EP3069014A1

EP3069014A1 - Method for operating an ignition system and a corresponding ignition system

Info

Publication number: EP3069014A1
Application number: EP14786676.8A
Authority: EP
Inventors: Tim Skowronek; Thomas Pawlak; Wolfgang Sinz
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2013-11-14
Filing date: 2014-10-21
Publication date: 2016-09-21
Anticipated expiration: 2034-10-21
Also published as: CN105705780A; US10018173B2; EP3069014B1; WO2015071055A1; DE102014216024A1; CN105705780B; US20170138329A1

Abstract

An ignition system and a method for inhibiting ignition spark discharge at a spark gap at an inappropriate point in time are proposed. The method is characterized by the detection of spark breakaway and/or failed ignition and, in response thereto, by the generation of a conductive path by an ignition spark at the spark gap at an appropriate point in time.

Description

Description title

Method for operating a Zündsvstems and corresponding Zündsvstem prior art

The present invention relates to an ignition system for an internal combustion engine and a method for operating an ignition system. In particular, a spark discharge at a spark gap should be suppressed at an inappropriate time. Ignition systems for spark ignition internal combustion engines are known in the prior art, in which, for example, a current flow through the primary side of an inductive system is interrupted, the secondary side a spark on a specially provided for this purpose

Spark gap in the combustion chamber of the internal combustion engine causes. If spark ignited at the ignition point, the mixture burns and drives the engine. Due to different

Circumstances, however, it can happen that the spark prematurely goes out or does not even come to pass. In this case, residual energy in the capacities of the ignition system, which may also be, for example, parasitic capacitances of the secondary winding or parasitic capacitances of other discrete components, such as EFU diodes (Einschaltfunkenunterdrückung) may remain. Thus, there is still a voltage across the spark gap. This can lead to an undesired discharge and thus spark formation in the combustion chamber at a later, inappropriate time since, for example, a lower mixture pressure and / or a lower turbulence of the mixture prevail in the combustion chamber at this time. Performs that

Residual charge generated spark to a combustion, serious damage in the unit can be the result.

It is therefore an object of the present invention to provide a

To suppress or prevent spark discharge at a spark gap at an inappropriate time. Disclosure of the invention

The above object is achieved by a method for suppressing a spark discharge at a spark gap at an inappropriate time and by an inventive ignition system, which supplements the prior art by a voltage measurement and means for carrying out the method according to the invention, for a

Internal combustion engine solved. The method includes generating a conductive path through a spark at the spark gap to a

Time that is before the fictitious inappropriate time. Thus, at least when a spark discharge is to be suppressed at an inappropriate time, the timely generation of a spark will degrade the remaining charge by creating a conductive path in the combustion chamber at the spark gap. The time is chosen so that damage to the engine can not be done.

The dependent claims show preferred developments of the invention. Preferably, the time for the generation of the conductive path is selected so that a comparatively low turbulence prevails in a mixture surrounding the spark gap. In this way it is prevented that by fluid movements in the combustion chamber and the controlled

Discharge ignition to suppress the spark discharge is not successful.

More preferably, the time for the generation of the conductive path is in a working cycle, in which a working and / or ejection of fluid takes place from a combustion chamber containing the spark gap. Since the working strokes working and discharging before the power strokes sucking and compressing (ie with respect to an uncontrolled ignition of the mixture, the much more critical work cycles), so the aggregate may be damaged uncontrolled ignition can be avoided. Alternatively or additionally, the time for the generation of the conductive path can be chosen so that the discharge ignition at an appropriate time in the working cycles "suction" and "compression" is when stored in one or more electrical energy storage of the ignition system Residual energy is below a predetermined threshold. The discharge ignition may therefore have only a residual amount of energy which is insufficient to ignite the fuel mixture in the combustion chamber. In this way can be prevented by an additional ignition later uncontrolled ignition and the internal combustion engine thereby protected.

More preferably, the spark ignition to be suppressed is caused by a spark break. In other words, initially an ignition leads to the risk of suppressing spark discharge. Subsequently, according to the invention, the conductive path for discharging the ignition system is produced at the appropriate time. In this way, a safe avoidance of spark discharges is ensured at inappropriate times.

More preferably, the inventive method comprises detecting a spark break and / or a detection of a misfire. In response, a conductive path through the spark at the

Spark gap generated. To realize these method steps, the ignition spark voltages or currents can be evaluated. The measurement of spark currents, for example, on the secondary side of the

Ignition system and carried out by an electronic evaluation, which in particular a respective spark gap (spark plug) is assigned. In this way, in the absence of spark arrest a standard discharge ignition at a suitable time is unnecessary, thereby saving energy and reduce the burden on the components of the ignition system.

As an alternative to the aforementioned embodiment, a standard generation of the conductive path through the spark at the spark gap in the wake of each ignition timing is possible. This may refer to individual (e.g., communicated by a controller) operating conditions as well as all operating states of the ignition system. In this way, an evaluation of current electrical or electrodynamic or

Thermodynamic sizes are unnecessary, whereby the hardware cost can be reduced. In addition, this method is more robust against measurement errors.

It is very advantageous, if it is determined temporally before generating the conductive path, whether residual energy in an electrical capacity of the ignition system is present, since it can be detected in this way, whether an unwanted spark discharge threatens.

In addition, it is checked in time before generating the conductive path, if no ignitable mixture is present in a combustion chamber of an internal combustion engine. In this way, it is ensured that the defined discharge of the residual energy, which has remained in the capacitance after a spark break, does not lead to an ignition in the combustion chamber of the internal combustion engine. To discharge the residual energy so only an electrically conductive spark gap is generated in a non-ignitable environment.

It is advantageous if the generation of a spark according to a first alternative internally in the ignition system, for example in an internal control unit or in internal electronic components, triggered, since in this way the ignition system recognizes autarkically, whether a defined discharge is necessary and thus the communication effort with a external control unit can be reduced. It is also advantageous if the production of a spark according to a second alternative also by an external control device, for example

Engine control unit is triggered, since in this way the effort can be reduced within the ignition system and depending on the detected operating conditions in the control unit combustion chamber conditions, the defined discharge can be controlled.

The ignition system for an internal combustion engine, with which the method according to the invention is carried out, comprises a first electrode and a second one

Electrode of a spark gap, at which a spark is generated and the combustible mixture for ignition in a combustion chamber of

Internal combustion engine is used. Furthermore, the ignition system comprises a

Voltage generator for generating a spark. The voltage generator can be designed, for example, inductively, by means of which a secondary-side ignition voltage is generated when switching off a primary-side current. In principle, the first voltage generator can also be further

Voltage generators are supported in the ignition or the maintenance of an existing spark. In addition, this includes

Ignition system, a control unit or control unit for controlling the

Voltage generator. By the control unit, for example, a

Zündzeitpunkt or a generation of a spark at a suitable Timing (see above) controlled and prompted. The control to the

Extinguishing spark can be implemented internally by the ignition system or externally by the control unit (parameterization of the ignition characteristic map), whereby a control depending on other operating parameters is possible (e.g., spark only if A) full load or B) high load EGR).

According to the invention, the ignition system is set up to carry out a method as has been described in detail above. In other words, the ignition system is capable of all in conjunction with the former

Invention aspects realized implementations. In addition, reference is therefore made to the above features and feature combinations and to the advantages associated with these.

The ignition system preferably comprises a voltage sensor which is set up after a regular ignition time

Combustion ignition to detect an electrical voltage remaining in the ignition system and to cause the generation of the conductive path through the spark at the spark gap in response to exceeding a predefined threshold value of the voltage. In other words, sensors are used to detect and cause a requirement for discharging the ignition system according to the invention. In this way, a standard discharge of the ignition system is unnecessary, for example, after a predefined time window, which at each regular

Zündzeitpunkt connects. In the context of the present invention, ignition is considered successful when sparkover occurs and the electrical energy stored is below a predefined value

Threshold degrades. In case of an unsuccessful ignition, a distinction must be made between two cases.

In the first case, the spark does not lead to mixture ignition, what as

Misfire is to be designated. The remaining residual energy in the ignition system can lead to malfunction in the further course. In a second case, the spark leads to mixture ignition, which is not a classic

Misfire corresponds and is to be described as a spark break, because the spark breaks off prematurely, whereby residual electrical energy remains in the ignition system. An unsuccessful in the context of the present invention ignition is therefore then the case when the remaining residual electrical energy in the ignition system exceeds a predefined threshold.

An ignition system, with which the method according to the invention is carried out, comprises a (discrete or parasitic) capacity, which in the case of an unsuccessful ignition with too high residual energy content by sparking off a voltage stores, which in turn by a spark at the

Spark gap is discharged at least proportionately at a suitable time. For example, the capacitance may be included in a secondary side mesh of the ignition system along with the spark gap to store energy used to maintain the spark after ignition. Since this capacity holds in the case of an unsuccessful ignition energy, which could cause a problematic uncontrolled and unwanted ignition in the combustion chamber to an inappropriate ignition, remedy can be created according to the invention.

More preferably, the conductive path is generated by the spark, in other words, the discharge ignition, at the

Spark gap by the same voltage generator, which to

has prepared suppressive spark discharge. In other words, only one additional drive of the voltage generator is required to implement the above invention in a known ignition system. There is therefore no need for additional hardware.

Brief description of the drawings

Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings. In the drawings:

Figure 1 is a schematic diagram of a portion of a

Embodiment of an ignition system according to the invention;

Figure 2 is a schematic circuit diagram of a part of an alternative

Embodiment of an ignition system according to the invention; Figure 3 is a pressure-crankshaft angle diagram illustrating principle pressure conditions during different power strokes of an internal combustion engine; and

Figure 4 is a flow chart illustrating steps of a

Embodiment of a method according to the invention.

Embodiments of the invention

FIG. 1 shows an ignition system 1, which has a transformer 2 with a primary side 3 and a secondary side 4 as a voltage generator. The primary side 3 and the secondary side 4 are magnetically coupled. Parallel to the secondary side 4 are both a capacitance C and a spark gap F. The secondary side 4 is grounded by an electrical contact with the electrical ground 5.

FIG. 2 shows an alternative exemplary embodiment of an ignition system 1 according to the invention. In contrast to the arrangement shown in FIG. 1, the capacitance C is arranged in series with the secondary side 4 of the transformer 2. The secondary side 4, the capacitance C and the spark gap F are thus in a single common mesh.

FIG. 3 shows an exemplary schematic pressure curve in the combustion chamber of an internal combustion engine over the crank angle (measured in degrees

This shows the four working cycles of an Otto engine intake I, compression II, combustion III and exhaust IV The working cycles intake I and compression II is a critical range X for the discharge of an uncontrolled spark while a controlled ignition in the Area of a transition from the second power stroke compaction II to the third power cycle burning III takes place, a discharge of the invention should

Ignition system according to the invention in the areas of burning III and

Ejecting IV (as the appropriate time required). In this way, a discharge takes place before the remaining charge in a next cycle, the X marked critical area allows damaging, uncontrolled combustion. Also in the areas I and II, a spark can be provoked, whereby it must be ensured that the discharge does not release enough energy for mixture ignition. FIG. 4 is a flow chart illustrating steps of FIG

Embodiment of a method according to the invention. In step 100, a detonation attempt of a mixture in the combustion chamber

made. The ignition attempt can fail, which corresponds to a misfire, a critical spark current break or a remaining, too high capacitive stored residual energy. This is determined in step 200 by determining and evaluating a secondary-side voltage and / or a

Secondary current detected. In the case of evaluation of the secondary side

Current is checked whether this exceeds a predetermined threshold. If this threshold is exceeded, it is checked whether there is a suitable time for the removal of the residual energy by determining whether there is no ignitable mixture in a combustion chamber of an internal combustion engine. If there is no ignitable mixture in the combustion chamber, proceed in step

300 a second ignition, so at a suitable time, preferably in the working cycles III, IV (see Figure 3).

It is a core idea of the present invention that after the

Combustion process in a non-critical state, a discharge spark is generated at the spark plug electrodes in the combustion chamber, as for example by the corresponding energizing and switching off the primary coil of the

Ignition coil can be done. The resulting discharge spark creates a conductive path, via which the remaining energy of the capacities of the secondary side of the ignition system can discharge. This process is preferably carried out at low turbulence in the combustion chamber. Due to the low turbulence, the spark breaks off at an uncritically low voltage value or current value. Thus, the stored energy is almost completely converted into sparks. The residual energy corresponding to the low value of the spark current is below the necessary energy for an uncontrolled

Ignition. The method according to the invention may optionally be triggered at each ignition, after a detected spark break-off or during a detected misfire (for example due to absence of a main ignition in the region of top dead center or of a spark break).

The generation of a spark in step 300 may be performed according to a first

Alternative internally in the ignition system, for example, in an internal control unit or in internal electronic modules, triggered. According to a second Alternatively, the generation of a spark may also be triggered by an external control device, such as engine control unit.

In the embodiments according to FIG. 1 and FIG. 2, the steps 200, 300 may include the following steps: The secondary-side current is determined and a spark-break and / or a misfire is detected on a sudden change in the secondary-side current. This is done by checking whether the amount of change in the secondary-side current exceeds a predetermined first threshold. If this is the case, one is

Exceeding condition fulfilled.

Instead of the secondary-side current and a secondary-side voltage can be detected, which is preferably determined only after a predetermined time delay after a start time of the method to have a steady state in the ignition system. The time delay is, for example, speed-dependent and / or dependent on one

Crankshaft angle. A spark break and / or misfire is detected by the detected secondary side voltage exceeding a predetermined second threshold. If this is the case, that is

Exceeding condition fulfilled.

Thereafter, it is determined whether an ignition condition is satisfied by checking whether an ignitable mixture in a combustion chamber of a

Internal combustion engine is present. If the overshoot condition and the ignition condition are satisfied, a conductive path is generated by a spark in step 300.

In a further embodiment, the ignition system additionally comprises a boost converter for maintaining a spark. Such an ignition system with a step-up converter is disclosed for example in DE 10 2013 21 8227 A1, the content of which is expressly intended to be part of the disclosure of this application.

The boost converter according to the invention comprises as in the in the

DE 10 2013 21 8227 A1 an inductance, a switch, a capacitance C and a diode. The inductance of the boost converter is in the form of a

Transformer formed with a primary side and a secondary side. The

Inductance serves as an energy store to charge the capacitor. The capacity C of the boost converter is as in Fig.2 in series to the secondary side 4 of the transformer 2 is arranged. The output power of the boost converter is with respect to Figure 2 via a between the secondary side 4 of the

Transformers 2 and the capacity C lying node in the

Secondary side 4 of the ignition system 1 fed and the spark gap F made available. The output voltage of the boost converter is correspondingly applied to the mentioned node.

According to the invention, it is also recognized in the further exemplary embodiment that residual energy is present in an electrical capacitance C of the ignition system. Then, at a suitable time, a spark is generated. The electrical capacitance C may be a capacitor of the boost converter or a parasitic capacitance in the ignition system.

In the embodiment with the boost converter, the step 200 comprises the following steps: First, it is determined whether the boost converter of the

Ignition system is switched off. If this is the case, one will

Output voltage of the boost converter measured, in particular after the lapse of a predetermined time after switching off the boost converter to have a steady state in the ignition system. Subsequently, it is determined whether the measured output voltage is a predetermined second

Threshold exceeds. If the second threshold is exceeded, one can conclude that the ignition is not successful, since too much residual energy is stored on the capacity of the boost converter and thus a

accidental ignition threatens at an inappropriate time. Thereafter, it is checked whether there is a suitable time for the removal of the residual energy by determining whether no ignitable mixture in a combustion chamber of a

Internal combustion engine is present. If there is no ignitable mixture in the combustion chamber, then there is an appropriate time and ignition according to step 300 is initiated.

Alternatively, in the other embodiment, the unsuccessful ignition can be detected by measuring a spark current. In this case, step 200 includes the following steps: First, the spark current is measured. It is then determined whether the measured spark current falls below a predetermined third threshold value.

If the third threshold value is undershot, an unsuccessful ignition can be concluded. Through the further operation of the Step-up converter after the unsuccessful ignition, the voltage continues to rise above the output capacitance of the boost converter, which increases the risk of an unwanted spark discharge. Therefore, it is determined whether the unsuccessful ignition with switched on or off boost converter. If the boost converter is switched on, it is additionally determined whether there is a time difference between the time of the first undershooting of the second threshold and a known end of the operation of the first

Step-up converter exceeds a predetermined fourth threshold. If the fourth threshold is exceeded, too much residual energy is stored in the capacitance of the boost converter, so that an accidental ignition threatens. Subsequently, it is checked whether there is a suitable time for reducing the residual energy by determining whether no ignitable mixture is present in a combustion chamber of the internal combustion engine. If not

Ignitable mixture is present in the combustion chamber and the above conditions are met, the ignition according to step 300 is initiated.

A computer program may be provided which is set up to carry out all described steps of the method according to the invention. The computer program is stored on a storage medium. As an alternative to the computer program, the method according to the invention can be controlled by an electronic circuit provided in the ignition system, an analog circuit or an ASIC or a microcontroller, which is set up to carry out all described steps of the method according to the invention.

Even if the aspects of the invention and advantageous

Embodiments with reference to the attached

Drawings illustrated embodiments have been described in detail, modifications and combinations of features of the illustrated embodiments are possible for the skilled person without departing from the scope of the present invention, the scope of which is defined by the appended claims.

Claims

claims

Method for operating an ignition system for an internal combustion engine, comprising a voltage generator and a spark gap (F) for generating a spark, characterized by the steps:

Detecting (200) a spark break and / or a misfire, in response thereto generating (300) the conductive path by a spark at the spark gap (F) in a suitable one

Operating cycle of the internal combustion engine or to a suitable

Ignition timing.

The method of claim 1, wherein the suitable power stroke is a power stroke (I, II, III, IV),

in which a working (III) and / or an expulsion (IV) of fluid from a combustion chamber containing the spark gap (F), and / or in which an intake (I) and / or compression (II) takes place and in which the in one or more electrical

Energy storage of the ignition system stored residual energy is below a predetermined threshold.

Method according to one of claims 1 to 4, wherein generating the conductive path through the spark at the spark gap (F) following each ignition of a considered

Operating state or all operating conditions, in particular on the occasion of signaling a control unit of the ignition system takes place.

Method according to one of the preceding claims, wherein the steps (200), (300) comprise the following steps:

Determining a secondary-side current,

Determining whether an overrun condition is met by determining whether a change in the secondary-side current exceeds a predetermined first threshold,

Determining whether an ignition condition is satisfied by determining whether an ignitable mixture is present in a combustion chamber of an internal combustion engine, Generating (300) a conductive path through a spark when the overshoot condition and the firing condition are met.

5. The method according to any one of the preceding claims, wherein the steps

(200), (300) include the following steps:

Determining a secondary-side voltage,

Determining whether an overshoot condition is met by determining if the secondary side voltage is a predetermined second one

Exceeds threshold,

Determining whether an ignition condition is fulfilled by determining whether an ignitable mixture is present in a combustion chamber of an internal combustion engine,

Generating (300) a conductive path through a spark when the overshoot condition and the firing condition are met.

6. The method of claim 1, wherein the ignition system additionally comprises a boost converter for maintaining a spark comprising an electrical capacitance for caching ignition energy, wherein the steps include: (300) the steps of:

Determining whether a condition condition is met by determining whether the boost converter of the ignition system is off,

Measuring an output voltage of the boost converter,

Determining whether an exceed condition is met by determining whether the measured output voltage is a predetermined second one

Exceeds threshold,

Determining whether an ignition condition is satisfied by determining whether an ignitable mixture is present in a combustion chamber of an internal combustion engine,

Generating (300) a conductive path through a spark when the

Condition condition, the overrun condition and the

Ignition condition are met.

A method according to any one of the preceding claims, wherein the ignition system additionally comprises a boost converter for maintaining a spark comprising an electrical capacity (C) for caching ignition energy, the steps (200), (300) comprising the steps of:

Determining whether a condition condition is satisfied by determining whether the boost converter of the ignition system is turned on,

Measuring a spark current,

Determining whether an underflow condition is met by determining whether the measured spark current is below a predetermined third threshold,

Determine if an overrun condition is met by determining if there is a time difference between the time of the first

Falling short of the third threshold and an end of the operation of the boost converter exceeds a predetermined fourth threshold,

Generating (300) a conductive path through a spark when the underflow condition, the condition condition, the

Exceeding condition and the ignition condition are satisfied.

Computer program adapted to carry out all the steps of the method according to one of Claims 1 to 5.

Machine-readable storage medium on which the computer program according to claim 8 is stored.

0. ignition system for an internal combustion engine comprising:

a first electrode and a second electrode of a spark gap (F),

a first voltage generator (2) for generating a spark,

a control unit for controlling the voltage generator (2), characterized in that

the ignition system (1) is adapted to perform a method according to any one of the preceding claims 1 to 7.

1 . An ignition system according to claim 10, comprising a voltage sensor configured to detect an electrical voltage remaining in the ignition system after an ignition timing and in response to a

Exceeding a predefined threshold voltage and a dead time to cause the generation of the conductive path through the spark at the spark gap (F).

2. An ignition system according to claim 10 or 1 1, comprising a capacitor (C), which stores in the case of an unsuccessful ignition a voltage which is discharged by a spark at the spark gap (F) at a suitable time, at least partially.

3. The method according to any one of claims 1 to 7 or ignition system according to

Claims 10 to 12, wherein generating (300) the conductive path through the spark at the spark gap (F) therethrough

Voltage generator (2) takes place, which to be suppressed

Spark discharge has prepared.