JPH06330837A - Ignition control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To exactly estimate an electrification time even in the case of late build-up of primary current by estimating the electrification time of the primary current based on coordinates over three points concerning built-up characteristic of the primary current decided by a time constant of impedance in an ignition coil. CONSTITUTION:Primary current building up by a time constant of impedance in an ignition coil is detected, and a means M1 judges that the primary current reaches respectively a plurality of set current values previously set lower than a target value. A mean M2 computes respectively required times in which the primary current is judged to reach respective set current values from beginning of build-up. Further based on the required times corresponding to the respective set current values, a mean M3 estimates a time in which the primary current reaches the target value, so as to set it as the electrification time of the primary current. Based on the estimated electrification time, a means M4 controls primary current of the ignition coil. Hereby the electrification time of primary current in the ignition coil is exactly estimated.

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, and more particularly to an ignition control device having a function of controlling an energization time according to a rising state of a primary current of an ignition coil. .

[0002]

2. Description of the Related Art With the recent increase in speed of internal combustion engines, the time that can be allocated to energize the primary current of the ignition coil is gradually shortened, and the target value of the primary current is set to compensate for the shortened energization time. Tend to be increased. Then, when the target value is increased in this way, a harmful effect caused when an error occurs in the energization time due to a difference in impedance characteristics (inductance, resistance) of the ignition coil, for example, the energization time is excessive. If the power transistor for controlling the primary current is burned out due to overload, and conversely the energization time is too short, sufficient ignition performance cannot be obtained. Therefore, in order to control the energization time of the primary current with higher accuracy, an ignition control device has been proposed in which the energization time is controlled according to the rising state of the primary current. For example, Nippon Denso Public Technical Report 53
-070, JP-A-60-116863, and Nippon Denso Koho Giho 29-154.

In the ignition control device described in Nippon Denso Public Technical Report 53-070, the principle of estimating the energization time Ton 'is shown in FIG.
, The primary current i1 of the ignition coil is 1 of the target value I1
The required time T1 / 2 to reach / 2 is measured, and the required time T1 / 2 is doubled to obtain the energization time Ton '.

Further, in the ignition control device described in JP-A-60-116863, a reference rise time required for the primary current of the ignition coil to reach a reference level set lower than a target value is stored in advance. Every time, the required time for the actual primary current to reach the reference level is measured, and the deviation of the required time from the reference rise time is set as the energization correction time. Thereafter, the energization time is corrected by this energization correction time. .

On the other hand, in the ignition control device described in Nippon Denso Koho Giho 29-154, paying attention to the fact that the required energization time decreases when the primary current of the ignition coil jumps, and the correction amount is calculated according to the following equation. ΔT is calculated, and the energization time is reduced and corrected by this correction amount ΔT.

ΔT = Δi × L / VB where Δi is the primary current value after a short time, L is the inductance of the ignition coil, and VB is the battery voltage.

[0007]

In the ignition control device described in the above-mentioned Nippon Denso Public Technical Report 53-070, the energization time Ton 'is calculated on the assumption that the primary current i1 of the ignition coil rises linearly. However, as is well known, the primary current i1
Rises like a quadratic curve in accordance with the characteristic of the ignition coil, that is, the rising characteristic determined by the time constant of impedance. Therefore, as shown in FIG. 7, the actual energization time Ton
The energization time Ton 'is calculated as a shorter value than
Ignition was performed when the next current i1 reached a current value I1 'lower than the normal target value I1, and there was a fear that sufficient ignition performance could not be obtained.

Further, in the ignition control device described in Japanese Patent Laid-Open No. 60-116863, when the ignition coil is replaced, the rising characteristics of the primary current change due to variations in manufacturing, etc., and accordingly the reference in the table is changed. It was necessary to rewrite the control program for the rise time.

On the other hand, in the ignition control device described in Nippon Denso Koho Giho 29-154, since the battery voltage VB detected as an analog value in the equation for obtaining the correction amount ΔT is used, a jumping phenomenon particularly occurs. In such a high rotation range, there is a possibility that A / D conversion will not be in time and control will be delayed. Moreover, since the inductance L of the ignition coil is used in the formula, it is necessary to rewrite the control program for the inductance L in the table when replacing the ignition coil.

Therefore, according to the present invention, the energization time of the primary current of the ignition coil can be accurately estimated, and the maintenance work can be improved by eliminating the rewriting work of the control program accompanying the replacement of the ignition coil and the like. A / D in the rotation range
An object of the present invention is to provide an ignition control device for an internal combustion engine that can avoid a control delay due to conversion.

[0011]

As shown in FIG. 1, an ignition control device for an internal combustion engine according to the present invention provides a rising characteristic of an ignition coil, that is, a primary current that rises as determined by an impedance time constant. Primary current value determination means M1 for detecting and determining that the primary current has reached a plurality of set current values set lower than a target value in advance, and a primary current value from the start of rising of the primary current. Based on the required time calculation means M2 for calculating the required time until the determination means M1 determines that each set current value has been reached, and the required time corresponding to each set current value, the primary current is the target. The energization time estimating means M3 that estimates the time required to reach the value to be the energization time of the primary current, and controls the primary current of the ignition coil based on the energization time estimated by the energization time estimating means M3. Those comprising a primary current control means M4.

[0012]

In the present invention, when the primary current value judging means M1 judges that the primary current rising in accordance with the rising characteristic has reached each set current value, it is necessary to reach the set current value. The time is calculated by the required time calculating means M2. Since a plurality of sets of set current values and corresponding required times can be obtained, coordinates of two or more points on the rising characteristic can be specified by each of these values, and the origin of the rising characteristic where both the time and the current value are 0 can be specified. The coordinates can also be specified.
Therefore, the time required for the primary current to reach the target value, that is, the energization time is estimated by the energization time estimation means M3 based on the coordinates of three or more points in total, and the primary current control means M4 is estimated based on the energization time. This controls the primary current of the ignition coil.

Therefore, even when the rising of the primary current is slow and far from the linear characteristic, the energization time can be accurately estimated, and the rising characteristic of the primary current can be changed by replacing the ignition coil. If the change occurs, the appropriate energization time is estimated accordingly, so there is no need to rewrite the control program when replacing the ignition coil, etc.
Further, since the analog battery voltage is not used for estimating the energization time, it is possible to avoid the control delay due to the A / D conversion.

[0014]

【Example】

[First Embodiment] An ignition control device for an internal combustion engine according to a first embodiment of the present invention will be described below.

FIG. 2 is an electric circuit diagram showing an ignition control device for an internal combustion engine which is a first embodiment of the present invention, and FIG. 3 is a transition of each signal of the ignition control device for an internal combustion engine which is the first embodiment of the present invention. 2 is a time chart showing.

As shown in the figure, the primary coil 1a of the ignition coil 1 is grounded between the collector and the emitter of the power transistor 2 for controlling the primary current and via the resistor 3 for detecting the primary current. The base of 2 is connected to a central processing unit (hereinafter, simply referred to as “CPU”) 4. The power transistor 2 is the ignition signal I from the CPU 4.
The primary current i1 is supplied to the primary side coil 1a by the battery voltage VB, which is controlled according to Gt. The non-inverting input terminals of the first comparator 5 and the second comparator 6 are connected between the emitter of the power transistor 2 and the resistor 3, and a voltage proportional to the primary current i1 is applied to each non-inverting input terminal. To be done. The inverting input terminal of the first comparator 5 receives the reference voltage Vref1
The reference voltage Vref2 is applied to the inverting input terminals of the comparators 6, and the outputs S1 and S of the comparators 5 and 6 are output.
2 is input to the CPU 4. Here, the reference voltage Vref1 of the first comparator 5 becomes "Hi" at the output S1 when the primary current i1 reaches the preset first set current value Iref1 (3.0A in this embodiment). The reference voltage Vref2 of the second comparator 6 is set so as to rise, and the output S2 is output when the primary current i1 reaches the preset second set current value Iref2 (6.0A in this embodiment). Is set to be launched to'Hi '.

The battery voltage VB is applied to the secondary coil 1b of the ignition coil 1, the primary current i1 reaches the target value I1 (6.5A in this embodiment), and the power transistor 2 is turned off. When cut off, a high-voltage ignition current is generated in the secondary coil 1b due to the mutual induction effect. A distributor 7 is connected to the secondary coil 1b, and the distributor 7 distributes and supplies the ignition current to the ignition plug 8 of each cylinder in synchronization with the rotation of an internal combustion engine (not shown). Although not shown, a read-only memory (hereinafter simply referred to as “ROM”) and a random access memory (hereinafter simply referred to as “RAM”) are connected to the CPU 4, and the ROM calculates an ignition timing tE and an energization time Ton. For storing various programs such as a program for controlling the primary current i1 and a RAM for the CPU
The processing data of 4 is temporarily stored.

Next, the operation of the ignition control device for the internal combustion engine configured as described above will be described.

The primary current i1 of the ignition coil 1 is an energization time Ton calculated according to the ignition timing tE calculated from the engine speed and the intake air amount, and the rising state of the primary current i1 as described later. And is controlled based on. That is, as shown in FIG. 3, immediately before the compression top dead center (TDC) of each cylinder, the ignition signal IGt of the CPU 4 is raised at the energization start timing tS that precedes the ignition timing tE by the energization time Ton. The primary current i1 starts to rise as the power transistor 2 turns on, and the ignition signal IGt falls at the ignition timing tE after the passage of the energization time Ton, and the primary current i1 goes off as the power transistor 2 turns off. Is cut off. Then, the ignition plug 8 of the corresponding cylinder is ignited by the ignition current generated when the primary current i1 is cut off.

The above-mentioned primary current i1 rises like a quadratic curve in accordance with the unique rising characteristic of the ignition coil 1.
As shown in, the primary current i1 is the first set current value Iref1
When (the first required time T1 has elapsed)
Then, the output S1 of the first comparator 5 rises, and 1
When the next current i1 reaches the second set current value Iref2 (when the second required time T2 elapses), the output S2 of the second comparator 6 is raised.

Here, the energization time Ton is the primary current i
1 is estimated as the time required to reach the target value I1, and in the ignition control device of the present embodiment, the coordinates of three points on the rising characteristic of the primary current i1, that is, the origin (t, i1) =
(0, 0) and the coordinates (T1, Iref1) of the two points described above,
Based on (T2, Iref2), the energization time Ton is calculated according to the following equation.
Is calculated. Since the origin is always (0, 0) regardless of the rising characteristics, the following equation is created on the assumption that this is the case, and the energization time Ton is actually calculated from the coordinates of the remaining two points.

[0022]

[Equation 1]

In this way, the energization time T is calculated based on the coordinates of three points including the origin on the rising characteristic of the primary current i1.
Since on is estimated, the primary current i1 rises slowly due to, for example, a large primary resistance of the ignition coil 1 or a drop in the battery voltage VB (in other words,
Even if it is far from the linear characteristic), the energization time Ton until the primary current i1 reaches the target value I1 can be accurately estimated. Therefore, as in the ignition control device described in Japanese Denso Public Technical Report 53-070 of the prior art, 1
It is possible to prevent an error in the energization time Ton that occurs because the rising characteristic of the next current i1 is assumed to be linear.

Further, when the rising characteristic of the primary current i1 is changed due to the replacement of the ignition coil 1 or the like, an appropriate energization time Ton according to the new rising characteristic is estimated based on the above equation (1). Therefore, the prior art of Japanese Patent Laid-Open No.
No. 0-116863 or Nippon Denso Public Technical Report 29-
Unlike the ignition control device described in 154, there is no need to rewrite the control program when replacing the ignition coil 1.

On the other hand, as is clear from the equation 1, unlike the ignition control device described in the Japanese Denso Koho Giho 29-154 of the prior art, the analog battery voltage VB is not used to estimate the energization time Ton. . Therefore, it is possible to avoid the control delay in the high rotation range, which occurs due to the A / D conversion of the battery voltage VB.

Here, for reference, a procedure for deriving Equation 1 for calculating the energization time Ton will be described.

FIG. 4 is an explanatory diagram showing the characteristics of the primary current of the ignition control device for the internal combustion engine according to the first embodiment of the present invention.

As shown in the figure, the primary current i1 rises like a quadratic curve that is asymptotic to VB / R, and as is well known, the primary current i1 at this time is

[0029]

[Equation 2]

It can be represented by Note that R is the resistance of the primary coil 1a, and L is the inductance of the primary coil 1a.

Here,

[0032]

[Equation 3]

From

[0034]

[Equation 4]

And ignoring the third term and below,

[0036]

[Equation 5]

The next, it can be expressed in the form of i1 = At ² + Bt.

Therefore, the origin (t, i1) = (0,
0) and the coordinates of two points (T1, Iref1), (T2, Iref
When 2) is defined, the simultaneous equations are solved to obtain the above-described expressions relating to A and B of the equation 1.

Further, when t (Ton) for which i1 = I1 is obtained by the root formula, the above-mentioned formula for Ton is obtained.

Next, C including the above estimation of the energization time Ton
The PU ignition control process will be described.

FIG. 5 is a flow chart showing an ignition control routine executed by the CPU of the ignition control device for the internal combustion engine according to the first embodiment of the present invention.

The routine shown in the figure is executed at a predetermined timing, and although not shown, before the step S1, a process for calculating the ignition timing tE from the well-known engine speed and the intake air amount, and the ignition timing tE are calculated. And a process for calculating the energization start timing tS from the energization time Ton. In addition, the energization time T estimated in the previous routine is stored in the RAM.
It is assumed that on data is stored. Then, when the internal combustion engine reaches the crank angle corresponding to the energization start timing tS, the CPU 4 executes the energization start process in step S1 to turn on the power transistor 2 to raise the primary current i1 as described above. It is started, and the energization start time tS is stored in the RAM in step S2. Then, step S
In step 3, the time tA when the output S1 of the first comparator 5 is raised to "Hi" (the primary current i1 reaches the first set current value Iref1) is stored in the RAM, and in step S4, The time tB when the output S2 of the second comparator 6 is raised to "Hi" (the primary current i1 reaches the second set current value Iref2) is stored in the RAM.

When the internal combustion engine reaches the crank angle corresponding to the ignition timing tE in step S5, energization termination processing is executed to turn off the power transistor 2 and cut off the primary current i1 as described above. Further, at step S6, the energization start timing tS is subtracted from the time tA described above to obtain the first required time T1 which is the required time until the primary current i1 reaches the first set current value Iref1. The energization start timing tS is subtracted from tB to obtain the second required time T2 which is the required time until the primary current i1 reaches the second set current value Iref2. After that, in step S7, the energization time Ton is calculated as the time required for the primary current i1 to reach the target value I1 according to the above-described equation 1, and RA is calculated.
Store in M and end this routine.

The energization time Ton thus estimated is used for calculating the energization start timing tS in the next routine, and the ignition coil 1 is calculated based on the energization start timing tS.
The primary current of is controlled.

As described above, in this embodiment, the resistor 3, the first comparator 5 and the second comparator 6 function as the primary current value determining means M1, and the required time calculating means M2 includes steps S2 to S4. The CPU 4 at the time of executing the processing of step S6, the energization time estimation means M3
CPU4 when executing the process of step S7 as
However, the CPU 4 functions as the primary current control unit M4 when executing the processes of step S1 and step S5.

As described above, the ignition control apparatus for the internal combustion engine of this embodiment has the first required time T1 until the primary current i1 reaches the first set current value Iref1 based on the outputs S1 and S2 of the comparator. And a second required time T2 until reaching the second set current value Iref2, and based on the coordinates (T1, Iref1), (T2, Iref2) of these two points, the origin of the rising curve (0, 0 The CPU 4 is provided with the energization time Ton calculated according to the equation (1) created based on (1) and controlling the primary current of the ignition coil based on the energization time Ton.

Therefore, since the energization time Ton is estimated based on the coordinates of the three points on the rising characteristic of the primary current i1, the rising time of the primary current i1 is slow and is far from the linear characteristic. Even if there is, the energization time Ton can be accurately estimated. In addition, when the rising characteristic of the primary current i1 changes due to the replacement of the ignition coil 1 or the like, an appropriate energization time Ton is estimated accordingly, so that it is necessary to rewrite the control program when replacing the ignition coil 1 or the like. There is nothing, and the maintainability can be greatly improved. Further, since the battery voltage VB of analog value is not used for estimating the energization time Ton, the control delay due to A / D conversion in the high rotation speed range can be avoided.

[Second Embodiment] An ignition control apparatus for an internal combustion engine according to a second embodiment of the present invention will be described below.

FIG. 6 is an explanatory view showing the principle of estimating the energization time in the ignition control device for the internal combustion engine according to the second embodiment of the present invention.

The configuration of the ignition control device of this embodiment is the same as that of the first embodiment shown in FIG. 2, and the difference is that the energization time T
It is in the estimation principle of on. Therefore, the difference will be mainly described. Now, as in the first embodiment, the primary current i1 is (t, i1) = (0, 0), (T1, Iref1), (T2
, Iref2) rises along a rising curve including the coordinates of three points, and for convenience of explanation, (T1, Iref1) is point A and (T2, Iref2) is point B. First, the t-axis intercept ΔT of the straight line 1 passing through the points A and B is obtained, the t-axis intercept ΔT is corrected to the point A, and the point A ′ (T1−kΔT, Iref1) is specified. Then, the time required for the straight line l'passing through the points A'and B to reach the target value I1 is determined, and the time is determined as the energization time Ton. Here, k is a constant set according to the set current values Iref1 and Iref2,
If this k is set to an appropriate value, the straight line l'and the primary current i
The time when 1 reaches the target value I1 coincides with each other, so that the accurate energization time Ton is obtained.

Then, for example, as described in the first embodiment, the first set current value Iref1 is set to 3.0A, the second set current value Iref2 is set to 6.0A, and the target value I1 is set to 6.5A. And the energization time Ton when the constant k is set to 1.0 is

[0052]

[Equation 6]

This can be represented by the following equation. In step S7 of FIG. 5, the energization time Ton is calculated according to this equation 6.

As described above, in the ignition control device of the present embodiment, the energization time Ton of the primary current i1 can be accurately estimated as in the first embodiment, and the control program needs to be rewritten when the ignition coil 1 is replaced. It is possible to greatly improve the maintainability without any use, and to avoid the control delay due to the A / D conversion in the high rotation range.

In addition, the equation 6 used in the calculation of the energization time Ton in this embodiment is a very simple equation as compared with the equation 1 in the first embodiment. Therefore, it is possible to complete the process of step S7 with a sufficient time even in the high engine speed range, and it is possible to sufficiently cope with the further increase in speed of the internal combustion engine in the future.

By the way, although the energization time Ton is estimated by different methods in the first and second embodiments, the present invention is not limited to these estimation methods, and the point is It suffices that the coordinates of three or more points including the origin on the rising curve of the primary current i1 be specified and the energization time Ton be estimated based on these coordinates. Therefore, the energization time Ton may be estimated by another method.

In the first and second embodiments, the energization time Ton is estimated based on the coordinates of three points including the origin on the rising curve of the primary current i1. Is not limited to this, and the energization time Ton may be estimated based on the coordinates of four or more points. Although the accuracy of estimating the energization time Ton improves as the number of specified coordinates increases, the equations (1 and 6) used for the calculation gradually become complicated. It is desirable to determine

[0058]

As described above, according to the ignition control apparatus for an internal combustion engine of the present invention, based on the coordinates of three or more points on the rising characteristic of the primary current determined by the time constant of the impedance of the ignition coil. Since the energization time is estimated, the energization time can be accurately estimated even when the rise of the primary current is slow and is far from the linear characteristic.
When the rising characteristic of the primary current changes due to the replacement of the ignition coil, etc., the appropriate energization time is estimated, so there is no need to rewrite the control program when replacing the ignition coil, and its maintainability is improved. This can be greatly improved, and since the analog battery voltage is not used for estimating the energization time, the control delay due to the A / D conversion in the high rotation speed range can be avoided.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram conceptually showing the content of one embodiment of the present invention.

FIG. 2 is an electric circuit diagram showing an ignition control device for an internal combustion engine which is a first embodiment of the present invention.

FIG. 3 is a time chart showing a transition of each signal of the ignition control device for the internal combustion engine according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing characteristics of a primary current of an ignition control device for an internal combustion engine which is a first embodiment of the present invention.

FIG. 5 is a flowchart showing an ignition control routine executed by the CPU of the ignition control device for the internal combustion engine according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing the principle of estimating the energization time in the ignition control device for the internal combustion engine according to the second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a principle of estimating energization time in a conventional ignition control device for an internal combustion engine.

[Explanation of symbols]

 M1 primary current value determination means M2 required time calculation means M3 energization time estimation means M4 primary current control means 1 ignition coil 3 resistance 4 CPU 5 first comparator 6 second comparator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasumitsu Tanaka 1-1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd.

Claims (1)

[Claims] 1. A primary current for detecting a primary current rising with a time constant of an impedance of an ignition coil, and determining whether the primary current has reached a plurality of preset current values set in advance lower than a target value. Current value determination means, required time calculation means for calculating the required time from the start of the rise of the primary current until it is determined by the primary current value determination means that each set current value has been reached, and each setting Based on the current value and the corresponding required time, the energization time estimating means for estimating the time required for the primary current to reach the target value to be the energization time of the primary current, and the energization time estimating means. An ignition control device for an internal combustion engine, comprising: a primary current control means for controlling a primary current of an ignition coil based on an energization time.