).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Futoshi Ito 2520 Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi, Ltd. Automotive Equipment Division

Claims (4)

[Claims] 1. An electronic control unit for an internal combustion engine (hereinafter "ECU")
Insulation gate bipolar transistor (hereinafter referred to as "IGBT") is used as a switching element for generating a high voltage on the secondary side of the primary current flowing through the ignition coil in response to the ignition control signal output from In the ignition device for an internal combustion engine configured as above, the ignition device and the ECU
An ignition device for an internal combustion engine, wherein an input impedance of the ignition device is set so that a connection terminal current between them becomes 1 mA or more. 2. The ignition device for an internal combustion engine according to claim 1, wherein a connection terminal between the ignition device and the ECU is formed by Sn plating. 3. The ignition device according to claim 1, wherein as a method for setting the input impedance of the ignition device, a resistor for adjusting a connection terminal current between the ignition control signal input terminal of the ignition device and GND (hereinafter referred to as "bleeder resistor"). An ignition device for an internal combustion engine, comprising: 4. A bleeder resistor according to claim 3, wherein the control circuit is Hy.
A firing or mounting resistor is provided in the HyIC part of the ignition device that is an IC. Alternatively, an ignition device for an internal combustion engine, characterized in that the IGBT and a protection circuit for protecting the IGBT are formed in a one-chip igniter by a diffusion resistance or polysilicon.