JPH06129333A - Ignition control system of internal combustion engine - Google Patents

Abstract

PURPOSE:To control the ignition energy required for applying power to an ignition coil (the power application time of the ignition coil) corresponding to the discharge voltage of an ignition plug. CONSTITUTION:Ignition timing (advanced value) is calculated on the basis of the speed NE of an internal combustion engine, the quantity QN of intake air and cooling water temperature TW (310, 320). Next, a correction factor for setting the power application time of an ignition coil shorter as the ignition timing is advanced is calculated (330) and the power application time of the ignition coil is calculated on the basis of the engine speed NE and battery voltage VB (340). It is then determined whether or not the speed of the internal combustion engine is high (350), and when the engine speed is not high the power application time is shortened by using the correction factor, whereas when the engine speed is high the power application time is not corrected. Finally, the ignition timing and the power application time are set as power application control parameters for the ignition coil (370) and (310) is reentered. By the above process the power application time can be made to correspond to the discharge voltage of an ignition plug and the rate of consumption of the energy required for ignition can then be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition control device for an internal combustion engine, which discharges an ignition plug at a desired ignition timing by controlling the energization time of an ignition coil based on the rotation speed of the internal combustion engine and a battery voltage. .

[0002]

2. Description of the Related Art Conventionally, the primary winding of an ignition coil is energized to accumulate ignition energy in the ignition coil, and when the energization is stopped, the ignition energy is discharged by a high voltage generated in the secondary winding of the ignition coil. In the so-called induction discharge type ignition device, the energization time of the ignition coil and the timing at which the energization of the ignition coil is stopped (that is, the ignition timing)
An ignition control device is provided for controlling and.

In this type of ignition control device, the combustion pressure at a predetermined angular position after top dead center is taken into consideration in consideration of the delay time until the fuel mixture in the cylinder actually burns due to the discharge of the spark plug. The ignition timing is determined based on the operating state of the internal combustion engine (rotational speed, load, engine temperature, etc.) such that

Further, the discharge voltage Vr required to discharge the spark plug is proportional to the product of the gap d between the discharge electrodes and the pressure P at the discharge electrode portion, as in the following equation (1) (Paschen's law). Therefore, Vr = K · P · d + C (1) where K: proportional constant, C: constant In this type of ignition control device, for example, the gap d of the spark plug becomes maximum due to wear, and the ignition timing is in the cylinder. To ensure that the spark plug can be discharged even when the pressure is near the top dead center of the internal combustion engine, the rotational speed of the internal combustion engine and the output voltage of the battery that energizes the ignition coil (the battery Voltage) and the energization time of the ignition coil is determined.

The rotation speed of the internal combustion engine is used to determine the energization time of the ignition coil because the power consumption of the ignition device increases in proportion to the number of ignitions per unit time.
This is to control this power consumption within the allowable power consumption range of the ignition device.

[0006]

Therefore, in the conventional ignition control device, the air-fuel mixture can be reliably ignited at the ignition timing according to the operating state, but the ignition energy required for energizing the ignition coil is always the maximum. Is the ignition energy for obtaining the discharge voltage Vr, and when the spark plug is not worn and the gap is small, or when the ignition timing is not near the top dead center of the internal combustion engine, the ignition energy is actually required. On the other hand, there is a problem that excessive ignition energy is consumed.

On the other hand, in order to solve these problems, the unstable state of the internal combustion engine due to the deterioration of the combustion of the air-fuel mixture is detected by the magnitude or vibration of the rotational fluctuation of the internal combustion engine to detect the unstable state of the internal combustion engine. A control device that increases the ignition energy (that is, the energization time) used to energize the ignition coil when detected is proposed (Japanese Patent Laid-Open No. 56-146068).
Issue). In other words, in the proposed device, the ignition energy consumption is reduced by increasing the energization time of the ignition coil more than usual only when the internal combustion engine becomes unstable due to the deterioration of the air-fuel mixture combustion. Is there.

However, the proposed apparatus increases the energization time of the ignition coil depending on whether the internal combustion engine is in an unstable state.
Since the non-increasing is simply switched, the consumption of ignition energy can be reduced as compared with the above-mentioned conventional ignition control device, but the ignition energy is suppressed to a necessary minimum corresponding to the discharge voltage Vr of the spark plug. I couldn't do that.

The present invention has been made in view of these problems, and controls the ignition energy required for energizing the ignition coil (that is, the energizing time of the ignition coil) to the minimum necessary amount in accordance with the discharge voltage of the ignition plug. It is an object of the present invention to provide an ignition control device for an internal combustion engine that can be realized.

[0010]

The invention according to claim 1 made in order to achieve the above object is, as shown in FIG. 1A, an ignition for calculating an ignition timing based on an operating state of an internal combustion engine. A timing calculation means, and an energization time calculation means for calculating the energization time of the ignition coil based on the rotation speed of the internal combustion engine and the battery voltage, and energizing the ignition coil according to the calculated ignition timing and energization time. In an ignition control device for an internal combustion engine that applies a high voltage for ignition to an ignition plug, the energization time of the ignition coil calculated by the energization time calculation means is set to the ignition timing calculated by the ignition timing calculation means. On the basis of the above, an energization time correction means for correcting the energization time so that the ignition timing is advanced toward the top dead center of the internal combustion engine is shortened.

On the other hand, the invention described in claim 2 is shown in FIG.
As illustrated in (b), ignition timing calculation means for calculating the ignition timing based on the operating state of the internal combustion engine, and energization time calculation means for calculating the energization time of the ignition coil based on the rotation speed of the internal combustion engine and the battery voltage, In an ignition control device for an internal combustion engine, which energizes an ignition coil according to the calculated ignition timing and energization time, and applies a high voltage for ignition to an ignition plug, a gap between discharge electrodes of the ignition plug. Based on the gap of the ignition plug detected by the gap detecting means, the energizing time of the ignition coil calculated by the gap detecting means for detecting And an energization time correction means for correcting the current to become longer.

[0012]

In the ignition control device of the present invention configured as described above, the ignition timing calculation means calculates the ignition timing based on the operating state of the internal combustion engine, and the energization time calculation means determines the internal combustion engine The energization time of the ignition coil is calculated based on the rotation speed and the battery voltage. Then, the energization time correction unit determines the energization time of the ignition coil calculated by the energization time calculation unit based on the ignition timing calculated by the ignition timing calculation unit with respect to the top dead center of the internal combustion engine. Correction is made so that the energization time becomes shorter as the position becomes more advanced.

That is, the discharge voltage required to discharge the spark plug becomes lower as the cylinder internal pressure of the internal combustion engine becomes lower, and the cylinder internal pressure is such that the ignition timing is advanced with respect to the top dead center of the internal combustion engine. Therefore, in the ignition control device according to claim 1, the ignition coil energization time is corrected to the discharge voltage of the ignition plug by correcting the energization time of the ignition coil based on the ignition timing as described above. It corresponds.

On the other hand, in the ignition control device according to the second aspect, the ignition timing calculating means calculates the ignition timing based on the operating state of the internal combustion engine and the energization time is the same as the ignition control device according to the first aspect. The calculation means calculates the energization time of the ignition coil based on the rotation speed of the internal combustion engine and the battery voltage. Then, the energization time correction means corrects the energization time of the ignition coil based on the gap between the discharge electrodes of the spark plug detected by the gap detection means such that the larger the gap, the longer the energization time.

That is, the discharge voltage required to discharge the spark plug is not limited to the cylinder pressure of the internal combustion engine,
It also changes depending on the gap between the discharge electrodes of the spark plug,
Since the discharge voltage increases as the gap increases, the ignition control device according to claim 2 corrects the energization time of the ignition coil based on the gap of the ignition plug as described above. That is, the current-carrying time is related to the discharge voltage of the spark plug.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 2 shows a four-cylinder internal combustion engine 2 to which the present invention is applied.
FIG. 3 is a schematic configuration diagram showing a peripheral device and its peripheral devices.

As shown in FIG. 2, the internal combustion engine 2 is provided with an intake pipe 8 provided with a throttle valve 4 which is opened and closed in conjunction with an accelerator pedal (not shown), a surge tank 6 for removing intake pulsation, and the like. Air is introduced via. Further, the fuel is supplied to each cylinder by opening the fuel injection valve 10, and is ignited by an ignition plug 12 provided in each cylinder. The exhaust gas after combustion by the ignition is exhausted through an exhaust pipe 16 provided with a three-way catalyst 14 for exhaust gas purification. In addition, the spark plug 12 of each cylinder,
The high voltage generated by the ignition coil 18 is sequentially distributed via the distributor 20, whereby ignition is executed for each cylinder. That is, the distributor 20
Is attached to a camshaft connected to the crankshaft of the internal combustion engine 2 via a timing belt, and the camshaft rotates once every two rotations of the crankshaft to generate a high voltage generated by the ignition coil 18. Are sequentially distributed to the ignition plugs 12 of each cylinder.

Next, in the internal combustion engine 2, an air flow meter 30 for detecting the amount of air flowing into the intake pipe 8 (intake air amount), a temperature of cooling water (cooling) as a sensor for detecting the operating state of the internal combustion engine 2. A water temperature sensor 32 for detecting a water temperature), a rotation angle sensor 34 attached to the distributor 20 for generating a rotation angle signal at every predetermined rotation angle of the internal combustion engine 2 (every 180 ° A in this embodiment), and also for the distributor 20. A cylinder discrimination sensor 36, etc., which is attached and generates a reference signal for discriminating the top dead center of the specific cylinder once every one revolution of the distributor 20, that is, once every two revolutions of the internal combustion engine 2, is provided. .

The detection signals from these sensors are supplied to the electronic control unit (ECU) 40 which receives power from the battery 38 and controls the energization of the ignition coil 18. EC
U40 is composed of a well-known microcomputer centering on a CPU, a ROM, and a RAM, and based on the detection signals from the above-mentioned sensors representing the operating state of the internal combustion engine 2, the energization time of the ignition coil 18 and the ignition coil 18 The power supply stop timing (that is, the ignition timing) is controlled.

Hereinafter, in order to perform such ignition control, E
The control process executed by the CU 40 will be described with reference to the flowcharts shown in FIGS. First, FIG. 3 shows E
6 is a flowchart showing an A / D conversion process executed as a timer interrupt process at every predetermined time in the CU 40.

As shown in FIG. 3, when this process is started, first, in step 110, the value of the counter C is incremented, and then in step 120, this counter C is incremented.
It is determined whether the value of is 1. Then, if the value of the counter C is 1, in the subsequent step 130, the battery 3
The terminal voltage (battery voltage) of No. 8 is read via an A / D converter for battery voltage (not shown), and the following Step 1
At 40, the read A / D converted battery voltage VB is stored in the RAM, the A / D conversion process is performed on the battery voltage VB, and the process ends.

On the other hand, if it is determined in step 120 that the value of the counter C is not 1, the process proceeds to step 150 and it is determined whether the value of the counter C is 2 or not. If the value of the counter C is 2, the following step 160
At, a water temperature signal representing the cooling water temperature output from the water temperature sensor 32 is read via an unillustrated water temperature A / D converter, and at step 170, the read A / D signal is read.
The A / D conversion process for the cooling water temperature TW is performed by the procedure of storing the cooling water temperature TW after D conversion in the RAM, and the process ends.

Next, when it is determined in step 150 that the value of the counter C is not 2, this time step 1
Moving to 80, the value of the counter C is set to 0. Then, in the following step 190, the intake air amount signal representing the intake air amount output from the air flow meter 30 is read through an intake air amount A / D converter (not shown), and in the following step 170, it is read. The intake air amount QN after the A / D conversion is stored in the RAM, the A / D conversion process for the intake air amount QN is performed, and the process ends.

That is, the ECU 40 uses the A / D shown in FIG.
By the conversion process, the battery voltage VB,
The cooling water temperature TW and the intake air amount QN are sequentially A / D converted and stored in the RAM. Next, FIG. 4 shows a rotation speed calculation process executed as an interrupt process each time the rotation angle sensor 34 outputs a rotation angle signal.

As shown in FIG. 4, when this rotation angle calculation processing is started, first, at step 210, the current time is read from a timer (not shown). Next step 220
Then, the previous interrupt time stored in the RAM when this process was executed last time is read. And the following step 230
Then, from each time read in step 210 and step 220, the interrupt time difference from the time when the process was started last time to the time when this process is started this time (that is, the rotation angle signal cycle).
Then, in step 240, the rotational speed NE of the internal combustion engine 2 is calculated from the interrupt time difference. Next, in step 250, this calculation result NE is stored in RAM, and in the following step 260, the current time read in step 210 is stored in RAM as the previous interrupt time for the next processing, The process ends.

That is, the ECU 40 obtains the rotational speed NE of the internal combustion engine 2 from the cycle of the rotational angle signal by this rotational speed calculation processing and stores it in the RAM. Next in FIG.
4 is a flowchart showing an ignition control process repeatedly executed as a main routine in the ECU 40.

As shown in FIG. 5, in this ignition control process, first, at step 310, the rotational speed NE and the intake speed of the internal combustion engine 2 stored in the RAM by the A / D conversion process and the rotational speed calculation process. The ignition timing (advance value with respect to the top dead center TDC of the internal combustion engine 2) is calculated based on the air amount QN, and in step 320, the calculated ignition timing is corrected based on the cooling water temperature TW stored in the RAM. Then, the processing as the ignition timing calculation means for determining the ignition timing used for the energization control of the ignition coil 18 is executed.

When the ignition timing is calculated in this manner, the energization time of the ignition coil 18 is set to the ignition timing (advance value) based on the calculated ignition timing in step 330.
Correction factor (≤
1) is calculated. In the following step 340, the RAM is
Based on the rotational speed NE of the internal combustion engine 2 and the battery voltage VB stored therein, a process as an energization time calculation means for calculating the energization time of the ignition coil 18 is executed.

In this step 340, the spark plug 1 is operated even under the condition that the discharge voltage of the spark plug 12 is maximum.
The maximum energization time that can discharge 2 is calculated. Further, the reason why the rotational speed NE of the internal combustion engine 2 is used for the calculation of the energization time is to keep the power consumption of the ignition device within the allowable power consumption as described in the section of the related art.

That is, when the internal combustion engine 2 is in the normal rotation speed range or higher (for example, 4000 [rpm] or higher),
The higher the rotational speed NE, the higher the temperature of the ignition device as the number of ignitions increases, so the energization time is shortened.
It should be noted that when the internal combustion engine 2 is at a high rotation speed, the ignition timing is set to a value that is more advanced than TDC compared to when the internal combustion engine 2 is at a low rotation speed due to the delay time until the fuel mixture burns. Since the discharge voltage becomes low, the required discharge voltage can be secured even if the energization time of the ignition coil 18 is shortened in order to suppress the power consumption of the ignition device within the allowable power consumption.

On the other hand, to calculate the energization time, the battery voltage V
B is used in the ignition coil 1 as shown in FIG.
The current value (primary current value) of the primary winding of 8 is the ignition coil 18
Energization time and battery voltage (14V, 12V, 10V
6), and as shown in FIG. 6B, the voltage (secondary generated voltage) generated in the secondary winding when the ignition coil 18 is de-energized changes according to the primary current value of the ignition coil 18. This is because.

That is, in order to make the secondary generated voltage of the ignition coil 18 equal to or higher than the discharge voltage of the ignition plug 12, the primary current value of the ignition coil 18 must be equal to or higher than a predetermined value corresponding to the discharge voltage. The battery voltage VB is used to calculate the energization time of the ignition coil 18, because it is necessary to determine the energization time in consideration of the battery voltage VB in order to increase the primary current value of the coil 18 to a predetermined value or more. .

In this way, when the energization time of the ignition coil 18 is calculated in step 340, this time, step 35
At 0, it is determined whether the internal combustion engine 2 is rotating at high speed by determining whether or not the rotational speed NE of the internal combustion engine 2 exceeds a preset high speed determination reference value NEO (for example, 3000 [rpm]). To judge. When the internal combustion engine 2 is rotating at a high speed, the process directly proceeds to step 370, and the ignition timing calculated in steps 310 and 320 and the energization time calculated in step 340 are set to the energization of the ignition coil 18. The parameter is set as a control parameter, and the process proceeds to step 310 again.

On the other hand, if it is determined in step 350 that the internal combustion engine 2 is not rotating at high speed, step 3
In step S60, the energization time is corrected by multiplying the energization time calculated in step 340 by the correction coefficient calculated in step 330 to execute a process as an energization time correction means, and then to step 370. , The ignition timing calculated in step 310 and step 320, and the corrected energization time obtained in step 360,
It is set as a parameter for controlling the energization of the ignition coil 18, and the process proceeds to step 310 again.

By the processing of step 350,
It is determined whether or not the internal combustion engine 2 is rotating at high speed, and when the internal combustion engine 2 is rotating at high speed, the correction (shortening correction) of the energization time of the ignition coil 18 in step 360 is not executed. When the rotational speed NE of the internal combustion engine 2 exceeds a high speed determination reference value NEO (3000 [rpm]), the air flow velocity in the cylinder of the internal combustion engine 2 increases,
This is because the air flow lengthens the discharge path between the electrodes of the spark plug 12 and increases the discharge voltage of the spark plug 12.

That is, in this embodiment, when the internal combustion engine 2 is rotating at a high speed, the correction of shortening the energization time of the ignition coil 18 is prohibited, so that the discharge voltage of the spark plug 12 becomes high as the airflow velocity in the cylinder increases. In this case, the ignition plug 12 is prevented from being unable to discharge due to the correction of shortening the energization time.

As described above, in this embodiment, the energization time of the ignition coil 18 calculated based on the rotational speed NE of the internal combustion engine 2 and the battery voltage VB is calculated based on the operating state of the internal combustion engine 2. Based on the (advance value), the energization time is corrected to be shorter as the ignition timing increases (that is, as the ignition timing advances from the top dead center).

As shown in FIG. 6 (c), this is because the cylinder internal pressure of the internal combustion engine 2 becomes lower as the ignition timing is advanced from the top dead center (TDC) of the internal combustion engine 2 to the inside of the cylinder. This is because the lower the pressure, the lower the discharge voltage of the spark plug 12. That is, in the present embodiment, the energization time of the ignition coil 18 is corrected as described above so that the energization time of the ignition coil 18 corresponds to the discharge voltage of the ignition plug 12.

Therefore, according to the present embodiment, the ignition coil 1
The energization time of 8, and eventually the ignition energy can be suppressed according to the discharge voltage of the ignition plug 12, and energy saving of the battery power can be achieved. Also, the ignition coil 1
8. In addition, since excessive ignition energy is not supplied to the spark plug 12, deterioration of these ignition devices can be suppressed and reliability of the ignition device can be improved.

Further, in the present embodiment, the correction of the energization time of the ignition coil 18 is prohibited during the high speed rotation of the internal combustion engine 2, so that the air flow velocity in the cylinder increases during the high speed rotation of the internal combustion engine 2. Even if the discharge voltage of the spark plug 12 becomes high, the spark plug 12 can be surely discharged.

Here, in the above-described embodiment, the correction of the energization time of the ignition coil 18 is prohibited during the high speed rotation of the internal combustion engine 2 to prevent the discharge failure due to the increase of the discharge voltage of the spark plug 12. However, when the internal combustion engine 2 is rotating at a high speed, the ignition coil 18 is corrected by correcting the energization time correction coefficient so as to approach 1 according to the rotation speed.
It is possible to more accurately correspond the energization time to the discharge voltage of the spark plug 12.

In the above embodiment, the case where the energization time of the ignition coil 18 is corrected on the basis of the ignition timing has been described.
Even if the correction is made based on the gap between the two discharge electrodes, the energization time can be made to correspond to the discharge voltage of the ignition plug 12, and the energization time of the ignition coil 18 can be set to the ignition timing and the gap of the ignition plug 12. If the correction is performed based on this, the energization time can be more accurately corresponded to the discharge voltage of the spark plug 12.

In order to correct the energization time of the ignition coil 18 based on the gap between the discharge electrodes of the ignition plug 12 as described above, a gap detecting means for detecting the gap is required. Can be realized by a simple electric circuit. That is, as shown in FIG. 7, the primary winding voltage of the ignition coil 18 becomes a constant voltage corresponding to the battery voltage when energized, and when the energization is stopped, the ignition energy stored in the ignition coil 18 due to the energization causes ignition. The voltage rises sharply until the discharge is started in the plug 12, and then becomes a predetermined high voltage until the discharge is completed (during the discharge time ΔT shown in the figure). Also, the ignition coil 1
The peak voltage Vp generated immediately after the stop of energization of No. 8 corresponds to the actual discharge voltage of the spark plug 12, and if the ignition energy is constant, the higher the peak voltage Vp is,
The discharge time ΔT becomes shorter. On the other hand, the discharge voltage of the spark plug 12 increases as the gap between the discharge electrodes of the spark plug 12 increases. Therefore, the peak voltage Vp of the primary winding of the ignition coil 18 when the spark plug 12 is discharged with the same ignition energy under a predetermined operating condition of the internal combustion engine 2,
Alternatively, if the discharge time ΔT at which the primary winding voltage becomes equal to or higher than the predetermined voltage Vh shown in the figure at that time is detected, the gap between the discharge electrodes of the spark plug 12 can be easily known from the detection result. Will be able to.

[0044]

As described in detail above, in the ignition control device according to the first aspect, the energization time of the ignition coil is made to correspond to the discharge voltage of the ignition plug by correcting the energization time based on the ignition timing. In the ignition control device according to the second aspect, the energization time of the ignition coil is made to correspond to the discharge voltage of the ignition plug by correcting the energization time based on the gap of the ignition plug. Therefore, according to the ignition control device described in each of these claims, the ignition energy required to discharge the spark plug can be made to correspond to the discharge voltage, and the consumption of the ignition energy can be suppressed. Further, since excessive ignition energy is not supplied to the ignition coil and eventually the ignition plug, deterioration of these ignition devices can be suppressed and the reliability of the ignition device can be improved. Furthermore, by combining the techniques described in claims 1 and 2, the ignition energy can be more accurately corresponded to the discharge voltage of the spark plug,
Ignition energy can be suppressed more optimally.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating the configuration of the invention.

FIG. 2 is a schematic configuration diagram showing a four-cylinder internal combustion engine and its peripheral devices according to an embodiment.

FIG. 3 is a flowchart showing A / D conversion processing executed by ECU 40.

FIG. 4 is a flowchart showing a rotational speed calculation process executed by the ECU 40.

FIG. 5 is a flowchart showing an ignition control process executed by an ECU 40.

FIG. 6 is an operation explanatory diagram illustrating an operation of an ignition control process.

FIG. 7 is an explanatory diagram illustrating a method of detecting a gap between discharge electrodes of an ignition plug.

[Explanation of symbols]

2 ... Internal combustion engine 12 ... Ignition coil 18 ... Ignition coil 20 ... Distributor 30 ... Air flow meter
32 ... Water temperature sensor 34 ... Rotation angle sensor 38 ... Battery 40 ... Electronic control unit (ECU)

Claims (2)

[Claims] 1. An ignition timing calculation means for calculating an ignition timing based on an operating state of an internal combustion engine, and an energization time calculation means for calculating an energization time of an ignition coil based on a rotation speed of an internal combustion engine and a battery voltage, In an ignition control device for an internal combustion engine, which energizes an ignition coil according to the calculated ignition timing and energization time to apply a high voltage for ignition to an ignition plug, the ignition coil calculated by the energization time calculating means. The energization time is corrected based on the ignition timing calculated by the ignition timing calculation means such that the energization time is shortened as the ignition timing is advanced toward the top dead center of the internal combustion engine. An ignition control device for an internal combustion engine, comprising a time correction means. 2. An ignition timing calculation means for calculating an ignition timing based on an operating state of the internal combustion engine, and an energization time calculation means for calculating an energization time of the ignition coil based on a rotation speed of the internal combustion engine and a battery voltage, An ignition control device for an internal combustion engine, which energizes an ignition coil according to the calculated ignition timing and energization time to apply a high voltage for ignition to an ignition plug, detects a gap between discharge electrodes of the ignition plug. The energization time of the ignition coil calculated by the gap detection means and the energization time calculation means is based on the gap of the ignition plug detected by the gap detection means, and the energization time becomes longer as the gap becomes larger. An ignition control device for an internal combustion engine, comprising: an energization time correction unit that corrects as described above.