JP3288376B2 - Control method of closing time - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for controlling a closing time in an ignition device for an internal combustion engine according to the preamble of claim 1.

The control of the closing time for internal combustion engines is already known, for example, from DE-A-340 2537. In this control, two comparators and two reference marks are used for setting the ignition timing and controlling the closing time. In this case, the closing time control is based on monitoring of the ignition coil current and two comparators (one of which responds when it reaches 80% of the required ignition coil current and the other when it reaches 100%). Respond). In this case, the time until the individual comparator threshold is reached must be constantly measured, and the charging time must be calculated from the measured time. This is a disadvantage. In this case, the hardware (80% -comparator and 100% -comparator) required for the solution and the special requirements of the processor and the required software require relatively high costs. German Patent Application No. 411970, which has not yet been published, discloses a method for adjusting the closing time. In this case, one comparator is provided. The comparator compares the current intensity of the ignition coil with the target value, and detects the output level of the comparator at each ignition point.

In this case, it is detected whether or not the energy stored in the ignition coil is sufficient to obtain a normal ignition spark. Here, an approximation to the optimum closing time is achieved by progressively increasing or decreasing the closing time based on the respective output level of the comparator by the control device. However, this method cannot quickly detect the desired closing time. This can result in too slow a closing time (which causes unnecessary power loss) or a too short closing time (which will cause a misfire).

Advantages of the invention The advantages obtained by the method according to the invention as set forth in the characterizing part of claim 1 are optimized by making a time measurement of the output closing time and of the time until the comparator responds. A short closing time is determined and is output during the subsequent ignition.

Advantageous embodiments and refinements of the invention are described in the dependent claims. With particular advantage, the comparison voltage supplied to the comparator can be adjusted to a predetermined current value of the charging characteristic curve of each ignition coil. This allows the method to be adjusted to different operating points of the engine. Further advantageously, the forced ignition is triggered for a predetermined time after the response of the comparator.
This eliminates unnecessary burden on the high-voltage guide and unnecessary power loss. A further advantage of the method is that a predetermined minimum closing time is ensured by monitoring the comparator output. Here, additional diagnostics can be performed based on the validity check.

This minimum closing time is checked. As a result, for example, the occurrence of a short circuit is detected, and ignition and fuel injection are interrupted for the corresponding cylinder in order to protect the catalyst and the ignition stage.
When the engine is restarted, the closing time at the time of the final engine stop is taken out to detect the closing time more quickly.
This operating process preferably takes place as a function of the engine temperature _Tmot . Therefore, only when the engine temperature T _motn at the time of restart _{shows a} deviation from the engine temperature T _mote at the time of the final engine stop by a predetermined value, the closing time at the time of the final engine stop is closed at the time of the restart. Used as time.

Drawings Embodiments of the present invention are shown in the drawings and are described in detail in the following specification.

FIG. 1 is a block circuit diagram of a circuit device for detecting an ignition coil current. FIG. 2 is a diagram showing a time lapse characteristic when the closing time is detected. FIG. 3 is a flowchart for detecting the closing time. FIG. 4 shows the ignition coil current for two closing times depending on the engine temperature.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a microprocessor 1 of a control device for an ignition stage of an ignition device of an internal combustion engine, not shown here.
It is shown. The microprocessor 1 is connected to the base of the ignition transistor 3 via a connection line. The collector side of the ignition transistor 3 is connected to the battery voltage U _B here not shown, for example the vehicle battery via the primary winding of the ignition coil 4.

The secondary side of the ignition coil is connected to the spark plug 5 at the other is connected to the battery voltage U _B while. The emitter side of the ignition transistor 3 is connected to the inverting input side of the comparator 6, and further connected in parallel to the ground via a measuring resistor 7. The non-inverting input of the comparator 6 is connected on the one hand to ground via a voltage divider formed by the resistors 8, 9 and on the other hand to the supply voltage U. The power supply voltage U is supplied from a stabilized voltage power supply (not shown). The comparison voltage U _{v at} the non-inverting input of the comparator 6 is adjusted via a voltage divider. In this case it is also possible to use one comparator with a plurality of separately connectable voltage dividers 8a, 8b to 9a, 9b, for example as shown in FIG. In this case, different comparison voltages U _va or U _vb depending on the processor via connection lines 10a, 10b.
Is adjusted in the comparator 6 via the switching elements 11a and 11b. Depending on what is being considered for the comparator, ie, what percentage (eg 90%... 95%) of the comparison value U to reach when the comparator is switched on from the start of the closing time A period up to the end of the time or a part of a predetermined period is detected. The further output stage of the ignition device, which is merely suggested here, is connected such that the emitters of the individual ignition transistors are integrated. In an internal combustion engine in which a closing angle overlap occurs, the cylinders with overlapping closing angles should be evaluated separately by a separate evaluation circuit with components 6-9. The output level IP of the comparator 6 is supplied to the microprocessor 1.

FIG. 2 shows the time course of the signal evaluated by the microprocessor. The upper signal curve in FIG. 2 shows the signal for the control of the ignition output stage 3 by the microprocessor 1 via the connection line 2. Time point T1
Then the microprocessor switches the signal ts from 0 to 1.
As a result, the starting point of the closing time is determined. In the microprocessor 1, this time T1 is measured (determined) and stored as a starting point (base) -time (time from the starting time for various events is measured). The microprocessor 1 also controls the end time T2 of the closing time (at which end the ignition takes place). This closing time SZ (=
T1 to T2) are determined during the preceding ignition cycle or are fixedly set, for example, by a microprocessor 1 at restart, for example, depending on the engine temperature or other operating parameters. . The period T _DIA shown between the closing time start point T1 and the closing time end point T2 represents the minimum closing time. This minimum closing time is constant and is used for identifying short circuits.

2 is an output level IP of the comparator 6.
Is shown. Here switches from the output of the comparator is 0 by the switching when reaching a predetermined ignition coil current through the comparison voltage U _v to 1.

When the ignition coil target current has been reached at time T3, the period t4 starts to start. At the end of this time t4, the closing time is ended by the microprocessor 1 anyway.

FIG. 3 shows a flowchart for processing the detected time as shown in FIG. The microprocessor 1 calculates the ignition timing based on the measured parameters (for example, rotation speed, temperature, pressure, etc.). For each ignition cycle of the internal combustion engine, the signal sequence ts is monitored by the microprocessor 1 in a processing step 20 for controlling the ignition stage and the comparator output level IP.

Subsequently, in the inquiry step 21, it is checked whether or not there has been a start T1 of the closing time. If there is a start, the process proceeds from the Yes-output side of the inquiry step 21 to the processing step 22.
In this processing step 22, the closing time start point T1 is temporarily stored as a base time for the subsequent calculation. When the start T1 of the closing time is not detected, an inquiry step 21 is performed.
To the inquiry step 23 from the No-output side. Here, the presence or absence of an ignition event, that is, the presence or absence of the closing time end point T2 is detected. If an ignition event has been detected, the inquiry step 23 returns Yes to the inquiry step 33 from the output side.
Proceed to. It is determined here whether the output level IP of the comparator 6 has an output level corresponding to the response state (IP = 1) after ignition (in this case the switching time and the discharge time are taken into account). Will be inspected. If not, that is, if the predetermined period (IP) = 0 after ignition, the process proceeds to the inquiry step 24 from the No-output side. In this inquiry step 24, it is checked whether the comparator 6 has completely responded. That is, an inquiry is made as to whether the period T3 during which the comparator 6 responds has reached. Response of the comparator is performed at the time the ignition coil is accumulated energy corresponding to the predetermined comparison value U _v. Inquiry step 24, Yes-
Depending on the output (= comparative response), in a subsequent processing step 25, based on the intermediately stored value T1 for the start of the closing time and the time T3 for the response of the comparator, the subsequent ignition cycle for the relevant ignition coil The closing time SZ _n is determined. In this case, SZ _n = T3
−T1.

If the No output of the inquiry step 24 is negative (= the comparator 6 did not respond from the ignition time to the end time T2 of the closing time), the flow proceeds to the inquiry step 26. In this interrogation step 26, it is checked whether the measured actual closing time (T2-T1) is greater than the optimum closing time (SZ) calculated by the microprocessor 1 in the preceding engine cycle. If the measured actual closing time (T2-T1) is not greater than the optimum closing time (SZ) calculated by the microprocessor 1 in the preceding engine cycle, for example after the calculation or after the closing time has been delivered, the engine Is loaded so much that the ignition timing is shifted forward in time, the process proceeds from the No-output side of the inquiry step 26 to the processing step 27. In this inquiry step 27 as well, the desired optimum closing time SZ is determined again as the closing time for the subsequent ignition (SZ _n = SZ). Such a case (SZ _n = SZ) occurs, for example, when the internal combustion engine is idling and the actually required ignition coil energy is lower than in the partial load range or the full load range. If the inquiry step 26 is Yes-output, ie the actual closing time (T2-T1) is equal to the desired closing time (SZ)
If more greater, in the processing step 28, the subsequent desired optimum closing time SZ _n is obtained as follows.
That is determined by adding the correction value K to the sent closed time _{(T2-T1) (SZ n} = T2-T1 + K).
This is to obtain the response of the comparator 6. In this case, the correction value K is a value determined for application to each engine type. This correction value ensures that the predetermined value of the ignition coil current is achieved by the subsequent ignition closing time. In this case, the correction value K is not added all at once, but is added incrementally in a plurality of pieces to the measured actual closing time.

If the inquiry 23 for the period T2 is No-output, that is, if no ignition event is detected, it is determined in the inquiry step 29 whether a rising edge (i.e. the response of the comparator) has occurred under the signal sequence IP. Is inspected. If a rising edge has occurred, the response time T3 of the comparator 6 is temporarily stored in the processing step 30. In a subsequent inquiry step 31, it is checked whether the response time T3 of the comparator 6 is smaller than the minimum closing time _TDIA . If the inquiry step 31 is Yes, the process proceeds to the processing step 32. In this processing step 32, the fact is determined as the occurrence of a short circuit in the ignition device,
Accordingly, ignition and fuel injection are interrupted in the corresponding cylinder. If the inquiry step 33 is Yes-output after the response of the comparator 6 when the ignition has taken place,
That is, if the comparator is still responsive after ignition, a fault in the comparator is identified in a subsequent processing step 34, and in a processing step 35 the closing time is, for example, the number of rotations and battery voltage detected by the microprocessor. Is sent based on Query step
If a rising edge is identified in the signal sequence IP after a change in the signal at the comparator output at 29, a subsequent interrogation step 36 determines whether the signal sequence IP = 1 holds, ie whether the comparator has already acted. A check is made for no. This inquiry step 36
If the output is Yes, the process proceeds to the inquiry step 37. In this inquiry step 37, it is checked whether the period t4 initiated by the comparator 6 (which represents the maximum permissible closing time SZ _max ) has elapsed. If so, the closing time is terminated by the microprocessor 1 at a time T4 in a processing step 38 and the forced ignition is triggered. This ensures that unnecessary loads on the high-voltage guide are avoided.

In the case of the No output of the inquiry step 36, the inquiry steps 37 and 31, and the processing steps 38, 32, 35, 25, 28 and 27, the processing proceeds to the processing step 39, respectively. This processing step 39
Then, the times T1 and T3 stored for the ignition cycle are deleted. Subsequently, in process step 40, the closing time detection for the next ignition cycle is newly started. According to the method described above, a very accurate detection of the closing time is possible. This is because the unnecessary conversion to the angle level is not performed, but the measured time is directly used by the microprocessor for closing time detection.

Furthermore, according to the method, a very good response to the dynamic characteristics is possible. Thereby, for example, the dynamic characteristic which occurs after the start of the closing time by the microprocessor and the closing time which varies, is determined by the difference between the desired closing time SZ and the actually determined closing time (T2-T1). is detected as a difference, closing time SZ _n subsequent ignition cycle is aligned correspondingly to the measured period. Errors in the detection of the closing time are avoided even under changing operating conditions, as in the case of dynamic characteristics.

FIG. 4 shows the temperature dependence of the rise of the ignition coil current. In this case, characteristic curve A shows the rise in current in the ignition coil at relatively low temperatures. Furthermore, the characteristic curve B shows an increase in the ignition coil current at relatively high temperatures. The ohmic resistance in the ignition coil changes when the temperature increases from a relatively low temperature to a relatively high temperature or when the temperature decreases from a relatively high temperature to a relatively low temperature. As a result, the degree of increase of the ignition coil current also changes. Here, when the internal combustion engine enters the stop state, the closing time determined for the characteristic curve B is stored because the engine temperature is usually relatively high. When the engine is restarted, first, the period t2 is set based on the detection of the closing time. However, the increase in the ignition coil current increases the steepness when the engine cools and the ohmic resistance decreases, so that the comparator responds at an extremely early time, for example, at time t1. As a result, a relatively long closing time (indicated by characteristic curve C) is delivered for the first closing time after the engine has been restarted, but with a subsequent closing time. Then, an instantaneous value of the closing time is immediately generated.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-67062 (JP, A) JP-A-56-104151 (JP, A) JP-A-63-246469 (JP, A) JP-A-54-104 13841 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02P 3/045

Claims (9)

(57) [Claims] 1. A method for controlling a closing time of an ignition device in an internal combustion engine comprising a microprocessor for sending a control signal to at least one ignition stage, comprising: A measuring resistor is provided in series, a primary current flowing through the ignition coil is detected during the closing period using the measuring resistor, and the detected value is supplied to a first input side of a comparator. Side to apply a predetermined comparison voltage, supply the output level of the comparator to the microprocessor, and if the measured value reaches a predetermined comparison value or a predetermined part of the comparison value, In the closing time control method for changing the output level of the comparator, the microprocessor (1) controls the output level of the comparator from the transmitted closing time start point (T1). Detecting a time to change the time (T3), closing a predetermined portion of the detected time period (T3-T1) and closing time (SZ _n) to or surveying periodically between (T3-T1) time evaluated as to (SZ _n), the closing time (SZ _n), closing time start time (T1) and closing time end time from the microprocessor (1) for subsequent ignition A closing time control method, characterized in that a corresponding signal for (T2) is sent to the ignition stage. 2. The method according to claim 1, wherein the comparison voltage (U _v ) applied to the comparator (6) is adjustable to a predetermined current value in a charging characteristic curve of each ignition coil. 3. The microprocessor (1) starts a period (t4) for monitoring the closing time (T2) using the change in the output level of the comparator (6), and the period (t4) At the end of the closing time (T
3. The method as claimed in claim 1, wherein the forced ignition is triggered by the microprocessor in the event of a failure in 2). 4. At the time of a new start, only when the measured engine temperature (T _motn ) at the time of the restart deviates from the engine temperature (T _mote ) at the end of operation by a predetermined value, the last time Closing time determined in the engine cycle (SZ _n )
A method according to any one of claims 1 to 3, wherein start-up using is started. 5. If the measured period from the closing time start point (T1) to the comparator output level change point (T3) is shorter than a predetermined minimum closing time (T _DIA ), it is short-circuited. 5. The method according to claim 1, wherein ignition and interruption of fuel injection for the corresponding cylinder are determined. 6. An output level (IP) of the comparator (6) is queried by the microprocessor (1) at the end of closing time (T2) as to whether or not there is a response of the comparator (6). No change in output level
If the actual closing time (T2-T1) is longer than or equal to the transmitted closing time (SZ), the subsequent closing time (SZ)
6. The method according to claim 1, wherein n) is set by adding a correction value (K) to the transmitted closing time (SZn = T2-T1 + K). 7. The method according to claim 6, wherein the correction value (K) is a value that can be set so that the comparator is responsive to the correction value (K) under application. 8. The correction value (K) is set to an actual closing time (T2
The method according to claim 6 or 7, wherein the method is incrementally added to -T1). 9. If there is no change in the output level of the comparator (6) and the actual closing time (T2-T1) is shorter than the transmitted closing time (SZ), the subsequent closing time is set. Again, the preceding closing time (SZn)
7. A method according to claim 1, wherein Z) is transmitted.
The method described in the section.