WO2006041330A1

WO2006041330A1 - Spark plug for an internal combustion engine

Info

Publication number: WO2006041330A1
Application number: PCT/RU2005/000460
Authority: WO
Inventors: Evgeny Anatolievich Monich; Anton Evgenevich Monich
Original assignee: Evgeny Anatolievich Monich; Anton Evgenevich Monich
Priority date: 2004-10-06
Filing date: 2005-09-12
Publication date: 2006-04-20
Also published as: RU2273082C1

Abstract

The invention relates to engine engineering, in particular to igniting devices for spark-ignition internal combustion engines. Said invention makes it possible to initiate the volume ignition of a fuel-air mixture in the combustion chamber of an internal combustion engine. The inventive spark plug is embodied in the form of an electric discharge arrester comprising a grounded metal body (1), a high-voltage electrode (2) which is provided with a dielectric insulating coating (11) on the side surface thereof and disposed along the central part of the body (1) and one or several side electrodes (3). Said plug is also provided with supporting capacitors whose number corresponds to the number of the side electrodes (3). One plate of each capacitor is electrically connected to the plug metal body (1) and the other plate is connected to one of the side electrodes (3).

Description

Spark plug for internal combustion engine.

The invention relates to the field of engine building, in particular, to ignition devices in internal combustion engines with forced ignition of a fuel-air or fuel-oxidative mixture.

Typically, in engines with positive ignition of the air-fuel mixture, electric spark plugs are used [l ÷ 3]. Electric discharge candles (hereinafter spark plugs) ignite the combustible mixture with the help of an electric discharge. For this, various types of self-sustained electric discharge in a gas are used, including a pulsed discharge in the gas gap between the electrodes [1], a combined pulsed discharge through the gas gap and on the surface of the dielectric [2], and a sliding discharge on the surface of the dielectric [3].

The closest structural embodiment to the present invention (prototype) is an electric spark plug for spark ignition of a fuel-air mixture in internal combustion engines described in [1]. In this device, as well as in analogues [2,3], a discharge occurs between the electrodes of the spark plug, one of which is supplied with high voltage pulses from the power unit of the ignition system, and the other electrode (or several electrodes) is in electrical contact with candle body (“grounded” side electrode). With this design of the candle, after the spark breakdown of the gas gap between its electrodes or breakdown on the surface of the dielectric, the electric potential of the high-voltage electrode sharply decreases. After the breakdown voltage is reached, the phase of spark discharge formation begins. The duration of this phase between the onset of breakdown and the moment of voltage drop depends on the rate of increase in voltage at the electrodes, and it is the smaller, the greater the rate of increase in voltage. The duration of the spark discharge formation phase can be, depending on conditions, from fractions to tens of microseconds. After the completion of the phase of formation of the spark discharge, the spark discharge proper occurs, heating the conductive channel. When discharging about, for a period of time of the order of 10 seconds, a sharp decrease in voltage (potential difference) occurs in the discharge gap by more than an order of magnitude from a value close to breakdown, and after about 10 seconds the voltage is only several tens of volts.

Using the prototype when igniting the air-fuel mixture in the combustion chamber does not allow you to create vibrational excitation of the molecules of the gas medium and, therefore

Replacement sheet thereby, carry out volumetric ignition of the combustible mixture. This is primarily due to the fact that after the breakdown of the gas gap between the electrodes of the spark plug, the potential of the high-voltage electrode drops by 2–3 orders of magnitude and cannot create an electric field of the required strength in a significant volume of the combustion chamber, and almost all the stored energy of the ignition system is spent on heating a conductive channel in a gas medium between the electrodes of the spark plug.

The technical result of the present invention is the implementation of volumetric ignition of the air-fuel mixture in the combustion chamber of internal combustion engines.

This result is achieved by the improvement of the known spark plug for an internal combustion engine, made in the form of an electric spark gap, consisting of a grounded metal casing, a high voltage electrode with a dielectric insulating coating on its side surface and installed along the central axis of the casing, and one or more side electrodes.

The improvement consists in the fact that retaining capacitors are additionally introduced into the candle by the number of side electrodes, one of the plates of each retaining capacitor is electrically connected to the metal housing of the candle, and the other to one of the side electrodes.

The supporting capacitor can be made in the form of a dielectric tube, the surface of which is metallized and is the outer lining of the capacitor, while the dielectric tube is placed between the metal housing of the spark plug and the dielectric insulating coating of the high voltage electrode, the electrical connection of the outer lining of the capacitor with the housing is carried out by direct contact, and the second capacitor plate is located inside the wall of the dielectric tube.

In one embodiment, the candles in the wall of the dielectric tube of the retaining capacitor have cavities open at one of the ends of the tube, the inner walls of the cavities are metallized, and the metal coating of the surface of each cavity is the second lining of the capacitor, with each side electrode inserted into the corresponding cavity and brought into electrical contact with a metal coating of the surface of the cavity.

In one case, the side electrodes are placed around the high-voltage electrode and form gas discharge gaps with it, and in the other, the ends of the side electrodes

Replacement sheet placed on the surface of the dielectric coating of the high voltage electrode to organize a sliding discharge on the surface of the dielectric.

The invention is illustrated by the accompanying drawings:

In FIG. 1 shows a longitudinal section of a spark plug with gas discharge gaps between the high voltage and side electrodes.

In FIG. 2 shows a longitudinal section of a spark plug with a sliding discharge over the surface of the dielectric between the high voltage and side electrodes.

In FIG. 3 shows a longitudinal section through a retaining capacitor with coaxial cavities in a four-cavity embodiment.

In FIG. 4 shows a cross section of a retaining capacitor with coaxial cavities in an embodiment with four cavities.

In FIG. 5 shows a longitudinal section through a backup capacitor in an embodiment with four side electrodes having metal tabs at the proximal end embedded inside the ceramic wall.

In FIG. 6 shows a cross section of a retaining capacitor in an embodiment with four side electrodes having metal tabs at the proximal end embedded inside the ceramic wall.

In FIG. 7 shows an electrical circuit for connecting a spark plug and its equivalent electrical circuit in accordance with the proposed invention.

In FIG. Figure 8 shows a characteristic change in the potential of the high-voltage electrode, the potential of the side electrodes, and the charging current of the retaining capacity of the proposed spark plug as a function of time during electrical breakdown of the discharge gaps between the high-voltage and side electrodes.

In FIG. Figure 9 shows a graph of a typical change in the potential difference between the electrodes versus time during electric breakdown of the gas gap in the spark phase of the discharge [4].

In FIG. Figure 10 shows the dependence of the fractions of energy transferred per unit time to the excitation of vibrational levels, to the excitation of electronic levels, and to ionization when an electron moves through molecular nitrogen with pressure P under the action of an electric field E _ycc on the magnitude of the reduced intensity of the accelerating field [5].

The spark plug for an internal combustion engine (Fig. 1) is made in the form of an electric spark gap and consists of a metal housing 1 with a high voltage electrode 2 installed along its central axis, one or more

Replacement sheet side electrodes 3 and retaining capacitors, which include a dielectric, in particular ceramic, tube 4 and two plates 5 and 6 (Fig. 3, 4). The lining 5 is a metal coating on the outer and inner surfaces of the tube 4. In the wall of the tube 4 there is a cavity 7 (Fig. 3, 4), coaxial with the cylindrical surfaces of the tube, and open at the top at the end of the tube. The tube 4 is placed inside the housing 1 so that its metal coating (cover 5) is in contact with the housing and carries out their electrical connection. The coaxial cavity 7, made in the wall of the tube 4, is divided by dielectric partitions 8 into sections (Fig. 4). The inner walls of each section of the cavity are metallized, and these metal coatings are the second plates 6 of retaining capacitors. Inside each section of the cavity, the proximal ends 9 (Fig. 1) of the side electrodes 3, which are in contact with the metal coating (lining 5), are placed, and thus they are electrically connected. In one embodiment, the side electrodes may have a metal lobe 10 in the shape of a cylinder sector at the proximal end 9 (Fig. 5, 6). The metal petals 10 of the side electrodes 3 are embedded inside the ceramic wall of the retaining capacitor (Fig. 5, 6) and are in this embodiment the second plates 6 of the retaining capacitors. The lateral surface of the high-voltage electrode 2 is protected by a dielectric coating 1 1. The distal ends of the side electrodes 3 are placed around the protruding part of the high-voltage electrode 2 and form discharge gas gaps with it (Fig. 1). In another embodiment, the distal ends of the side electrodes 3 are placed on the surface of the dielectric coating 1 1 (Fig. 2). In this case, a sliding discharge is realized over the surface of the dielectric between the electrodes 2 and 3.

The principle of operation of the proposed spark plug is that the discharge between the electrodes of the spark plug is automatically interrupted before all the energy accumulated in the power unit of the ignition system is dissipated in the discharge gap during a spark discharge or sliding across the surface of the dielectric. In accordance with FIG. 7 by the connection diagram of the plug from the power unit 12 to the high-voltage electrode 2 by control signals from the system switch 13

Replacement sheet The ignition receives an increasing voltage U ₂ - a high-voltage electric pulse. After the potential difference between the high-voltage 2 and side 3 electrodes of the candle reaches ΔU ,, _poб ., At which the field strength between the electrode electrodes E _2-3 becomes higher than the breakdown voltage E _sample j, there is a spark breakdown of the gas gap. Rising in accordance with FIG. 8, a discharge current flows between the electrodes 2 and 3 and charges the retaining capacitance C (FIG. 7). After the capacitance C is charged in the circuit: power block 12 - high-voltage electrode 2 - discharge gap - side electrode 3 - capacitance C, the potentials of the electrodes U ₂ and U ₃ candles practically equalize and the discharge current between them stops. Moreover, the potential equalization of the electrodes 2 and 3 does not occur due to a decrease in the potential U _{2 of the} electrode 2, as occurs with the prototype (Fig. 9), but due to an increase in the potential U _{3 of the} side electrode 3 (Fig. 8). The nominal value of the retaining capacitance C is selected so that only part of the energy contained in the drive of the power unit 12 and in the own capacitance of the high-voltage circuit Co is used to charge it (Fig. 7). A spark discharge in the stage of charging the retaining capacitance C is a source of electromagnetic radiation, including a sufficiently hard one, capable of photo-ionizing components of a gaseous medium having a low ionization potential (hydrocarbon fuel components), as well as causing photoemission from the metal walls of the combustion chamber and thereby enriching gas medium of the combustion chamber by free electrons.

Similarly, during charging of the retaining capacitance With a charging current (along the circuit: power block 12 — high voltage electrode 2 — discharge gap — side electrode 3 — capacitance C), the gaseous medium is enriched with free electrons and, in the design of the plug, with a sliding discharge on the dielectric surface insulating the central high-voltage electrode of the candle (Fig. 2).

Further, after charging the retaining capacity and increasing the potential on the side electrodes 3 of the spark plug, these electrodes, together with the high-voltage electrode 2, on the one hand, and the metal walls and other structural parts of the combustion chamber 14 located under the ground potential (Fig. 7 ), on the other hand, create an electric field E _ycc in the volume of the combustion chamber. Free electrons formed in

Replacement sheet the gas medium of the air-fuel mixture filling the combustion chamber is accelerated by the electric field E _ycc and carry out a non-self-discharge in the gas along the circuit: power block 12 - high-voltage electrode 2 + side electrode 3 (or a set of side electrodes) - gas medium - walls of the combustion chamber 14 When moving in a gaseous medium, during a non-self-sustained discharge, free electrons experience inelastic collisions (with the transfer of part or all of the accumulated energy) with the molecules of the gaseous medium. The air-fuel mixture is formed by the molecules of hydrocarbons and intermediate products of their incomplete oxidation, as well as by the molecules of gases that form the air. Therefore, free electrons moving through a molecular gas will mainly experience collisions with nitrogen molecules, which make up about 75% of all molecules of the air-fuel mixture. In inelastic collisions, the electrons transfer the energy accumulated between collisions to various degrees of freedom of the molecules. From FIG. Figure 10 shows that for reduced electric field strengths E / P <10 V / cm torr (volts per centimeter per torr) - corresponds to <7.6 sq / cm-atm (kilovolts per centimeter per atmosphere), the main mechanism of electron energy loss in molecular nitrogen is the excitation of molecular vibrations. The dependences of the excitation efficiency for other molecular gases have a similar form. When excited by electron impact, molecular gases such as CO ₂ ; CO; N ₂ , for which the maximum cross section for excitation of molecular vibrations σ _v 10 10 cm is located in the range of 1–2 eV and the cross section decreases sharply with increasing and decreasing electron energy, about 98% of the electron energy is spent on excitation of vibrations, and the discharge is stable to pressures P ∞ [6]. In practice, in order to maintain the required non-self-sustained discharge and efficiently excite the vibrational degrees of freedom of the molecules of the gas medium, a field with a strength E _{y (L} ~ 2 ÷ 3 kV / cm-atm is sufficient).

Free electrons, periodically gaining energy in the process of acceleration under the influence of an electric field E _ycc and transferring it during inelastic collisions to gas molecules, “transfer” the electric energy stored in the ignition system directly to the vibrational levels of gas molecules. This is “mechanism,” which carries out an almost instantaneous energetic effect on

Replacement sheet a relatively large volume of gaseous medium in the combustion chamber. Under the action of inelastic collisions with electrons, nitrogen molecules pass from the lower level Vo to excited vibrational levels V | _÷ g. Vibrationally excited nitrogen molecules having a zero dipole moment live in an excited state for a very long time (on atomic scales), and essentially the only mechanism for removing their vibrational energy is collisions with unexcited molecules, including molecules of intermediate products of incomplete oxidation of hydrocarbons. During these collisions, vibrationally excited nitrogen molecules exchange vibrational quanta, which are 0.29 eV, with other molecules. Ultimately, this leads to the excitation of vibrational levels of metastable and other molecules of intermediate products of incomplete oxidation of hydrocarbons, as well as oxygen molecules involved in the chain reaction of hydrocarbon oxidation, which leads to a rapid branching of the chain reaction and volumetric chain explosion of the air-fuel mixture.

The effectiveness of the above-described mechanism for the excitation of vibrational states of molecules of a gaseous medium through inelastic collisions with free electrons strongly depends on the concentration of free electrons in the gas. Therefore, one of the main reasons for improving the design of the proposed spark plug was the desire to create the largest possible number of free electrons in the entire volume of the combustion chamber. So, in some implementations, the candle has several side electrodes, each of which is connected to the "ground" potential through a separate retaining capacity. The use of several side electrodes makes it possible to more uniformly “surround” the volume of the combustion chamber with hard electromagnetic radiation. This is possible because the value of each retaining capacity Cj is selected so that the energy Wi stored in it is much less than the stored energy W _∑ in the ignition system. Then, during electrical breakdown of the first and each subsequent discharge gaps, the potential U _{2 of the} central high-voltage electrode 2 decreases slightly (Fig. 8), and the potential difference between the central high-voltage electrode and side electrodes 3 of the yet “broken” discharge gaps quickly recovers and almost constantly exceeds ΔU _ppob .- Therefore discharge sequentially involves all discharge gaps between the central high voltage electrode 2 and all

Replacement sheet side electrodes 3. An embodiment of a spark plug using a sliding discharge over the surface of the dielectric, shown in FIG. 2, has a higher • efficiency for generating hard electromagnetic radiation in comparison with the embodiment of FIG. 1, in which the discharge occurs through gas gaps. In a sliding discharge over the surface of the dielectric due to the polarization of the dielectric and the appearance of coupled electric charges on its surface, as a rule, a greater overvoltage is realized in the discharge gap. Therefore, the emissivity of a sliding discharge in the field of hard electromagnetic radiation is higher.

Using the proposed spark plug in an internal combustion engine can significantly improve the technical characteristics of the engine. The proposed spark plug provides stimulated volumetric self-ignition of the combustible mixture in the desired phase of the duty cycle. During the implementation of volumetric self-ignition, practically at the “dead dead point”, all the hidden possibilities of reciprocating internal combustion engines are realized. Fast, but synchronous in almost the entire volume of the combustion chamber, the development of ignition and complete combustion of the fuel make it possible to increase the permissible compression ratio ε of the combustible mixture based on gasoline of ordinary grades N; R (AI 80 ÷ AI 92) to values ε> 16 and use the “poor”

(α ~ l. l ÷ l, 7) air-fuel mixtures. At the same time, the efficiency, power, torque and elasticity of the engine are significantly increased at the same time as a significant increase in efficiency and environmental cleanliness of the working cycle.

Sources of information used:

1. Levis B., v. Elbe G. "Combustion, Flates apd Exploiofs Gases". N. Y., 1951.

2. U.S. Rat 4,092,558.

3. RF patent JN ° 2161728 RU.

4. J. M. Samerville "Electric arc", M.-L., Gosenergoizdat, 1962, p.8.

5. W.L. Nighap, Phs. Rev. A2, 1989 (1970).

6. A.M. Prokhorov et al., Quantum Electronics, 1977, v. 4, p. 457.

Replacement sheet

Claims

Claim

1. Spark plug for an internal combustion engine, made in the form of an electric spark gap, consisting of a grounded metal casing, a high-voltage electrode with a dielectric insulating coating on its side surface and installed along the central axis of the casing, and one or more side electrodes, about l and h And with the fact that retaining capacitors are additionally introduced into the candle by the number of side electrodes, one of the plates of each retaining capacitor is electrically connected to a metal Kim plug body and the other with one of the side electrodes.

2. The spark plug according to claim 1, characterized in that the retaining capacitor is made in the form of a dielectric tube, the surface of which is metallized and is the outer lining of the capacitor, the dielectric tube is placed between the metal body of the candle and the dielectric insulating coating of the high-voltage electrode of the candle, and the electrical connection of the outer lining the capacitor with the candle body is made by their direct contact, while the second lining of the capacitor is placed inside the dielectric wall ubki.

3. The spark plug according to claim 2, characterized in that in the wall of the dielectric tube of the retaining capacitor there are cavities open at one of the ends of the tube, the inner walls of the cavities are metallized, and the metal coating on the surface of each cavity is the second lining of the capacitor, with each side electrode inserted into the corresponding cavity and brought into electrical contact with a metallization layer.

4. The spark plug according to claim 1, characterized in that the side electrodes of the spark plug are placed around the high-voltage electrode and form gas discharge gaps with it.

5. The spark plug according to claim 1, characterized in that the ends of the side electrodes are placed on the surface of the dielectric coating of the high voltage electrode of the candle and form discharge gaps on the surface of the dielectric.

Replacement sheet