JP6331618B2 - Ignition device for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition device used for an internal combustion engine (engine), and more particularly to a technique for continuing spark discharge.

As a technology to reduce the burden on the spark plug, suppress unnecessary power consumption, and continue the spark discharge, the first spark discharge (referred to as main ignition) is started by a well-known ignition circuit (referred to as main ignition circuit), During main ignition, electric energy is input from the negative side of the primary coil toward the battery voltage supply line, and a secondary current in the same direction is continuously supplied to the secondary coil, so that the spark discharge generated by the main ignition has the same polarity. Thus, an "energy input circuit" that can be continued for an arbitrary period (hereinafter referred to as a discharge duration) has been devised (not a known technique).
Hereinafter, the spark discharge that is continued by the energy input circuit (that is, the spark discharge following the main ignition) is referred to as “continuous spark discharge”.

The energy input circuit controls the secondary current to maintain the spark discharge by controlling the input energy input to the primary coil during the discharge continuation period. With this technique, it is possible to reduce the burden on the spark plug and to suppress unnecessary power consumption, and to continue the spark discharge.
Next, for the purpose of assisting understanding of the background art, a specific example of an energy input circuit to which the characteristic technique of the present invention is not applied will be described with reference to FIG. In addition, the code | symbol used for FIG. 3 attaches | subjects the same code | symbol to the same function thing as the "Example" mentioned later.

The ignition device shown in FIG. 3 includes a full-tra type main ignition circuit 7 that performs main ignition by switching the ignition switching means 10 and an energy input circuit 8 that performs continuous spark discharge.
The energy input circuit 8 is
A booster circuit 12 that boosts the battery voltage and stores it in the capacitor 13;
An energy input switching means 14 for controlling the electric energy input to the negative side of the primary coil 3 and an energy input driver circuit 15;
It is configured with.

The main ignition circuit 7 operates based on an ignition signal IGT given from an ECU (abbreviation of engine control unit) or the like. When the ignition signal IGT is turned on, the primary coil 3 is energized. The When the ignition signal IGT is turned OFF and the primary coil 3 is de-energized, a high voltage is generated in the secondary coil 4, and main ignition is started in the spark plug 1.
On the other hand, the energy input circuit 8 operates based on a discharge continuation signal IGW given from an ECU or the like, and the discharge continuation period signal IGW is turned on to change the primary coil 3 from the minus side to the plus side. Input the electric energy to go. Specifically, the secondary current is controlled to be substantially constant by ON-OFF control of the energy input switching means 14.

(problem)
In order to start the continuous spark discharge before the main ignition is extinguished, it is necessary to turn on the discharge continuation signal IGW immediately after the ignition signal IGT is switched from the ON state to the OFF state.
However, if the ON timing of the discharge continuation signal IGW is delayed after the ignition signal IGT is turned OFF, the energy input circuit 8 may operate with a delay after the main ignition is extinguished. When the start of the input of electric energy by the energy input circuit 8 is delayed, the generated voltage of the secondary voltage is low only by the delayed electric energy, and reignition is not caused. For this reason, there is a concern that the continuous spark discharge cannot be continued due to a delay in the operation timing of the energy input circuit 8.

  On the contrary, if the discharge continuation signal IGW is turned on early before the ignition signal IGT is turned off, the electric energy stored in the capacitor 13 flows to the ground side via the ignition switching means 10. That is, there is a problem that a short-circuit current is generated by the flying operation of the energy input circuit 8.

JP 2005-217774 A

  The present invention has been made in view of the above problems, and an object thereof is to provide an internal combustion engine ignition device capable of operating an energy input circuit simultaneously with the occurrence of main ignition.

  According to the energy input circuit of the ignition device for an internal combustion engine of the present invention, as described in "Claim 1 of Claims", the input signal generation unit is in the ON state of the ignition signal IGT (from the time of ON to immediately before the OFF). The discharge continuation signal IGW is continuously turned on from any period) until the end of the spark continuation period. And only when the discharge continuation signal IGW is in the ON state and the ignition signal IGT is in the OFF state, the energy input circuit is provided with a prohibition section setting unit that causes the primary coil to input electric energy.

By providing in this way, the energy input circuit can be operated simultaneously with the ignition signal IGT switching from ON to OFF, and the main ignition and the continuous spark discharge can be started almost simultaneously. As a result, it is possible to prevent the occurrence of a continuous spark discharge due to a delay in the operation of the energy input circuit and to prevent the occurrence of a short-circuit current due to the flying operation of the energy input circuit.
In addition, as another effect, the peak generation timing of the secondary current at the time of main ignition (that is, the main ignition timing) and the generation timing of the secondary current accompanying the start of the continuous spark discharge can be substantially matched. The secondary current can be superimposed. Thereby, it becomes possible to suppress the power consumption of the main ignition circuit 7 and to start main ignition with a large current, and it is possible to provide an ignition device excellent in ignitability and energy saving.

1 is a schematic configuration diagram of an ignition device for an internal combustion engine (Example 1). (Example 1) which is a time chart for demonstrating the action | operation of the ignition device for internal combustion engines. It is a schematic block diagram of the ignition device for internal combustion engines (reference example: it is not a well-known technique).

  Hereinafter, “DETAILED DESCRIPTION OF THE INVENTION” will be described in detail.

  A specific example (example) of the present invention will be described with reference to the drawings. The following “Example” discloses a specific example, and it goes without saying that the present invention is not limited to the “Example”.

[Example 1]
A first embodiment will be described with reference to FIGS.
The ignition device according to the first embodiment is used for a spark ignition engine for running a vehicle, and ignites (ignites) an air-fuel mixture in a combustion chamber at a predetermined ignition timing (ignition timing). An example of an engine is a direct injection engine capable of lean burn using gasoline as fuel, equipped with an EGR device that returns a part of the exhaust gas to the engine intake side as EGR gas, and a cylinder A swirling flow control means for generating a swirling flow (tumble flow, swirl flow, etc.) of the air-fuel mixture is provided.

The ignition device in the first embodiment is a DI (abbreviation for direct ignition) type that uses an ignition coil 2 corresponding to each ignition plug 1 of each cylinder.
This ignition device controls energization of the primary coil 3 of the ignition coil 2 based on instruction signals (ignition signal IGT and discharge continuation signal IGW) given from an ECU that forms the center of engine control. By controlling the energization, the electric energy generated in the secondary coil 4 of the ignition coil 2 is controlled, and the spark discharge of the spark plug 1 is controlled.

  The ECU generates and outputs an ignition signal IGT and a discharge continuation signal IGW corresponding to the operating state of the engine. Specific engine operating states are engine parameters (warm-up state, engine speed, engine load, etc.) acquired from various sensors and engine control states (presence of lean combustion, degree of swirling flow, etc.).

Here, the means for outputting the ignition signal IGT in accordance with the operating state of the engine in the ECU is referred to as an ignition signal generator 5.
The ignition signal IGT is an instruction signal for energizing the primary coil 3 in order to perform main ignition, and the ignition signal generation unit 5 is arranged before a predetermined timing of main ignition start as shown by “IGT” in FIG. The ignition signal IGT is continuously turned on for a period from the start of main ignition to the start of main ignition.

Further, a means for outputting the discharge continuation signal IGW in accordance with the operating state of the engine in the ECU is referred to as a making signal generation unit 6.
The discharge continuation signal IGW is an instruction signal for the continuation period of the continuous spark discharge following the main ignition, and the making signal generator 6 starts the spark from when the ignition signal IGT is ON (any period from the time of ON to just before OFF). The discharge continuation signal IGW is continuously turned on for a period until the end of the continuation period. As a specific example, in this embodiment, as shown in “IGW” in FIG. 2, the making signal generation unit 6 switches the discharge continuation signal IGW to the ON state simultaneously with the ignition signal IGT being turned on, It is provided to keep the ON state until the end and to switch the discharge continuation signal IGW to the OFF state at the end of the discharge continuation period.

The ignition device
A spark plug 1 mounted for each cylinder;
An ignition coil 2 mounted for each spark plug 1;
A main ignition circuit 7 that performs full tiger operation;
An energy input circuit 8 that performs continuous spark discharge;
It is configured with.

  The main parts of the main ignition circuit 7 and the energy input circuit 8 are housed and arranged in a common case as an “ignition circuit unit”, and are installed in a place different from the spark plug 1 and the ignition coil 2.

  The spark plug 1 is a well-known one, and includes a center electrode connected to one end of the secondary coil 4 and an outer electrode grounded via an engine cylinder head or the like, and is applied from the secondary coil 4. A high voltage causes a spark discharge between the center electrode and the outer electrode.

The ignition coil 2 is a well-known one and includes a primary coil 3 and a secondary coil 4 having a larger number of turns than the number of turns of the primary coil 3.
One end of the primary coil 3 is connected to a battery voltage supply line α that receives power from the positive electrode of the in-vehicle battery 9.
The other end of the primary coil 3 is grounded via an ignition switching means 10 (for example, a power transistor, a MOS transistor, a thyristor, etc.) of the main ignition circuit 7.

One end of the secondary coil 4 is connected to the center electrode of the spark plug 1 as described above.
The other end of the secondary coil 4 is connected to the battery voltage supply line α or grounded. FIG. 1 is an example in which the other end of the secondary coil 4 is grounded via a first diode 11 that suppresses generation of an unnecessary 2 o'clock voltage when the primary coil 3 is energized.

  The main ignition circuit 7 performs energization control of the primary coil 3 based on the ignition signal IGT. Specifically, the main ignition circuit 7 turns on the ignition switching means 10 over the ON period of the ignition signal IGT. When the ignition switching means 10 is turned on, the primary coil 3 of the ignition coil 2 is turned on. Energized.

The energy input circuit 8 supplies electric energy to the primary coil 3 based on the discharge continuation signal IGW so that a current in the same direction is continuously supplied to the secondary coil 4, and the main ignition circuit 7 is activated. The started spark discharge of the same polarity is continued.
Specifically, the energy input circuit 8 continues the spark discharge in an operation state in which the ignitability decreases (during lean combustion, generation of strong swirling flow, high EGR rate, low temperature start, etc.) To improve the ignitability of
A booster circuit 12 that boosts the battery voltage;
A capacitor 13 for storing electrical energy boosted by the booster circuit 12, and
An energy input switching means 14 (for example, a MOS transistor, a power transistor, etc.) for turning on and off an energy input line β for inputting electric energy stored in the capacitor 13 to the primary coil 3;
An energy input driver circuit 15 for controlling the ON-OFF operation of the energy input switching means 14;
A second diode 16 for flowing current from the capacitor 13 only to the primary coil 3;
It is configured with.

The booster circuit 12 is a DC-DC converter that boosts a DC voltage,
A choke coil 17 having one end connected to the battery voltage supply line α,
A step-up switching means 18 (for example, a magnetic field effect transistor, a power transistor, etc.) for intermittently energizing the choke coil 17;
A boosting driver circuit 19 for repeatedly turning on and off the boosting switching means 18;
A third diode 20 for preventing electrical energy stored in the capacitor 13 from flowing back to the choke coil 17 side;
It is configured with.

  The step-up driver circuit 19 is provided so as to repeatedly turn on and off the step-up switching means 18 at a predetermined period over a period when the ignition signal IGT is given from the ignition signal generation unit 5.

  The energy input driver circuit 15 controls the ON / OFF state of the energy input switching means 14 and controls the electric energy input to the primary coil 3 so that a secondary discharge signal is given over a period of time. The current is maintained within a predetermined target range.

  A specific example of the energy input driver circuit 15 is to turn on the energy input switching means 14 so that the secondary current is monitored using a current detection sensor or the like, and the monitored secondary current maintains a predetermined target range. -Feedback control of the OFF state. Alternatively, the energy input switching means 14 may be ON / OFF controlled by open loop control so that the secondary current maintains a predetermined target range. Further, the target value of the secondary current during the continuous spark discharge may be constant, or may be changed according to the engine operating state (instruction signal (not shown) given from the ECU).

Here, in the energy input circuit 8 of the first embodiment, even when the discharge continuation signal IGW is in the ON state, when the ignition signal IGT is in the ON state, the input of electrical energy to the primary coil 3 is prohibited. Only when the discharge continuation signal IGW is in the on state and the ignition signal IGT is in the off state, a prohibition section setting unit 21 that causes the primary coil 3 to input electric energy is provided.
That is, even when the discharge continuation signal IGW is in the ON state, the prohibition section setting unit 21 prohibits the operation of the energy input circuit 8 while the ignition signal IGT is ON, so that the electric energy is input to the primary coil 3. It is forbidden.

  For example, the prohibited section setting unit 21 is provided by a logic circuit in which an AND circuit 22 and a knot circuit 23 are combined. Specifically, the output of the ignition signal generator 5 is input to the AND circuit 22 via the knot circuit 23, and the output of the making signal generator 6 is directly input to the AND circuit 22. As a result, the AND circuit 22 has the output in the ON state (Hi state) only when the discharge continuation signal IGW is in the ON state (Hi state) and the ignition signal IGT is in the OFF state (Lo state).

  The output of the prohibited section setting unit 21 is an output of the AND circuit 22 and a driver input signal IGD that activates the energy input driver circuit 15. Therefore, only when the discharge continuation signal IGW is ON and the ignition signal IGT is OFF, the driver input signal IGD is switched to the ON state as shown by “IGD” in FIG.

(Description of operation of the first embodiment)
Next, the operation of the first embodiment will be described with reference to FIG.
In FIG. 2,
・ "IGT" is the ON-OFF signal of the ignition signal IGT,
・ "IGW" is the ON-OFF signal of the discharge continuation signal IGW,
・ "IGD" is the ON-OFF signal of the driver input signal IGD,
"I1" is the primary current flowing through the primary coil 3,
"V1" is the primary voltage of the primary coil 3,
“FET” is an ON-OFF signal that activates the switching means 18 for boosting;
"Vdc" is the charging voltage of the capacitor 13,
"V2" is the secondary voltage of the secondary coil 4,
"I2" is the secondary current that flows through the secondary coil 4,
It is.

When the ignition signal IGT switches from OFF to ON,
(A) While the ignition switching means 10 is turned on over the period in which the ignition signal IGT is output,
(B) During the period when the ignition signal IGT is output, the boosting switching means 18 is repeatedly turned on and off to perform the boosting operation, and the boosted electrical energy is stored in the capacitor 13.

(C) When the ignition signal IGT is switched from ON to OFF, the ignition switching means 10 is turned OFF, and the energized state of the primary coil 3 is suddenly cut off. As a result, the primary voltage rises as soon as the primary current stops. As a result, the secondary voltage rises and a high voltage is applied to the spark plug 1, and main ignition occurs in the spark plug 1.

(D) On the other hand, when the ignition signal IGT is switched from ON to OFF, the driver input signal IGD is switched from OFF to ON by the prohibited section setting unit 21. Then, the energy input switching means 14 is ON / OFF controlled, and the electric energy stored in the capacitor 13 is applied to the negative side of the primary coil 3.
However, the primary voltage is higher than the charging voltage of the capacitor 13 (Vdc voltage <primary voltage) during a very short time until the main ignition starts (see arrow A in FIG. 2). For this reason, the electric energy stored in the capacitor 13 is not input to the primary coil 3 even when the energy input switching means 14 is turned on until the main ignition is started.

(E) When main ignition occurs in the spark plug 1, the primary voltage drops rapidly. For this reason, when the main ignition starts, the electric energy stored in the capacitor 13 flows from the negative side of the primary coil 3 toward the battery voltage supply line α. Specifically, every time the energy input switching means 14 is turned on, an additional current flows from the negative side of the primary coil 3 toward the battery voltage supply line α. Then, whenever a current is added, a secondary current in the same direction as the secondary current after the main ignition is sequentially added to the secondary coil 4 and flows.
In this way, by performing ON-OFF control of the energy input switching means 14, the secondary current continuously flows to such an extent that the spark discharge can be maintained.

More specifically, when a spark discharge is caused to flow by a strong swirling flow generated in the cylinder and the spark discharge is bent and acts in a direction in which the secondary current decreases, the secondary current generated by the energy input driver circuit 15 is reduced. The ON ratio of the energy input switching means 14 is increased by the control, and the amount of electric energy input to the primary coil 3 is increased. As a result, even if the spark discharge is swirled by the swirl flow and bent, the secondary current is kept substantially constant, and the blow-off of the spark discharge is avoided.
Thus, while the discharge continuation signal IGW is continued, the spark discharge due to the continuous spark discharge can be continued in the spark plug 1, and high ignitability can be obtained.

(F) When the ignition continuation signal IGW is switched from ON to OFF, the driver input signal IGD is also switched from ON to OFF, the energy input driver circuit 15 is stopped, and the energy input switching means 14 is turned off. As a result, the energy input circuit 8 stops and the continuous spark discharge ends.

(Effect 1 of Example 1)
In the ignition device according to the first embodiment, as described above, the input signal generation unit 6 turns on the discharge continuation signal IGW in advance while the ignition signal IGT is on. Then, only when the discharge continuation signal IGW is in the ON state and the ignition signal IGT is in the OFF state, the driver input signal IGD is turned on to cause the primary coil 3 to input electric energy.

By providing in this way, the energy input circuit 8 can be operated simultaneously with the ignition signal IGT switching from ON to OFF, and the main ignition and the continuous spark discharge can be started almost simultaneously.
Accordingly, it is possible to reliably prevent the occurrence of continuous spark discharge due to the delay in operation of the energy input circuit 8 and to reliably prevent the occurrence of a short-circuit current due to the flying operation of the energy input circuit 8. That is, according to the present invention, the reliability of the ignition device equipped with the energy input circuit 8 can be improved.

(Effect 2 of Example 1)
As described above, the ignition device of Embodiment 1 can start main ignition and continuous spark discharge almost simultaneously. As a result, the peak generation timing of the secondary current at the time of main ignition and the generation timing of the secondary current accompanying the start of continuous spark discharge can be substantially matched, and both secondary currents can be superimposed.
Thereby, it becomes possible to suppress the power consumption of the main ignition circuit 7 and to start main ignition with a large current, and it is possible to provide an energy-saving ignition device having excellent ignitability.

  In the above embodiment, an example in which the ignition device of the present invention is used for a gasoline engine has been described. You may do it. Of course, ignitability can be improved by continuous spark discharge even when used in an engine in which poor fuel may be used.

  The above embodiment shows an example in which the ignition device of the present invention is used in a lean burn engine capable of lean burn (lean burn combustion) operation, and the ignitability at the lean burn where the ignitability is deteriorated is improved by continuous spark discharge. However, since it is possible to improve ignitability by continuous spark discharge even in a combustion state different from lean combustion, it is not limited to application to lean burn engines, and is used for engines that do not perform lean combustion. May be.

Further, the present invention may be applied to a high EGR engine (an engine capable of increasing the return rate of exhaust gas returned to the engine as EGR gas) to generate continuous spark discharge at high EGR, thereby improving ignitability.
Similarly, continuous spark discharge may be performed at a low engine temperature at which the ignitability decreases to improve the ignitability at a low engine temperature.

  In the above embodiment, an example in which the ignition device of the present invention is used for a direct injection engine that directly injects fuel into a combustion chamber has been shown. However, a port injection type that injects fuel to the intake upstream side (inside the intake port) of the intake valve. It may be used for other engines.

  In the above-described embodiment, the ignition device of the present invention is used for an engine that actively generates a swirling flow of air-fuel mixture (tumble flow, swirl flow, etc.) in a cylinder, and “ Although an example of avoiding “blow-off” has been disclosed, it may be used for an engine having no swirl flow control means (tumble flow control valve, swirl flow control valve, etc.).

  In the above embodiment, the present invention is applied to a DI type ignition device. However, the present invention is not limited to the DI type. For example, the present invention may be applied to an ignition device of a single cylinder engine (for example, a motorcycle). good.

  In the above embodiment, an example in which a full tiger is used as an example of the main ignition circuit 7 is shown, but the type of the main ignition circuit 7 is not limited. That is, the main ignition circuit 7 may be a circuit that can perform main ignition by controlling the energization state of the primary coil 3, and may use an ignition circuit other than a full-trailer such as a CDI ignition circuit.

2 Ignition coil 3 Primary coil 5 Ignition signal generator 6 Input signal generator 7 Main ignition circuit 8 Energy input circuit 21 Prohibited section setting unit

Claims (1)

An ignition signal generator (5) that outputs an ignition signal (IGT) that is an instruction signal of an ignition operation in accordance with an operating state of the internal combustion engine;
An input signal generator (6) that outputs a discharge continuation signal (IGW) that is an instruction signal for continuation of sparks according to the operating state of the internal combustion engine;
A main ignition circuit (7) for controlling energization of the primary coil (3) of the ignition coil (2) based on the ignition signal (IGT);
Based on the discharge continuation signal (IGW), electric energy is input to the primary coil (3) to continue the spark discharge of the same polarity started by the operation of the main ignition circuit (7) (8 )
The input signal generation unit (6) turns on the discharge continuation signal (IGW) in advance while the ignition signal (IGT) is on, and from the on time of the ignition signal (IGT) to the end of the spark continuation period. Provided to continuously turn on the discharge continuation signal (IGW),
The energy input circuit (8) supplies electric energy to the primary coil (3) when the ignition signal (IGT) is in an ON state even when the discharge continuation signal (IGW) is in an ON state. Only when the discharge continuation signal (IGW) is in the on state and the ignition signal (IGT) is in the off state, the prohibition section setting unit (21) performs the input of electric energy to the primary coil (3). ) ignition device, characterized in that it comprises a.

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