DE102006020452A1 - Method for producing ignition spark and igniter, involves electrical high voltage at an ignition coil and control voltage is pulsed in such way that pulses arrive in resonance area of ignition coil - Google Patents

Abstract

Method involves electrical high voltage (6) at an ignition coil. The control voltage is pulsed in such a way that the pulses arrive in a resonance area (10) of the ignition coil. The resonance area covers the natural frequency (8) of the ignition coil and a deviation from plus or minus 20 percent, preferably plus minus 10 percent, above all plus minus 5 percent around natural frequency of the ignition coil. An independent claim is also included for the igniter.

Description

The The invention relates to a method for generating a spark and an igniter with means of implementation of such a procedure. In particular, the invention relates to a Method for generating a spark to ignite an internal combustion engine.

In order to Internal combustion engines can work, must be a fuel-air mixture first compressed and then ignited at the right time.

It is between self-ignition engines (diesel principle) and engines with spark ignition (Ottoprinzip) distinguished.

Around in gasoline engines to ignite the fuel-air mixture are Voltages of 5 to 20 kV required. The requirements for the Ignition are different, so the ignition voltage requirement depends depends on several factors, for example the type of Kraftstoffes, the compression ratio, the compression of the Motors, the temperature of the air, the engine speed (load range), the number of cylinders, the shape and design of the electrodes of the spark plugs, the electrode spacing of the spark plugs or the composition of the fuel-air mixture.

To the Ignite the fuel-air mixture is a specific ignition energy required, so a specific electrical work. To be sure the ignition must initiate the generated ignition voltage to be taller as the ignition voltage requirement of the engine (ignition voltage reserve).

The Duration from the onset of ignition until complete combustion is about 2 milliseconds. The spark must therefore skip so early, that the combustion pressure is just past the top dead center of the piston (OT) its maximum value reached.

created the spark too early, will be the upward movement the piston is braked; If it is too late, it starts burning in the downward movement of the piston. In both cases would be the engine power low and fuel consumption high, resulting in a higher thermal Load on the engine components. The ignition timing is set that the engine is always one possible great achievement and economic and economic operation is achieved.

The Duration between mixture inflammation and Mixture combustion always remains with the same mixture composition same. Would the ignition point rigid to a specific ignition angle set before TDC, so would with increasing speed the time of combustion in the direction of "late" adjust, because the time to reach the top dead center of the piston lower becomes. Therefore, constructive measures must be taken to ensure that the highest Combusting pressure always prevails at the same piston position, namely some Grade after OT. For this reason, a speed-dependent ignition timing required, the ignition timing with increasing speed in the direction of "early" adjusted.

A such regulation is for example via a centrifugal force adjustment achievable: The centrifugal force adjuster (only with coil ignition) provides the ignition timing dependent on from the speed. He only responds when a higher speed as the idling speed is adjusted. Until reaching the Response speed, the ignition remains constant and is used as the basic ignition designated. Two rotatably mounted flyweights move with increasing Speed due to the centrifugal force to the outside and adjust the breaker cam over the lever in the direction of rotation, in the direction of pre-ignition.

When Alternative to speed-dependent ignition timing adjustment Among other things, the load-dependent ignition timing applied, which is realized by a vacuum adjustment. When Measure for this spark The vacuum in the intake manifold near the throttle valve serves. she consists essentially from one or two membrane doses, which are replaced by a Pull rod connected to the rotatably mounted breaker plate is or are. The suction of the membrane is with a carburetor connected intake pipe connected. By opening the throttle in the Inlet pipe, the negative pressure is greater and acts on the membrane. These then pulls the breaker base plate counter to the direction of rotation, So in the direction of "early".

At the Idling the engine should set the ignition are not affected, therefore, the negative pressure adjuster arranged in front of the throttle.

at certain engine conditions (e.g., idling, coasting), the ignition timing becomes exhaust gas improvement adjusted in the direction of "late". It will the vacuum in the intake manifold is removed behind the throttle valve. The retardation system is the early adjustment system subordinate; simultaneous negative pressure in both doses causes the required partial load adjustment in the direction of "early".

Another alternative is the octane adjustment: The ignition timing is adjusted depending on the octane number of the fuel. The Octane number is a measure of the knock resistance of the carburetor fuel. For fuels with different octane numbers, a specific basic setting is required in order to achieve maximum performance in the knock-free working range. In modern vehicles, this is achieved by plugging a multiple connector on the carburetor or by pressing a switch in the passenger compartment.

Finally is nor the electronic ignition adjustment consistently: At the electronic ignition timing detect sensors and actuators the working conditions of Motors, in particular the speed, the cure belwinkel (measurement via a Hall sender in the distributor or over an induction sensor on the crankshaft), the intake manifold pressure (measurement via a Pressure sensor in the control unit), the special conditions Idle or full load (measurement via a throttle valve switch), the intake air temperature (measurement via a Temperature sensor in the intake manifold), the engine temperature (measurement via a Water or oil temperature sensor on Engine), the knock signal (measurement via a knock sensor on the engine) and the battery voltage.

One Microcomputer further processes these input signals and calculates due to the stored ignition map the required ignition angle. He gives the output signal to the power output stage in the control unit, the the primary circle the ignition coil on.

When comparing the different adjustment systems, it becomes clear that the electronic control better meets the requirements of the engine:
Conventional ignition distributor of breaker or transistor ignition systems with centrifugal force and vacuum-controlled ignition timing can realize only simple Verstellkennlinien. They only approximate the requirements of the engines. The full load adjustment is done by the centrifugal force adjuster. The progression of the full load line is determined by the maximum of the engine power and the knock limit.

The Full load line is at high speed in the power maximum. at It must be decreasing in order not to get too close to the knock limit to come down. The partial load adjustment takes place through the vacuum adjuster. He works between the highest full load pressure and the maximum part load pressure.

in the Map of an electronic adjustment system, however, eliminates the mechanical ignition adjustment in the distributor. For that will be a transmitter signal for the trigger the ignition process used as speed signal. An additional pressure sensor provides that Load signal. The microcomputer calculates the required spark timing and accordingly modifies the output signal passed to a switching device becomes.

The has several advantages: The ignition timing is adapted to the requirements of the engine, involving more Control parameter (e.g., engine temperature) is possible, it will be a good starting behavior a better idle control and lower fuel consumption reached, and it is a knock control possible.

The ignition timing at an electronic control contains for every possible operating point of the engine, i.e. For every speed and Load point, the ignition angle selected as the best compromise in the motor design. The ignition angle for a certain operating point is based on fuel consumption, Torque, exhaust gas, distance to the knock limit, temperature of the engine, Drivability etc. selected.

were so far the Zündverstellsysteme explains Below are the different versions of ignition systems be presented in gasoline engine.

The Selection of the ignition system depends on the type of ignition trip, the Ignition timing as well as the type of distribution and transmission of the high voltage between coil ignition, Transistorized ignition, electronic ignition and fully electronic ignition.

For internal combustion engines different ignition methods are used:
First, a battery ignition system is known, also called ordinary coil ignition. The conventional coil ignition system is contact-controlled. This means that the current flowing through the ignition coil is mechanically switched on and off via a contact in the ignition distributor (ignition interrupter). This ignition system is the simplest version of an ignition, in which all functions are realized.

core this coil ignition is a coil with a primary side Part and a secondary side Part that interact as a transformer. The primary part becomes subjected to an operating voltage. The resulting current flow creates a strong magnetic field. Switch off the voltage with a breaker leads to a sudden drop in the magnetic field and induced to Energy conservation, in the secondary part of the Coil such a high voltage that the distance between anode and Mass of a connected spark plug so far ionized that it comes to sparking. After that, the in the ignition coil stored magnetic energy as electrical energy in the Sparks off.

With other words and explained in detail: the ignition coil stores the ignition energy and gives it in the form of a high voltage pulse over the ignition wires to an ignition start switch in the primary circuit the ignition coil. A series resistor closes when starting to raise the voltage short. A breaker includes and interrupts the primary circuit the ignition coil, to save energy and force the voltage transformation. A firing capacitor takes care of it a lossless interruption of the primary coil current. He also suppresses the sparking at the breaker contact. An ignition distributor distributes the ignition voltage on the spark plugs in the specified firing order. The ignition point can as explained above be adjusted. The spark plug contains doing the for the emergence of the spark most important Parts (electrodes) and seals the combustion chamber to the outside from.

The Synchronization with the crankshaft (position of the pistons in the Cylinders) is due to the mechanical coupling of the distributor secured to the camshaft or other drive point. It works the ignition distributor shaft in four-stroke engines with half the number of revolutions of the crankshaft. A twisting of the distributor leads to a Shifting of the ignition point. One with the top of the distributor shaft coupled distributor finger ensures with the supply of high voltage power lines to the individual spark plugs for the right one Distribution of high voltage.

in the Operation is the battery voltage through the ignition lock on the ignition coil at. When the breaker is closed, the current flows over the primary the ignition coil against mass. As a result, a magnetic field is built up in the ignition coil, in which the ignition energy is stored. The charging time is determined by the closing angle (Duration of the closed breaker contact) determined, given through the execution of the distributor cam.

At the End of closing time opens the Distributor cam the breaker contact and thus interrupts the coil current. Of the Current and the turn-off time as well as the number of turns of the secondary side of the ignition coil determine the secondary side induced ignition voltage. Since the current has a tendency to continue to flow, would be at the breaker contact a Forming an arc. For this reason, the breaker is a capacitor connected in parallel. As a result, until the breakdown of the Ignition voltage of primary current in the condenser and charging this on. In this way arise at the input terminal of the ignition coil short-time voltages of a few 100 V. The high voltage thus generated loads the Connection to the middle dome of the distributor, leads there between distributor finger and outer electrode to a breakthrough, invites then the high voltage line to the respective spark plug up and leads after all at the spark plug to the spark.

After that flows in the ignition coil stored magnetic energy steadily as electrical energy in the sparks. At the spark plug this results in a burning voltage of about 400 V.

After this the ignition coil is unloaded, the cam of the distributor switches the breaker again on and the ignition coil will be charged again. The continuing distributor finger transmits the ignition voltage according to the given firing order to the next Spark plug. For multi-cylinder engines must the high voltage pulses are supplied to the individual spark plugs in accordance with the firing order. This task takes over in the secondary circuit built-in ignition distributor. In it are breakers, distributors and components for automatic control the ignition timing united.

The ignition coil has as the most important component a primary and a secondary winding. On an iron core, the secondary coil and the primary coil wound. Thus, the heat generated by the primary flow better be derived.

The currently the most common used cultivation or Topfzündspulen are executed in economy circuit. Here is the end of the secondary winding with the beginning of the primary winding connected, whereby the manufacture of the ignition coil is simplified. The End of the secondary coil is over a compression spring connected to the high voltage terminal. In one Insulating cover are the connecting bolts for the two Winding ends of the primary coil. An aluminum housing takes up the coils with the core, and a flange connects housing and Insulating cap. Remaining voids in the ignition coil are filled with potting compound, the heat derives.

By longer by flowing a quiescent current, for example caused by switched on ignition when the engine is stopped and the breaker is closed, it can go through the heat development for liquefying come of the insulating material, which then penetrates to the outside. For normal ignition coils will be about 400-600 turns for the primary coil and about 4000 turns for the secondary coil used.

The ignition interrupter is controlled via the interrupter cam. The number of cams is the same as the number of cylinders. The cam is designed so that one of the Zündspu le and the number of spark corresponding locking angle is formed. The angle of rotation of the ignition distributor shaft, at which the contact is closed, is called the closing angle. The closing angle is fixed and can not be changed over the entire speed range. However, the closing angle during the life of the engine changes due to the wear of the slider on the breaker lever (breaker nose). As a result, the breaker opens later (delayed ignition), which among other things leads to higher fuel consumption.

at breaker-controlled ignition systems is as part of maintenance activities check the condition of the breaker contacts. The texture of the Contacts gives the specialist information about the condition of the ignition system. Strong crater or cusp formation at clean contact points indicates that the contacts worn out are and need to be replaced. Uniform, gray coating on the whole contact area indicates that due to weak contact pressure or too small Contact distance an oxidation has begun. Heavily burned or blue contacts indicate a defect on the capacitor or on a defective ignition coil out.

Either the ignition voltage as well as the ignition energy but always by the electrical and mechanical switching performance limited by the breaker.

Higher expectations are met by the use of electronic semiconductor devices that considerable Bringing advantages: This way, a constant ignition voltage supply and greater ignition energy are achieved also achieved at high engine speeds as well as a delay-free Work, maintenance-free, better emissions and longer life.

in the Ever stricter emission regulations especially in the US and efforts to reduce fuel consumption is a contactless controlled TCI been developed. It is not just the primary current switching contactless, but also the control pulses are without mechanical generated moving contacts.

At the point of the breaker occurs the ignition pulse. He is located yourself like the breaker in the distributor, and its job is to generate electrical control impulses each one ignition trigger. Two types of donors have prevailed in the market, namely the Transistor coil ignition with Hall sender and the transistor coil ignition with Induction donors. In both types of transistor ignition, the current flows the ignition coil is not above the Breaker contact, but is turned on and off by the transistor.

Also at the transistor ignition However, disadvantages remain: a transistor ignition is retrofitted, ie on the normal ignition coil operated, there may be a drop in the ignition performance. In addition, the spark breaks also with the transistor ignition suddenly from.

The thyristor achieved with an ordinary ignition coil by a powerless ignition energy storage and taking advantage of the voltage increase, increasing the Ignition performance over the normal measure of ignition coils out. This will also overheat the ignition coil avoided as they were during the ignition break is de-energized. However, the thyristor ignition has because of the very short spark the tendency to misfire, the voltage-dependent Performance and the high production cost some serious disadvantages for the Practice.

at the electronic ignition not applicable - as at the beginning explained - the mechanical spark in the distributor, and it can improved Verstellkennlinien be realized. The electronic ignition is especially suitable for combination with other engine control functions. Together with the electronic injection this creates in a single controller the basic version a motronic.

at fully electronic ignition will be complete waived mechanical components.

The fully electronic ignition is mainly characterized by two properties: It contains the functions the electronic ignition and dispenses with the rotating high-voltage distribution (ignition distributor). This results in significant advantages: First, a significant lower electrical noise level, because there are no open sparks. There are no rotating parts exist, the life is increased, and at the same time Noise reduction. Especially in view of a lower required number of high voltage connections create constructive advantages for the engine manufacturer.

at fully electronic ignition the high-voltage distribution takes place in three different ways, namely about distribution with two-spark ignition coils (Double-spark ignition coils) or over Distribution with single spark ignition coils or over Distribution with four-spark ignition coils.

Instead of the distributor, double-spark ignition coils are used, for example, in four-cylinder engines. The two double-spark ignition coils are alternately energized via one ignition output stage each. At the time of ignition (determined by the characteristic map), two ignitions spark generated at the same time. The two spark plugs where the sparks are generated are each electrically connected in series with the ignition coil in such a way that a spark plug is connected to each high voltage output of the ignition coil. The spark plugs must be arranged so that one ignites a spark plug in the working stroke of one cylinder, while the other ignites spark plug in the exhaust stroke of the cylinder offset by 360 °. One crankshaft revolution later, the two cylinders continue to work two strokes and the corresponding spark plugs ignite again.

Also generates the second double spark ignition coil each two sparks, but by 180 ° crank angle across from the first one moved. In a four-cylinder engine always light cylinders 1 and 4 and cylinders 3 and 2 simultaneously (firing order 1-3-4-2). Of the Reference marker on the crankshaft is used in addition to the Zündwinkelberechnung also for controlling the correct ignition coil. Only engines with straighter Number of cylinders are for this type of static high-voltage distribution suitable. Each half the number of cylinders gives the number of required ignition coils.

A fully electronic ignition for odd cylinder numbers requires for Each cylinder has its own ignition coil (Single-spark ignition coils are synonymous in conjunction with the fully electronic ignition for straight Number of cylinders suitable). The actual stress distribution too the ignition coils takes place on the low-voltage side in a power module with distributor logic. For the odd number of cylinders, one cycle goes over two Crankshaft revolutions. Therefore, in this case also enough OT signal of the crankshaft not off. For synchronization must be from the camshaft a signal per camshaft revolution are triggered.

at a plasma jet ignition system a plasma formation takes place by flashover in a small Cavity of a detonator. The plasma then emerges from an opening in the detonator as a jet into the actual combustion chamber and ignites there a big Gas volume, for example, more inert mixtures.

all ignition systems equal is the formation of the spark at the spark plug.

Before the ignition begins, the spark gap at the candle electrode is perfect non-conductive. about the high-voltage insulated ignition cable is the ignition pulse to the likewise isolated center electrode of the spark plug introduced. If a certain voltage is reached, then the spark gap suddenly electrically conductive and the spark can skip (ionization). The voltage at which this happens is the ignition voltage or ionizing voltage.

After this the gas mixture is conductive, the ignition voltage drops because of the current load the ignition coil abruptly on the much lower burning voltage, as soon as the sparkover current strong starts. In the course of the electrode voltage are clear recognizable two sections that identify the spark, namely a high short-term ignition voltage (Needle) and then a longer one continuous burning voltage as after-discharge.

The Burning time determines the actual burning time of the spark. As soon as the ignition coil supplied energy falls below a certain minimum value, can the spark can no longer be sustained, he tears off. The spark gap at the candle is now electrically non-conductive again. The still to disposal Standing residual energy oscillates in the form of damped oscillations of tension and electricity out. This is called decaying. Will more tension needed as the ignition coil can deliver, no spark arrives the candle (misfire).

A well-known approach for a fairly complex ignition provides the EP 0 211 133 B1 ,

all ignition systems but together is a very short spark. The sparkover tears inside from about 20 ns, and hence the associated current flow. simultaneously decreases with increasing discharge time, ie during the ignition transfer in the arc phase and glow phase, as well as with increasing electrically stored energy of the Efficiency of energy transfer from. As a result, inconsistent and even incomplete combustion often occurs of the gas mixture in the combustion chamber.

Of the The invention is based on the object, an improved ignition method to disposal to deliver.

To In a first aspect of the invention, this object solves a method for generating a spark to ignite an internal combustion engine with a high electrical voltage an ignition coil, being a primary part the ignition coil is applied with a control voltage and wherein the ignition coil has a natural frequency, wherein the control voltage is pulsed is that the pulses in a resonance range of the natural frequency the ignition coil get to this.

The control voltage corresponds to the operating voltage of a conventional coil ignition. However, the invention provides that the control voltage by means of an electronic control so is controlled that voltage pulses are applied to the primary part of the ignition coil. In other words, the voltage on the primary part of the ignition coil fluctuates, with each peak of the voltage being a pulse. The invention is based on the recognition that a pulsed control voltage can make use of the natural frequency of the ignition coil, more precisely of the primary part of the ignition coil: Each coil, and thus also each part of a coil, has a natural frequency. In this case, the natural frequency is the frequency in which the component comes into resonance with the same frequency excitation. The particular advantage of the natural frequency is therefore that with only a low energy input per pulse can be achieved that the energy in the coil system increases extremely high.

This phenomenon is particularly important to observe accurate excitation in the natural frequency. costly However, attempts by the inventor have shown that even with a Fluctuation of 20% around the natural frequency around the excitation is particularly effective, so this area under the present Application is referred to as resonance range. As especially suitable have frequencies in the range of +/- 10%, especially +/- 5%, around the natural frequency of the ignition coil proved, more precisely around the natural frequency of the primary part of the ignition coil.

If the primary part the ignition coil in this way in its resonance range from the pulsed control voltage is excited, rips the spark is not more off. As long as the control voltage within an experimental to be determined ignition range is pulsed, the burning time of the spark is maintained.

there also describes the ignition range in the context of this application a frequency spectrum which is not necessary is congruent with the resonance range, with the resonance range however similarity in the order of magnitude can have. The resonance range describes the limits of the permissible distance the control voltage pulse frequency, within which the invention is realized. In contrast, describes the ignition range the limits of permissible Distance of the control voltage pulse frequency, so that a spark once ignited does not break off.

there it should be noted that the natural frequency of the ignition coil dependent on the environmental conditions fluctuate. For example, it warms up during ignition, what immediately to a change the natural frequency leads. This also shifts the ignition range, wherein the natural frequency of the ignition coil is normally within the original Resonance range will hold. The natural frequency of the ignition coil As a rule, the operation of the ignition does not fluctuate by orders of magnitude.

A Application of the presented aspect of the invention thus leads to that the burning time of the spark over any Time can be maintained. In experiments by the inventor was without Another achieves a burning time of 24 hours and more. Such Burning times are indeed for the ignition of an internal combustion engine not applicable, however, show that Potential of the invention. In practice, the invention leads to that be significantly extended in the combustion chamber of the burning process can. this leads to to a much more homogeneous and especially complete combustion in the combustion chamber.

in the Practical use can be an ignition system under Exploitation of the invention, the sparks each dynamically adapt to the requirements of the engine system. This results in considerable advantages of a better ignition behavior at cold start, ignition by ignore Gases (e.g., lean mixtures), the potential use of larger electrode spacings, and overall a more fuel-efficient operation or, conversely, an increase in performance the engines with at the same time no or not substantial increase of costs in the production. In addition, you can Existing systems can easily be exchanged or expanded. The invention may moreover also be used in diesel engines.

in the Opposed to current ignition systems the system according to the invention not just the magnetic coupling of coils for voltage transmission but mainly uses the laws of resonance for the transformation of tension.

It has already been explained that the method can be used particularly well when the control voltage as possible close to the natural frequency of the ignition coil is pulsed, especially if they are pulsed exactly in the natural frequency of the ignition coil is.

It is understood that preferably an electronic control system is used, which generates a frequency in the control voltage that is in the ignition coil causes the described permanent resonance. About the resonance in the ignition coil can be a continuous spark be generated.

Advantageously, in the operation of the proposed method, the burning time of the spark is predetermined before the start of the ignition process. Depending on the circumstances of the internal combustion engine, this can be determined experimentally, depending in particular on engine data such as engine speed, power demand or knock sensor. The tax The electronic system adapts the frequency of the control voltage for high voltage generation to the electrical properties of the ignition coil primary coil. The control electronics calculates immediately and generates the pulse pause modulation, so that the preset burning time of the spark is also achieved during operation of the internal combustion engine.

To In a second aspect of the invention, the object solves a method for generating a spark to ignite an internal combustion engine with a high electrical voltage an ignition coil, wherein a fundamental frequency of the high voltage is a modulation frequency is modulated.

According to this aspect of the invention, therefore, a frequency modulation of the control voltage is made to the effect that the fundamental frequency is added to a modulation frequency. The fundamental frequency corresponds as accurately as possible to the natural frequency of the primary part of the ignition coil. By means of the separate modulation frequency, the system can be controlled highly dynamically:
Thus, in an internal combustion engine of a motor vehicle, the primary coil of a spark plug, for example, have a fundamental frequency of about 7,500 Hz, and the modulation frequency, which is added by way of frequency modulation to the fundamental frequency, for example, 200 Hz. In this case, therefore, the primary side of the ignition coil of the control voltage would be applied to a frequency between 7,400 and 7,600 Hz. In this case, the amplitude can remain constant on the primary side, and yet in the secondary part of the coil, the local voltage is modulated in the amplitude. If the fundamental frequency of 7,500 Hz corresponds to the natural frequency of the coil, the strongest ignition would be observed at 7,500 Hz. An ignition range of, for example, +/- 50 Hz can result around this central frequency of the strongest ignition, so that within a control pulse pulse frequency of 7,450 Hz to 7,550 Hz the spark ignites or burn duration persists, whereas outside this ignition range there is no ignition occurs or the burning time breaks off.

If these values are known, for example by experimental determination, is it possible that Control voltage in a non-igniting Frequency to operate, however, very close to the ignition range is, for example, between 7,400 Hz and 7,430 Hz. If from this Standby state from now the ignition be brought about should be enough to slightly increase the modulated frequency so that the control voltage pulse frequency from a total of 7,430 Hz in the ignition into it, that is, in the chosen one Example over 7,450 Hz is rising. The ignition takes place immediately, the presented aspect of the invention the rule intensity of the ignition system kept to a minimum. So it is sufficient in the above-described example, the control voltage pulse frequency only to increase by about 20 Hz, for an ignition to reach. This can be done in a short time Time has happened. Likewise, if necessary, the control voltage pulse frequency within a short time Time again from the ignition area be out-regulated and then again if necessary hochdyna mix in the ignition area be regulated. Thus, the beginning and end of the ignition duration can be with the utmost precision and generate just as short-term. The precision of the burning process is considerably elevated. Also the plasma generation is greatly facilitated.

To a third aspect of the invention solves the task Method for generating a spark to ignite an internal combustion engine with a high electrical voltage an ignition coil, wherein a control voltage is modulated in amplitude.

To the second aspect of the invention described above is the Frequency of the control voltage modulated, which controls the burning time can be. By the now proposed amplitude modulation and Thus, the regulated power supply will be the power and thus the Energy transport in the burning spark adjustable. According to experimental results of the inventor, the amplitude modulation practically completely independent of the frequency modulation take place.

From It is particularly advantageous if two of the above-described Invention aspects are combined, so if, for example, a frequency modulation the control voltage is around the natural frequency of the ignition coil around, or when the control voltage is pulsed in the resonance region and during the Burning time is modulated in its amplitude, or if the control voltage during the Burning process or to generate the ignition both in frequency as well as being modulated in amplitude.

It is understood that particularly excellent results are achieved when all three methods are applied simultaneously, so if the Control voltage in the resonance range of the coil or around the resonance range The frequency of the coil is frequency modulated and also modulated in amplitude becomes.

As well It is understood that there is an ignition device with means of implementation one of the methods described above allows this method in to practice.

All in all the invention thus provides a method and an apparatus for available which cause it, on the one hand no longer an acute demolition the flashover comes and that on the other hand the spark in its achievement the respective Requirement can be adjusted, resulting in a performance-optimal and as possible full Combustion can take place. Burning time of the spark and power of the Spark are thus freely adjustable.

The The invention will be described below with reference to a measuring example with reference closer to the drawing explained. Show it

1 a diagram in which the voltage at the spark plug is plotted on the ordinate over time on the abscissa,

2 in an identically constructed diagram the Zündspannungsverlauf in a conventional ignition and

3 a schematic diagram of an ignition system according to the invention.

The trace 1 in 1 shows the Zündspannungsverlauf in an ignition according to the invention. In the course of a time 2 is before a start of ignition 3 at a time of "0" at the spark plug no voltage 4 at.

At the start of ignition 3 there is a sudden increase 5 the ignition voltage up to a maximum ignition voltage 6 in the amount of about 20 kV. This starts a spark duration 7 , The control voltage is briefly within a range 8th pulsed in the resonant frequency of the primary part of the ignition coil.

Thereafter, the ignition voltage curve is modeled adapted to the required conditions, so that a power modulation curve 9 arises. During the burning time 7 the control voltage is kept within an ignition range around the natural frequency of the coil (for clarity by the vibration 10 shown), wherein at the same time the intensity of the spark is achieved via an amplitude modulation of the control voltage. At a time end 11 the burning time 7 the frequency of the control voltage pulses is modulated out of the firing range, causing the spark to break off at the time 11 comes. The ignition voltage 4 drops to well below 5 kV and oscillates in a reverberation phase 12 approximately to a voltage of zero.

In the example shown, the spark is maintained with a modeled focal intensity over a period of just over a thousandth of a second. In contrast, in a conventional ignition, as shown in 2 is shown, at the start of firing, although also a strong increase 5 also determine the maximum ignition voltage 6 of about 20 kV leads. Instead of the power modulation curve 9 However, only a Zündspannungsnadel arises 13 , which in no time 14 the ignition duration ends and the ignition voltage drops to well below 5 kV. During the entire spark duration 15 of about 1.5 ms is the ignition voltage 16 only about 2 kV. At this level, she goes straight into the decay process 17 above.

It should be noted that the ignition duration and the spark duration 14 respectively. 15 can not be varied significantly in a conventional spark plug and a conventional control. In contrast, the invention can provide both the power modulation curve 9 in the amplitude over the amplitude modulation of the control voltage model as well as - independently of this - the spark duration 7 and thus individually control the combustion duration in the combustion chamber.

In a repeatedly successfully tested practical example, the following values resulted:
For a Bosch ^® TCI ignition coil for electronic ignition systems from Mercedes-Benz ^® , the coil's own resonance frequency is 50 kHz. The control pulses are 10 μs long, followed by a 10 μs pause at a 50% duty cycle. With an applied voltage of 12 volts without current limitation, a maximum voltage is reached on the secondary side.

at a very small high-voltage transformer with fixed coupling of the coils and an inductance of 80 μH at 0.4 ohms of DC resistance are applied at 12.5 kHz (40 μs pulse duration) achieved equivalent output voltages and spark levels.

The Control electronics in the test setup enabled manual adjustment the carrier frequency of 1666 Hz to 100 kHz, which corresponds to a pulse time of 10 μs to 600 μs. The duration of this carrier frequency can be from 20 μs be set to 5 ms and thus corresponds to the spark duration current systems up to the entire burning time of an optimal Combustion.

The Energy density of the spark is determined by the carrier frequency determined and can be optimized by their pulse-pause ratio. These Optimization of the energy density by pulse-pause modulation allows the Modeling the geometry of the spark while its burning time.

The mentioned settings can without Problems are externally triggered and remotely controlled. This would be optimal be carried out by a fully electronic control, all motor-relevant data recorded immediately, evaluates and accordingly the ignition system continuously adjusted. The modification of existing electronic ignition systems through software customization conceivable and probably the simplest and cheapest kind the upgrade an existing ignition system to a system according to the invention.

1

Zündspannungsmesskurve

2

over time

3

ignition timing

4

tension on the ignition coil

5

rise the tension

6

ignition

7

spark duration

8th

ignition time in the resonance frequency

9

Power modulation curve

10

pulse rate

11

The End the spark duration

12

decay phase

13

Zündspannungsnadel

14

30 ms ignition duration

15

spark duration

16

spark voltage

17

decaying

Claims (12)

Method for generating a spark ( 8th ) for igniting an internal combustion engine with a high electrical voltage ( 6 ) to an ignition coil, wherein a primary part of the ignition coil with a control voltage ( 6 ) is applied and wherein the ignition coil has a natural frequency ( 8th ), characterized in that the control voltage is pulsed such that the pulses in a resonance range ( 10 ) of the ignition coil to reach this, wherein the resonance range detects the natural frequency of the ignition coil and a deviation of +/- 20%, preferably +/- 10%, especially +/- 5%, around the natural frequency of the ignition coil around. Method according to claim 1, characterized in that that the control voltage is exactly in the natural frequency of the ignition coil is pulsed. Method according to claim 1 or 2, characterized an electronic control unit generates a frequency in the control voltage, in the ignition coil causes a permanent resonance. Method according to claim 3, characterized that over the resonance in the ignition coil continuous spark is produced. Method according to one of the preceding claims, characterized in that a burning time ( 7 ) of the spark before starting ( 3 ) of the ignition process is specified. Method for generating a spark for igniting an internal combustion engine with a high electrical voltage ( 6 ) to an ignition coil, characterized in that a modulation frequency is modulated on a fundamental frequency of the high voltage. Method for generating a spark for igniting an internal combustion engine with a high electrical voltage ( 6 ) to an ignition coil, characterized in that a control voltage is modulated in amplitude. Method according to Claim 1 and according to Claim 6. Method according to claim 1 and according to claim 7. Method according to Claim 6 and according to Claim 7. Method according to one of claims 1, 6 and 7. detonator with means for performing a Method according to one of the preceding claims.