JPH0660620B2 - Ignition timing control device - Google Patents

Description

The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to an electronic ignition timing control device.

A device for electronically controlling the ignition timing of an internal combustion engine is generally known, and in this kind of ignition timing control device, various sensors detect the engine speed and the operating condition of the engine to optimize the operating condition of the engine. It is possible to determine various ignition timings and energization periods. However, in order to always ensure reliable ignition regardless of changes in the engine speed and operating conditions, the ignition coil must generate a constant and constant ignition energy, and the ignition timing must also be properly controlled without change. I have to. Various improvements have been made in the past to achieve this goal. For example, in the product description “Microcomputer Control Engine Control System” of the applicant company of the present application (edited by Nippon Denso Co., Ltd., issued October 20, 1981), ignition control (Electronic Sp
ark Advance) is described, and in this ignition control, the operating level and the rising speed of the closing angle control signal are changed by the ignition signal from the computer according to whether the engine speed in the igniter is high or low, and the closing angle ( Energization period) is increased or decreased. Further, in the igniter, feedback type constant current control is performed in order to always keep the current (primary current) of the ignition coil constant. As described above, in the igniter, circuits for closing angle control and constant current control are required, and since these circuits are complicated, the structure of the ignition control device as a whole is inevitably complicated and the manufacturing cost is high. There is a drawback that becomes.

Japanese Unexamined Patent Publication No. 56-23564 discloses a method for controlling the energization time in the ignition coil. In this method as well, in order to secure the ignition energy required for ignition, the constant current time target value and the previous constant value are set. When calculating the current-carrying time by adding the correction to the difference between the current-time measurement value, monitor the current-carrying current on the primary side of the ignition coil in the igniter,
A circuit for generating a constant current signal indicating the time when a certain constant current is reached and sending it to the arithmetic unit is required, which has the same drawbacks as described above.

An object of the present invention is to improve these drawbacks in the conventional device, and by a simpler circuit, ignition timing control that can secure uniform ignition energy and proper ignition timing over the entire engine rotation region. It is to provide a device.

In the present invention, the energization start timing and ignition timing of the ignition coil are calculated based on the output from the sensor that detects the operating state of the engine in response to the signal of the rotation angle sensor that outputs a signal for each predetermined crank angle. Is set to the time limit setting means, and the start and interruption of the power supply to the ignition coil are directly controlled by a signal from the time limit setting means indicating that the energization start timing and the ignition timing are reached. In this case, it is determined whether the engine speed is higher or lower than a predetermined reference speed, and whether the ignition coil is already energized, it is determined that the engine speed is lower than the predetermined reference speed, Further, when the ignition coil is energized, setting of the newly calculated ignition timing in the time limit setting means is prohibited.

Therefore, the energization start timing is calculated for each predetermined crank angle regardless of the engine speed, and the energization of the ignition coil is started at the updated energization start timing. When the engine speed is low, the ignition timing is not updated after the start of energization, and when the engine speed is high, it is updated after the energization is started. Therefore, when the engine is running at a low speed, securing a predetermined energization period is prioritized over precise ignition timing, and conversely, when the engine is running at high speed, a precise ignition timing is prioritized over securing a predetermined energization period. .

However, when the engine is running at low speed, the energization angle (closing angle) corresponding to a certain energization period becomes small, so even if the accuracy of the ignition timing slightly decreases, the effect on the actual period of operation is small and the predetermined energization By always securing the period, a predetermined ignition energy can be secured, and the conventional constant current control of the ignition coil can be omitted. Also, at high speed,
Precise ignition timing is preferentially secured, but the energization period changes depending on the operating state of the engine or fluctuations in the rotational speed. However, since the energization angle corresponding to a constant energization period increases at high rotation speed, even if the ignition timing changes slightly, the effect on the energization period is small and almost uniform ignition energy can be secured.

Further, in the present invention, in addition to calculating the energization start timing and the ignition timing for each predetermined crank angle, the ignition timing is calculated in response to the signal indicating the arrival of the energization start timing from the time limit setting means. The energization start timing is set when the engine is running at low speed by setting the energization start timing in the setting means and calculating the energization start timing in response to the signal indicating the arrival of the ignition timing from the time setting means. It is calculated and ignition is performed at the set ignition timing.

An embodiment of the present invention is shown in FIG.
Further description will be made with reference to FIG. 2 showing a main part (calculation flowchart) of a control program of the microcomputer described later. In FIG. 1, 1 is an engine control unit (hereinafter abbreviated as ECU) similar to the conventional one,
Input signal processing circuit 2 from various sensors similar to the conventional one,
And a free running counter such as 6801 (corresponding to the time limit setting means in the device of the present invention, hereinafter abbreviated as a timer) for calculating energization start timing and ignition timing based on the input signal. It comprises a microcomputer 3 (which will be abbreviated as a microcomputer hereinafter) and a drive circuit 5 for starting and stopping energization (ignition) of the ignition coil 4 based on its output signal.

Reference numeral 6 denotes an operating state of the engine, for example, a load sensor for detecting a load, 7 is a water temperature sensor for detecting the water temperature of the engine, 8 is a rotation angle sensor for outputting a signal at every predetermined crank angle, and 9 is a power source.

Next, control of energization and ignition will be described with reference to FIG. 2. FIG. 2 (a) shows a specific crank angle, for example, 30 ° C.
The interrupt routine for each A is shown. 11 indicates the start of interrupt processing of a specific angle, and 12 indicates the ignition timing (T
_OFF (θ)) and energization start timing (T _on (θ)) are shown. In the calculation, the ignition timing (T _off (θ)) is the load ( _Pm ), the engine speed (N) calculated based on the output signal of the rotation angle sensor 8, and the correction term (Temp) based on the water temperature detected by the water temperature sensor 7. Regarding the energization start timing (T _on (θ)), a constant time t ₀ mainly determined by the characteristics of the ignition coil, for example,
1.5 ms is subtracted from the previously calculated ignition timing T _off (θ), and the power supply voltage correction term f (+ B) is added to obtain the formula T _on (θ) = T _off (θ) -T ₀ + f (+ B) It is calculated.

13 is a state in which the ignition coil 4 is not energized by judging the energization state to the ignition coil 4 by a calculation flag or the like (not ON)
Then, at 14, the energization start time T _on (θ) is set in the timer. On the other hand, in the energized state (ON), it is determined whether the engine speed is higher or lower than a predetermined reference speed at 15 and the reference speed is as shown in FIG. 2 (b). N ₂ rpm (eg 2200 rpm) or higher or N ₁ rpm (eg 1800 rpm)
If it is less than or equal to, and if more than (f (N) = 1), 1
In 6, the ignition timing T _off (θ) previously calculated for each specific crank angle in 12 is set in the timer. In the following case (f (N) = 0), the ignition timing previously calculated in 12 is set. Is not set. Here, the reference rotational speeds are N ₁ and N ₂
The width is given by and, but this is in consideration of the influence of fluctuation (chattering) of the calculated rotation speed.

Next, the routine for setting the ignition timing (T _off (θ)) by the on interruption shown in FIG. 2 (c) will be described.
When the energization start time T _on (θ) set in the timer is reached in step 14 of FIG. 2A, the output signal from the microcomputer 3 is sent to the drive circuit 5 in response to the signal indicating the ON time from the timer. Then, the energization of the ignition coil 4 is started, and at the same time, the on-interrupt routine is started in step 17 of FIG. 2 (c) showing that the energization start timing set in the timer has been reached. Then, at 12 ', the same ignition timing T as that of 12 is again obtained.
Calculation of _off (θ) is performed, and in 16 ′, the calculated ignition timing T _off (θ) is set in the timer as in the case of 16.

Energization start time T due to the off interrupt in FIG. 2 (d)
Similarly, the _on (θ) setting routine is started with the arrival of the ignition timing in step 19 indicating that the energization cutoff timing (ignition timing) set in the timer has been reached, and the same calculation as 12 is performed at 12 ″. Power on start time T _on
(Θ) is set to 14 'in the timer.

The above operation will be described with reference to FIG. 3 showing a time chart and FIG. 2 showing a calculation flowchart. The thick line in FIG. 3 schematically shows the relationship between the set value set in the timer and the arrival time of the timer.

Indicates the ON set value T _on 14 of the timer shown in FIG. Is the ON set value of 14 'in FIG. 2 (d), Indicates the off set value 16 in FIG. 2 (a), Shows the off set value of 16 'in FIG. 2 (c). FIG. 3 (a) shows the case of low rotation of N ₁ or less, and FIG. 3 (b) shows the case of high rotation of N ₂ or more. As shown in FIG. 3 (b), when the engine speed is high, the on / off setting of the timer is performed for each specific crank angle and at the start of turning on / off, but as shown in FIG. 3 (a). During low rotation, step 13 in Fig. 2 (a)
As is known from the determination result of the energized state in (1), after being turned on once (while the ignition coil is energized), the off setting (ignition timing setting) for each specific crank angle is prohibited.

As described above, the reason why the setting method of the ignition timing T _off (θ) in the timer is different between the low rotation speed and the high rotation speed of the engine is that in the actual engine, the rotation fluctuation due to the combustion fluctuation or the sudden engine fluctuation is caused. This is because, when there is a change in the number of revolutions due to acceleration, etc., the influence of these variations on the energization period (τ, τ ′) and the ignition timing (θig and θig ′ are different between the low revolution and the high revolution.

First, regarding the energization period (τ, τ ′), FIG. 2 (a)
As a result of the determination in step 15 of step f (N) in FIG.
When the engine speed is low (= 0), step 16 is bypassed and the ignition timing setting value is not changed during energization, so that a constant energization period τ can be obtained.
When f (N) = 1 is high, the second (a)
Due to the resetting of the ignition timing in step 16 in the figure, the energization period is not constant, and changes with the occurrence of rotation fluctuation, rotation speed change, and the like. However, at high rotation speed, the time required for one rotation of the engine is shortened, so that the influence of the ignition timing deviation is small. That is, during the most rapid racing of the rotation speed change, for example, when the vehicle is suddenly accelerated at an acceleration α = 6000 rpm / sec, within a time Δt corresponding to a crank angle interval for ignition timing calculation between before and after the acceleration. The change ΔN in the number of revolutions of Δ is ΔN = α × Δt, but ΔN is small because the value of Δt at the time of high rotation is small, and therefore the change in the ignition timing calculation value before and after the acceleration is small. The change in the energizing engine τ is small, and the necessary energizing period can be obtained. On the other hand, when the engine speed is low, since the time required for one revolution of the engine is long, the rotational speed change ΔN in the calculation interval is large, and thus the change in the ignition timing calculation value for each calculation is also large. Since the ignition timing is not set again during the process, the energization period τ is not changed and the required energization period is maintained.The ignition timings θig and θig ′ are set to a specific crank even during energization at high rotation with a large energization angle. Since the ignition timing is set again for each angle, the optimal ignition timing for the operating condition of the engine is secured. At low revolutions, almost the desired value can be obtained as the ignition timing without resetting the ignition timing during energization. Because it will be longer, compared to this time,
The desired energization period becomes much shorter (one rotation time >> energization period), and even if the deviation of the ignition timing between calculations increases due to fluctuations in the number of revolutions, etc., these deviations of the energization period and ignition timing Even if converted to an angle, the angle width is small,
This is because it is possible to obtain the same ignition timing accuracy as in the conventional case, even if the angle is not set finely. Actually, if a sudden acceleration such as racing occurs at low speed, the ignition timing will not be set accordingly, but the ignition timing will be delayed, but at this time the energization angle is small and the effect is small and acceptable. Instead, since a constant energization period is secured, it is possible to avoid ignition energy shortage due to shortening the energization period due to rapid acceleration. In order to shorten the energization period (angle) of the ignition coil, if a so-called high-speed engine ignition coil with a coil specification in which the primary inductance of the coil is reduced and the primary current is increased is used, the desired energization period is secured. Will be easier.

As described above, the ignition timing control device according to the present invention controls the energization period with priority at low revolutions and the ignition timing with priority at high revolutions. It can be kept within an allowable range that does not hinder the operation of.

Thus, according to the invention, the aforementioned drawbacks of the prior art device are eliminated and a more simplified construction is used to ensure uniform ignition energy and proper ignition timing over the entire engine speed range. It is possible to obtain an ignition timing control device capable of

Further, for details of the timer setting method in the present embodiment, for example, in the case where a microcomputer that uses two system timer functions for setting the energization period and the ignition timing can be used, for example, the interrupt processing method is changed. It goes without saying that the processing method can be changed so as to perform on-timer and off-timer parallel processing. Also, in combination with the conventional setting method for performing acceleration correction for the purpose of improving the accuracy of the ignition timing, for example, acceleration correction is performed only at the energization start point (on setting) at low revolutions, and at high revolutions energization starts. Point (on setting) and ignition timing (off setting)
It is needless to say that both of them can be easily combined with the method of the previous embodiment in which priority is given to the energization period at low revolutions and priority to ignition timing at high revolutions, such as acceleration correction.

[Brief description of drawings]

FIG. 1 is an overall block diagram of an ignition timing control device of the present invention, FIG. 2 is a diagram showing a main part of a control program executed by the ignition timing control device of FIG. 1, and FIG. It is a time chart figure explaining operation of a timer. (Description of symbols) 1 ... Engine control unit, 2 ... Input signal processing circuit, 3 ... Microcomputer, 4 ... Ignition coil, 5 ... Ignition coil 4 drive circuit, 6 ... Load sensor, 7 ... ... water temperature sensor, 8 ... rotation angle sensor, 12 ... calculation of energization start timing and ignition timing, 13 ... determination of energization state of ignition coil, 14 ... setting of energization start timing, 15 ... engine speed Judgment and prohibition of ignition timing setting at low speed, 16 ... Ignition timing setting.

Claims (3)

[Claims] 1. An ignition timing is determined based on output signals from a rotation angle sensor that outputs a rotation angle signal for each predetermined crank angle and a sensor that detects an operating state of an internal combustion engine, and the energization start and energization of an ignition coil are performed. An ignition timing control device for controlling shutoff, which is responsive to a rotation angle signal from the rotation angle sensor, and based on an operating state of the internal combustion engine, a plurality of times during one operation cycle of the internal combustion engine, A device for calculating the energization start timing and ignition timing of the ignition coil, a time limit setting means for setting the calculation result of the energization start timing and the ignition timing, a device for determining whether or not the ignition coil is energized, the internal combustion engine Is higher than the specified reference speed,
Or a device for determining whether it is low, the calculated energization start timing and ignition timing, when the device for determining whether the ignition coil is energized indicates that it is not energized, the energization start timing is set to the time limit. Means for setting the ignition timing to the time limit setting means when it is set to the means, and responding to a signal indicating the arrival of the energization start timing and the ignition timing from the time limit setting means. And a device that outputs a signal that controls the start of energization of the ignition coil and the interruption of the energization current, and the device that determines the rotational speed of the internal combustion engine determines that the rotational speed is lower than the predetermined reference rotational speed. If it is determined that the ignition coil is in the energized state by the device that determines whether or not the ignition coil is energized, the device that sets the time limit setting means uses the newly calculated ignition. Ignition timing control device is prohibited to set a period in the time period setting means. 2. The device according to claim 1, wherein the device for calculating the energization start timing and the ignition timing of the ignition coil includes the energization start timing and the ignition timing for each of the predetermined crank angles. In addition to calculating the ignition timing in response to the signal from the time limit setting means indicating the arrival of the energization start timing, and in response to the signal from the time limit setting means indicating the arrival of the ignition timing. An ignition timing control device for calculating the energization start timing, and the calculated ignition timing and energization start timing are set in the time limit setting means by a device for setting the time setting means in each case. 3. The device according to claim 2, wherein when it is determined that the rotation speed of the internal combustion engine is lower than the predetermined reference rotation speed, the time setting means outputs the time. Ignition timing is calculated in response to a signal indicating that the energization start timing has been reached, and energization to the ignition coil is cut off according to the set ignition timing. Ignition timing control device whose settings are not updated.