RU2084998C1 - Sparking plug for internal combustion engine - Google Patents

Abstract

FIELD: electric equipment for internal combustion engines. SUBSTANCE: sparking plug has metal body, insulator with built-in central electrode, common "mass" side electrode attached to body and mounted with some clearance relative to central electrode. Opposite surfaces of electrodes have sharp surface elements such as protrusions, bosses, slits which value amounts to 10-20 % thickness of common electrode to enhance, operational stability of internal combustion engine, to ensure total burning of fuel mixture with simultaneous simplification of structural and technological realization. EFFECT: improved functional characteristics of internal combustion engine.

Description

 The invention relates to the automotive industry, to internal combustion engines (ICE), and more particularly to elements of electrical equipment of engines. The invention relates to the design of candles for internal combustion engines.

One of the important systems of automobiles, internal combustion engines is the ignition system, a set of instruments and devices for the timely supply of an electric spark to the internal combustion engine cylinders to ignite the working mixture [1, 335] Elements of this system are spark plugs, the design of which includes a metal body, an insulator with a central an electrode, a side electrode mounted in the end of the housing [1, p. 343]
Since candles work in harsh operating conditions, at high temperatures, aggressive chemical exposure to fuels and combustion products, special corrosion-resistant materials (NMts-5, X25T, etc.) are used. At the same time, the stability of the internal combustion engine, the ease of starting and the reliability of ignition of the combustible mixture, the reduction of toxicity of exhaust gases are caused not only by materials, but also by design factors.

Technical solutions are known when, on comfortable cars (Rolls-Royce, etc.), two spark plugs were used for each cylinder to facilitate the start of the internal combustion engine and the stability of its operation. Moreover, one of them was included in the ignition system from magneto, and the second in the battery ignition system from the battery [2, p. 81]
A technical solution is also known when, in order to intensify sparking in the intake tract of a combustible mixture of an internal combustion engine, electrodes are additionally mounted on which a high voltage of about 4 kV is supplied from an autonomous source. The ionizer is made in the form of concentric insulated pipes installed with a certain gap and provided with needles on the surface [3]. When the internal combustion engine is operated, a high voltage is used to ionize the combustible mixture, increase the number of charged particles, which improves spark formation in the combustion chamber of the engine cylinders. The main disadvantage of this analogue is that the ionization of the combustible mixture is carried out in the intake tract outside the combustion chamber. With further movement into the combustion chamber, the ionized fuel mixture contacts the metal elements of the internal combustion engine, therefore, the ionization effect is significantly weakened. This drawback is eliminated in the known invention [4] when directly in the combustion chamber during the engine’s duty cycle a high-frequency voltage is applied to the spark gap, the magnitude of which is regulated.

 The main disadvantage of the considered analogues is the complexity of the structural and technological implementation, operation of the internal combustion engine.

The closest analogue of the claimed technical solution is the invention [5] in which a spark plug for an internal combustion engine is considered, comprising a metal housing ("mass") insulator with an electrode mounted therein. In this case, the opposite electrode, referred to in the invention as "mass", is fixed at both ends with preliminary bending in the opposite direction relative to the insulated electrode. The "bulk" electrode is made of an elastic material. The disadvantages of this prototype are the complexity of the structural and technological implementation, the difficulty of starting and stable operation of the internal combustion engine even with slight contamination ("oiling") of the candle. In the latter case, the spark gap between the electrodes is deprived of the possibility of natural cleaning from constantly forming soot during the implementation of ICE cycles "fuel supply-compression-stroke-release". At the same time, it is necessary to note the optimal design of the “mass” counter electrode in standard candles, which has a L-shaped shape [1, p. 244, fig. 108]
Also known is the design of the spark plug for an internal combustion engine, which is selected by the authors as a prototype [6] In the prototype, the candle has a housing, an insulator, central and common, connected to the mass, electrodes installed with a certain discharge gap between them. Moreover, the common electrode has through holes located opposite the central electrode symmetrically to the longitudinal axis of the latter, which increases the stability and reliability of the ignition of the mixture. The inventors explain the increase in the efficiency of the internal combustion engine by the fact that after ignition of the spark part of the working mixture in the interelectrode gap under pressure, the torch is ejected from the discharge gap and ignites the remainder of the mixture in the volume of the compression chamber. In this case, the main direction of the torch flow is formed in the radial direction from the axis of the central electrode of the candle, and the additional through holes in the common "mass" electrode.

 Literature and patent analysis suggested that the last technical solution in essence is the closest to the claimed invention.

 The disadvantages of this prototype as a whole are the same as those of the above analogues. Additionally, it can be noted that the presence of a hole in the body of a common "mass" electrode weakens the structure of the latter, increases the possibility of a break in the zone of location of the hole wall. When a debris enters the cavity of the cylinder of an internal combustion engine, the latter fails.

 Analysis of analogues, a prototype of the claimed technical solution, as well as foreign technical solutions (US patent 4535735, MKM F 02 P 15/08, publ. 05.20.87, US patent 4061122, MKI F 02 P 13/00, publ. 06.12.77 G. and others) indicates the presence of plane-parallel surfaces of the electrodes in the spark gap. As you know, the efficiency of the internal combustion engine, the reliability of its launch, the completeness of combustion of the combustible mixture is determined by the power of the spark discharge. The latter is determined by the strength of the discharge current, the voltage by the size of the discharge gap, the duration of the discharge [1] Certain factors of the ignition system of the internal combustion engine can be classified as constant, for example, the voltage of the vehicle’s on-board network is 12 V. At the same time, the voltage across the spark gap and the discharge current can vary significantly limits.

 It is known that the discharge gap with plane-parallel surfaces of the electrodes is unfavorable for powerful sparking. The surface density of electric charges in conductors of various shapes for different parts of the surface is not the same. In particular, the highest density is observed on the protruding points, therefore, the point-to-plane type spark gap can be recognized as the most favorable for powerful spark formation.

 However, the internal combustion engine spark plugs, in which the discharge gap has the form of a “plane-tip”, are complex in the design and technological execution. On the other hand, the operation of engine spark plugs is characterized by a range of 10-20 thousand km. Assuming an average vehicle speed of 50 km / h, 200-400 h can be considered the operating time of the candles. Simultaneously with the formation of carbon, during the operation of the candle in the spark gap there are microerosion phenomena, destruction and wear of the surface of the electrodes by fusion, evaporation and ejection of the material. This is the reason for a typical adjustment operation during the operation of internal combustion engines of automobiles, adjustment of the gaps of spark plugs.

 The analysis shows that the optimal form of the point-to-plane spark gap due to microerosion phenomena will quickly lose shape due to the destruction of the point. This made it possible to formulate the theoretical background of the claimed technical solution to present the discharge gap of the internal combustion engine spark plug in the form of a combination of optimal “tip-plane” types. At the same time, the authors of the claimed invention set the goal of maximally preserving the standard type of candles regulated by GOST 2043-74, ST SEV 767-77 "Spark plugs."

 The aim of the invention is to ensure the stability of internal combustion engines of vehicles, facilitate starting, ensure the completeness of combustion of the hot mixture, reduce harmful emissions into the atmosphere while simplifying and cheapening the design in comparison with analogues and prototype.

 This goal is achieved by the fact that in the known spark plug of an internal combustion engine having a metal casing, an insulator with a central electrode mounted, a common "mass" electrode mounted on the casing and mounted relative to the central electrode with a gap, the opposite electrode surfaces are made with sharp surface elements such as protrusions, tubercles, cuts. The magnitude of the sharp surface elements is 10-20% of the thickness of the total side electrode. The distance between the elements is at least half their size.

 In FIG. 1 is a general view of the internal combustion engine spark plug. The candle has a metal housing 1, an insulator 2, into which a central electrode 3 is mounted. The common lateral "mass" electrode 4 is connected to the housing and has a L-shaped shape. The surface of the side electrode 4, opposite the central electrode 3, has slots 5 with sharp elements 6.

 In FIG. 2 shows an enlarged view along arrow A of the working surface of the side common electrode 4. This surface facing the electrode 3 has slots 5 with sharp surface elements 6. The value h of these slots is 10-20% of the thickness H of the common side electrode 4, which substantiated theoretically and confirmed by experience. If the depth of the slots is less than 10% of the thickness of the common electrode, then the effect of the influence on the spark formation of the set of discharge gaps "tip-plane" is weakened as the candle works. Otherwise, when the depth of the slots exceeds 20%, then, without affecting the power of the spark discharge, this weakens the rigidity and strength of the candle electrode structure.

 Such structural elements with sharp surfaces for the implementation of the set of discharge gaps "tip-plane" can in principle be performed both on the working surface of the common lateral "mass" electrode, and the central one. The distance between the elements is at least half the thickness of the common electrode, due to technological considerations.

 Example. To implement the claimed invention, sets of spark plugs for the engines of Zaporozhets and Zhiguli automobiles were taken, which have a certain operating time of more than a year.

 The slots on the working surface of the common "mass" electrode of a standard design candle were performed by EDM on machines 43721 and 4531. A flat profile electrode tool 0.12 mm thick and a non-profiled electrode wire 0.08 mm were used. The processing was carried out under standard conditions, reflected in the technological recommendations for the operation of machine tools, as a result of which slots were obtained with a depth of 0.20 mm or about 17% of the electrode thickness (1.20 mm). After setting a set of candles with slots on the engines, as a result of operation, it was noted that the start of the engines was significantly facilitated, especially in cold weather. Increased engine throttle response, especially under variable engine operating conditions, slightly reduced fuel consumption.

 Compared with the known technical solutions, the claimed invention provides stable engine operation, facilitating its start-up, improving the fuel combustion process in combination with a simple structural and technological implementation.

Claims (1)

 Spark plug for an internal combustion engine having a metal housing, an insulator with a built-in central electrode, a common "mass" side electrode mounted on the housing and mounted relative to the central electrode with some clearance, characterized in that the opposite surfaces of the electrodes are made with sharp surface elements such as protrusions, tubercles, cuts, the value of which is 10 20% of the thickness of the common electrode.

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