JP2007154829A - Multiple point ignition device provided with ion current detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device not spoiling characteristics of a multiple point ignition device to reduce fuel consumption and reduce HC concentration even in a cylinder direct injection internal combustion engine of high compression lean air fuel mixture. <P>SOLUTION: This device is provided with at least two spark plugs per one cylinder, includes an ignition coil independent for each spark plug, is provided with a drive circuit in a primary side of each ignition coil and the spark plug and an ion current detection circuit in a secondary side, includes a bypass circuit in a current source of the ion current detection circuit, is constructed to enable to select the ion detection circuit according to an operation condition, and is constructed to operate the bypass circuit when information is not required. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device including an ion current detection device used for an internal combustion engine, and mainly has at least two ignition plugs in one cylinder of a direct injection internal combustion engine, and detects a combustion ion current generated after discharge ignition. Thus, combustion control such as ignition timing is performed while maintaining ignitability.

Conventionally, there are Japanese Patent Laid-Open Nos. 2003-184724 and 2003-184725 as ignition devices for internal combustion engines having multiple ignition plugs in one cylinder for detecting ion current. There has been proposed a system for improving the accuracy and reliability of misfire detection taking into account changes in the corresponding ion current waveform.
JP 2003-184724 A JP 2003-184725 A

  In a direct-injection internal combustion engine with a high compression lean mixture for exhaust gas countermeasures and fuel efficiency improvement, it is not enough to obtain the original target value simply by igniting multiple points with a normal current interrupting ignition device. While a high-energy ignition device with a long discharge duration that can withstand high compression overflow in an extremely lean mixture is required, the combustion ion current is also low, so it can detect combustion conditions such as misfires and knocks. If the combustion state detection time is not long enough, accurate combustion information cannot be obtained. However, even if it is simply combined with a high energy ignition device, the detection time cannot be increased.

  For exhaust gas countermeasures and fuel efficiency improvement of direct injection internal combustion engines, detailed information on changes in ion current is collected from the start of the internal combustion engine to the high speed range, and fuel is spray controlled by combining the air-fuel ratio with EGR. Since the system is desired, it is confirmed that about 15 degrees after the top dead center is an important time zone for determining the ion current in order to detect the combustion deterioration state or knocking at the above ion current. However, when an ignition device with high output energy is simply used, the discharge duration is long even when the engine speed is high, so that sufficient time required for ion current detection cannot be obtained.

  In addition, a part of the ignition energy is temporarily stored in the capacitor and used as an ion detection current source after the end of discharge, and its charging voltage is used in the range of about 70V to 300V, and is set to a higher voltage. As a result, it is possible to increase the degree of design freedom while maintaining a low S / N ratio for low ion current detection such as in a lean-air mixture combustion engine. However, if the voltage is increased, the energy of the ignition device that is originally required for discharge is impaired. Has a problem that a heat dissipation design that can withstand the loss is required.

  In order to solve the above-described problems, the present invention has the following configuration. In claim 1, at least two ignition plugs are provided in one cylinder, each ignition plug has an independent ignition coil, each drive circuit on the primary side of the ignition coil, and each of the drive circuits on the secondary side. It has an ignition plug and an ion current detection circuit, further has a bypass circuit in the current source of each of the ion current detection circuits, and can be configured to select the combustion state information of each of the ion detection circuits according to the operating state of the internal combustion engine, By adopting a configuration in which the bypass circuit is operated when combustion state information is not required, a multipoint ignition device including an ion current detection device that obtains effective combustion information with little ignition energy loss can be obtained.

  According to claim 2 of the present invention, at least one of the drive circuits for each of the ignition coils is a multiple discharge type drive circuit, so that a multipoint ignition having an ion current detection device capable of arbitrarily changing the discharge duration is provided. Get the device.

  According to a third aspect of the present invention, the combustion state information of each of the ion current detection circuits described above is provided with an ion current detection device capable of complementing a small amount of ion current information in the lean air-fuel mixture by adopting a combined judgment control configuration. Get fire equipment.

  According to a fourth aspect of the present invention, an ignition device having a long discharge duration is provided in an ignition plug having a fast arrival time of the fuel suction flow, and the ignition plug having a short arrival time of the fuel suction flow has a short discharge duration and combustion state information. By using an ignition device having a long detection time, a multipoint ignition device including an ion current detection device that ensures the spread of the ignition nucleus and at the same time has sufficient time for obtaining ion current information is obtained.

  According to claim 5 of the present invention, two ignition plugs are provided in one cylinder, each ignition plug has an independent ignition coil, and the primary side of the ignition coil of the ignition plug having a fast arrival time of the fuel intake flow A multi-discharge type drive circuit, a current cut-off type drive circuit on the primary side of the ignition coil of the spark plug having a slow arrival time of the fuel suction flow, and an ion current detection device only on the secondary side of the latter ignition coil Thus, a multipoint ignition device including an ion current detection device with high cost performance is obtained.

  According to a fifth aspect of the present invention, an ignition device having a long discharge duration is provided in an ignition plug having a fast arrival time of the fuel intake flow, and the discharge duration is short in the ignition plug having a short arrival time of the fuel intake flow. An ionic current detector that has an ignition device with a long detection time, and that the latter spark plug is used only for ionic current detection depending on the operating state of the internal combustion engine, thereby preventing knocking in an operating region where the combustion speed is high. To obtain a multipoint ignition device.

  According to the present invention, in order to cope with a fuel direct injection internal combustion engine with a highly compressed lean air-fuel mixture having a multi-point spark plug in one cylinder suitable for recent exhaust gas countermeasures and fuel consumption improvement, discharge is performed for each spark plug. The optimal combination of ignition devices with different durations and ion current detection circuits enables detailed collection of information on changes in combustion ion current from the start of the internal combustion engine to the high engine speed range. By controlling ignition timing and ignition presence / absence control with a preset program, stable engine output can be obtained, and at the same time, the ion current source voltage is increased to improve ion current detection performance. Even if it sets, a multipoint ignition device provided with the ion current detection device with little ignition energy loss can be obtained.

  In addition, it is necessary to meticulously detect the combustion deterioration state and knocking state due to the ionic current in combination with a multiple discharge type ignition device with a high degree of freedom that can appropriately change the discharge time according to the engine speed and load conditions. It is possible to obtain a multipoint ignition device including an ion current detection device that secures a discrimination time from about 15 degrees ATDC by changing the discharge duration according to the engine speed and suppresses power consumption.

  FIG. 1 shows an embodiment of the present invention in which some circuits are shown in a block diagram. 2 (A), 2 (B), and 2 (C) are explanatory views showing the arrangement of the spark plugs of the embodiment as viewed from the upper part of the cylinder, and FIG. 3 is a characteristic diagram showing the net fuel consumption rate by each arrangement. It is.

  In FIG. 1, an ignition device 101 and 102 that operate in response to a command from the ECU 100 are connected to an engine-controlled ECU 100 so that the ignition devices 101 and 102 are respectively output to two spark plugs 1 and 2 provided in one cylinder. Has been.

  The ignition device 101 includes a multiple discharge type drive circuit 3 that operates in response to an output from the ECU 100, an ignition plug 1 on the high voltage side of the output line wheel of the ignition coil 4 that receives electric power from the multiple discharge type drive circuit 3, A terminal 51 of the ion current detection device 5 is connected to the side, and is grounded via a ground terminal 52 of the ion current detection device 5. The ion current detection device 5 has two other terminals, one of which outputs an ion current detection signal to the ECU 100 via the terminal 53, and the other terminal 54 receives a signal from the ECU 100. In response, the operation of the ion current detector 5 is stopped.

  The ion current detecting device 5 is connected from a terminal 51 to a ground terminal 52 through a series circuit of a capacitor 6 and a diode 7, and the series circuit is bypassed by each of a constant voltage diode 8 and a switching element 9. Further, the diode 7 is shunted by a series circuit of the reverse direction diode 10 and the register 11, the connection point of the series circuit is connected to the input of the ion detection circuit 12, and the output of the ion detection circuit 12 is connected to the terminal 53. Has been.

  The other ignition devices 102 are equivalent in function to the ignition device 101, and the same reference numerals indicate the same or equivalent functions. Reference numeral 30 is different from the multiple discharge type drive circuit 3 described above, and is a single discharge type drive circuit 30 such as a current interruption type that outputs when an ignition command from the ECU 100 is received.

  The two pairs of ignition devices other than the ECU 100 are units per cylinder of the internal combustion engine, and are usually configured by multiple cylinders sharing the ECU 100. However, in this embodiment, the units of the other cylinders are omitted. ing.

  2A, 2B and 2C show examples of arrangement of the spark plugs 1 and 2 output from the pair of ignition devices above the cylinder. In the figure, 13 is a fuel injection valve, 14 is an intake valve, and 15 is an exhaust valve. In all three cases, the upper cylinder combustion chamber has a pent roof, flat, etc. so that the arrangement of the spark plugs 1 and 2 is changed. Three or four exhaust valves are formed, and the discharge timing and discharge duration to the spark plugs 1 and 2 are controlled according to the operating state of the engine described later.

  When a power source (not shown) is turned on, the air taken in from the intake valve 14 enters the compression stroke, and fuel is injected from the fuel injection valve 13 to become a mixed air flow. At the same time that the switching element 9 of the device 101 is turned on, the multiple discharge type drive circuit 3 is activated to be boosted by the ignition coil 4, and at first, the arrival time of the mixed air flow in the cylinder by the multiple output voltage with the low pressure side positive. Discharge is performed on the spark plug 1 disposed at an early location, and the mixture is ignited to start combustion. In addition, since the discharge current in the spark plug 1 flows through the switching element 9 and the constant voltage diode 8 of the ion current detector 5, the ion detection circuit 12 does not function at all.

  At the same time or slightly behind the ignition command to the ignition device 101, an ignition timing command from the ECU 100 is also issued to the ignition device 102, and an ON signal is output to the terminal 54 of the ion detection circuit 5 at the same time as a single discharge type. By actuating the drive circuit 30, the ignition coil 4 is boosted, and the discharge is performed on the spark plug 2 disposed in a place where the arrival time of the mixed airflow in the cylinder is slow with an output voltage in which the low pressure side is positive. The combustion is facilitated by igniting the unburned mixture in the vicinity of the inner wall of the low-temperature cylinder which is difficult to be burned by the spark discharge of the spark plug 1. Here again, since the discharge current in the spark plug 2 flows through the switching element 9 and the constant voltage diode 8 (not shown) similar to the ion current detection device 5 of the ignition device 101, the ion detection circuit 12 does not function at all. .

  Next, before the discharge of the spark plug 2 due to the operation of the ignition device 102, an off output is output from the ECU 100 to the switching element 9 (not shown) via the terminal 54 of the ion current detection device 5 of the ignition device 102, Similarly, the capacitor 6 is charged up to a charge voltage limited by the constant voltage diode 8 via a diode 7 (not shown), and at the same time as the discharge of the spark plug 2 is completed, the charge voltage of the capacitor 8 is applied across the electrodes of the spark plug 2. By being applied to the part, combustion ions from the in-cylinder combustion flow through the spark plug 2 and are captured by a diode 10, a resistor 11 and an ion current detection circuit 12 (not shown) of the ion current detection device 5.

When the initial combustion ion current captured by the ion current detection device 5 of the ignition device 102 is normal, the switching element 9 is turned off via the terminal 54 of the ignition device 101 by a signal from the ECU 100, Like the ion current detection device 5 of the ignition device 102, before the multiple discharge type driving circuit 3 finishes driving, that is, before the multiple discharge of the spark plug 1 finishes, it is limited to the constant voltage diode 8 via the diode 7. The capacitor 6 is charged up to the charge voltage, and at the same time as the discharge of the spark plug 1 is completed, the charge voltage of the capacitor 8 is applied to both ends of the electrode of the spark plug 1 so that the combustion ions due to the combustion in the cylinder are generated. It flows through the spark plug 1 and is captured by the diode 10, the resistor 11, and the ion current detection circuit 12 of the ion current detection device 5.

  The signals from the ion current detection devices 5 of the ignition devices 101 and 102 may be processed separately in the ECU 100 or may be combined. That is, separate processing is preferable when detecting knocks centered on output improvement, and summing processing is preferable when controlling the fuel spray amount and EGR amount for exhaust gas countermeasures and fuel efficiency improvement.

  If the initial value of the ionic current captured by the spark plug 2 is extremely high, such as when the temperature in the cylinder is low, or if the spark plug 2 has smoldering, the ignition device 101 The operation of the multiple discharge type drive circuit 3 can be continued up to about 4 mS at the maximum, and the series of ignition operations starting from the ignition command of the ECU 100 can be terminated without operating the ion current detection device 5.

  In addition, when the engine speed such as full load is high, detection of knock becomes important, and at the same time, an ignition device is used to prevent an increase in the amount of NOx in the exhaust gas due to an increase in the combustion speed of the air-fuel mixture. The drive output of the single-discharge drive circuit 30 of 102 is limited, and the boosted output of the ignition coil 4 is insufficient for discharging to the spark plug 2 and is about 2 to 6 kV, which is sufficiently higher than the limit voltage of the constant voltage diode 8. By using a voltage, the ignition device 102 is used only as a simple ion current detection device.

  Further, the ignition timing of the start of discharge to the spark plug 1 of the ignition device 101 and the start of discharge to the spark plug 2 of the ignition device 102 is delayed by several mS when the in-cylinder temperature is low, such as at the start. Startability can be improved.

  FIG. 3 shows typical characteristics of the air-fuel ratio A / F and the net fuel consumption rate BSFC when the engine speed is near 1600 rpm, and the curve a is a cylinder upper structure of FIG. The characteristic obtained by operating the ignition device, curve b, is obtained by operating the cylinder upper structure of FIG. 2A using a multiple discharge ignition device as the ignition plug 1 and a single discharge ignition device as the ignition plug 2. The obtained characteristic curve c is a tendency characteristic obtained by the multipoint ignition device provided with the ion current detection device according to the present invention in each cylinder upper structure of FIGS. 2 (A), (B), and (C).

  2 (A) and 2 (B), the spark plug 1 having the cylinder upper structure is installed at a substantially central portion of the cylinder and is close to the fuel injection valve 13 and the intake valve 14 and reaches the intake mixed airflow. Although the spark plug 2 is in a part where the time is long and the arrival time of the intake mixed airflow is slow, it is needless to say that the arrival time greatly depends on the structure in the upper part of the cylinder.

  In the description of the above embodiment, a single discharge ignition device is used as the ignition device 102. However, a multi-discharge ignition device similar to the ignition device 101 can be used for engine startability and smoldering countermeasures. In this case, the control for shortening the discharge duration of the ignition device 102 is performed from an early stage in inverse proportion to the rotational speed.

  As the multiple discharge type ignition device, a known alternating current type ignition device, a capacitive discharge and an inductive discharge can be alternately repeated, or a composite multiple discharge type ignition device can be selected. Only the charging direction of the current source capacitor 6 needs to be controlled. However, the internal circuit configuration of the ion current detection device 5 is not limited to the above embodiment.

  Furthermore, in order to reduce costs, the ion current detection device 5 added to each of the ignition devices 101 and 102 may be simplified by adding only to the ignition device 102 mainly performing ion current detection.

The figure which shows the Example of invention. (A), (B), (C) is a top view of the cylinder of the embodiment of the invention. The characteristic view of the Example of invention.

Explanation of symbols

100: ECU
101, 102: ignition device 1, 2: ignition plug 3, 30: ignition drive circuit 4: ignition coil 5: ion current detection device 51, 52, 53, 54: terminal of ion current detection device 6: capacitor 7, 10: Diode 8: Constant voltage diode 9: Switching element 11: Register 12: Ion detection circuit

Claims (6)

Each cylinder has at least two spark plugs, each of which has an independent ignition coil, each drive circuit on the primary side of the ignition coil, and each spark plug and ion current detection on the secondary side And a bypass circuit in the current source of each of the ion current detection circuits, the combustion state information of each of the ion detection circuits can be selected according to the operating state of the internal combustion engine, and the combustion state information is required. A multipoint ignition device including an ion current detection device configured to operate the bypass circuit when not in operation. A multipoint ignition device comprising the ion current detection device according to claim 1, wherein at least one of the drive circuits of each ignition coil is a multiple discharge type drive circuit. A multipoint ignition device comprising the ion current detection device according to claim 1 or 2, wherein the combustion state information of each of the ion current detection circuits is configured to be a combined determination control configuration. An ignition device with a long discharge duration is provided in an ignition plug with a fast arrival time of the fuel intake flow, and an ignition device with a short discharge duration and a long combustion state information detection time is provided in an ignition plug with a slow arrival time of the fuel intake flow A multipoint ignition device comprising the ion current detection device according to claim 1. Two ignition plugs are provided in one cylinder, and each of the ignition plugs has an independent ignition coil. A multiple discharge type drive circuit is provided on the primary side of the ignition coil of the ignition plug whose arrival time of the fuel intake flow is fast. Multi-point equipped with an ion current detection device equipped with a current interrupting type drive circuit on the primary side of the ignition coil of the ignition plug with a slow flow arrival time, and further provided with an ion current detection device only on the secondary side of the latter ignition coil Fire equipment. An ignition device with a long discharge duration is provided in an ignition plug with a fast arrival time of the fuel intake flow, and an ignition device with a short discharge duration and a long combustion state information detection time is provided in an ignition plug with a slow arrival time of the fuel intake flow, The multipoint ignition device provided with the ion current detection device according to any one of claims 1 to 5, wherein the latter spark plug is used only for ion current detection according to an operating state of the internal combustion engine.

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