• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    An electrically conductive cover which in assembly is received over at least part of a spark plug boot and at least part of a nut portion of a metal body of a spark plug received in the boot. The cover may have an opening through which an arm portion of the boot extends which arm portion receives an electric wire for supplying a current at a high potential voltage to the spark plug.To be published with: Fig 1
    公开号:SE1551661A1
    申请号:SE1551661
    申请日:2015-12-16
    公开日:2016-07-17
    发明作者:L Linton Robby
    申请人:Walbro Llc；
    IPC主号:
    专利说明:

    [1] [0001] This patent application claims the benefit under 35 U.S.C. §ll9(e)of the earlier filed provisional patent application, Ser. No. 62/ l04,403, filedunder 35 U.S.C. §l 1 l(b) on January 16, 2015, Which is incorporated herein in its entirety by reference.
    [3] [0003] Gasoline powered spark ignition internal combustion engines andparticularly light duty and small engines are used on a large variety ofproducts including handheld, laWn and garden, marine, snowmobile and otherhome and commercial products. These engines are typically two-cycle orfour-cycle engines With one or more cylinders and have a spark plug for eachcylinder Which in use initiates combustion of a fuel-and-air mixture in thecylinder. The spark plug is typically threaded or otherwise secured in a borein a metal cylinder head or cylinder of the engine Which provides a ground fora metal shell or body of the spark plug Which has an electrical ground electrode adjacent one end and for installing or removing the spark plug a non- Circular and typically hexagonal nut portion adjacent its other end. Anelectrically conductive center electrode typically With a copper core extendsthrough the metal body With one end spaced by a gap from the groundelectrode and is received in a typically ceramic insulator Which projects fromthe other end of the body and carries an electrically conductive terminalconnected to the center electrode.
    [4] [0004] In use, though an insulated Wire With an end clip removablyconnected to the terminal, a high potential voltage current is supplied to thecenter electrode to produce an arc or spark in the gap. Typically, anelectrically insulating boot is generally coaxially received over the terminaland an exposed portion of the insulator of the spark plug and terrninates shortof or adjacent the upper end of the spark plug shell or body. Typically, theboot has an integral arm portion through Which the insulated electric Wireextends and this arm portion typically is inclined at an acute included angleusually of about 90° or 45° to the longitudinal axis of the main body of theboot and the spark plug. In many small engine applications, in use the highpotential voltage is supplied to this Wire by a so-called switch or modulecontrolling the ignition timing Which is typically part of an electromagnetocapacitive discharge ignition system.
    [5] [0005] When in use in an operating engine, the arcing or spark producedby the spark plug creates electromagnetic interference (EMI) Which mayadversely affect the circuitry of the module controlling ignition timing and/orother engine operations Which adversely affects engine performance or it may adversely affect other electronic circuitry of the product on Which the engine is used or in some instances other devices or products in the vicinity in which the engine is operating.
    [6] [0006] In at least some implementations, an electrically conductive coveris configured to be received over at least a significant portion of the main bodyof a spark plug boot and to extend over at least part of the nut portion of themetal body of the spark plug. The cover may have a f1rm friction fit such asan interference fit with the nut portion of the spark plug body. The cover mayhave a closed end and/or an opening thorough which an arm of the bootextends for receiving a portion of an electric wire for supplying power to aspark plug. The cover may be made of an electrically conductive syntheticrubber material with a surface resistance of less than 8,000 ohms per square and/or a volume resistance of less than 85,000 ohms-centimeter.
    [7] [0007] The following detailed description of certain embo diments and bestmode will be set forth with reference to the accompanying drawings, in which:[0008] FIG. 1 is a an exploded perspective view of one embodiment of theinvention with a portion of an electric circuit inserted therein and a spark plug.
    [9] [0009] FIG. 2 is an end view of one embodiment of the invention.
    [10] [0010] FIG. 3 is a cross-sectional view taken along lines A-A of Figure 2.
    [11] [0011] FIG. 4 is a side view of one embodiment of the invention.
    [12] [0012] FIG. 5 is an enlarged sectional view of one embodiment of the invention received over a spark plug boot assembled on a spark plug.
    [13] [0013] Referring to Figure 1, one embodiment of the invention isgenerally indicated at 10. The invention 10 includes a conductive coverassembly 10 for a spark plug, generally shown at 12. The spark plug 12includes a terrninal 14 that is electrically connected to an electrical circuit,represented by wire 16 and switch 18. The spark plug 12 includes a ceramicbody 20, a ground electrode 22 and a nut surface 24. The nut surface 24 isdisposed between the ceramic body 20 and the ground electrode 22 and is thesurface about which a manual tool is used to tighten the spark plug 12 onto aninternal combustion engine (not shown).
    [14] [0014] The electrical circuit 16 also includes a connector (not shown),which is a spring electrode that is forced over the terrninal 14 to complete theelectrical connection between the switch 18 and the spark plug 12. This springelectrode is covered by a spark plug boot 26 (only partially shown in Figure1).
    [15] [0015] Referring now to all of the Figures, the conductive cover assembly10 includes a base 28. The base 28 def1nes an inner base diameter 30(identified in Figure 3). The inner base diameter 30 complements the nutsurface 24 of the spark plug 12. More specifically, the inner base diameter 30is of a dimension that allows it to be forced over the nut surface 24 of the spark plug 12 in a manner in which the conductive cover assembly 10 is friction fit to the nut surface 24 With enough force to keep the conductivecover assembly 10 in place.
    [16] [0016] The conductive cover assembly 10 includes an conducting cover 32that extends up from the base 28. The conducting cover 32 covers the sparkplug 12 and the spark plug boot 26. More specifically, the conducting cover32 covers the portion of the spark plug 12 that is exposed outside the intemalcombustion engine and the portion of the spark plug boot 26 that is coaxialWith the spark plug 12. As is shown in Figure 1, a portion of the spark plugboot 26 extends out from the conducting cover 32 (discussed in greater detailsubsequently).
    [17] [0017] The conductive cover assembly 10 is fabricated from ethylenepropylene diene monomer (EPDM) rubber. The EPDM rubber is infused Withgraphite such that the EPDM rubber is conductive. The EPDM rubber infusedWith graphite Within the conductive cover assembly 10 creates a groundingshield to protect the area disposed immediately adjacent the spark plugelectrode 14 from electromagnetic interference (EMI). In an altemativeembodiment, the EPDM rubber may be infused With carbon black instead ofgraphite. In a preferred embodiment, the conductive cover assembly 10 has asurface resistivity less than or equal to 108 Qcm and a volume resistivity ofless than or equal to 109 Qcm.
    [18] [0018] The EPDM rubber has been tested to have a hardness of 55 ShoreA at a temperature of 350° Fahrenheit after ten minutes of heating. The tensilestrength of the EPDM rubber is 1,819 psi at the same temperature for the same time.
    [19] [0019] The conducting cover 32 def1nes a cover inner diameter 34 (Figure3) that is less than the inner base diameter 30. A relief surface 36 extendsbetween an inner base surface 38 and an inner cover surface 40. The coverinner diameter 34 may be large enough to create an air gap 42 between theinner cover surface 40 on the one hand and spark plug l2 and the spark plugboot 26 on the other hand. The air gap 42 provides a level of insulation, whichadds to the insulation provided by the spark plug boot 26. Any EMI thatpasses through these layers is dissipated by the conductive properties of theEPDM rubber and the conductive cover assembly l0, which act as a groundedmaterial.
    [20] [0020] The conducting cover 32 includes a closed distal end 44 and acircuit opening 46. The circuit opening 46 is disposed between the closeddistal end 44 and the base 28 of the conductive cover assembly l0. The circuitopening 46 provides access allowing a portion of the spark plug boot 26shown in Figure l to extend out from the conductive cover assembly l0 andallow the electrical circuit l6 to extend into the conductive cover assembly l0.[0021] As shown in FIG. 5, in assembly and in use, the separate coverassembly l0 is received over the main body 50 of the boot 26 which isdisposed on the spark plug l2. The main body 50 of the boot terrninates shortof or bears on the upper end of the spark plug metal shell or body 52, and anarm 54 of the boot projects outwardly through the opening 46 in the coverassembly. The lower base portion 28 of the boot desirably, but notnecessarily, extends over the entire axial extent of the nut portion 56 of the spark plug l2 preferably with a slight interference fit and preferably is slightly stretched Within its elastic limit to provide a f1rm interference fit With the nutportion 156 over substantially the entire axial and circumferential extent of theperipheral nut surface 24 to thereby provide a good electrical connection orgrounding between the cover assembly 10 and the spark plug shell 52. Thisfrictional engagement With the shell may releasably retain the cover on theboot and the spark plug. Desirably, there may also be a slight interference fitbetween at least a portion of the cover sidewall inner surface 40 and the mainbody portion 50 of the boot 26 to releasably retain the cover assembly 10 onthe boot 26.
    [22] [0022] Preferably, the base portion 28 of the cover assembly 10 carriesaxially doWnWardly beyond the nut portion 56 and over at least as much of thecylindrical portion 58 of the shell 52 of the spark plug and terrninates closelyadjacent to the cylinder head or cylinder body on Which the spark plug isassembled When in use.
    [23] [0023] Desirably, the cover assembly 10 is made of an at least somewhatresilient and flexible synthetic rubber Which has been doped or infused Withgraphite, carbon black, or other conductive material so that the cover assemblyis conductive and preferably has a surface resistance of less than 8,000 ohmsper square and a volume resistance of less than 85,000 ohms-cm as measuredand deterrnined in accordance With ASTM Standard D257. Suitable syntheticrubber materials include EPDM, silicone, therrnoplastic elastomers (TPE), andthe like. Desirably, the synthetic rubber has good heat, ozone and Weatherresistance. Preferably, the synthetic rubber has a relatively high temperature resistance of at least about 250°F. and preferably 350°F. Preferably, the synthetic rubber has a durometer on the Shore A scale in the range of about 50to 60 at a temperature of 350°F.
    [24] [0024] For ease of assembly, preferably the cover 10 is assembled over theboot 26 before the boot and cover are assembled over the spark plug 12. Evenif the high tension insulated Wire 16 is assembled in the boot 26 before thecover 10, the cover may be readily assembled over the boot by inserting thebody portion 50 of the boot through the opening 46 in the resilient coverassembly 10 and into the interior of the cover. This installation of the separatecover assembly 10 is advantageous both When the cover is assembled duringoriginal equipment manufacture (OEM) of the spark plug boot 26, before orafter insertion of the high tension Wire 16 into the boot 26, before or after thehigh tension Wire 16 is attached to an ignition module 18, before or aftermanufacture of the spark ignition engine, after the engine has been assembledinto the product it poWers, and even in the aftermarket after the engine or theend or product it poWers has been distributed or sold. The manufacture or useof a separate cover is also less expensive than overrnolding the conductivecover on an electrically insulative boot during manufacture of the boot.
    [25] [0025] While the forms of the invention herein disclosed constitutepresently preferred embodiments, many others are possible. It is not intendedherein to mention all the possible equivalent forms or ramifications of theinvention. It is understood that the terms used herein are merely descriptive,rather than limiting, and that various changes may be made Without departing from the spirit or scope of the invention.
    According to one aspect, the invention can be identified as below.
    A conducting cover for a spark plug boot for a spark plug havingan electrode terrninal and an insulator carried by and projecting from aconducting metal shell With a nut portion, the conducting cover comprising: a separate body of an electrically conductive material having anannular portion configured to receive therein at least part of a boot configuredto receive therein the terminal and at least part of the insulator of the sparkplug, and the body having an integral annular base portion conf1gured inassembly to extend around the periphery and over at least part of the nutportion of the metal shell of the spark plug and frictionally engaging the nut portion in an electrically conductive connection With the metal shell.
    The conducting cover of claim l Wherein the material of the coverbody is a synthetic rubber having a surface resistance of less than 8,000 ohms per square.
    The conducting cover of claim l Wherein the material of the coverbody is an electrically conductive synthetic rubber having a surface resistanceof less than 8,000 ohms per square and a volume resistance of less than 85,000 ohms-cm.
    The conducting cover of claim l Wherein the body material is atleast one of EPDM, rubber, silicone rubber, or TPE and is infused With at least one of graphite or carbon black.
    The conductive cover of claim 1 Wherein the base has an insidediameter less than the outside diameter of the nut portion of the metal shell ofthe spark plug When the cover is an unstretched state and is at least someWhat flexible and resilient.
    The conducting cover of claim l Wherein at least a part of theannular body has an inside diameter larger than a complimentary portion of the boot to create an air gap between them When in assembly.
    The conducting cover of claim 1 Wherein the body includes a closed end distal from the base of the body.
    The cover assembly of claim 1 Wherein the body includes a closeddistal end and a circuit opening disposed between the closed distal end and thebase and conf1gured to have an arm portion of the boot extend therethroughfor receiving a high potential voltage Wire for connection to the terminal of the spark plug When received in the boot.
    The cover of claim 8 Wherein the material of the body is an at leastsomeWhat resilient and flexible synthetic rubber having a surface resistance of less than 8,000 ohms per square.
    The cover of claim 9 Wherein the synthetic rubber material has a volume resistance of less than 85,000 ohms-cm.
    The cover assembly of claim 8 Wherein the material of the body isat least one of an EPDM rubber, silicone rubber, or TPE having a surface electrical resistance of less than 8,000 ohms per square.
    A conducting cover assembly for a spark plug boot for a spark plughaving a metal nut surface and an electrode for electrical connection to anelectrical circuit, said conducting cover assembly comprising: a base def1ning an inner base diameter complementing the nut surfaceof the spark plug; and a conductive cover extending up from said base for covering at leastpart of the spark plug boot, Wherein said base and said conductive cover are ethylene propylene diene monomer rubber infused With graphite.
    The conducting cover assembly as set forth in claim 12 having a surface resistivity less than or equal to 108 Qcm.
    The conducting cover assembly 12 as set forth in claim 1 Wherein said cover defines a cover inner diameter less than said inner base diameter.
    The conducting cover assembly as set forth in claim 14 Wherein saidcover inner diameter is large enough to create an air gap between at least a portion of said cover and the spark plug and/or the spark plug boot.
    The conducting cover assembly as set for in claim 12 Wherein saidcover includes a closed distal end. 11 The conducting cover assembly as set forth in claim 16 Wherein saidcover includes a circuit opening disposed between said base and said closed distal end to have a portion of an electrical circuit extend therethrough.
    The conducting cover assembly as set forth in claim 12 having avolume resistivity less than or equal to 109 Q-cm.The conducting cover assembly set forth in claim 12 having a surface resistivity less than or equal to 8,000 ohms per square.
    The conducting cover assembly set forth in claim 12 having a volume resistivity less than or equal to 85,000 ohms-cm. 12
    权利要求:
    Claims (18)
    [1] 1. l. A conducting cover for a spark plug boot for a spark plug havingan electrode terrninal and an insulator carried by and projecting from aconducting metal shell With a nut portion, the conducting cover comprising: a separate body of an electrically conductive material having anannular portion configured to receive therein at least part of a boot configuredto receive therein the terminal and at least part of the insulator of the sparkplug, and the body having an integral annular base portion conf1gured inassembly to extend around the periphery and over at least part of the nutportion of the metal shell of the spark plug and frictionally engaging the nut portion in an electrically conductive connection With the metal shell.
    [2] 2. The conducting cover of claim l Wherein the material of thecover body is a synthetic rubber having a surface resistance of less than 8,000 ohms per square.
    [3] 3. The conducting cover of claim l Wherein the material of thecover body is an electrically conductive synthetic rubber having a surfaceresistance of less than 8,000 ohms per square and a volume resistance of less than 85,000 ohms-cm. 13
    [4] 4. The conducting cover of claim l Wherein the body material is atleast one of EPDM, rubber, Silicone rubber, or TPE and is infused With at least one of graphite or carbon black.
    [5] 5. The conductive cover of claim l Wherein the base has an insidediameter less than the outside diameter of the nut portion of the metal shell ofthe spark plug When the cover is an unstretched state and is at least someWhat flexible and resilient.
    [6] 6. The conducting cover of claim l Wherein at least a part of theannular body has an inside diameter larger than a complimentary portion of the boot to create an air gap between them When in assembly.
    [7] 7. The conducting cover of claim l Wherein the body includes a closed end distal from the base of the body.
    [8] 8. The cover assembly of claim l Wherein the body includes aclosed distal end and a circuit opening disposed between the closed distal endand the base and conf1gured to have an arm portion of the boot extendtherethrough for receiving a high potential voltage Wire for connection to the terminal of the spark plug When received in the boot.
    [9] 9. The cover of claim 8 Wherein the material of the body is an atleast someWhat resilient and flexible synthetic rubber having a surface resistance of less than 8,000 ohms per square. l4
    [10] 10. The cover of claim 9 Wherein the synthetic rubber material has a Volume resistance of less than 85,000 ohms-cm.
    [11] 11. The cover assembly of claim 8 Wherein the material of the bodyis at least one of an EPDM rubber, silicone rubber, or TPE having a surface electrical resistance of less than 8,000 ohms per square.
    [12] 12. A conducting cover assembly for a spark plug boot for a spark plughaving a metal nut surface and an electrode for electrical connection to anelectrical circuit, said conducting cover assembly comprising: a base def1ning an inner base diameter complementing the nut surfaceof the spark plug; and a conductive cover extending up from said base for covering at leastpart of the spark plug boot, Wherein said base and said conductive cover are ethylene propylene diene monomer rubber infused With graphite.
    [13] 13. The conducting cover assembly 12 as set forth in claim 1 Wherein said cover defines a cover inner diameter less than said inner base diameter.
    [14] 14. The conducting cover assembly as set forth in claim 13 Whereinsaid cover inner diameter is large enough to create an air gap between at least a portion of said cover and the spark plug and/or the spark plug boot.
    [15] 15. The conducting cover assembly as set for in claim 12 Wherein said cover includes a closed distal end.
    [16] 16. The conducting cover assembly as set forth in claim 15 Whereinsaid cover includes a circuit opening disposed between said base and said closed distal end to have a portion of an electrical circuit extend therethrough.
    [17] 17. The conducting cover assembly set forth in claim 12 having a surface resistivity less than or equal to 8,000 ohms per square.
    [18] 18. The conducting cover assembly set forth in claim 12 having a volume resistivity less than or equal to 85,000 ohms-cm. 16
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US1967480A|1932-06-04|1934-07-24|Walter H Ruther|Spark plug|
    DE19509793C2|1995-03-17|1997-04-30|Audi Ag|Spark plug connector|
    CN2835631Y|2005-10-18|2006-11-08|重庆瑜欣平瑞电子有限公司|Anti-interference spark plug cap|
    JP5765297B2|2012-06-14|2015-08-19|住友電装株式会社|connector|
    JP6065228B2|2013-11-27|2017-01-25|住友電装株式会社|connector|
    CN203835597U|2014-01-23|2014-09-17|绍兴锋龙电机有限公司|Ignition device with EMC shielding device|CN110594070B|2019-09-12|2021-07-09|潍坊内燃机质量检验中心有限公司|Gas engine ignition system and method for detecting air leakage of spark plug|
    法律状态:
    2021-08-03| NUG| Patent has lapsed|
    优先权:
    申请号 | 申请日 | 专利标题
    US201562104403P| true| 2015-01-16|2015-01-16|
    US14/963,376|US9705290B2|2015-01-16|2015-12-09|Spark plug boot cover assembly|
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