JP6214118B2 - Ignition device for internal combustion engine - Google Patents

Description

  Conventionally, in order to solve environmental problems and fossil fuel depletion problems, internal combustion engines have performed lean combustion with lean fuel with a high air-fuel ratio of the air-fuel mixture in the cylinder. In order to improve the ignitability with respect to fuel, it has been aimed to increase the output of the ignition coil. However, it is known that, due to the high output of the ignition coil, the discharge voltage of the spark plug also increases, and electrode wear of the spark plug occurs due to long-term use.

  In order to solve this problem, a method of suppressing the discharge current of the spark plug by gradually energizing the primary current of the switching element is conceivable. Problems that cause engine misfires arise. As a countermeasure, there is an ignition device that is provided with a constant voltage path on the high voltage side of the secondary coil to avoid an increase in the discharge voltage of the spark plug. For example, JP 2013-160201 A (hereinafter “Patent Document 1”). Has been proposed.

  FIG. 4 shows a configuration diagram of the ignition coil disclosed in Patent Document 1. In FIG. 4, the ignition coil 40 includes a primary coil 10 and a secondary coil 20 magnetically coupled to the coil. Further, one end of the both ends of the primary coil 10 is connected to the positive electrode side of the battery 70, and the other end is grounded via an input / output terminal of a switching element 50 which is an electronically controlled opening / closing means.

  One end of the both ends of the secondary coil 20 is connected to a portion having a ground potential via the low-voltage side path L1. Furthermore, the other end is connected to the center electrode 80a via the connection path L2.

  In addition, a constant voltage path L3 having one end grounded is connected to the connection path L2. Further, the constant voltage path L3 includes a Zener diode 118 as a constant voltage element and a current detection resistor 120 in order from the connection path L2 side. Specifically, the anode of the Zener diode 118 is connected to the connection path L2 side, and the cathode is connected to one end of the resistor 120.

  Here, the ignition control by the ECU will be described. First, the switching signal 50 is turned on when the ignition signal input to the gate of the switching element 50 is turned on. As a result, the flow of the primary current from the battery 70 to the primary coil 10 is started, and the accumulation of magnetic energy in the ignition coil 40 is started. Incidentally, when the primary coil 10 is energized, the polarity on the center electrode 80a side of both ends of the secondary coil 20 is positive, and the polarity on the low voltage side path L1 side is negative.

  When the switching element 50 is turned off by switching the ignition signal to the off ignition signal after the primary coil 10 is energized, the polarity at both ends of the secondary coil 20 is reversed and the secondary coil 20 is reversed. A high voltage is induced. As a result, a high voltage is applied to the gap between the center electrode 80a and the ground electrode 80b of the spark plug.

  Here, the Zener diode 118 is provided in the constant voltage path L3. Therefore, when the secondary voltage in the gap of the spark plug 80 tries to exceed the breakdown voltage of the Zener diode 118, a voltage drop corresponding to the breakdown voltage occurs in the Zener diode 118, so that the secondary voltage is broken down. Limited by voltage. That is, an ignition device is described in which the secondary voltage is maintained at the breakdown voltage during a period in which the secondary voltage tends to exceed the breakdown voltage.

JP2013-160201A

  However, the conventional ignition device for an internal combustion engine has the following problems. That is, in the ignition device of Patent Document 1, when the gas state in the gap is suitable for discharge in the period in which the secondary voltage is maintained at the breakdown voltage, a discharge spark is generated in the spark plug gap and grounding is performed. Although it can be avoided that the discharge current flows from the electrode to the center electrode and the discharge voltage of the spark plug becomes high, there is a problem that the corona electrode generated on the spark plug electrode grows because the period limited by the breakdown voltage is long. This leads to consumption of the spark plug.

  The present invention has been made in view of the above problems, and prevents the corona discharge generated at the electrode of the spark plug from growing, has a quick rise voltage that burns off the spark plug, and suppresses the discharge voltage from the ignition coil. It is an object of the present invention to provide an ignition device for an internal combustion engine that prevents wear of the spark plug.

  In order to solve the above problems, the present invention is configured as follows. That is, for an internal combustion engine that includes an ignition coil in which a primary coil and a secondary coil are electromagnetically coupled, and an igniter including a first switching element that switches ON / OFF of energization to the primary coil. In this ignition device, the high voltage side of the primary coil is connected to the collector side of the first switching element, and the connection point between the high voltage side of the primary coil and the collector side of the first switching element is fixed. A voltage element is connected to the collector side of the second switching element, the constant voltage element has an anode connected to the second switching element, and the high voltage side of the primary coil and the first switching element The collector-side connection point is connected to the second resistor and the gate side of the second switching element via the first resistor. .

  In the above invention, the constant voltage element may have a capacitance of 150 to 360V.

  With the above configuration, the high voltage side of the primary coil is connected to the collector side of the first switching element, and the connection point between the high voltage side of the primary coil and the collector side of the first switching element is connected via the constant voltage element. Connected to the collector side of the second switching element, the constant voltage element connects the anode to the second switching element, and the connection point between the high voltage side of the primary coil and the collector side of the first switching element is By connecting to the second resistor and the gate side of the second switching element via the resistor 1, the corona discharge generated on the electrode of the spark plug is prevented from growing and the rising of the spark plug is quickly burned out. An ignition device for an internal combustion engine that has a voltage and suppresses the discharge voltage from the ignition coil to prevent the wear of the spark plug can be realized.

1 is a block diagram of an ignition device for an internal combustion engine according to a first embodiment of the present invention. (A) A block diagram showing a rising voltage operation of the ignition device, (B) a block diagram showing a constant voltage operation of the ignition device. 3 is a time chart illustrating the operation of the ignition device according to the first embodiment. The block diagram of the ignition coil of patent document 1 is shown.

  An example showing the embodiment of the present invention will be described below with reference to FIGS.

  1 is a block diagram of an ignition device for an internal combustion engine according to a first embodiment of the present invention, FIG. 1A is a block diagram showing a rising voltage operation of the ignition device, and FIG. 1B is a block showing a constant voltage operation of the ignition device. FIG. 2 shows a diagram, and FIG. 3 shows a time chart showing the operation of the ignition device.

  In FIG. 1, an ignition device 100 includes an ignition coil 40 and an igniter 50. The ignition coil 40 includes a primary coil 10 composed of a primary winding, a secondary coil 20 composed of a secondary winding, and a silicon steel plate. It consists of an iron core 30. The igniter 50 includes an IGBT (insulated gate bipolar transistor) as a first transistor 52 and a gate drive 54. Further, the gate drive 54 is connected to an ECU (engine control unit) that supplies an ignition signal that is an appropriate discharge timing of the internal combustion engine, generates a pulse wave based on the ignition signal from the ECU, and the first drive This is supplied to the transistor 52.

  The high voltage side 10a of the primary coil 10 is connected to the collector side of the first transistor 52, and is connected to the ground via the emitter side of the first transistor 52. Further, the gate side of the first transistor 52 is connected to the gate drive 54, and a diode 56 having a cathode terminal connected to the collector side on the collector side and the gate side is provided.

  The connection point between the high voltage side 10a of the primary coil and the collector side of the first transistor 52 is connected to the collector side of the second transistor 60 via the Zener diode 62, and the emitter of the second transistor 60 is connected. Connect to ground through side. Further, the Zener diode 62 has an anode terminal connected to the collector side of the second transistor 60.

  The connection point between the high-voltage side 10a of the primary coil and the collector side of the first transistor 52 is connected to the gate side of the second transistor 60 via the first resistor 64a. A connection point on the gate side of 64a and the second transistor 60 is connected to the ground via a second resistor 64b. Further, the diode 56 has a capacitance of 400V, so that the breakdown voltage of the primary coil 10 is determined.

Further, the Zener diode 62 has a capacitance of 360 V, so that a clamp voltage V _CL branching between the collector and the emitter of the second transistor 60 is determined. Further, the low voltage side 10b of the primary coil 10 is connected to the battery power source 70 of the automobile.

The high voltage side 20a of the secondary coil 20 is connected to a spark plug 80 for discharging into the cylinder of the internal combustion engine, and the low voltage side 20b of the secondary coil 20 is connected to the ground. The spark plug 80 has a plug insulator dielectric breakdown limit voltage, and the clamp voltage V _CL determined by the Zener diode 62 is lower than the dielectric breakdown limit voltage.

2A, the igniter 50 supplies the pulse wave generated in the gate drive 54 to the gate side of the first transistor 52 when the ignition device 100 receives an ignition signal from the ECU. . In the first transistor 52, when a current flows between the gate and the emitter, a current flows between the collector and the emitter. Therefore, the first transistor 52 is primary through the path of the power source 70 → the primary coil 10 → the first transistor 52 → ground. current _{I 1} flows. As a result, a rising voltage is generated in the primary coil 10, and the primary current is stored in the primary coil 10.

In FIG. 2B, when the primary current flowing through the primary coil 10 increases, a path is generated between the gate and the emitter of the second transistor 60 via the first resistor 64a. When a current flows between the gate and the emitter of the second transistor 60, a current flows between the collector and the emitter. Therefore, the power source 70 → the primary coil 10 → the Zener diode 62 → the second transistor 60 → the ground. primary current _{I c} flows through a path of. Further, since the Zener diode 62 has a capacitance of 360 V, the voltage generated between the collector and the emitter of the second transistor 60 has a constant voltage operation that reaches a peak at the clamp voltage V _CL .

The primary current I ₁ ′ flowing through the primary coil 10 during constant voltage operation is the primary current I _a flowing between the collector and the emitter of the first transistor 52 and the second current from the first resistor 64a. a primary current I _b flowing between the gate of the transistor 60, and a primary current I _c flowing between the collector and emitter of the Zener diode 62 → the second transistor 60, made of.

Further, a voltage is generated between the collector and the emitter of the first diode 52 so that the voltage applied between the collector and the emitter of the second transistor 60 exceeds the clamp voltage _VCL . As a result, the rise of the voltage exceeding the clamp voltage V _CL applied to the primary coil 10 becomes gradual.

In FIG. 3, the switching operation of the first transistor 52 is switched ON / OFF by a pulse wave from the gate drive 54. Further, the switching operation of the second transistor 60 is the first primary current between the gate and emitter of said through said first resistor 64a transistor 52 from rose up to ON the second transistor 60 I _b Is switched on by flowing. Further, in the second transistor 60, the first transistor 52 falls to OFF, and the primary current _Ib is cut off between the gate and the emitter of the second transistor 60 via the first resistor 64a. Can be switched off.

Further, the primary voltage generated in the primary coil 10 in the first embodiment maintains the clamp voltage V _CL set to be equal to or lower than the dielectric breakdown limit voltage of the spark plug 80. Further, the secondary voltage generated in the secondary coil 20 that is electromagnetically coupled to the primary coil 10 rises quickly to the clamp voltage V _CL due to the influence of the induced electromotive force, and reaches the maximum output voltage V _MAX after the clamp voltage V _CL. Stand up slowly.

However, in the conventional ignition system that does not perform a constant voltage operation (conventional example 1), the secondary voltage generated in the secondary coil 20 is increased to maximum output voltage V _MAX to v ₁ higher maximum output voltage V _MAX exceeding _' As a result, the spark plug 80 is consumed quickly. Further, in the ignition device (conventional example 2) in which a constant voltage operation is performed by a constant voltage element provided in parallel with the ignition plug 80 on the high voltage side 20a of the secondary coil, the secondary voltage generated in the secondary coil 20 is a clamp voltage V. since it suppressed to _CL, the time in which the voltage generated is extended by t ₁ between the electrodes of the spark plug 80, the corona electrode that occurs in the electrode of the spark plug 80 will grow. Furthermore, in the ignition device (conventional example 3) that suppresses the discharge current of the spark plug by gently applying the primary current that is energized to the primary coil 10, the time during which the voltage is generated between the electrodes of the spark plug 80 is t _2. As a result, the corona electrode generated at the electrode of the spark plug 80 grows and the rise of the secondary voltage to the clamp voltage V _{CL of the} secondary coil 20 becomes slow. I can't burn it out.

With the above configuration, the connection point between the high voltage side 10a of the primary coil and the collector side of the first transistor 52 is connected to the collector side of the second transistor 60 via the Zener diode 62, and the Zener diode 62 Has an anode terminal connected to the collector side of the second transistor 60, and a connection point between the high voltage side 10a of the primary coil and the collector side of the first transistor 52 is connected to the first resistor 64a through the first resistor 64a. The first resistor 64a and the gate side of the second transistor 60 are connected to the ground via the second resistor 64b. since the primary voltage generated in the coil 10 to maintain the clamp voltage V _CL which is set below the breakdown limit voltage of the spark plug 80, the ignition plug by suppressing the discharge voltage from the ignition coil 40 It can be an ignition device to prevent 80 wear of.

Further, since the secondary voltage generated in the secondary coil 20 that is electromagnetically coupled to the primary coil 10 quickly rises to the clamp voltage V _CL, it is possible to prevent the corona discharge generated in the electrode of the spark plug 80 from growing. The fog generated between the electrodes of the spark plug 80 can be burned out.

As a modification of the first embodiment, the configuration of the igniter 50 can be arbitrarily changed depending on design circumstances. The second transistor 60 may be changed to a switching element such as a thyristor. Further, the Zener diode 62 may be a constant voltage element that obtains a constant voltage, and the Zener diode 62 has a capacitance of 360 V. However, depending on the dielectric breakdown limit voltage of the spark plug 80, You may determine in the range of 150-360V by the clamp voltage _VCL to determine.

  Further, the first resistor 64a and the second resistor 64b may be changed to arbitrary circuit configurations depending on design circumstances as long as they are voltage dividing circuits for the gate side of the second transistor 60.

10: 1 primary coil
10a: High pressure side
10b: Low pressure side
20: Secondary coil
20a: High pressure side
20b: Low pressure side
30: Iron core
40: Ignition coil
50: Igniter
52: First transistor (first switching element)
54: Gate drive
56: Diode
60: Second transistor (second switching element)
62: Zener diode (constant voltage element)
64a: first resistor
64b: Second resistance
70: Power supply
80: Spark plug
100: Ignition device

Claims (2)

An ignition coil 40 in which a primary coil 10 and a secondary coil 20 are electromagnetically coupled;
In an ignition device 100 for an internal combustion engine comprising: an igniter 50 including a first switching element 52 that switches ON / OFF of energization to the primary coil 10;
The high voltage side 10a of the primary coil is connected to the collector side of the first switching element 52;
The connection point between the high-voltage side 10a of the primary coil and the collector side of the first switching element 52 is connected to the collector side of the second switching element 60 via the constant voltage element 62;
The constant voltage element 62 has an anode connected to the second switching element 60,
The connection point between the high voltage side 10a of the primary coil and the collector side of the first switching element 52 is connected to the second resistor 64b and the gate side of the second switching element 60 via the first resistor 64a. An ignition device 100 for an internal combustion engine.   The ignition device for an internal combustion engine according to claim 1, wherein the constant voltage element (62) has a capacitance of 150 to 360V.

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