Spark Plug Cleaner and Tester ABSTRACT Ignition system is one of the most important parts in motorcycle spark ignition (SI) engine. If prolems occur on this system! the comustion process cannot e done and these results the engine cannot e start. Typically Typically motorcycle motorcycle users do not use a proper tool to diagnose the prolem. Thus they are e"posed to high #oltage shock ha$ard. A tool is needs to diagnose the prolem. The main purpose of this report is to design and de#elop a spark plug tester for motorcycle user to test the spark plug and ignition %ire connecti#ity. Thus the risk of high #oltage shock %ill e minimi$ed. This report %ill sho% the process design and de#elopment of the portale spark plug tester. The de#elopment of this de#ice is start from product architecture that descripts all function and elements of the components in this de#ice.
S&'PSIS Ignition system is one of the most particular parts of motorcycle that causes of the malfunction of an engine. The most crucial parts of this system are the spark plug. The spark plug need to supply a proper spark to the engine. If the proper spark not eing supplied to the engine! the com comus usti tion on proc proces ess s cann cannot ot e done done.. The The pro prole lem m of igni ignitio tion n cir circuit cuit connecti#ity may pre#ent the engine from eing turned on ecause it cannot allo% the current to spark plug. These %ill caused the spark plug cannot ale to create the spark to start the comustion process. The critical factor of this prolem is that it must e identied at an early stage of the diagnosis efore repairing. Typically! motorcycle user does not use a proper tool to test the spark plug thus they are e"posing themsel#es to the risk of high #oltage shock. They also need to use multimeter to check the connecti#ity of ignition circuit.
The most spark plugs don*t need to e replaced+ they are simply less e,cient ecause of the caron content spreader o#er the spark plug. The electr electrode ode is prese present nt in the centre centre of the spark spark plug. plug. In the spark spark plug al%ays %e need to maintain the gap et%een the electrode and the spark pin. -hile on engine running the high #oltage current %ill e passing through the spark plug to generate the spark inside the engine to urn the air fuel mi"ture inside the engine cylinder. ue to this process the caron cont conten entt sp sprread ead o#er o#er the the sp spar ark k plug plug.. By runn runnin ing g the the #ehi #ehicl cle e %ith %ith out out cleaning the spark plugs causes many damages to the #ehicle. /or eg! mile mileag age e drop drop!! prod produc uce e soun sound! d! dama damage ge the the cyli cylind nder er due due to une# une#en en se0uen se0uencin cing g of spark spark produ produced ced inside inside the cylind cylinder er.. After fter remo remo#in #ing g the caron content in the spark plug %e can reuse the spark plug. It %ill gi#e more e,ciency as compare to old one. Automoile %orkshops the spark plug cleaning and e"act testing consumes more time y using the manual testing! so make simplication setup in testing and cleaning! %e are going to design and faricate a single setup to sa#e the time.
ry Sand Arasion Tester Application This tester used to determine the %ear resistance of materials to scratching arasion under specied condition using dry sand1alumina 0uarts1silicon caride as arasi#e /eature Conforms to manually controlled preset re#olution counter for particular time.
/igure 23 The typical %ay of a motorcycle user to check the spark of spark plug
/igure 43 Check the connecti#ity of ignition circuit y using multimeter
A special tool is needed to properly diagnosing the prolem. 5ence! there is a need to design and de#elop a spark plug tester for a motorcycle user to test the %ire and spark plug conducti#ity.
B67CTI87 The o9ecti#e of this pro9ect is to design and de#elop a portale spark plug tester for the motorcycle user that allo% the motorcycle user to test the connecti#ity of ignition %ire and spark plug %ithout e"posing themsel#es to the risk of high #oltage shock.
SCP7 The scopes of this study include3 2. Come out %ith a design of a portale spark plug tester %ith dual functions 4. A de#elopment of a prototype to test out the conceptual design
:IT7RAT;R7 R78I7:iterature re#ie% is a pulished research or information that %ill e used as reference and guide for a ne% research. This literature re#ie% co#ers the pre#ious study and information that are related to this pro9ect. The information %ill e used as #alue added or reference for this pro9ect. The information can e found from ook! internet! 9ournal! paper %ork and so on.
<TRC&C:7 I='ITI' S&ST7< In early motorcycle internal comustion engine design de#elopment there are three elements that are important. The elements of engine design are ignition! caruretion and lurication. To achie#e the rotational force it is necessary to make the engine crank y using force from e"plosion of a sustance. The sustance that is most commonly used is a mi"ture of fuel and air and ignition source that %ill cause the e"plosion. In early de#elopment of internal comustion engine! oth mi"ing of fuel> air mi"ture and igniting are 0uite tricky and dangerous. (Ste#en 7. Alford! Su$anne /erriss ! 4??@) 7arly design of ignition system undergoes three type of system that is ame! hot tue and magneto ignition. Bet%een all the system! the magneto system is commonly use ecause it has a controlled spark that ignites the mi"ture. These systems use an e"ternal po%er like attery! rather than using an internal y%heel magnet to create a spark to ignite the mi"ture. These technologies lasted until 2?s ecause introduced of more ad#anced ignition system. (Ste#en 7. Alford! Su$anne /erriss! 4??@). /or more ad#anced ignition system! the rst modern spark ignition systems use in motorcycle is eginning in late
2?s %ere of points and condenser type. This ignition system %as used for a long time as it facilitate and ha#e a great reliaility ut eing mechanical! it has some inherent failings. :ater it is enhanced to electronic ignition system. (Adam -ade! 4??D) The main purpose of an ignition System is a spark that %ill ignite the air and fuel mi"ture in the comustion chamer. /or each cylinder in the engine! the ignition system has three main functions that are to generate enough electrical spark to ignite the mi"ture in comustion chamer! must maintain the spark to allo% complete comustion! and it has to deli#er the spark on time to each cylinder. (7d%ard Ado ! 4?24)
/igure E3 Simplied dra%ing of the asic components of an ignition system ( 7d%ardAdo ! 4?24)
/igure E sho%s the asic component of ignition system and the connections and interactions et%een components to allo% the system to e functional. The functions of all components are diFerent. Po%er source uses the magnetism principle to produce a #oltage and ignition s%itch allo%s the po%er source to pro#ide electrical po%er to the ignition system. In ignition coil the current %ill pass through the transformer. /rom 24 #olt input! the ignition coil %ill produce 4?!??? to ?!??? #olts or e#en more and the high #oltage is connected to the spark plug. Then spark plug %ill
create the spark to start the comustion of air>fuel mi"ture. (7d%ard Ado ! 4?24)
Spark Plug A spark plug is a de#ice for deli#ering electric current from an ignition system to the comustion chamer of a spark>ignition engine to ignite the compressed fuel1air mi"ture y an electric spark! %hile containing comustion
pressure
%ithin
the
engine.
A
spark
plug
has
a
metal threaded shell! electrically isolated from a central electrode y a porcelain insulator. The central electrode! %hich may contain a resistor! is connected y a hea#ily insulated %ire to the output terminal of an ignition coil or magneto. The spark plugGs metal shell is scre%ed into the engineGs cylinder head and thus electrically grounded. The central electrode protrudes through the porcelain insulator into the comustion chamer! forming one or more spark gaps et%een the inner end of the central electrode and usually one or more protuerances or structures attached to the inner end of the threaded shell and designated the side! earth! or ground electrode.
Operation The plug is connected to the high #oltage generated y an ignition coil or magneto. As current o%s from the coil! a #oltage de#elops et%een the central and side electrodes. Initially no current can o% ecause the fuel and air in the gap is an insulator! ut as the #oltage rises further it egins to change the structure of the gases et%een the electrodes. nce the #oltage e"ceeds the dielectric strength of the gases! the gases ecome ioni$ed. The ioni$ed gas ecomes a conductor and allo%s current to o% across the gap. Spark plugs usually re0uire #oltage of 24!???H4!??? #olts or more to JreJ properly! although it can go up to D!??? #olts. They supply higher current during the discharge process! resulting in a hotter and longer>duration spark. As the current of electrons surges across the gap! it raises the temperature of the spark channel to ?!??? K . The intense heat in the spark channel causes the ioni$ed gas to e"pand #ery 0uickly! like a small e"plosion. This is the JclickJ heard %hen oser#ing a spark! similar to lightning and thunder. The heat and pressure force the gases to react %ith each other! and at the end of the spark e#ent there should e a small all of re in the spark gap as the gases urn on their o%n. The si$e of this reall! or kernel! depends on the e"act composition of the mi"ture et%een the electrodes and the le#el of comustion chamer turulence at the time of the spark. A small kernel %ill make the engine run as though the ignition timing %as retarded! and a large one as though the timing %as ad#anced.
Spark plug construction A spark plug is composed of a shell! insulator and the central conductor. It passes through the %all of the comustion chamer and therefore must
also
seal
the
comustion
chamer
against
high
pressures
and
temperatures %ithout deteriorating o#er long periods of time and e"tended use. Spark plugs are specied y si$e! either thread or nut ! sealing type and spark gap. Common thread (nut) si$es in 7urope are 2? mm (2 mm)! 2D mm (42 mm+ sometimes! 2 mm)! and 2L mm (4D mm! sometimes! 42 mm). In the ;nited States! common thread (nut) si$es are 2?mm (2mm)! 24mm (2Dmm! 2mm or 2@.mm)! 2Dmm (2mm! 4?.Emm) and 2Lmm (4?.Emm).
Parts of the plug Terminal The top of the spark plug contains a terminal to connect to the ignition system. The e"act terminal construction #aries depending on the use of the spark plug.
Insulator The main part of the insulator is typically made from sintered alumina! a #ery hard ceramic material %ith high dielectric strength! printed %ith the manufacturerGs name and identifying marks! then gla$ed to impro#e resistance to surface spark tracking. Its ma9or functions are to pro#ide
mechanical support and electrical insulation for the central electrode! %hile also pro#iding an e"tended spark path for asho#er protection. This e"tended portion! particularly in engines %ith deeply recessed plugs! helps e"tend the terminal ao#e the cylinder head so as to make it more readily accessile.
Ribs By lengthening the surface et%een the high #oltage terminal and the grounded metal case of the spark plug! the physical shape of the ris functions to impro#e the electrical insulation and pre#ent 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 e#en in the presence of dirt and
moisture. Some spark
plugs
are
manufactured %ithout
ris+
impro#ements in the dielectric strength of the insulator make them less important
Insulator tip n modern (post 2E?s) spark plugs! the tip of the insulator protruding into the comustion chamer is the same sintered aluminium o"ide (alumina) ceramic as the upper portion! merely ungla$ed. It is designed to %ithstand ? MC (2!4?? M/) and ? k8. The dimensions of the insulator and the metal conductor core determine the heat range of the plug. Short insulators are usually JcoolerJ plugs! %hile JhotterJ plugs are made %ith a lengthened path to the metal ody! though this also depends on the thermally conducti#e metal core. lder spark plugs! particularly in aircraft! used an insulator made of stacked layers of mica! compressed y tension in the centre electrode.
-ith the de#elopment of leaded petrol in the 2E?s! lead deposits on the mica ecame a prolem and reduced the inter#al et%een needing to clean the spark plug. Sintered alumina %as de#eloped y Siemens in =ermany to counteract this.NLO Sintered alumina is a superior material to mica or porcelain ecause it is a relati#ely good thermal conductor for a ceramic! it maintains good mechanical strength and (thermal) shock resistance at higher temperatures! and this aility to run hot allo%s it to e run at Jself cleaningJ temperatures %ithout rapid degradation. It also allo%s a simple single piece construction at lo% cost ut high mechanical reliaility.
Seals Because the spark plug also seals the comustion chamer or the engine %hen installed! seals are re0uired to ensure there is no leakage from the comustion chamer. The internal seals of modern plugs are made of compressed glass1metal po%der! ut old style seals %ere typically made y the use of a multi>layer ra$e. The e"ternal seal is usually a crush %asher! ut some manufacturers use the cheaper method of a taper interface and simple compression to attempt sealing.
Metal case/shell The metal case1shell (or the 9acket! as many people call it) of the spark plug %ithstands the tor0ue of tightening the plug! ser#es to remo#e heat from the insulator and pass it on to the cylinder head! and acts as the ground for the sparks passing through the central electrode to the side electrode. Spark plug threads are cold rolled to pre#ent thermal cycle fatigue. ItGs important to install spark plugs %ith the correct Jreach!J or thread length. Spark plugs can #ary in reach from ?.? to 4.D cm (?.?E@
to
2.?DE in)!
such
for
automoti#e
and
small
engine
applications! Also! a marine spark plugGs shell is doule>dipped! $inc> chromate coated metal.
Central electrode The central electrode is connected to the terminal through an internal %ire and commonly a ceramic series resistance to reduce emission of R/ noise from the sparking. 'on>resistor spark plugs! commonly sold %ithout an JRJ in the plug type part numer! lack this element to reduce electro> magnetic interference %ith radios and other sensiti#e e0uipment. The tip can e made of a comination of copper! nickel>iron! chromium! or nole metals. In the late 2@?s! the de#elopment of engines reached a stage %here the heat range of con#entional spark plugs %ith solid nickel alloy centre electrodes %as unale to cope %ith their demands. A plug that %as cold enough to cope %ith the demands of high speed dri#ing %ould not e ale to urn oF the caron deposits caused y stopHstart uran conditions! and %ould foul in these conditions! making the engine misre. Similarly! a plug that %as hot enough to run smoothly in to%n could melt %hen called upon to cope %ith e"tended high speed running on motor%ays. The ans%er to this prolem! de#ised y the spark plug manufacturers! %as to use a diFerent material and design for the centre electrode that %ould e ale to carry the heat of comustion a%ay from the tip more eFecti#ely than a solid nickel alloy could. Copper %as the material chosen for the task and a method for manufacturing the copper> cored centre electrode %as created y /loform. The central electrode is usually the one designed to e9ect the electrons (the cathode! i.e. negati#e polarityN22O) ecause it is the hottest (normally) part of the plug+ it is easier to emit electrons from a hot surface! ecause of the same physical la%s that increase emissions of #apor from hot surfaces (see thermionic emission). In addition! electrons are emitted %here the electrical eld strength is greatest+ this is from %here#er the radius of cur#ature of the surface is smallest! from a sharp point or edge rather than a at surface (see corona discharge). It %ould e easiest to pull electrons from a pointed electrode ut a pointed electrode %ould
erode after only a fe% seconds. Instead! the electrons emit from the sharp edges of the end of the electrode+ as these edges erode! the spark ecomes %eaker and less reliale. At one time it %as common to remo#e the spark plugs! clean deposits oF the ends either manually or %ith speciali$ed sandlasting e0uipment and le the end of the electrode to restore the sharp edges! ut this practice has ecome less fre0uent for three reasons3 2. cleaning %ith tools such as a %ire rush lea#es traces of metal on the insulator %hich can pro#ide a %eak conduction path and thus %eaken the spark (increasing emissions) 4. plugs are so cheap relati#e to laor cost! economics dictate replacement! particularly %ith modern long>life plugs. E. iridium and platinum plugs that ha#e longer lifetimes than copper ha#e ecome more common The de#elopment of nole metal high temperature electrodes (using metals such as yttrium! iridium! tungsten! or palladium! as %ell as the relati#ely high #alue platinum! sil#er or gold) allo%s the use of a smaller center %ire! %hich has sharper edges ut %ill not melt or corrode a%ay. These materials are used ecause of their high melting points and duraility! not ecause of their electrical conducti#ity (%hich is irrele#ant in series %ith the plug resistor or %ires). The smaller electrode also asors less heat from the spark and initial ame energy. At one point! /irestone marketed plugs %ith polonium in the tip! under the theory that the radioacti#ity %ould ioni$e the air in the gap! easing spark formation.
Side (ground, earth) electrode The side electrode (also kno%n as the Jground strapJ) is made from high nickel steel and is %elded or hot forged to the side of the metal shell. The
side electrode also runs #ery hot! especially on pro9ected nose plugs. Some designs ha#e pro#ided a copper core to this electrode! so as to increase heat conduction.
J to JJ electrode) than electrical current itself (from JJ to J>J electrode)! it is actually more often from the surface of the side electrode! that is grounded to J>J electrode of the car attery and alternator! %here electrons are e9ected from to%ards central electrode. ThatGs %hy it is important to ha#e edge shaped area or e#en more areas there (9ust like some Bosch spark plugs %ith t%o edges in spear>like head)! that are least e"posed to the erosion forces from comustion process thus keeping ignition system in good %orking
condition
as
long
as
possile
(2?!???H4!??? km N!4??H
2!?? miO for common spark plugs). 7dge or pike is the area from %here the spark 9umps oF most easily (if there are diFerent options for current %ith similar gap et%een JJ and J>J electrode) and %ith less #oltage drop (since the gap creates resistance in the circuit). Therefore! some spark plugs can e easily and sometimes e#en repeatedly rene%ed y 9ust mild re>sharping these edges (as long as other #ital parts and characteristics of spark plugs are not compromised) to the original %orking state or e#en re> modelating the original side electrode design (%hich is #ery tricky if you are not 0ualied electrician or physicist). But one has to e careful %ith a %elded 9oint side electrode as repeatedly re>ad9usting the gap et%een the electrodes may cause metal fatigue and losing part of the side electrode in the cylinder chamer %ill result in immediate ignition malfunction and almost certainly result in serious damage to the specially surface>treated cylinder %alls or piston sealing rings. The #ery same prolem can occur as a result of protruding akes due to poor 0uality %elding! since they are prone to ecome loose during prolonged ser#ice life of common spark plug. Therefore! any aking should e treated y ruing oF if spark plug is reused eyond its recommended ser#ice life.
Spark plug gap Spark plugs are typically designed to ha#e a spark gap %hich can e ad9usted y the technician installing the spark plug! y ending the ground electrode slightly. The same plug may e specied for se#eral diFerent engines! re0uiring a diFerent gap for each. Spark plugs in automoiles generally ha#e a gap et%een ?. and 2.L mm (?.?4D and ?.?@2 in). The gap may re0uire ad9ustment from the out>of>the>o" gap. A spark plug gap gauge is a disc %ith a sloping edge! or %ith round %ires of precise diameters! and is used to measure the gap. ;se of a feeler gauge %ith
at
lades
instead
of
round
%ires!
as
is
used
on distriutor points or #al#e lash! %ill gi#e erroneous results! due to the shape of spark plug electrodes The simplest gauges are a collection of keys of #arious thicknesses %hich match the desired gaps and the gap is ad9usted until the key ts snugly. -ith current engine technology! uni#ersally
incorporating
solid
state
ignition
systems
and
computeri$ed fuel in9ection! the gaps used are larger on a#erage than in the era of caruretors and reaker point distriutors! to the e"tent that spark plug gauges from that era cannot al%ays measure the re0uired gaps of current cars 8ehicles using compressed natural gas generally re0uire narro%er gaps than #ehicles using gasoline. The gap ad9ustment can e crucial to proper engine operation. A narro% gap may gi#e too small and %eak a spark to eFecti#ely ignite the fuel>air mi"ture! ut the plug %ill almost al%ays re on each cycle. A gap that is too %ide might pre#ent a spark from ring at all or may misre at high speeds! ut %ill usually ha#e a spark that is strong for a clean urn. A spark %hich intermittently fails to ignite the fuel>air mi"ture may not e noticeale directly! ut %ill sho% up as a reduction in the engineGs po%er and fuel e,ciency.
Variations on the basic design #er the years #ariations on the asic spark plug design ha#e attempted to pro#ide either etter ignition! longer life! or oth. Such #ariations include the use of t%o! three! or four e0ually spaced ground electrodes surrounding the central electrode. ther #ariations include using a recessed central electrode surrounded y the spark plug thread! %hich eFecti#ely ecomes the ground electrode (see Jsurface>discharge spark plugJ! elo%). Also there is the use of a 8>shaped notch in the tip of the ground electrode.
Surface-discharge spark plug A piston engine has a part of the comustion chamer that is al%ays out of reach of the piston+ and this $one is %here the con#entional spark plug is located. A -ankel engine has a permanently #arying comustion area+ and the spark plug is ine#italy s%ept y the tip seals. Clearly! if a spark plug %ere to protrude into the -ankelGs comustion chamer it %ould foul the rotating tip+ and if the plug %ere recessed to a#oid this! the sunken spark might lead to poor comustion. So a ne% type of Jsurface dischargeJ plug %as de#eloped for the -ankel. Such a plug presents an almost at face to the comustion chamer. A stuy centre electrode pro9ects only #ery slightly+ and the entire earthed ody of the plug acts as the side electrode. The ad#antage is that the plug sits 9ust eneath the tip>seal that s%eeps o#er it! keeping the spark accessile to the fuel1air mi"ture. The Jplug gapJ remains constant throughout its life+ and the spark path %ill continually #ary (instead of darting from the centre to the side electrode as in a con#entional plug). -hereas a con#entional side
electrode %ill (admittedly! rarely) come adrift in use and potentially cause engine damage! this is impossile %ith a surface discharge plug! as there is nothing to reak oF. Surface>discharge spark plugs ha#e een produced y inter alia! enso! '=K! Champion and Bosch.
Sealing to the cylinder head use hollo% or folded metal %asher %hich is crushed slightly et%een the at surface of the head and that of the plug! 9ust ao#e the threads. Some spark plugs ha#e a tapered seat that uses no %asher. The tor0ue for installing these plugs is supposed to e lo%er than a %asher>sealed plug.N2DO Spark plugs %ith tapered seats should ne#er e installed in #ehicles %ith heads re0uiring %ashers! and #ice #ersa. ther%ise! a poor seal or incorrect reach %ould result ecause of the threads not properly seating in the heads.
Tip protrusion The length of the threaded portion of the plug should e closely matched to the thickness of the head. If a plug e"tends too far into the comustion chamer! it may e struck y the piston! damaging the engine internally. :ess dramatically! if the threads of the plug e"tend into the comustion chamer! the sharp edges of the threads act as point sources of heat %hich may cause pre>ignition+ in addition! deposits %hich form et%een the e"posed threads may make it di,cult to remo#e the plugs! e#en damaging the threads on aluminium heads in the process of remo#al. The protrusion of the tip into the chamer also aFects plug performance! ho%e#er+ the more centrally located the spark gap is! generally the etter the ignition of the air>fuel mi"ture %ill e! although e"perts elie#e the process is more comple" and dependent on comustion chamer shape. n the other hand! if an engine is Jurning oilJ! the e"cess oil leaking into the comustion chamer tends to foul the plug tip and inhiit the spark+ in such cases! a plug %ith less protrusion than the engine %ould normally
call for often collects less fouling and performs etter! for a longer period. In fact! special Janti>foulingJ adapters are sold %hich t et%een the plug and the head to reduce the protrusion of the plug for 9ust this reason! on older engines %ith se#ere oil urning prolems+ this %ill cause the ignition of the fuel>air mi"ture to e less eFecti#e! ut in such cases! this is of lesser signicance.
eat !ange The operating
temperature of
a
spark
plug
is
the
actual
physical temperature at the tip of the spark plug %ithin the running engine! normally et%een ?? and L?? MC (E4 and 2!D@4 M/). This is important ecause it determines the e,ciency of plug self>cleaning and is determined y a numer of factors! ut primarily the actual temperature %ithin the comustion chamer. There is no direct relationship et%een the actual operating temperature of the spark plug and spark #oltage. 5o%e#er! the le#el of tor0ue currently eing produced y the engine %ill strongly inuence spark plug operating temperature ecause the ma"imal temperature and pressure occur %hen the engine is operating near peak tor0ue
output
(tor0ue
and
rotational
speed
directly
determine
the po%er output). The temperature of the insulator responds to the thermal conditions it is e"posed to in the comustion chamer! ut not #ice #ersa. If the tip of the spark plug is too hot! it can cause pre>ignition or sometimes detonation1knocking! and damage may occur. If it is too cold! electrically conducti#e 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 e JhotJ if it is a etter heat insulator! keeping more heat in the tip of the spark plug. A spark plug is said to e JcoldJ if it can conduct more heat out of the spark plug tip and lo%er the tipGs temperature. -hether a spark plug is JhotJ or JcoldJ is kno%n as the heat range of the spark plug. The heat range of a spark plug is typically specied as a numer! %ith some manufacturers using ascending numers for hotter plugs! and others doing the opposite H using ascending numers for colder plugs. The heat range of a spark plug is aFected y the construction of the spark plug3 the types of materials used! the length of insulator and the surface area of the plug e"posed %ithin the comustion chamer. /or normal use! the selection of a spark plug heat range is a alance et%een keeping the tip hot enough at idle to pre#ent fouling and cold enough at ma"imal po%er to pre#ent pre>ignition or engine knocking. By e"amining JhotterJ and JcoolerJ spark plugs of the same manufacturer side y side! the principle in#ol#ed can e #ery clearly seen+ the cooler plugs ha#e a more sustantial ceramic insulator lling the gap et%een the center electrode and the shell! eFecti#ely allo%ing more heat to e carried oF y the shell! %hile the hotter plugs ha#e less ceramic material! so that the tip is more isolated from the ody of the plug and retains heat etter. 5eat from the comustion chamer escapes through the e"haust gases! the side %alls of the cylinder and the spark plug itself. The heat range of a spark plug has only a minute eFect on comustion chamer and o#erall engine temperature. A cold plug %ill not materially cool do%n an engineGs running temperature. (A too hot plug may! ho%e#er! indirectly lead to a runa%ay pre>ignition condition that can increase engine temperature.) Rather! the main eFect of a JhotJ or JcoldJ plug is to aFect the temperature of the tip of the spark plug. It %as common efore the modern era of computeri$ed fuel in9ection to specify at least a couple of diFerent heat ranges for plugs for an automoile engine+ a hotter plug for cars that %ere mostly dri#en slo%ly
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 %ithin a narro% range! for purposes of limiting emissions. Racing engines! ho%e#er! still enet from picking a proper plug heat range. 8ery old racing engines %ill sometimes ha#e t%o sets of plugs! one 9ust for starting and another to e installed for dri#ing once the engine is %armed up. Spark plug manufacturers use diFerent numers to denote heat range of
their spark plugs. Figure 4: Illustration of cross sectional of spark plug
7SCRIPTI' of cleaner The spark plug cleaner and tester is of metal construction, and is supplied in both floor and bench models. It is designed to sandblast clean, and make spark gap tests, on 7 /8-inch, !-, 4-, and 8-mm spark plugs. This unit operates from a "-#olt d-c outside po$er source. %atter& clips are pro#ided for this purpose. 'n outside source of compressed air is re(uired for the sandblast cleaning operation. CONTROLS AND INSTRUMENTS
Push Button. The test utton located on the front of the case is pushed to supply ignition #oltage to the spark plug during the gap test. Air 8al#e Control. The air #al#e control is a %ing>type handle on the top of the cleaner>tester! and is marked JAIR.J It has three positions! %hich are marked on the top of the case! namely3 J//!J JAIR!J and JSA'.J This control is used to control the o% of air and sand for sandlast cleaning of plugs. 'eedle 8al#e. The needle #al#e! located et%een the t%o test openings on top of the case! is turned clock%ise to decrease! and counterclock%ise to increase the pressure of air for the spark plug gap test. d. Pressure =age. The pressure gage! mounted in the top of the case at the right>hand test opening! registers the pressure applied duringG the spark plug gap test. It is calirated from ? to E?? pounds per s0uare inch.
The adapters and gaskets are kept on t%o Gposts to the rear of the cleaner>tester %hen not in use. They are used to install diFerent si$e plugs in the test openings. =ap =ages. Three %ire>type gages are supplied %ith the unit for the purpose of checking and ad9usting spark plug gaps. T< >LED D C:7A'7R A' T7ST7R! SPARK P:;=>'o. D?>C>2?22 D. P7RATI'. . Preliminary Instructions. Install cleaner>tester on a ench or other suitale ase %ith tester openings to the front! air control #al#e to the left! and spark plug cleaner opening to the right. Scre% or olt do%n through the holes pro#ided in the ase of the unit. Connect air line from 24 to 2? pounds per s0uare inch air supply to Q1D>inch pipe tapped air inlet to the rear of the air control #al#e. =round the case y connecting the ground clip in the rear of the unit to the nearest suitale %ater pipe or ground pipe. CA;TI'3 Spark plug gap test %ill not e satisfactory %ithout case ade0uately grounded. Remo#e air e"haust ag and screen! and pour 2 to 2214 pounds of arasi#e into sand chamer. Replace ag and screen! and tighten securely in place. Attach attery ciips to 24>#olt storage attery (%hite %ire to negati#e and lack %ire to positi#e terminal).
Sandlast Cleaning. If there are not t%o spark plugs in the gap test openings! e sure the needle #al#e is closed efore doing sandlast cleaning.
outer end of plug %ith a circular motion! so that cleaner last can penetrate all cre#ices! for aout seconds. -ithout remo#ing plug from opening! turn air #al#e 2L? M to the JAIRJ position! and again oscillate plug for a fe% seconds to clear out all particles of loosened caron or cleaning compound. Return the air #al#e to J//J position and remo#e the cleaned plug. Shake out! or 9ar loose any particles of arasi#e remaining et%een the plug porcelain and shell. CA;TI'3 o not turn the air control #al#e to JSA'J position %hen there is no plug in the cleaner opening! as cleaning compound %ould e lo%n out through the cleaner opening at su,cient #elocity
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IC used in machine
LM555 timer
Features
)irect *eplacement for +/ Timing from icroseconds through 0ours 1perates in %oth 'stable and onostable odes
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in9urious.
