US20090297998A1 - System for fastening spark plugs of boilers or the like - Google Patents

System for fastening spark plugs of boilers or the like Download PDF

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Publication number
US20090297998A1
US20090297998A1 US11/569,186 US56918605A US2009297998A1 US 20090297998 A1 US20090297998 A1 US 20090297998A1 US 56918605 A US56918605 A US 56918605A US 2009297998 A1 US2009297998 A1 US 2009297998A1
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United States
Prior art keywords
ring
retainer
recess
extension
tightening ring
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Abandoned
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US11/569,186
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English (en)
Inventor
Giorgio Offredi
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Castfutura SpA
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Castfutura SpA
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Assigned to CASTFUTURA SPA reassignment CASTFUTURA SPA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: OFFREDI, GIORGIO
Publication of US20090297998A1 publication Critical patent/US20090297998A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23Q—IGNITION; EXTINGUISHING-DEVICES
    • F23Q3/00—Igniters using electrically-produced sparks
    • F23Q3/006—Details

Definitions

  • the present invention relates to a fastening system for spark plugs of boilers, burners, hot plates, or the like, comprising a fastening plate or retainer having an hole housing the ceramic body of the spark plug.
  • spark plugs Each one acts for keeping a spark plug in a predetermined position useful for generating ignition sparks for liquid or gaseous fuels.
  • another type of spark plug acts for indicating the presence of flame.
  • Said spark plugs generally comprise a coating ceramic member with an elongated shape, generally cylindrical, for heat and electric insulation wherein a metal conducting member is included projecting outside thereof on both ends. To one end the electric conductor is connected, while at the opposite end the spark is generated.
  • the spark plug has to be firmly supported in a determinate position, particularly at a constant in time and predetermined distance from the ground member.
  • Retainer type providing at the housing hole for the spark plug a cylindrical member with an axial extension greater than the retainer thickness, and a further cylindrical member as an axially open ring that is fitted on the ceramic body of the spark plug and axially forced inside the cylindrical member in order to obtain an inwards elastic deformation and to tighten the spark plug body, do not guarantee the pressure tight.
  • the drawback of the manufacturing of a shaped ceramic body is a positioning limit of the spark plug on the retainer.
  • the system with threaded spark plug body and fastening screw provides a long mounting and sometimes it is difficult due to overall dimensions of burner components or the location inside furnace cavities in locations difficult to reach or where working areas are small.
  • the present invention aims to overcome all the above drawbacks, and by simple and inexpensive means it allows to manufacture a fastening system of the type disclosed hereinbefore allowing a simple, fast, inexpensive and firm in time fastening of the spark plug on the retainer in a determinate position and with a perfect orthogonal arrangement with respect to the two faces of the retainer, using a very small amount of components. Moreover it is desired that fastening of the spark plug on the retainer is of the pressure tight type, such to allow the use even with condensating boilers.
  • the invention attains the above aims by means of a fastening system of the type described hereinbefore wherein the hole housing the spark plug axially projects for a certain length at least on one side of the retainer beyond the thickness thereof such to form a cylindrical housing for the ceramic body of the spark plug. It is further provided a cylindrical tightening ring having such inner and external radial dimensions that it can be inserted by force fit between the inner wall of the cylindrical housing of the retainer and the external wall of the ceramic body of the spark plug such to generate a predetermined radial tightening force of the spark plug inside the cylindrical housing of the retainer and such to obtain a tight seal between one side and the other one of the retainer.
  • the retainer and the ring are made of metal material in order to guarantee a positioning firmness in time of the spark plug. While any metal materials can be used, metal materials having a good thermal resistance are preferred, in the sense of wear thereof due to thermal stress.
  • Metal materials of the retainer and the ring can be the same or different one with respect to the other. In the case of different metal materials it is advantageous to provide two metal materials whose difference in thermoelectric potential is negligible. That for avoiding electric corrosion situations and eddy current overlapping situations that can influence the proper operation of the spark plug.
  • the locking fit provides that during the pressure force fit of the ring between the inner edge of the hole housing the spark plug and the external wall of the spark plug, a partial deformation is obtained in the sense of an expansion of the housing hole in the retainer and a partial deformation in the sense of a radial compression of the ring.
  • the relation between the deformation of the retainer hole in the sense of an expansion thereof and of the ring in the sense of a compression thereof depends on the fact if materials of the retainer and ring are the same or different one with respect to the other or anyway if they have the same or different deformation capacity.
  • the inside diameter of the hole housing the spark plug has a such size with respect to the external diameter of the spark plug that the difference in diameter is slightly less than the ring thickness.
  • the ring particularly is a member for compensating and recovering the tightening radial pressure that eventually exceeds a predetermined pressure value for properly tightening the spark plug inside the cylindrical housing of the retainer and such to avoid the breaking or the cracking of the ceramic body.
  • the latter has a conical thinning or tapering allowing the entry between inner edge of the hole and external surface of the spark plug in a position for the axial force fit compression in the final position locking the spark plug in the retainer hole.
  • the ring and the retainer are made of brass has the advantage to provide the two parts made of a quite ductile metal.
  • brass has a low resistance to thermal stress and moreover particularly the ring has to be made with forming techniques, that is quite expensive.
  • the fastening of the spark plug is made in a proper way.
  • the fact of manufacturing the ring with brass and the retainer with a different material such as steel, stainless steel, or the like allows to manufacture at least the retainer with a less expensive material and that can be processed or molded by shearing.
  • the obtained fastening is also a good one.
  • the combination of the two different materials leads to a thermoelectric potential that cannot be absolutely ignored and to the arise of deterioration cases due to said difference in potential.
  • said means can be an annular widening of one of the two circular head edges of the cylindrical tightening ring constituting an abutment annular flange stopping the insertion of the tightening ring inside the cylindrical housing of the retainer.
  • the circular head end of the tightening ring faced to the one having the annular flange may have a beveled or rounded external edge for facilitating the insertion of the tightening ring inside the cylindrical housing of the retainer.
  • the advantages of the fastening system just disclosed are considerable.
  • the presence of a sort of cylindrical glass housing the spark plug allows the perfect orthogonality between the spark plug and the retainer surface, while the use of a tightening ring made of metal material that can be deformed allows to work in a precise way without exceeding the compression force that the ceramic can support.
  • the maximum axial positioning freedom of the spark plug on the retainer is guaranteed, and the fastening is firm, safe and it avoids casual disengagements.
  • the use of a not open cylindrical ring allows to obtain the desired pressure tight between a face and the other face of the retainer.
  • a second type of the fastening system according to the present invention provides both for the retainer and the ring to use metal materials having a good resistance to thermal stress and generating a negligible difference in thermoelectric potential one with respect to the other at the same time constituting a low cost metal and easy to work particularly by shearing.
  • the present invention overcomes the drawback disclosed above by means of a retainer of the type described hereinbefore wherein even in this case the housing hole axially projects for a certain length at least on one side of the retainer beyond the thickness thereof such to form a cylindrical housing for the ceramic body of the spark plug, but the tightening ring is made of a material, particularly metal, with a low ductility or deformation capacity, particularly it is made of the same material as the retainer, particularly steel, stainless steel or the like.
  • the ring may be shaped such to have one or more areas for compensating and recovering the tightening radial pressure that eventually exceeds a predetermined pressure value that can be supported by the ceramic.
  • the tightening ring may have one or more openings for the release and recovering of the radial deformation of the ring when the spark plug is tightened inside the cylindrical housing of the retainer.
  • the tightening ring may have at least one, preferably a plurality of notches originating from the two opposite head circular edges of the ring and extending only for a portion of the axial extension of the ring, such to guarantee the pressure tight by the ring itself.
  • Said notches may have all the same lengthways extension.
  • Particularly said extension may be comprised between about a third and about an half of the axial extension of the ring.
  • Particularly and advantageously notches have such an axial length to delimit an intermediate continuous annular band of the ring having a very small axial size and such that it can be easily deformed.
  • Such intermediate continuous annular band has an axial size of some millimeters and more precisely from 1 to 3 mm.
  • Said notches can be arranged with alternate positions one with respect to the other, that is each notch can originate from an head circular edge of the tightening ring opposite to the head circular edge from which the immediately next notch originates.
  • This embodiment allows to compensate the low ductility and the low compressibility of the ring material and at the same time it guarantees the proper seal since it generates no axial continuous through slot.
  • the tightening ring at the intermediate annular band may have at least an opening or slot for the release or recover of the radial narrowing occurring in said intermediate annular band when the spark plug is tightened inside the cylindrical housing of the retainer.
  • said slot may be sickle-shaped with the two ends arranged along an axis parallel to the central axis of the tightening ring, and it may extend at a central annular band corresponding to notch end portions arranged at the closed ends thereof.
  • the tightening ring may be manufactured as an open one, while maintaining the pressure tight between one side and the other side of the retainer.
  • the ring at two faced head edges of a strip that is bent and closed on itself in a cylindrical shape has an hooking recess that narrows as regards its dimension in the axial direction of the ring at the corresponding head edge of the strip forming the ring and which hooking recess cooperates with a hooking extension that has a shape that is complementary to the hooking recess and it has a material portion for the connection to the corresponding head side of the bent strip forming the ring with an axial size smaller than the remaining part of said hooking extension.
  • Said hooking recess and the cooperating hooking extension are complementary means for the reciprocal fastening of faced head sides of the bent strip, that is means for closing the ring.
  • the recess and extension closing the tightening ring may be provided in substantially intermediate positions of respective straight portions of head sides of the strip forming the ring, with which straight portions said recess and said extension connect in a rounded way.
  • the extension closing the tightening ring may have a root with a narrow shape projecting in the substantially circumferential direction of the ring with a substantially circular shape widened part, while the corresponding recess placed on the opposite end of the tightening ring may have a shape substantially complementary to the one of said extension.
  • the hooking recess and the corresponding hooking extension of the tightening ring have complementary shapes but the hooking recess has sizes slightly smaller than the hooking extension ones and they can be secured one inside the other by force fit, causing a firm closing of the ring.
  • one or both head circular edges of the ring may have an entrance beveling in order to facilitate the insertion by force fit of the ring inside the cylindrical housing.
  • the ring Due to the arrangements considered in said second embodiment of the invention, if required, it is possible to manufacture the ring with the same material as the retainer guaranteeing both the possibility to recover the tightening radial deformation and the pressure tight between one side and the other side of the retainer. All this is due to the fact that axial notches are not through notches and hooking means of the two faced head sides of the bent strip forming the ring engaging by force fit avoid the leak of gas. Particularly the seal is guaranteed if the ring both is submitted to an inwards compression and an outwards expansion.
  • the ring is easy to manufacture, for example by means of shearing, and subsequent closing on itself.
  • the constructive manufacturing of the ring by means of a metal material strip that is sheared from a continuous metal material sheet allows to work with a quick and inexpensive manufacturing method and allowing to obtain considerable performances.
  • the dimensional interference between the hooking recess and the hooking extension is automatically obtained by means of the shearing operation allowing to form the hooking extension of a preceding material strip with the part removed for making the hooking recess of the immediately subsequent material strip. All this is due to the fact that the shearing of the sheet generally causes the cutting of the material for about a third of its thickness, while the remaining two thirds of the material thickness is broken and therefore deformed generating small dimensional differences between hooking recess and hooking extension leading to a reciprocal engagement by force fit.
  • FIG. 1 is a perspective view of an spark plug being secured on a retainer according to the present invention by means of a first tightening ring embodiment.
  • FIG. 2 is an exploded view of the assembly of FIG. 1 .
  • FIG. 3 is a perspective view of the first tightening ring embodiment.
  • FIG. 4 is a side view of assembly of FIG. 1 , in combination with a wall dividing the combustion chamber and the external environment.
  • FIG. 5 is a top plant view of assembly of FIG. 1 .
  • FIG. 6 is a perspective view of a spark plug being secured on a retainer according to the present invention by means of a second tightening ring embodiment.
  • FIG. 7 is an exploded view of assembly of FIG. 6 .
  • FIG. 8 is a perspective view of the second tightening ring embodiment.
  • FIG. 9 is a part section side view, of the second tightening ring embodiment.
  • FIG. 10 is a plant view of the second tightening ring embodiment in the expanded condition.
  • FIG. 11 is a perspective view of a variant of the tightening ring according to FIGS. 8 to 10 .
  • FIG. 14 is a perspective axial section of the fastening plate, the cylindrical ceramic body of the spark plug and the tightening ring according to FIG. 13 in the mounted condition.
  • FIG. 15 is a perspective view of a further embodiment of the retainer.
  • the retainer 1 comprises a substantially flat annular plate-like part connecting to a remaining. part of retainer 1 , which has a hole 2 for the passage of a screw fastening the retainer 1 on the boiler.
  • the retainer 1 is completely flat, but it can be fabricated in any shape with respect to the device to which it has to be matched.
  • the retainer 1 further comprises an hole for housing the spark plug 4 , which hole has a complementary shape with respect to the external section of the spark plug 4 that generally is fabricated with a cylindrical shape.
  • the spark plug 4 is composed of a cylindrical ceramic body 104 provided with an axial hole 404 inside which there is provided a metal electrode 204 provided with an annular widening 304 stopping the insertion of the electrode 204 inside the hole 404 of the ceramic body 104 . With the electrode 204 being fastened inside the hole 404 of the ceramic body 104 , said electrode 204 projects to a predetermined extent from both ends thereof.
  • a projecting end has a shape such that it can be connected to an electric conductor for example by means of a Faston type connector or the like, while the opposite end projects from the ceramic body 104 to a greater extent and, in the shown embodiment, it is angularly bent such that, with the spark plug 4 applied on the boiler, it is at a predetermined distance from the ground member for generating the ignition spark.
  • the inside diameter of the cylindrical housing 5 is greater than the external diameter of the ceramic body 104 , a first embodiment of cylindrical tightening ring 6 being provided having such inside and external radial dimensions that it can be inserted by force fit between the inside wall of the cylindrical housing 5 of the retainer 1 and the external wall of the ceramic body 104 of the spark plug 4 such to provide a predetermined radial tightening force of the spark plug 4 inside the cylindrical housing 5 of the retainer 1 and such to have a tight seal between one side and the other side of the retainer 1 .
  • the pressure tight between the combustion environment and the external environment can be further guaranteed by the presence of a wall 7 dividing said two environments that is provided inside the boiler.
  • the tightening ring 6 is made of a material having predetermined deformation and ductility characteristics, particularly metal. According to a preferred embodiment, the tightening ring 6 is made of brass.
  • the ring 6 When the ring 6 is inserted by force fit in the space comprises between the inner wall of the cylindrical housing 5 and the external wall of the ceramic body 104 of the spark plug 4 , the ring 6 . suffers a slight deformation tightening the ceramic body 104 and firmly secures in position the spark plug 4 on the retainer 1 .
  • the ductility of brass compensates and recovers the tightening radial pressure that eventually exceeds a predetermined pressure value for proper tightening the spark plug 4 inside the cylindrical housing 5 of the retainer 1 and it avoids the possible breaking of ceramic. Even the retainer suffers a partial deformation relevant to the expansion of the hole housing the spark plug that in this case is less than the deformation of the ring due to the relation between the brass and steel deformation.
  • the cylindrical housing 5 Due to the fact that the cylindrical housing 5 has a certain axial extension and it is perpendicular to the surface of retainer 1 , the perfect orthogonality is guaranteed between the spark plug 4 and the surface of retainer 1 , while the presence of the ring 6 with a continuous cylindrical extension guarantees the pressure tight between a side and the other side of the retainer 1 .
  • the circular edge of the cylindrical housing 5 that is coplanar to one of the two faces of the retainer 1 has an entrance flare 105 .
  • one of the two circular head edges of the cylindrical tightening ring 6 has an abutment annular flange stopping the insertion of the tightening ring 6 inside the cylindrical housing 5 of the retainer 1 .
  • the opposite circular head end of the tightening ring 6 has a beveled or rounded edge 206 for facilitating the insertion of the tightening ring 6 inside the cylindrical housing 5 of the retainer 1 .
  • FIGS. 6 to 10 a second system for fastening the spark plug 4 on the retainer 1 is shown based on a second tightening ring embodiment 8 that in this case is made of the same material as the retainer 1 , generally steel, in order to satisfy particular situations wherein the presence of two different metals, that of the ring 6 and that of the retainer 1 , can cause the above drawbacks, such as eddy current or the like.
  • the spark plug 4 is secured on the retainer 1 introducing by force fit the tightening ring 8 between the inner wall of the cylindrical housing 5 and the external wall of the ceramic body 104 of the spark plug 4 .
  • the tightening ring 8 since the tightening ring 8 is made of a material that substantially is not much capable of being deformed or having a greater resistance to deformation, it has a plurality of notches 108 originating from two opposite circular head edges of the ring 8 and extending between about a third and about an half of the axial extension of the ring 8 . Said notches 108 are arranged in alternate positions one with respect to the other, that is each notch 108 originates from a circular head edge of the tightening ring 8 opposite to the circular head edge from which the immediately adjacent notch 108 originates and a continuous intermediate annular band is formed there between having a very little size in the axial direction of the ring particularly between 1 and 3 mm.
  • the tightening ring 8 is manufactured by shearing and rolling it in a cylindrical shape a strip of metal material and therefore it is substantially an open ring with an opening cut that is rectilinear and parallel to the central axis of the ring 8 .
  • an head side on one end of the material strip forming the tightening ring 8 placed at the opening cut has a recess 208
  • the head side of the opposite end has an extension 308 intended for the engagement in said recess 208 for closing the tightening ring 8 .
  • the recess 208 and the extension 308 closing the tightening ring 8 are provided in positions that are substantially intermediate in the respective straight portions of head sides of ends of the ring 8 , and said recess 208 and said extension 308 connect in a rounded way with said straight portions.
  • the extension 308 closing the tightening ring 8 has a root 408 of narrow shape extending in the substantially circumferential direction of the ring 8 with a widened portion of substantially circular shape, while the corresponding recess 208 placed on the opposite end of the tightening ring 8 has a shape that is substantially complementary to the one of said extension 308 .
  • the size of the extension 308 is slightly greater than that of the hooking recess 208 .
  • the extension 308 engages by force fit the recess 208 , making a firm mechanical connection of the two faced head ends of the strip forming the ring and generating a seal adhesion of perimetral edges of the hooking recess with the hooking extension.
  • the fastening system allows to have gas tight conditions need for the use in condensing boilers even if the ring is a substantially open ring.
  • the manufacturing of the open ring allows in turn the manufacturing thereof by shearing the material strip from a continuous material band. Moreover, considering the effect that the shearing process has on the material, namely that said process incises and cuts the material for about a third of the thickness and for the remaining two thirds of thickness the separation can be compared to a breaking, the deformation generated by the breaking causes an expansion of the extension dimensions and/or a narrowing of the recess dimensions, therefore the relative dimensioning between recess and extension is automatically generated that is necessary to obtain the engagement of said two portions by reciprocal force fit. That allows to obtain the hooking extension and recess without material off-cuts, the removed portion of the material strip forming the hooking recess at the same time forms the hooking extension of a following material strip.
  • FIG. 11 illustrates a variant embodiment of the tightening ring described with reference to FIGS. 6 to 10 .
  • the facing ends of the open ring have respectively a protrusion 308 ′ and a recess 208 ′ which have a constant axial width. So that in the rolled up form of the metal strip, particularly of the steel strip of FIG. 11 , the side edges of the protrusion 308 ′ and of the recess 208 ′ which are oriented in the circumferential direction of the ring can slide one against the other.
  • the axial width of the protrusion and of the recess are identical within the limits of high tolerances so that a sealing effect is achieved when the protrusion is fit inside the recess, and in any case at least when the deformation of the ring has occurred after having forced it together with the ceramic body of the spark plug in the retainer bushing.
  • the protrusion which is arched correspondingly to the radius of the ring does not completely fit inside the recess but it is in a position with it end at a certain distance of the axial bottom edge of the recess.
  • the depth of the recess and the length of the protrusion are such that between the axial edges of the protrusion and of the recess and the resting facing axial surfaces of the ring on both sides of the protrusion and of the recess a certain distance is maintained helping in allowing to receive the expansion of the material of the ring when it is compressed between the ceramic body and the cylindrical seat 5 of the retainer 1 in order to avoid excessive radial forces on the ceramic body.
  • the tightening ring according to this variant and in the rolled condition of the metal strip forming the ring, has an axial cut forming two facing ends.
  • the axial cut has a certain width so that the said two ends are at a predetermined distance one form the other.
  • a first end has a central protrusion 308 ′and the opposite end has a recess 208 ′ coinciding with the said central protrusion.
  • the central protrusion- is curved essentially with the same radius as the ring and has circumferential side edges extending along a plane perpendicular to the ring axis.
  • the recess has circumferential side edges extending along the same plane perpendicular to the ring axis as the side edges of the said central protrusion 308 ′.
  • the axial width of the central protrusion and the axial width of the recess are almost identical such that the protrusion fits in the said recess with the side edges of the said central protrusion coming into contact with the corresponding side edges of the recess.
  • the said recess has an angular extension which corresponds essentially to the width of the axial cut.
  • the axial width of the protrusion of one end of the tightening ring and the axial width of the recess are such that the side edges of the protrusion and the corresponding side edges of the recess extending in circumferential direction of the ring adheres one to the other in a sealing way, at least after being forced together with the ceramic body of the spark plug ( 4 ) in the retainer.
  • the axial dimension of the protrusion 308 ′ and of the cooperating recess 208 ′ are less than the total axial extension of the ring and the said protrusion and the said recess are almost centered relatively to the said total axial extension of the ring. So at both sides of the protrusion 308 ′ and of the recess 208 ′ axial end surfaces of the two facing ends of the ring are left.
  • the ring has also the axial notches 108 ′ as in the embodiment according to FIGS. 6 to 10 .
  • the radial compression of the tightening ring can be partly compensated by a circumferential sliding of the protrusion 308 ′ inside the recess 208 ′. So the expansion of the material of the tightening ring due to the compression is partly compensated by this sliding and the radial compression forces exerted on the ceramic body can be maintained below the threshold which ensures that no damage is caused to the ceramic body of the spark plug 4 but a tight securing of the said spark plug is obtained which also ensures a sealing against passage of gas.
  • FIG. 12 illustrate an embodiment of the retainer 1 .
  • the cylindrical seat 5 for the ring and for the ceramic body of the spark plug 4 has a first entrance flare 105 at the circular edge of the cylindrical housing 5 that is coplanar to one of the two faces of the retainer 1 as described with respect to the embodiment of FIG. 1 to 5 which is followed by a cylindrical part extending for the width of the fastening plate 101 of the retainer 1 .
  • a frustoconical part 205 reduces further the internal diameter of the cylindrical seat to the end diameter of the cylindrical seat formed by a cylindrical bushing 305 .
  • the thickness of the fastening plate is bigger than the thickness of the walls of the cylindrical bushing or extension 5 forming the seat for the ceramic body of the park plug 4 and of the tightening ring 8 .
  • the above internal shape of the seat allows to maintain the diameter of the hole passing the fastening plate 101 with a diameter slightly larger. This allows to avoid that high radial stresses are exerted on the ceramic body of the spark plug at the crossing of the fastening plate 101 which has a high radial resistance to deformation due to its increased thickness.
  • the bushing itself, or at least the cylindrical seat 5 has a reduced thickness of the walls, particularly for the part having the final correct diameter for press fitting the tightening ring and the ceramic body of the spark plug 4 . This allows that radial forces can be at least partially absorbed by a deformation not only of the tightening ring but also of the cylindrical seat 5 , i.e. of the terminal cylindrical extension 305 .
  • An increased thickness of the fastening plate 101 of the retainer is very helpful since during securing of the plate by means of screws passing through holes 201 in the fastening plate 101 the fastening plate could arcuate or bend or be submitted to other deformations when the screws are tightened. This is particularly relevant not only for the correct positioning of the spark plug 4 relatively for example to a burner, but also in connection with gas tight combustion chambers, since a deformation of the fastening plate could lead to leakage.
  • the retainer can be built in a simple manner by drawing or pressing since the material which has to be eliminated for forming the hole in the fastening plate for the spark plug is sufficient to form the seat 5 with a reduced wall thickness.
  • FIGS. 13 and 14 illustrates the ceramic body of the spark plug 4 and the tightening ring 6 according to the embodiment of FIGS. 1 to 5 in combination with a retainer according to FIG. 12 and respectively in the non mounted condition and in the condition in which the ceramic body of the spark plug 4 with the tightening ring 6 are forced inside the retainer 1 .
  • the retainer according to FIG. 12 can be used in combination with every one of the embodiments of the rings 6 or 8 described above.
  • the fastening plate has a thickness from about 3 mm to about 5 mm, while the walls of the cylindrical seat 5 has a thickness of about 1 mm to 2 mm.
  • FIG. 15 illustrates such a stiffened fastening plate 101 which in this embodiment is provided with a peripheral rib 301 .
  • the thickness of the plate 101 is less than 3 mm according to the plate 101 of the embodiment of FIGS. 1 to 10 and the stiffening rib is obtained by deformation of the peripheral edge of the plate 101 by means of stamping or drawing.
  • a further feature which appears in the embodiment of FIG. 15 and which can be provided for each of the different embodiments of the fastening plate 101 of the retainer 1 consist in a mean for connecting electrically and mechanically a conductor, particularly a cable for generating an electrical connection to earth potential.
  • the mean for connecting electrically and mechanically a conductor consist in a shaped protrusion, such as a metallic tongue 401 which is dimensioned and shaped in such a way as to cooperate with the female part of a so called FASTOM® connector.
  • the tongue is made in one piece with the retainer and it is obtained together with the other features of the retainer in a one shot operation of stamping or drawing from a metallic sheet.
  • the retainer can be made of any kind of metal, particularly of brass, copper, copper-nickel alloy, steel.
  • FIG. 14 shows that in contrast to the embodiment according to FIGS. 1 to 5 , the hole in the fastening plate 101 for housing the ceramic body 104 of the spark plug 4 can have advantageously such a radius that the flange 106 of the tightening ring 6 passes through this hole, namely the said hole has a larger radius as the external radius of the flange 106 .
  • the flange 106 abuts against the inner surface of the reduction of the frustoconical part 205 on the other side of the fastening plate 101 , which has a larger radius and a shorter radius being respectively bigger and smaller than the external radius of the flange 106 of the tightening ring 6 .
  • the said flange 106 and the corresponding end of the ring 6 are completely embedded within the thickness of the fastening plate 101 .
  • the trough hole in the fastening plate 101 for the ceramic body of the spark plug 4 has a greater diameter than the said ceramic body together with the tightening ring on it, while the cylindrical seat 5 ; 305 with the reduced diameter for force fitting the said ceramic body and the tightening ring is provided on one side of the fastening plate 101 outside the thickness of the fastening plate and is connected to the said hole of the fastening plate 101 with a frustoconical part 205 .

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Spark Plugs (AREA)
US11/569,186 2004-05-17 2005-05-11 System for fastening spark plugs of boilers or the like Abandoned US20090297998A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IT000022A ITSV20040022A1 (it) 2004-05-17 2004-05-17 Sistema di fissaggio per candele d'accensione di caldaie o simili
ITSV2004A000022 2004-05-17
PCT/EP2005/052146 WO2005111500A2 (fr) 2004-05-17 2005-05-11 Systeme pour fixer des bougies d'allumage de chaudieres ou analogue

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US20090297998A1 true US20090297998A1 (en) 2009-12-03

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US (1) US20090297998A1 (fr)
EP (1) EP1747402A2 (fr)
BR (1) BRPI0510876A (fr)
IT (1) ITSV20040022A1 (fr)
MX (1) MXPA06013486A (fr)
RU (1) RU2006140467A (fr)
WO (1) WO2005111500A2 (fr)

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US20110236840A1 (en) * 2010-03-25 2011-09-29 Whirlpool Corporation Attachment system for an igniter electrode for a gas burner
US20150380864A1 (en) * 2014-06-30 2015-12-31 Agilent Technologies, Inc. Connector assembly for an inductively coupled plasma source
US11635207B2 (en) * 2018-09-20 2023-04-25 Anton Paar Provetec Gmbh Electric ignition for flashpoint tester

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RU2006140467A (ru) 2008-06-27
BRPI0510876A (pt) 2007-11-27
EP1747402A2 (fr) 2007-01-31
WO2005111500A3 (fr) 2006-06-01
MXPA06013486A (es) 2007-06-12
WO2005111500A2 (fr) 2005-11-24
ITSV20040022A1 (it) 2004-08-17

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