A spark plug (also, very rarely nowadays, in British English: a sparking plug) is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed aerosol gasoline by means of an electric spark. British English or UK English ( BrE, BE, en-GB) is the broad term used to distinguish the forms of the English language used in the In an Internal combustion engine, the cylinder head sits atop the cylinders and consists of a platform containing part of the Combustion chamber and the The internal combustion engine is an engine in which the Combustion of Fuel and an Oxidizer (typically air occurs in a confined space called a Particulates, alternatively referred to as particulate matter (PM or fine particles, are tiny particles of solid or liquid suspended in a gas Spark plugs have an insulated center electrode which is connected by a heavily insulated wire to an ignition coil or magneto circuit on the outside, forming, with a grounded terminal on the base of the plug, a spark gap inside the cylinder. An ignition coil (also called a spark Coil) is an Induction coil in an Automobile 's Ignition system which transforms This article is about the Engine component For other uses of the term see Magneto (disambiguation. A spark gap consists of an arrangement of two conducting Electrodes separated by a gap usually filled with a Gas such as Air.
Early patents for spark plugs included those by Nikola Tesla (in for an ignition timing system, 1898), Richard Simms (GB 24859/1898, 1898) and Robert Bosch (GB 26907/1898). There have already been discussions about Tesla's ethnicity on the talk page Year 1898 ( MDCCCXCVIII) was a Common year starting on Saturday (link will display the full calendar of the Gregorian calendar (or a Common Robert Bosch ( September 23, 1861 - March 12, 1942) was a German industrialist founder of Robert Bosch GmbH. Some historians have reported that Edmond Berger invented an early spark plug on February 2, 1839. Karl Benz is also credited with the invention. Karl Friedrich Benz, sometimes spelled Carl, ( November 25, 1844, Karlsruhe, Germany – April 4, 1929, Ladenburg But only the invention of the first commercially viable high-voltage spark plug as part of a magneto-based ignition system by Robert Bosch's engineer Gottlob Honold in 1902 made possible the development of the internal combustion engine. An ignition system is a system for igniting a fuel-air mixture Gottlob Honold (August 26 1876 - March 17 1923 was the leading engineer in the workshop of Robert Bosch and with Bosch was the inventor of the Spark plug and
Internal combustion engines can be divided into spark-ignition engines, which require spark plugs to begin combustion, and compression-ignition engines (diesel engines), which compress the air and then inject diesel fuel into the heated compressed air mixture where it autoignites. A diesel engine is an Internal combustion engine which operates using the Diesel cycle (named after Dr Compression-ignition engines may use glow plugs to improve cold start characteristics. For the similar device used in model aircraft engines, see Glow plug (model engine.
Spark plugs may also be used in other applications such as furnaces where a combustible mixture should be ignited. A furnace is a device used for Heating The name derives from Latin fornax, Oven. In this case, they are sometimes referred to as flame igniters.
The plug is connected to the high voltage generated by an ignition coil or magneto. An ignition coil (also called a spark Coil) is an Induction coil in an Automobile 's Ignition system which transforms This article is about the Engine component For other uses of the term see Magneto (disambiguation. As the electrons flow from the coil, a voltage difference develops between the center electrode and side electrode. No current can flow because the fuel and air in the gap is an insulator, but as the voltage rises further, it begins to change the structure of the gases between the electrodes. Once the voltage exceeds the dielectric strength of the gases, the gases become ionized. In Physics, the term dielectric strength has the following meanings Of an insulating material the maximum electric Field strength that it can withstand Ionization is the physical process of converting an Atom or Molecule into an Ion by adding or removing charged particles such as Electrons The ionized gas becomes a conductor and allow electrons to flow across the gap. Spark plugs usually require voltage in excess of 20,000 volts to 'fire' properly.
As the current of electrons surges across the gap, it raises the temperature of the spark channel to 60,000 K. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The intense heat in the spark channel causes the ionized gas to expand very quickly, like a small explosion. This is the "click" heard when observing a spark, similar to lightning and thunder. Lightning is an atmospheric discharge of Electricity, which typically occurs during Thunderstorms and sometimes during volcanic eruptions or Thunder is the sound made by Lightning. Depending on the nature of the lightning and distance of the listener it can range from a sharp A new plug called a pulse plug released in 2007 incorporates a peaking capacitor into the plug itself that releases all its contents into the plug gap giving a much more intense spark.
The heat and pressure force the gases to react with each other, and at the end of the spark event there should be a small ball of fire in the spark gap as the gases burn on their own. A spark gap consists of an arrangement of two conducting Electrodes separated by a gap usually filled with a Gas such as Air. The size of this fireball or kernel depends on the exact composition of the mixture between the electrodes and the level of combustion chamber turbulence at the time of the spark. A small kernel will make the engine run as though the ignition timing was retarded, and a large one as though the timing was advanced.
A spark plug is composed of a shell, insulator and the conductor. It pierces the wall of the combustion chamber and therefore must also seal the combustion chamber against high pressures and temperatures, without deteriorating over long periods of time and extended use. A combustion chamber is the part of an Engine in which Fuel is burned
The top of the spark plug contains a terminal to connect to the ignition system. An ignition system is a system for igniting a fuel-air mixture The exact terminal construction varies depending on the use of the spark plug. Most passenger car spark plug wires snap onto the terminal of the plug, but some wires have spade connectors which are fastened onto the plug under a nut. Plugs which are used for these applications often have the end of the terminal serve a double purpose as the nut on a thin threaded shaft so that they can be used for either type of connection. These are a necessary part of the spark plug.
By lengthening the surface between the high voltage terminal and the grounded metal case of the spark plug, the physical shape of the ribs functions to improve the electrical insulation and prevent electrical energy from leaking along the insulator surface from the terminal to the metal case. The disrupted and longer path makes the electricity encounter more resistance along the surface of the spark plug even in the presence of dirt and moisture.
The insulator is typically made from an aluminium oxide ceramic and is designed to withstand 650 °C and 60,000 V. The word ceramic is derived from the Greek word κεραμικός ( keramikos) The Celsius Temperature scale was previously known as the centigrade scale. The volt (symbol V) is the SI derived unit of electric Potential difference or Electromotive force. It extends from the metal case into the combustion chamber. The exact composition and length of the insulator partly determines the heat range of the plug.
Older sparkplugs, particularly in aircraft, used an insulator made of stacked layers of mica, compressed by tension in the centre electrode. The word "mica" is thought to be derived from the Latin word la micare, "glitteren" in reference to the brilliant appearance of this mineral (especially
As the spark plug also seals the combustion chamber of the engine when installed, the seals ensure there is no leakage from the combustion chamber. A mechanical seal is a device which helps join systems or mechanisms together by preventing leakage (e The seal is typically made by the use of a multi-layer braze as there are no braze compositions that will wet both the ceramic and metal case and therefore intermediary alloys are required. Brazing is a joining process whereby a Filler metal or Alloy is heated to melting temperature above - or by the traditional definition in the United States Wetting is the contact between a liquid and a solid surface resulting from intermolecular interactions when the two are brought together An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has
The metal case (or the "jacket" as many people call it) of the spark plug bears the torque of tightening the plug, serves to remove heat from the insulator and pass it on to the cylinder head, and acts as the ground for the sparks passing through the center electrode to the side electrode. As it acts as the ground, it can be harmful if touched while igniting.
The tip of the insulator surrounding the center electrode is within the combustion chamber and directly affects the spark plug performance, particularly the heat range.
The side electrode is made from high nickel steel and is welded to the side of the metal case. Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 The side electrode also runs very hot, especially on projected nose plugs. Some spark plug designs use multiple side electrodes that do not overlap the center electrode.
The center electrode is connected to the terminal through an internal wire and commonly a ceramic series resistance to reduce emission of radio noise from the sparking. The tip can be made of a combination of copper, nickel-iron, chromium, or precious metals. Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Nickel (ˈnɪkəl is a metallic Chemical element with the symbol Ni and Atomic number 28 Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Chromium (ˈkroʊmiəm is a Chemical element which has the symbol Cr and Atomic number 24 Precious Metal is the eighteenth episode in the of the popular American Crime drama, which is set in Las Vegas, Nevada. In the late seventies, the development of engines reached a stage where the ‘heat range’ of conventional spark plugs with solid nickel alloy centre electrodes was unable to cope with their demands. A plug that was ‘cold’ enough to cope with the demands of high speed driving would not be able to burn off the carbon deposits caused by stop-start urban conditions, and would foul in these conditions, making the engine misfire. Similarly, a plug that was ‘hot’ enough to run smoothly in town, could actually melt when called upon to cope with extended high speed running on motorways, causing serious damage to the engine.  The answer to this problem, devised by the spark plug manufacturers, was a centre electrode that carried the heat of combustion away from the tip more effectively than was possible with a solid nickel alloy. Copper was the material chosen for the task and a method for manufacturing the Copper cored center electrode was created by Floform. prod concern = This article doesn't establish notability per [[WPN]]
The center electrode is usually the one designed to eject the electrons (the cathode) because it is the hottest (normally) part of the plug; it is easier to emit electrons from a hot surface, because of the same physical laws that increase emissions of vapor from hot surfaces (see Thermionic emission). A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device Thermionic emission is the flow of Charge carriers from a surface or over some other kind of Electrical potential barrier caused by thermal vibrational energy In addition, electrons are emitted where the electrical field strength is greatest; this is from wherever the radius of curvature of the surface is smallest, i. e. from a sharp point or edge rather than a flat surface (see Corona discharge). In Electricity, a corona discharge is an Electrical discharge brought on by the Ionization of a Fluid surrounding a conductor, which It would be easiest to pull electrons from a pointed electrode but a pointed electrode would erode after only a few seconds. Instead, the electrons emit from the sharp edges of the end of the electrode; as these edges erode, the spark becomes weaker and less reliable.
At one time it was common to remove the spark plugs, clean deposits off the ends either manually or with specialized sandblasting equipment and file the end of the electrode to restore the sharp edges, but this practice has become less frequent as spark plugs are now merely replaced, at much longer intervals. Sandblasting or Bead blasting is a generic term for the process of smoothing shaping and cleaning a hard surface by forcing solid particles across that surface at high speeds The development of precious metal high temperature electrodes (using metals such as yttrium, iridium, platinum, tungsten, or palladium, as well as the relatively prosaic silver or gold) allows the use of a smaller center wire, which has sharper edges but will not melt or corrode away. Yttrium (ˈɪtriəm is a Chemical element with symbol Y and Atomic number 39 Iridium (ɪˈrɪdiəm is a Chemical element that has the symbol Ir and Atomic number 77 Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 Tungsten (ˈtʌŋstən also known as wolfram (/ˈwʊlfrəm/ is a Chemical element that has the symbol W and Atomic number 74 Palladium (pronounced \pəˈleɪdiəm\ is a rare and lustrous silvery-white metal that was discovered in 1803 by William Hyde Wollaston, who named it palladium after the Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 The smaller electrode also absorbs less heat from the spark and initial flame energy. At one point, Firestone marketed plugs with polonium in the tip, under the questionable theory that the radioactivity would ionize the air in the gap, easing spark formation. The Firestone Tire and Rubber Company was founded by Harvey Firestone in 1900 to supply pneumatic tires for wagons buggies and other forms of wheeled transportation Polonium (pəˈloʊniəm is a Chemical element with the symbol Po and Atomic number 84 discovered in 1898 by Marie and Pierre Curie (See external link below)
Spark plugs are typically designed to have a spark gap which can be adjusted by the technician installing the spark plug, by the simple method of bending the ground electrode slightly to bring it closer to or further from the center electrode. The belief that plugs are properly gapped as delivered in their box from the factory is only partially true, as proven by the fact that the same plug may be specified for several different engines, requiring a different gap for each. It can depend on the engine: new spark plugs might be pre-gapped for a V-8 engine, installing all 8 plugs unchanged; however if installed in a 6-cylinder engine, all (6) plugs would be require re-gapping.
A spark plug gap gauge is a disc with a sloping edge, or with round wires of precise diameters, and is used to measure the gap; use of a feeler gauge with flat blades instead of round wires, as is used on distributor points or valve lash, will give erroneous results, due to the shape of spark plug electrodes. In Engineering, a gauge or gage, is used to make Measurements Various types of gauges include A feeler gauge is a simple Tool used to measure gap-widths The feeler gauge was first patented in 1954 by Andrejs Muiza a Latvian immigrant to the United States (Nashville A distributor is a device in the Ignition system of an Internal combustion engine that routes High voltage from the Ignition coil to the A poppet valve is a Valve consisting of a hole usually round or oval and a tapered plug usually a disk shape on the end of a shaft also called a valve stem The simplest gauges are a collection of keys of various thicknesses which match the desired gaps and the gap is adjusted until the key fits snugly. With current engine technology, universally incorporating solid state ignitions and computerized fuel injection, the gaps used are much larger than in the era of carburetors and breaker point distributors, to the extent that spark plug gauges from that era are much too small for measuring the gaps of current cars. Fuel injection is a system for mixing fuel with air in an Internal combustion engine.
The gap adjustment can be fairly critical, and if it is maladjusted the engine may run badly, or not at all. A narrow gap may give too small and weak a spark to effectively ignite the fuel-air mixture, while a gap that is too wide might prevent a spark from firing at all. Either way, a spark which only intermittently fails to ignite the fuel-air mixture may not be noticeable directly, but will show up as a reduction in the engine's power and fuel efficiency. The main issues with spark plug gaps are:
A properly gapped plug will be wide enough to burn hot, but not so wide that it skips or misses at high speeds, causing that cylinder to drag, or the engine to begin to rattle.
As a plug ages, and the metal of both the tip and hook erode, the gap will tend to widen; therefore experienced mechanics often set the gap on new plugs at the engine manufacturer's minimum recommended gap, rather than in the center of the specified acceptable range, to ensure longer life between plug changes. On the other hand, since a larger gap gives a "hotter" or "fatter" spark and more reliable ignition of the fuel-air mixture, and since a new plug with sharp edges on the center electrode will spark more reliably than an older, eroded plug, experienced mechanics also realize that the maximum gap specified by the engine manufacturer is the largest which will spark reliably even with old plugs and will in fact be a bit narrower than necessary to ensure sparking with new plugs; therefore, it is possible to set the plugs to an extremely wide gap for more reliable ignition in high performance applications, at the cost of having to replace or re-gap the plugs much more frequently, as soon as the tip begins to erode.
Over the years variations on the basic spark plug design have attempted to provide either better ignition, longer life, or both. Such variations include the use of two, three, or four equally spaced ground electrodes surrounding the center electrode. Other variations include using a recessed center electrode surrounded by the sparkplug thread, which effectively becomes the ground electrode. Also there is the use of a V-shaped notch in the tip of the ground electrode.
Most spark plugs seal to the cylinder head with a hollow metal washer which is crushed slightly between the flat surface of the head and that of the plug, just above the threads. If the torque used to install the plugs is not excessive, the washer can be reused when the plug is removed and reinserted, although this practice is, strictly speaking, not recommended and replacement washers are available.
Ford engines, however, were once distinct in using a tapered hole and a matching taper on the bottom of the plug above the threads, in order to seal the plug. Ford Motor Company is an American Multinational corporation and the world's fourth largest automaker based on Worldwide vehicle sales, following The torque for installing and removing these plugs was higher and it was easier to break them if the wrench was applied partially off axis.
More recently, some types of Ford Fiesta, and Ka also had a similar sealing system. The Ford Ka is a City car from the Ford Motor Company marketed in Europe and elsewhere The torque required to install these plugs is less than with the above type, and it is extremely critical that they not be overtightened, since overtightening can result in it being difficult or impossible to remove them. In addition, they have been known to corrode into the cylinder head, particularly if left in too long between removals. In such a situation, it is not unknown for a plug to snap below the hexagonal nut, leaving just the threaded portion (and the outer electrode) in the cylinder head. Ford has on occasion issued TSB's reminding technicians to use the correct methods of installation. Technical Service Bulletins, or TSB's are recommended procedures for repairing vehicles An auto mechanic (or car mechanic in British English and motor mechanic in Australian English) is a Mechanic who specializes in
The length of the threaded portion of the plug should be closely matched to the thickness of the head. In an Internal combustion engine, the cylinder head sits atop the cylinders and consists of a platform containing part of the Combustion chamber and the If a plug extends too far into the combustion chamber, it may be struck by the piston, damaging the engine internally. Less dramatically, if the threads of the plug extend into the combustion chamber, the sharp edges of the threads act as point sources of heat which may cause preignition; in addition, deposits which form between the exposed threads may make it difficult to remove the plugs, even damaging the threads on aluminium heads in the process of removal. The protrusion of the tip into the chamber also affects plug performance, however; the more centrally located the spark gap is, generally the better the ignition of the air-fuel mixture will be, although experts believe the process is actually much more complex and dependent on combustion chamber shape. On the other hand, if an engine is "burning oil", the excess oil leaking into the combustion chamber tends to foul the plug tip and inhibit the spark; in such cases, a plug with less protrusion than the engine would normally call for often collects less fouling and performs better, for a longer period. In fact, special "antifouling" adapters are sold which fit between the plug and the head to reduce the protrusion of the plug for just this reason, on older engines with severe oil burning problems; this will cause the ignition of the fuel-air mixture to be less effective, but in such cases, this is of lesser significance.
The operating temperature of a spark plug is the actual physical temperature at the tip of the spark plug within the running engine. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature This is determined by a number of factors, but primarily the actual temperature within the combustion chamber. There is no direct relationship between the actual operating temperature of the spark plug and spark voltage. However, the level of torque currently being produced by the engine will strongly influence spark plug operating temperature because the maximum temperature and pressure occurs when the engine is operating near peak torque output (torque and RPM directly determine the power output). A torque (τ in Physics, also called a moment (of force is a pseudo- vector that measures the tendency of a force to rotate an object about In Physics, power (symbol P) is the rate at which work is performed or energy is transmitted or the amount of energy required or expended for The temperature of the insulator responds to the thermal conditions it is exposed to in the combustion chamber but not vice versa. If the tip of the spark plug is too hot it can cause pre-ignition leading to detonation/knocking and damage may occur. Knocking (also called knock, detonation or spark knock, pinking in UK English or pinging in US English in spark-ignition If it is too cold, electrically conductive deposits may form on the insulator causing a loss of spark energy or the actual shorting-out of the spark current.
A spark plug is said to be "hot" if it is a better heat insulator, keeping more heat in the tip of the spark plug. A spark plug is said to be "cold" if it can conduct more heat out of the spark plug tip and lower the tip's temperature. Whether a spark plug is "hot" or "cold" is known as the heat range of the spark plug. The heat range of a spark plug is typically specified as a number, with some manufacturers using ascending numbers for hotter plugs and others doing the opposite, using ascending numbers for colder plugs.
The heat range of a spark plug (i. e. in scientific terms its thermal conductivity characteristics) is affected by the construction of the spark plug: the types of materials used, the length of insulator and the surface area of the plug exposed within the combustion chamber. In Physics, thermal conductivity, k is the property of a material that indicates its ability to conduct Heat. An insulator, also called a Dielectric, is a material that resists the flow of Electric current. Surface area is the measure of how much exposed Area an object has For normal use, the selection of a spark plug heat range is a balance between keeping the tip hot enough at idle to prevent fouling and cold enough at maximum power to prevent pre-ignition leading to engine knocking. Knocking (also called knock, detonation or spark knock, pinking in UK English or pinging in US English in spark-ignition By examining "hotter" and "cooler" spark plugs of the same manufacturer side by side, the principle involved can be very clearly seen; the cooler plugs have more substantial ceramic insulators filling the gap between the center electrode and the shell, effectively carrying off the heat, while the hotter plugs have less ceramic material, so that the tip is more isolated from the body of the plug and retains heat better.
Heat from the combustion chamber escapes through the exhaust gases, the side walls of the cylinder and the spark plug itself. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature The heat range of a spark plug has only a minute effect on combustion chamber and overall engine temperature. A cold plug will not materially cool down an engine's running temperature. (Too hot of a plug may, however, indirectly lead to a runaway pre-ignition condition that can increase engine temperature. ) Rather, the main effect of a "hot" or "cold" plug is to affect the temperature of the tip of the spark plug.
It was common before the modern era of computerized fuel injection to specify at least a couple of different heat ranges for plugs for an automobile engine; a hotter plug for cars which were mostly driven mildly around the city, and a colder plug for sustained high speed highway use. This practice has, however, largely become obsolete now that cars' fuel/air mixtures and cylinder temperatures are maintained within a narrow range, for purposes of limiting emissions. Racing engines, however, still benefit from picking a proper plug heat range. Very old racing engines will sometimes have two sets of plugs, one just for starting and another to be installed once the engine is warmed up, for actually driving the car.
The spark plug's firing end will be affected by the internal environment of the combustion chamber. As the spark plug can be removed for inspection, the effects of combustion on the plug can be examined. An examination, or "reading" of the characteristic markings on the firing end of the spark plug can indicate conditions within the running engine. The spark plug tip will bear the marks as evidence of what is happening inside the engine. Usually there is no other way to know what is going on inside an engine running at peak power. Engine and spark plug manufacturers will publish information about the characteristic markings in spark plug reading charts (e. g. a general spark plug reading chart)
A light brownish discoloration of the tip of the block indicates proper operation; other conditions may indicate malfunction. For example, a sandblasted look to the tip of the spark plug means persistent, light detonation is occurring, often unheard. Knocking (also called knock, detonation or spark knock, pinking in UK English or pinging in US English in spark-ignition The damage that is occurring to the tip of the spark plug is also occurring on the inside of the cylinder. Heavy detonation can cause outright breakage of the spark plug insulator and internal engine parts before appearing as sandblasted erosion but is easily heard. As another example, if the plug is too cold, there will be deposits on the nose of the plug. Conversely if the plug is too hot, the porcelain will be porous looking, almost like sugar. The material which seals the center electrode to the insulator will boil out. Sometimes the end of the plug will appear glazed, as the deposits have melted.
An idling engine will have a different impact on the spark plugs than one running at full throttle. A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction Spark plug readings are only valid for the most recent engine operating conditions and running the engine under different conditions may erase or obscure characteristic marks previously left on the spark plugs. Thus, the most valuable information is gathered by running the engine at high speed and full load, immediately cutting the ignition off and stopping without idling or low speed operation and removing the plugs for reading.
Spark plug reading viewers, which are simply combined flashlight/magnifiers, are available to improve the reading of the spark plugs.
Once again, however, the practice of reading spark plugs has largely become obsolete now that cars' fuel/air mixtures and cylinder temperatures are maintained within a narrow range, but is still valuable for racing applications.
A matter of some debate is the "indexing" of plugs upon installation, usually only for high performance or racing applications; this involves installing them so that the open area of the spark gap, not shrouded by the ground electrode, faces the center of the combustion chamber, towards the intake valve, rather than the wall. Many experts believe that this will maximize the exposure of the fuel-air mixture to the spark, and therefore result in better ignition; others, however, believe that this is useful only to keep the ground electrode out of the way of the piston in ultra-high-compression engines if clearance is insufficient. The compression ratio is a single number that can be used to predict the performance of any engine particularly piston engines (but can be used on essentially any Internal-combustion In any event, this is accomplished by marking the location of the gap on the outside of the plug, installing it, and noting the direction in which the mark faces; then the plug is removed and additional washers are added so as to change the orientation of the tightened plug. This must be done individually for each plug, as the orientation of the gap with respect to the threads of the shell is random. Randomness is a lack of order Purpose, cause, or predictability