WO2002027183A1 - Systeme d'allumage a jet de plasma - Google Patents

Systeme d'allumage a jet de plasma Download PDF

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Publication number
WO2002027183A1
WO2002027183A1 PCT/DE2001/003682 DE0103682W WO0227183A1 WO 2002027183 A1 WO2002027183 A1 WO 2002027183A1 DE 0103682 W DE0103682 W DE 0103682W WO 0227183 A1 WO0227183 A1 WO 0227183A1
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WO
WIPO (PCT)
Prior art keywords
voltage
radiation
ignition
switching tube
ignition system
Prior art date
Application number
PCT/DE2001/003682
Other languages
German (de)
English (en)
Inventor
Christoph Körber
Original Assignee
Koerber Christoph
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE2000148053 external-priority patent/DE10048053A1/de
Application filed by Koerber Christoph filed Critical Koerber Christoph
Priority to AU2002213810A priority Critical patent/AU2002213810A1/en
Priority to DE10194131T priority patent/DE10194131D2/de
Publication of WO2002027183A1 publication Critical patent/WO2002027183A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P23/00—Other ignition
    • F02P23/04—Other physical ignition means, e.g. using laser rays
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P9/00—Electric spark ignition control, not otherwise provided for
    • F02P9/002—Control of spark intensity, intensifying, lengthening, suppression
    • F02P9/007—Control of spark intensity, intensifying, lengthening, suppression by supplementary electrical discharge in the pre-ionised electrode interspace of the sparking plug, e.g. plasma jet ignition

Definitions

  • the invention relates to a plasma jet ignition system with high-voltage generation and with a high-voltage electrical discharge circuit, which has a parallel connection of at least one capacitor with a series circuit comprising an ignition device and a gas-filled switching tube, these components being arranged in spatial proximity to one another, in particular for internal combustion engines with spark ignition ,
  • a method for plasma jet ignition under high voltage generation using a high-voltage side electrical discharge circuit which has a parallel connection of at least one capacitance with a series circuit containing an ignition device and a gas-filled switching tube, and a switching tube for a plasma beam ignition system.
  • a storage capacitor is located in the high-voltage circuit of plasma jet ignition systems parallel to the discharge path (see FIG. 9).
  • the electrical conductivity of the discharge path alone determines the during the Spark build-up, the breakthrough phase, flowing current (Rompe, Weizel "Theory of electrical arcs and sparks", Johann Ambrosius Barth Verlag, 1949, III. Chap., ⁇ 3, especially p. 80f.).
  • the ignition device and the switching tube preferably have optical elements for decoupling radiation generated in the engine during combustion. Additionally or alternatively, the optical guide device can be used to transmit the radiation to the system control unit.
  • the possibility of integrating optical elements into the ignition device and the switching tube for decoupling the radiation generated during combustion in the engine and of using the optical waveguide for transmitting the radiation to the system control unit or a control module make it practical and cost-effective, to implement the optical combustion analysis previously used only in the laboratory area in large-series engines. In particular, it is possible to detect motor knocking, so that the known body scarf runners for knock detection can be dispensed with.
  • Intermediate circuit voltage absorbs the amount of energy that can be recovered from the latter when the parasitic capacitances of the high-voltage circuit are discharged. This enables energy recovery and optimal use of the available energy.
  • the latter is preferably provided with a demagnetization winding which is arranged close to a first winding of the transformer for magnetic coupling.
  • a device for activating the trigger radiation in particular a comparator, preferably detects the sign of the voltage on the demagnetizing winding in order to determine a change in polarity. In this way, the optimal triggering time can be detected.
  • Figure 8 shows another embodiment of a circuit arrangement according to the invention.
  • FIG. 1 shows a high voltage portion 20 of a plasma jet ignition system including a device 21 for triggering the ignition.
  • the high voltage is generated with the aid of a transformer HT and led to the igniter unit 23 via an ignition cable 22.
  • the igniter unit 23 consists of a plasma jet igniter PI, a gas-filled high-voltage switching tube SW and the high-voltage capacitor C. These components are electrically connected in series and form a closed discharge circuit 24, the capacitor C being connected to the ground point of the igniter PI.
  • the igniter PI and the switching tube SW together form a discharge path.
  • the capacitor C is charged to the desired nominal value of the high voltage within a period of time .DELTA.t A via a diode D, which is located essentially directly next to the capacitor between the ignition cable 22 and the capacitor C.
  • the capacitance of the capacitor C is dimensioned such that the amount of energy to be released in the breakthrough is stored therein.
  • the parasitic capacitances of the high-voltage circuit are discharged within a period of time ⁇ t E.
  • the parasitic capacitances include in particular the capacitance of the ignition cable 22 and the stray capacitances of the transformer HT.
  • the diode D prevents the discharge of the capacitor C.
  • At least part of the surface of the cathode 9 of the switching tube SW lying in the interior of the SW is provided with a sufficiently thick coating 14 (see FIG. 7), the electronic work function of which is preferably just large enough that the number of the operating temperature of the cathode during the high-voltage standing time ⁇ t s due to electrons released by thermal emission is statistically so low that the probability that an undesired electrical breakdown is triggered by thermally emitted electrons can be neglected.
  • a sufficiently small value is sought for the required work function of the covering 14 in order to deal with visible or ultraviolet radiation To be able to trigger photoelectrons from it.
  • the trigger radiation can be projected onto the covering 14 in a focusing manner.
  • a housing 2 of the switching tube SW which can be seen in FIG. 7 is provided with an optical window or a partial region which is continuous for the release radiation and which enables the illumination of the cathode coating, in particular a transparent or translucent region.
  • the window or the partial area thus allow the trigger radiation to pass through and thereby illuminate the cathode coating of the switching tube SW.
  • the release radiation is generated after the discharge of the parasitic capacitances on the high-voltage side with the aid of a suitable luminescence or laser diode UV-LED 30 (FIG. 1) or another suitable radiation source.
  • the trigger radiation is brought to the switching tube SW via a light waveguide 12.
  • the optical waveguide 12 can be guided coaxially in the interior of the ignition cable 22 and can be surrounded by the high-voltage conductor of the ignition cable 22.
  • the plasma jet igniter PI and the switching tube SW can be realized as a common unit that can be replaced like a conventional spark plug.
  • the capacitor C and the rectifier or the diode D can be integrated on the cable side into the connection between the ignition cable 22 and the igniter unit 23.
  • the voltage drop caused by the regenerative current at D1 is detected with the aid of a comparator K, which activates the luminescence or laser diode UV-LED and thus triggers the breakdown in the discharge circuit 24.
  • a diode D2 only serves to protect the coparator input.
  • An adjustable voltage drop U3 is used to set the operating point (order of magnitude: 100 mV).
  • the signal of the comparator is also fed back into the control of the system (“feedback” signal). There, the stray capacitance on the high-voltage side can be determined on the basis of the time delay between the opening of the circuit breaker SW1 and the comparator signal or on the duration of the comparator signal, so that the in energy to be stored in the ignition coil and thus the switch-off current can be adapted accordingly.
  • the luminescence or laser diode can also be switched by the control of the system in order to trigger the exact triggering of the ignition independent of the switch-off time of the circuit breaker SW3 and thus of the in to keep the ignition coil stored energy.
  • the comparator can be maintained in order to indicate to the controller the earliest possible time for the ignition and to enable the parasitic capacitances on the high-voltage side to be calculated.
  • Figure 9 shows the prior art. Deviating from the prior art, however, according to the invention, according to the principle shown in FIG.
  • FIG. 3 a complete energy transfer from an intermediate circuit capacitor C1 into a high-voltage side capacitor C2 is ideally achieved before the ignition.
  • Figure 3 shows a parallel resonant circuit, consisting of the capacitors or capacitors C1 and C2, an inductor L, a diode D and a switch SW3, all of which are electrically connected in series. Before the switch SW3 is closed, the intermediate circuit capacitor Cl is charged to the voltage UI. The voltage U2 across the capacitor C2 becomes zero. A complete energy transfer from Cl to C2 is possible if both capacities are of the same size.
  • C2 is coupled to the other components of the resonant circuit via a transformer with a gear ratio s ü.
  • the arrangement according to FIG. 7 is essentially rotationally symmetrical about a longitudinal axis 1.
  • the igniter consists of a metallic housing 2 with spark plug thread 3, hexagon 4 for assembly and thread 5 for a union nut, not shown, which is located on the connection of the connector shown in the illustration of ignition cable 22 is brought to the right and secures its seat.
  • the apex lines of the cathode and central electrode that run outside the representation plane are indicated by dashed lines. Between these, the rollover should take place in the switching tube (identified by reference number 8). Consequently, the electric field strength should have the highest amount within the switching tube. When determining the greatest field strength, the field running radially on the sides of the cathode body in the direction of the housing must be taken into account. If necessary, the electrical field distribution within the switching tube must be optimized using a numerical simulation. The surfaces are preferably polished to avoid microscopic field distortions.
  • the field distribution can be made very inhomogeneous as in a Geiger-Müller counting tube (tip /
  • the cathode body forms one
  • the cathode 9 can be fixed gas-tight directly inside the insulator 6 if the filling of the gas space to others
  • the cathode support 11 is connected to the insulator 6 in a gas-tight manner, for example by means of glass solder (“frit”), so that there is sufficient heat flow from the cathode 9 to the insulator 6
  • the optical waveguide 12 is arranged coaxially within the cathode 9 and directs the trigger radiation fed in via the ignition cable 22 into the interior of the switching tube for the ignition.
  • the radiation exit surface is designed to be convex in order to reduce the divergence of the beam within the switching tube.
  • the radiation falls on a dichroic mirror 13 mounted on the center electrode 7, as is known, for example, from color television technology or laser technology (for example Naumann et al., "Components of Optics: Paperback of Technical Optics", 6th edition, Carl Hanser Verlag , 1992, pp. 255ff, p. 559f.)
  • the mirror preferably reflects the wavelength range of the trigger radiation and is otherwise largely transparent.
  • the mirror carrier is advantageously of the smallest possible and uniform thickness.
  • the focal length of the mirror is approximately half this distance in order to obtain a sharp image. A slight blurring can be accepted.
  • the sizes of the object and the image are related to each other like their distances from the mirror apex, so that the image is about the same size as the object.
  • the width of the cathode covering ring 14 projected into the mirror plane should therefore correspond to the radius r L of the light waveguide 12 projected into the mirror plane. Since the inside diameter of the cathode covering ring should not be smaller than r L , the surface of the covering 14 becomes at least three times as large as the exit surface of the light guide projected into the mirror plane.
  • the covering area A F > 2.4 mm 2 .
  • the shape of the mirror is created by rotating a parabola with a suitable half parameter around a suitable diameter or - depending on the geometric conditions - around a straight line that is slightly oblique to the diameters.
  • the size of the mirror depends on the divergence of the radiation emerging from the light guide 12, which preferably falls completely on the mirror.
  • the mirror can be attached to the center electrode with glass solder or melted directly onto it.
  • the space that borders on the side of the mirror facing away from the trigger radiation should not be sealed gas-tight, so that the mirror is not deformed or destroyed when the switching tube is filled with compressed gas.
  • a dichroic mirror is chosen if the combustion chamber radiation of the engine is to be recorded as described below. Otherwise, the surface of the center electrode can be shaped and polished accordingly. Due to the shape of the cathode surface and the positioning of its coating 14, a rollover between the coating and the central electrode 7 is largely unlikely, since the coating lies within a cavity formed by the cathode surface, into which the electric field penetrates only weakly. On the other hand, the photoelectrons are released in the vicinity of the smallest distance between the center electrode and the cathode, so that the impact ionization of the gas filling can start in the area of the highest electric field strength.
  • FIG. 8 shows a further embodiment of a circuit structure according to the invention with a control device, which is implemented here in analog hardware, but can also be partially implemented in digital technology and / or in software.
  • operational amplifiers are designated with “A ", coparators with an open collector output with "K.. JJ switches with” SW ... “and signals with” S ... ".
  • the primary current of the transformer HT is detected with a measuring resistor R5, which is connected between the emitter of the circuit breaker SW1, an IGBT, and ground.
  • R5 When determining the ohmic resistance of the primary winding of the transformer, the value of R5 must be subtracted from the calculated resistance value R P (FIG. 5).
  • R5 In order to enable a large winding resistance, R5 is chosen to be sufficiently small, for example 50 m ⁇ , and thus the voltage at R5 and with A2, R3, R4 is amplified.
  • Diode D14 is only used to protect ZDl and the output of AI.
  • the limit voltage of ZDl should be less than half the supply voltage of the timer, so that the maximum switch-off current is actually determined by ZDl and not by a possibly fluctuating supply voltage of the timer.R3 and R4 are dimensioned so that the voltage at R5 is just increased to the value specified by ZDl when the Maximum flow flows.
  • Variants in bipolar and CMOS technology are available from timer module 555. The versions with the strongest output currents are preferred so that SW1 is advantageously switched quickly. Some CMOS versions have significantly lower output currents than the bipolar standard version.
  • the power supply to the module, not shown in FIG. 8, is preferably adequately capacitively buffered.
  • the output of the comparator Kl is initially "low” because the inverting input via R6 is at + U0 in the idle state. If the input is sufficiently high
  • D3 cathode becomes negative ( ⁇ 0 V). This is the case when magnetic energy from the ignition coil is fed back into the power supply via D2.
  • the voltage drop across D3 is determined by R6; the current is preferably in the order of a few ⁇ A to mA.
  • its operational input voltage range should expediently include the negative supply voltage.
  • R16 and D4 serve to protect the inverting input of Kl against negative ones
  • the generation of the tripping radiation thus begins with the start of the recovery of magnetic energy from the transformer HT.
  • the tripping radiation goes out as soon as C9 is charged via R9 to the value determined by R7 and R8.
  • This ignition interval is chosen to be sufficiently long to enable the electrical discharge to build up.
  • RIO a clean switching hysteresis for K2 is set (for example 10 mV).
  • C5 includes the junction capacity of D9.
  • C5 forms a capacitive voltage divider.
  • the ohmic resistance of the high-voltage winding of the ignition coil is electrically parallel to the parasitic capacitances, due to its size (a few ... ten k ⁇ ) negligible. If you choose C5 a tenth as large as the parasitic capacitances, eg 100 pF, appears on Coupling capacitor C6 at breakdown a voltage jump equal to one eleventh of the high voltage.
  • This voltage jump is divided down to low voltage by the voltage divider R14 / R15.
  • the sum of these two resistances, in practice essentially R13, together with the source capacitance of the voltage jump determine the time constant with which the voltage jump decays on the low voltage side.
  • the time constant should be so large that the monoflop MF1 is reliably triggered by the voltage jump.
  • MFl should not be triggered by the reduction of the charge on the parasitic capacitances of the high-voltage circuit, which results in an upper limit for the time constant.
  • ZD3 only serves to protect the input of the monoflop MFl.
  • the time-determining elements of MFI are not shown in FIG. 8.
  • the output pulse from MFl preferably lasts at least until the trigger radiation goes out.
  • each of the outputs of MFl enables the detection of premature and / or missing breakthroughs based on its status at the beginning and end of the active phase of S2.
  • MF1 / Q is therefore brought out as signal FB2 in order to enable function analyzes by controlling the system.
  • the switches SW6a to SW6d are known CMOS analog switches (for example type 4066). In the idle state, SW6a is open and SW6b is closed. But because switch SW6c is open, the gate of the small-power N-channel MOS transistor SW4 (enhancement type) is connected via R15 to + U0. Therefore, SW4 shorts the current of the constant current source LM334 to ground ("0 V") in the idle state.
  • the constant current source can also be implemented with other components.
  • Decisive for the selection of the current strength are, among other things, the requirements for the measuring accuracy and thus the channel resistance of the SW4 , the dynamic behavior of the constant current source, the parasitic capacitances of SW4, D15 and the circuit structure, as well as the temperature dependence of the current in connection with the self-heating of the constant current source.
  • the order of magnitude of 1 A proves to be expedient.
  • Closing SW6c results in the gate of SW4 being connected to its source, so that SW4 locks.
  • the current of the current source LM334 flows into the capacitor C7 via D15.
  • C7 is discharged during the inductive charging of the ignition coil (signal S1 positive) via the small-power N-channel MOS switching transistor SW5.
  • the charge accumulation on C7 continues until either the tripping radiation goes out (S2 becomes inactive and opens SW6c) or until MFI is triggered by a breakdown in the high-voltage circuit.
  • the pulse generated by MFl opens SW6b, so that the connection of the gate from SW4 to ground is broken. If MFl is triggered by a premature breakdown before activation of the trigger radiation, the opening of SW6c by signal S2 has no influence on SW4, so that C7 receives no charge from the constant current source LM334 in the cycle concerned.
  • SW6a which is closed when SW6b is opened, is used to speed up the switching on of SW4.
  • the resistor R15 can therefore have a relatively high resistance (eg -100 k ⁇ ).
  • the switch-on time can be shorter than the switch-off time for certain commercially available versions of analog switches.
  • an undesirably high current can temporarily flow from the power supply + U0 to ground (0 V).
  • the supply voltage is preferably capacitively well buffered.
  • D15 prevents the charge collected in C7 from escaping.
  • a sufficiently fast signal switching diode with a small reverse delay charge and a small reverse current is selected for the D15.
  • Schottky diodes are less suitable because of their generally high reverse current.
  • the voltage reached at C7 is a measure of the time delay between the activation of the tripping radiation and the high-voltage breakdown.
  • the voltage at C7 therefore represents the actual controlled variable, which, however, has statistical spread. Regulation based on individual cycles therefore proves to be less sensible.
  • Filters is determined by the ratio of the capacities of C7 and C8 certainly.
  • SW6d is briefly closed by signal S3 after the measurement interval corresponding to the pulse duration on S2 has elapsed, in order to enable voltage compensation between C7 and C8.
  • S3 is generated by the monoflop MF2, which is triggered by the falling edge of S2.
  • the minimum pulse duration (order of magnitude: l ⁇ s ... lms) should be an appropriate multiple of the time constant determined by the ohmic resistance of SW6d and the series connection of C7 and C8.
  • the pulse is preferably terminated at the beginning of the following ignition cycle, since C7 is short-circuited via SW5 when S1 is activated (maximum pulse duration e.g. 8 ms).
  • High-quality, low-loss capacitors with low leakage current should be used for the C7 and C8, for example plastic film capacitors made of polypropylene or polystyrene.
  • the capacitors are preferably of the same type in order to minimize temperature influences on the corner frequency of the filter. Also pay attention to low leakage current circuit design.
  • the voltage at C8 is fed as a controlled variable to the proportional regulator 28 realized with AI.
  • the input current at the non-inverting input of AI should also be negligible.
  • amplifiers with MOS input transistors can be used, or one of the known methods for compensating the input current of operational amplifiers is used (not shown in Figure 8).
  • the controlled system Because of the low-pass filtering by SW6d and SW5, the controlled system exhibits low-pass behavior. In addition, the static characteristic is strongly non-linear. Accordingly, the control gain determined by Rl and R2 must be set according to known control engineering methods so that the system is stable and sufficiently damped. For example, the static characteristic of the The controlled system at the operating point is automatically determined during operation and the control gain can be adjusted accordingly. As an alternative to low-pass filtering of the controlled variable with SW6d and C8, a variety of methods for noise suppression are available. On the other hand, an absolutely precise regulation of the breakthrough time is of little importance; It is of primary interest that, if possible, all breakthroughs take place while the trigger radiation is active.
  • the monoflop MF1 and the switches SW6a to SW6c are used in order to minimize the number of (standard) components used; a monoflop is useful for MF2, an analog switch for SW6d.
  • a monoflop is useful for MF2, an analog switch for SW6d.
  • an RS flip-flop can be used, which is set by the breakthrough pulse occurring at R14.
  • an RS flip-flop must be reset by a suitable signal before the next ignition cycle (for example, by S1 or S3).
  • the switches SW6a to SW6c can be replaced by a suitable logic combination of the signal S2 with at least one of the outputs of the monoflop (or RS flip-flop) MF1.
  • the controller has an integral part, an undesirably large manipulated variable can be accumulated when the system is started due to deviations between a fixed start high voltage and the high voltage actually required.
  • the initially required high voltage can be determined by test ignitions with the engine stopped.
  • the high voltage should be increased step by step from low values to higher to prevent premature, independent breakdowns.
  • the ignition energy changes with the square of the high voltage. As long as the voltage variation remains small, this should be practically insignificant.
  • deviations in the breakdown voltage between the individual igniters should be sufficiently small, since otherwise the igniter with the lowest ignition energy determines the leanability of the entire engine.
  • a classification of the detonators according to their breakdown voltage is possible. In order to achieve good reproducibility in the manufacture of the detonators, care must be taken to ensure that the materials used in the switching tube are of high purity. None of these materials should contain radioactive substances. For example, because of the natural radioactivity of carbon (C14), it can make sense to do without carbon-containing materials.
  • the composition of the filling gas of the switching tube SW can be determined empirically and optimized.
  • the filling gas should have the highest possible thermal conductivity in order to release the energy introduced into the filling gas into the environment as quickly as possible (insulator 6, center electrode 7, cathode 9).
  • a high thermal conductivity is also synonymous with a large mean free path of the gas particles, which in turn enables the impact ionization by ionized gas particles even with a relatively low electric field strength.
  • the filling gas is therefore preferably as light as possible and also chemically inert. These requirements are well met by helium; however, the ionization energy is very high at just under 35 eV, and the cross section of impact ionization by electrons is comparatively low.
  • the breakdown field strength is advantageously low at around 1.4 kV / mm at normal pressure (0.1 MPa), so that a high gas pressure can be achieved.
  • helium even diffuses through many types of glass.
  • Neon has a lower ionization energy and an even lower breakdown field strength than helium (-22.5 eV, -0.4 kV / mm).
  • Hydrogen (-15.4 eV, -2.6 kV / mm) shows a particularly fast switching behavior when used in thyratrons (Pasley, "Pulse Power Switching Devices - An Overview"). It should be noted that hydrogen as an electropositive element is the work function
  • nitrogen -14.5 eV, -4.5 kV / mm
  • nitrogen -14.5 eV, -4.5 kV / mm
  • the filling pressure is preferably set so high that within the
  • Tripping radiation of triggered breakdowns is observed by detecting the radiation emanating from the switching tube.
  • the photo emission is described by the Fowler Fix equations. With semiconducting cathode materials, the work function for thermally emitted electrons is generally lower than for photoelectrons.
  • electrical conductors are preferably used as the covering material, although their photoelectric quantum yield is relatively low in the wavelength range of interest.
  • the melting point of the covering material is advantageously well above the operating temperature of the cathode, in order to prevent the covering from flowing and / or a complete alloying of the covering material with a carrier material.
  • Suitable elemental substances can be found, for example, among the rare earths or the alkaline earth metals.
  • the standing time ⁇ t s should at most leave ("permissible dark current"), determined or determined.
  • the cathode temperature T Most of the engines are water-cooled, and the igniter along with the switching tube is screwed into the cylinder head, through which cooling water flows. As a rule, the temperature in the spark plug thread cannot exceed 150 ° C (423 K). Even if the cathode of the switching tube SW is not connected to the capacitor C as in FIG. 1, but rather forms a unit with the center electrode 7 (FIG. 7) of the igniter PI, it is possible to keep the temperature of the photocatode below 500 K (227 ° C. ) to keep.
  • sufficient heat flow from the center electrode via the insulator of the igniter must be ensured, for example by mechanical extension, by increasing the diameter and / or by reducing the cross section of the part of the center electrode surrounded by the insulator.
  • the connection of the cathode of the switching tube SW2 to the center electrode 7 of the igniter can offer design advantages because the guidance of the optical waveguide or the radiation emerging therefrom is simplified on the ignition side.
  • the polarities of the diode D2 and the high-voltage winding of the transformer HT must be interchanged so that C is charged to positive instead of negative, as shown in FIG. 1, to ground.
  • the circuit for high voltage generation is designed.
  • the standing time is largely freely selectable due to the dimensioning of the frequency-determining components and can generally be shorter are held as when using a flyback converter according to FIG. 2. In the latter case, it must first be determined or determined:
  • the high-voltage parasitic capacitances consisting of the sum of the stray capacitances of the ignition coil and the capacitance of the
  • the nominal value of the high voltage is preferably as high as possible in order to achieve a good efficiency of the energy input into the mixture.
  • the higher the voltage the more atoms or molecules of the filling gas of the switching tube can ionize a single photoelectron.
  • the capacitance of the capacitor C which is to store the energy W 2 at the high voltage, is advantageously chosen to be significantly larger than the parasitic capacitances C P on the high voltage side, in order not to have to provide too much ballast energy for the parasitic capacitances C P. This results in an upper limit.
  • Example: U 2 30 kV.
  • the time interval t x for the inductive charging of the ignition coil is advantageously as long as possible in order to keep the alternating current load on the power supply low in amplitude and also to keep it low-frequency.
  • recharging can only take place after the energy recovery from the Parasitic capacitances of the high-voltage circuit begin, that is, after the ignition coil has been completely demagnetized.
  • the inductive charging should therefore preferably not take up significantly more than half the minimum time between two ignitions of a cylinder.
  • Example: t : 10 ms.
  • the capacitance C can be designed, for example, as a vacuum capacitor.
  • C and the parasitic capacitance C P should advantageously be charged together to the nominal value of the high voltage.
  • the losses W V> H in the high-voltage circuit are assumed to be a flat 15 mJ.
  • the ignition coil is preferably made with little scatter, that is to say with a largely closed core, since the energy stored in the pri-side leakage inductance is largely lost.
  • a core cross-section that is as large as possible is to be aimed at in order to enable a small number of turns with a small air gap length. The magnetic energy absorption of the core material and thus the magnetic losses are neglected here due to the presence of the air gap.
  • L s , C and C P form an oscillating circuit.
  • the build-up time of the high voltage corresponds to a quarter
  • t A ⁇ W HV / (0 X ⁇ J x (1 + W VIH / W suspend V ) *.
  • the permissible work function changes by 0.0992 eV if the argument of the logarithm changes by an order of magnitude. For example, when the area of the photocathode is reduced from 10 to 1 mm 2, the permissible current density J TH is increased by a factor of 10, so that the minimum work function is then only 2.66 eV.
  • the work function is reduced by 0.0992 eV, corresponding to a tenfold increase in thermal emission, with a field strength of approximately 6800 V / mm. Such a value can occur in particular if the electrical field between the electrodes is approximately homogeneous with a small electrode spacing.
  • the cathode coating can be applied, for example, on the perimeter of the cathode to be made convex or in a cavity thereof. This also prevents the covering from being damaged by rollovers.
  • the Schottky effect can be used advantageously to reduce the work function of a covering material with a work function that is too high in order to increase the photo emission.
  • Metals are preferred as the covering material, since in semiconductors the photoelectric work function exceeds the thermal work function by the distance between the Fermi level and the valence band. This obviously leads to undesirably high thermal emissions. On the other hand, however, the quantum yield of semiconductors is significantly higher than that of metals, so that empirical studies are preferably carried out in individual cases. In the present case, calcium (W A «2.8 ... 3.2 eV), cerium (W A * 2.88 eV) strontium (W A « 2.74 eV) and magnesium (W A «3, 6 eV) can be used. Adsorbed metallic surface layers (monolayers) reduce the work function.
  • the work function becomes even less than the work function of the surface material itself.
  • the work function can be reduced by filling the switching tube with an electropositive gas such as hydrogen.
  • the actual work function also depends on the purity of the material. If and to what extent targeted contamination brings advantages, must be determined if necessary. For a given substance, the work function values for both thermal and photo emissions should be determined separately.
  • the cathode coating is advantageously chosen to have a thickness of at least a thousand atom layers (approximately 0.1 ⁇ m) if it is to have the work function of the pure coating material. In the case of thinner layers, interactions between the covering and the carrier material can lead to a significant reduction in the work function. The same applies to contamination of the covering material.
  • the cathode coating should be freed of adsorbed gases before the switching tube is filled with gas, for example by heating in a vacuum. Methods for this are described in Bretting, "Technical Tubes", Hüthig, 1991, p. 146Ff (chap. 2.5.3).
  • luminescent diodes based on GaN, which emit at a wavelength of 370 nm (photon energy 3.35 eV), are suitable as the radiation source.
  • the radiant power in DC operation is 0.75 mW. It can be increased by a factor of 3 in pulse mode.
  • the aperture angle of the radiation cone is only 15 ° with a lens diameter of 4 mm, so that at least% of the radiation power - about 100 ⁇ W, corresponding to 1.8 ⁇ 10 14 photons per second - can be coupled into a common plastic optical fiber with a 1 mm fiber diameter ,
  • violet (at 405 nm / 3.06 eV) laser diodes with a continuous wave power of 10 mW can be used. At least 20 mW can be achieved in pulse mode. As you know, at
  • Laser diodes emit a high proportion of radiation ( ⁇ 50 #) into one Optical fiber are coupled. This corresponds to about 2 ⁇ 10 16 photons per second.
  • the attenuation of common plastic fiber optic fibers is well below 1 db / m, so that less than 2QX of the photons in the fiber are lost with a length of one meter.
  • a further 5 can be estimated for reflection losses at each optical interface (entry and exit surfaces of optical fibers), i.e. a total of 20% for two optical fiber sections.
  • ⁇ (W P - W A ) / (kT) with: ⁇ P : "quantum yield”, depending on the coating material and the wavelength of the radiation; dimension: m 2 s; order of magnitude: 10 "37 m 2 s, A R : Richardson constant, T: temperature, k: Boltzann constant.
  • a capacitive system according to FIG. 4 for high voltage generation that is to say a flux converter
  • a flux converter For reasons of the higher expenditure compared to an inductive system (flyback converter), the use of a flux converter is particularly suitable when the ignition energy is high. It can be particularly useful if disproportionately large ignition coils are required for inductive energy storage or if the product of the primary-side maximum voltage and current to be switched off in an inductive system has to be uneconomically large in order to achieve an acceptable high-voltage build-up time.
  • the diode D8 should not be dispensed with, since otherwise the electrical discharge is not safely restricted to the breakdown phase. For example, you can do the following:
  • the leakage inductance is chosen to be smaller, the build-up time of the high voltage is shortened, but the current load during the switching process also increases, which is particularly important for the intermediate circuit.
  • the winding ratio N2 / N1 depends on the dielectric strength of the other components and the supply voltage U 0 . It may be appropriate to use the number of turns to choose identical from N2 and Nl and to realize the windings in one operation with twin strand.
  • the maximum voltage between adjacent windings can be limited to the intermediate circuit voltage U 2 by appropriate pin assignment. If the parameters of the transformer are fixed, the DC link capacitances Cla and Clb can be determined, for example, by analytical calculation according to Böning, or by numerical circuit simulation. The objective here is that at the time when the high voltage reaches a maximum for the first time, there is as little charge on Cla and Clb as possible.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)

Abstract

L'invention concerne un système d'allumage à jet de plasma avec génération de haute tension, pourvu d'un circuit de décharge électrique (24) côté haute tension, qui comprend un montage en parallèle constitué d'au moins une capacité (C, C3, C4, C5) et d'un montage en série contenant un dispositif d'allumage (PI) et un tube commutateur rempli de gaz (SW, SW2), ces éléments étant placés à proximité spatiale les uns des autres, et destiné notamment à des moteurs à combustion interne à allumage externe. Le système selon l'invention comprend un dispositif (D, D3, D8, 30) servant à la limitation dans le temps du flux de courant dans le circuit de décharge (24) ou au transfert d'énergie dans l'étincelle d'allumage à la phase de rupture de la voie de décharge (25), la rupture électrique étant déclenchée par irradiation. L'invention concerne également un procédé pour l'allumage par jet de plasma avec génération de haute tension, en utilisant un circuit de décharge électrique (24) côté haute tension, qui comprend un montage en parallèle constitué d'au moins une capacité (C, C3, C4, C5) et d'un montage en série contenant un dispositif d'allumage (PI) et un tube commutateur rempli de gaz (SW). Selon ce procédé, la décharge électrique dans le circuit de décharge (24) est déclenchée par irradiation du tube commutateur rempli de gaz (SW).
PCT/DE2001/003682 2000-09-28 2001-09-26 Systeme d'allumage a jet de plasma WO2002027183A1 (fr)

Priority Applications (2)

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AU2002213810A AU2002213810A1 (en) 2000-09-28 2001-09-26 Plasma jet ignition system
DE10194131T DE10194131D2 (de) 2000-09-28 2001-09-26 Plasmastrahl-Zündsystem

Applications Claiming Priority (4)

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DE2000148053 DE10048053A1 (de) 2000-09-28 2000-09-28 Plasmastrahl-Zündsystem
DE10048053.5 2000-09-28
DE10050756.5 2000-10-13
DE2000150756 DE10050756A1 (de) 2000-09-28 2000-10-13 Plasmastrahl-Zündsystem

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3501071A1 (fr) * 2016-08-17 2019-06-26 General Electric Company Éclateur exempt de krypton 85 à photoémission
CN111120111A (zh) * 2019-11-15 2020-05-08 陕西航空电气有限责任公司 一种航空发动机长时连续工作点火装置高压电路

Families Citing this family (3)

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Publication number Priority date Publication date Assignee Title
DE102010015344B4 (de) * 2010-04-17 2013-07-25 Borgwarner Beru Systems Gmbh Verfahren zum Zünden eines Brennstoff-Luft-Gemisches einer Verbrennungskammer, insbesondere in einem Verbrennungsmotor durch Erzeugen einer Korona-Entladung
DE102010024396B4 (de) * 2010-05-07 2012-09-20 Borgwarner Beru Systems Gmbh Verfahren zum Zünden eines Brennstoff-Luft-Gemisches einer Verbrennungskammer, insbesondere in einem Verbrennungsmotor durch Erzeugen einer Korona-Entladung
US8701638B2 (en) 2010-05-07 2014-04-22 Borgwarner Beru Systems Gmbh Method for igniting a fuel-air mixture of a combustion chamber, particularly in an internal combustion engine by generating a corona discharge

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3501071A1 (fr) * 2016-08-17 2019-06-26 General Electric Company Éclateur exempt de krypton 85 à photoémission
CN111120111A (zh) * 2019-11-15 2020-05-08 陕西航空电气有限责任公司 一种航空发动机长时连续工作点火装置高压电路

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DE10194131D2 (de) 2003-11-13
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