JP2828255B2 - Ignition timing control device - Google Patents

Description

The present invention relates to a device for controlling the ignition timing of an engine.

(Prior Art) In order to accurately control the ignition timing of an engine to a predetermined timing near the compression top dead center in accordance with the operation state, it is necessary to accurately measure the actual crank angle.

As one of the devices for measuring the crank angle, there is a crank angle sensor that outputs a position signal every 120 ° representing a reference angular position and a 2 ° signal obtained by dividing one rotation into 180 as a unit angle signal, In this case, the 2 ° signal is counted from the rise of the reference signal, which is a 120 ° signal, and when a predetermined crank angle is reached, an ignition signal (high voltage pulse) is output to cause ignition. ("ECCSL Engine Technical Manual" published by Nissan Motor Co., Ltd., 1979) On the other hand, only the reference signal of a predetermined crank angle is obtained, and the generation period of the reference signal is equally divided by a computer or the like, and There is a time-division measurement method for determining the crank angle from the passage.

(Problems to be Solved by the Invention) When the measurement method using the crank angle sensor and the time-division measurement method are compared, in both cases, considering that the arithmetic operation of the ignition timing control is performed by a computer, the unit signal is used together with the reference signal. Compared with the time-division measurement method, the measurement method using the output crank angle sensor complicates the structure of the mechanical sensor part by the amount of outputting the unit signal, and is expensive in cost.

However, in the time-sharing method, which is advantageous in terms of cost, the ignition timing is determined from the passage of time based on the reference signal, so if there is any abnormality in the reference signal, the crank which is far from the original ignition timing In some cases, ignition occurred at an angular position, causing a misfire or backfire.

The present invention focuses on such a problem, and an object of the present invention is to provide an ignition timing control device that reliably prevents ignition from being performed at an abnormal timing in measuring a crank angle by time division. And

(Means for Solving the Problems) Accordingly, the present invention provides a crank angle detecting means 50 for outputting a crank angle reference signal at equal intervals corresponding to the number of cylinders, and equally dividing the cycle of each reference signal in time. Means 51 for counting,
A means 52 for setting an ignition timing according to an operation state; a means 53 for outputting an ignition signal when a temporal count value from a reference signal matches the set ignition timing; and the ignition output for each cylinder. Means 54 for detecting a time interval between signals, and determining whether a difference between a previous detection value and a current detection value of the time interval is included in a predetermined time range related to a generation cycle of the reference signal, If it is not included, a means 55 for outputting an ignition signal included in the range in place of the ignition signal is provided.

(Operation) Therefore, when the difference between the previous detection value and the present detection value of the time interval at which the ignition signal is output is not within the predetermined time range, that is, since the difference between the time when the previous reference crank angle signal was output If the next ignition signal starting from the next reference signal is not included in the predetermined time range, it is determined that an abnormal state has occurred, and the next ignition signal due to noise output before the time range is interrupted. When the next ignition signal is about to pass the time range due to the lack of the reference signal, the next ignition signal is forcibly output at that moment. As a result, even when the reference signal is lost or an erroneous signal due to noise is generated, the ignition action is performed within a range that does not impair the combustion of the engine.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

This embodiment shows an example of application of the present invention to a four-cylinder engine. In FIG. 2, reference numeral 1 denotes a rotor which rotates together with a camshaft. Prepare. Reference numeral 2 denotes a pickup provided near the rotor 1 for detecting the passage of each projection 1a as the rotor 1 rotates. This detection signal is input to a controller 4 for controlling the ignition timing. Since the camshaft rotates in synchronism with 1/2 rotation of the crankshaft, in this embodiment, the pickup 2 is set to the reference (R
EF) signal is output, and the output position of the signal is set to be a predetermined angle before the top dead center of each cylinder.

The controller 4 is composed of a microcomputer or the like, and determines an optimal ignition timing at each time based on various detection signals representative of an operating state such as an intake air amount and a rotation speed of the engine, and will be described later. Like so
The ignition coil 5 is driven at a predetermined crank timing obtained by time-dividing the reference signal from the pickup 2.

The high-voltage current from the ignition coil 5 is distributed to the ignition plug 6 of each cylinder of the engine 3 via the distributor 7 and discharges ignition spark at a predetermined timing.

The controller 4 determines whether or not the crank angle for outputting the ignition signal is appropriate based on the calculation operation as shown in the flowchart of FIG. Even when the ignition is performed, the ignition operation is performed at a timing within a range necessary for combustion at a minimum.

The configuration required to determine and control the ignition timing will be described with reference to FIG.

The calculation operation of this flowchart is executed every predetermined short time.

First, in step P1, the rise time (time n) of the REF signal (180 ° signal) input from the pickup is measured. And the rise time (time n−
1) and the time difference Tn between this time and Tn = (time n) − (time n
-1) (step P2).

This time difference Tn is proportional to the engine speed, and the time difference becomes smaller as the engine speed increases.

In step P3, the engine intake air amount Qa is measured from the output of the intake air amount sensor (not shown in FIG. 2),
The optimum ignition timing (ignition advance angle before top dead center) ADVn for the operating condition determined from Qa and Tn is obtained by calculation (step P4). The optimum value of the optimum ignition timing is set in advance by experiments and the like using Qa and Tn as parameters.

Next, in step P5, as shown in FIG. 4, a limit value (time) LMT of the fluctuation range of the ignition, which takes different values under the neutral condition of the transmission and other conditions, is set to a value Tn proportional to the engine speed. (The neutral condition is determined based on a signal from a neutral switch (not shown)).

The limit value LMT, as described later, is used as a criterion for determining when the REF signal from the pickup 2 is missing or when a signal due to noise is input. If the ignition interval from the current ignition to the current ignition is not within an appropriate range, it is determined to be an abnormal signal, and it is necessary to perform ignition at a predetermined timing calculated from the previous reference signal.

In steps P6 and P7, timers 1 and 2 are started. In step P8, the value of another timer 3 which started counting in synchronization with the previous rise of the REF signal is set to the limit value of the later ignition timing. Compare with As will be described later, this corresponds to the maximum allowable ignition interval from the previous ignition to the next ignition. If the calculated value of the timer 3 becomes longer than this, it is determined that the REF signal is missing, and the step is immediately performed. P11
Go to and ignite.

If the count value of the timer 3 is smaller than the maximum ignition interval, the count value of the timer 1
ADVn is compared with a value converted into the elapsed time from the rise of the REF signal, and if NO, the process returns by one step until the value matches, and waits for the elapse of time.

When the predetermined ignition timing has been reached in this way, the process proceeds to step P10, in which the count value of the timer 3 that has started counting from the previous rising of the REF signal is set to the earlier limit value of the current ignition timing (the previous ignition timing). (The minimum allowable ignition interval from the current ignition to the current ignition), and if it is larger, it is determined to be normal, and ignition is performed in step P11.

On the other hand, if NO, it is determined that an erroneous REF signal due to noise has occurred between the normal REF signals, and the routine proceeds to step P18 without firing and the timers 1 and 2 are cleared.

After ignition in step P11, the cylinder register for cylinder discrimination is increased by count 1 in step P12,
Further, it is determined whether or not the cylinder register is 4 (step P13). Note that the cylinder registers are 0, 1, 2, and 3 corresponding to the # 1, # 3, # 4, and # 2 cylinders according to the ignition order.

If the count value is 4, the cylinder register is returned to 0 in step P14, and the timers 1 and 3 are cleared in steps P15 and P16.

After the next rise of the REF signal, the count value of the timer 2 is compared with the limit value of the ignition timing to determine whether the ignition timing is appropriate. Therefore, timers 2 and 3 are started alternately every other REF signal.

Based on the above-described configuration, the process of generating the ignition signal will be described with respect to the case where the REF signal output from the pickup 2 is normal, the case where the REF signal is missing, and the case where noise is generated.
This will be described with reference to the drawings.

First, as shown in (A), the REF signal is generated regularly at every 180 ° of the crank angle during normal operation.

The rise of this signal occurs at CRSET (deg) that is a predetermined angle before the top dead center.

Then, the generation cycle of each signal is T ₀ , T ₁ , T ₂ ,.
Assuming that each ignition timing is ADV _O , ADV ₁ , ADV ₂ ... (゜ BTDC), T _-1 (CR
SET−ADV ₀ ) / 180, T ₀ (CRSET−ADV ₁ ) / 180, T ₁ (CRSET−A
The ignition is performed after DV ₂ ) / 180….

A predetermined range before and after ignition is defined as a limit value LMT,
This is determined as the allowable fluctuation range of the next ignition, and if the ignition is performed within this range, it is determined that the state is normal.

The limit value LMT is determined according to the engine speed as shown in FIG. 4, but is set to a different characteristic value depending on the neutral condition of the transmission and other conditions. Generally, when the transmission is in a neutral condition, the moment of inertia of the output shaft system is smaller than at other times, so that the rotation fluctuation accompanying the torque fluctuation of the engine tends to be large and the fluctuation range of the ignition becomes large. , Limit value LMT
Needs to be increased. Therefore, the LMT is set so as to take a necessary and minimum value in consideration of the maximum engine rotation fluctuation value and the maximum change speed of the ignition timing.

FIG. 5B shows a case where the REF signal is missing (missing). In FIG. 5 (B), # 4
Although only the determination of the lack of the REF signal corresponding to the cylinder is illustrated, it is needless to say that the determination is performed for each cylinder.

# 3 ignition of the cylinder are as described above, the timing t ₁ RE
T ₀ (CRSET−ADV ₁ ) / 180, counted from the rise of the F signal
However, in order to determine whether or not the next ignition is performed within an appropriate range, the period of the previous REF signal generation cycle T ₀ (time) from the rise of the REF signal is determined at the same time. , This ignition timing T ₀ (CRSET−ADV ₁ ) / 180
And a value obtained by adding LMT / 2 corresponding to half of the limit value,
In other words, we are looking at the limit time of the later ignition interval, and if this limit time is passed before the next ignition is performed, the next
It is determined that the REF signal is missing, and at that moment, the next cylinder is ignited.

Although this ignition is delayed from the regular ignition timing, as described above, by limiting the limit value LMT to the required minimum value, the engine somehow explodes and the range near the top dead center where there is no misfire It is stored in.

On the other hand, as shown in FIG. 5C, when an erroneous signal different from the normal REF signal is interposed due to generation of noise, the earlier limit time until the next ignition is reached. This is determined by looking at the (allowed minimum ignition interval). In FIG. 5 (C), only the determination of the noise of the REF signal corresponding to the # 3 cylinder is illustrated.
Needless to say, the judgment is made for each cylinder.

In other words, before the elapsed time from the previous rise of the REF signal exceeds T ₀ + T ₀ (CRSET−ADV ₁ ) / 180−LMT / 2,
Starting from an incorrect REF signal, ignition timing (time) T ₁ (C
When RSET−ADV ₂ ) / 180 is reached, it is determined that the vehicle is in an abnormal state where noise has occurred, and ignition is not performed at that time.

In this case, since timer 3 is not cleared,
When the next correct REF signal is input, the arrival time to the new ignition timing calculated based on this signal is compared with the above-mentioned limit time of the later ignition, and if it is within the range, the correct (next) The ignition is performed at the timing calculated from the REF signal.

In this way, even if the reference crank angle signal is missing or an erroneous signal is added due to noise, these are definitely determined, and when the missing signal is detected, ignition is performed within a range where the engine is not misfired by provisional ignition timing. In addition, when noise occurs, unnecessary ignition can be avoided to prevent backfire and the like.

(Effect of the Invention) As described above, according to the present invention, it is determined whether or not the ignition signal is output properly by determining the time interval of each ignition in relation to the generation cycle of the reference signal. In addition, when an abnormality occurs, the ignition signal is generated within a predetermined time interval. Therefore, even when the reference signal is lost or an erroneous signal is generated due to noise, the ignition function can be performed accurately, and engine misfire or Backfire can be avoided.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is a flowchart showing the operation of determination and control of ignition timing, and FIG. FIG. 5 is a timing chart for explaining the actual ignition operation with respect to the reference signal. DESCRIPTION OF SYMBOLS 1 ... rotor, 2 ... pickup (reference crank angle detection means), 3 ... engine, 4 ... controller, 6
... spark plug.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02P 5/15 F02P 5/152

Claims (1)

(57) [Claims] 1. Crank angle detecting means for outputting a crank angle reference signal at equal intervals corresponding to the number of cylinders, means for counting the period of each reference signal by equally dividing it in time, and Means for setting an ignition timing; means for outputting an ignition signal when a temporal count value from a reference signal matches the set ignition timing; and detecting a time interval between the ignition signals output for each cylinder. Means for determining whether or not the difference between the previous detection value of the time interval and the current detection value falls within a predetermined time range related to the generation cycle of the reference signal; A means for outputting an ignition signal included in the range in place of the ignition timing control device.