GB2060151A - Spark ignition electrode - Google Patents
Spark ignition electrode Download PDFInfo
- Publication number
- GB2060151A GB2060151A GB7933550A GB7933550A GB2060151A GB 2060151 A GB2060151 A GB 2060151A GB 7933550 A GB7933550 A GB 7933550A GB 7933550 A GB7933550 A GB 7933550A GB 2060151 A GB2060151 A GB 2060151A
- Authority
- GB
- United Kingdom
- Prior art keywords
- holding portion
- bore
- insulator
- electrode
- grooves
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T13/00—Sparking plugs
- H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
- H01T13/34—Sparking plugs characterised by features of the electrodes or insulation characterised by the mounting of electrodes in insulation, e.g. by embedding
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T21/00—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs
- H01T21/02—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs of sparking plugs
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Spark Plugs (AREA)
Abstract
A spark ignition electrode device comprising a wire electrode 10, a hollow elongate ceramic insulator 11, and a shaped metal mounting member 12, in which part of the electrode is deformed to form a holding portion 20 which has a width which is greater than the wire diameter and a thickness which is less than the wire diameter, and to form transverse edges on the body at or adjacent the ends of the holding portion; said deformation being such that the holding portion is a non- rotatable press-in interference fit in a non-circular bore of the insulator, and serves to thrust said edges against the bore to secure together the electrode and the insulator, without requiring the use of cement or separate mechanical fixings. <IMAGE>
Description
SPECIFICATION
Improvements in or relating to electrode devices for spark ignition apparatus for gas appliances
This invention concerns electrode devices for spark ignition apparatus for gas appliances.
Electrode devices are known in which a wire electrode is cemented into an elongate hollow ceramic insulator, and a shaped metal mounting member is fitted onto the insulator for mounting the device on the appliance. The use of cement has well known disadvantages, and many expedients have been tried to obviate such disadvantages, e.g. providing mechanical fixings to connect one end part of the insulator to the electrode, but such expedients are relatively expensive.
What is needed is a simple and inexpensive way of securing the electrode and insulator together.
According to the present invention there is provided an electrode device comprising a wire electrode, a hollow elongate ceramic insulator, and a shaped metal mounting member, wherein: - (a) the wire electrode has an elongate body formed from wire of substantially constant diameter, which body is disposed between a spark tip and a cold terminal end portion of the electrode;
(b) part of the body is deformed to form a holding portion which has a width which is greater than the wire diameter and a thickness which is less than the wire diameter, and to form transverse edges on the body at or adjacent the ends of the holding portion;
(c) the insulator has a bore of a non-circular transverse cross-section which is grooved longitudinally of the bore to accept the holding portion;;
(d) the body has a hot end portion between the holding portion and the spark tip, which hot end portion is a sliding fit in said bore; and
(e) said deformation is such that the holding portion is a non-rotatable press-in interference fit in said bore and serves to thrust said edges against the bore.
The mounting or an extension of the mounting preferably surrounds and grips an internally loaded portion of the insulator around said holding portion, or a separate collar may be provided around said internally loaded portion, whereby to support the latter against the loads generated by the interference fit. The mounting or a part of the mounting is preferably disposed between the hot end portion and said loaded portion to conduct heat from the insulator and thereby thermally protect the loaded portion.
The invention also provides an improved method of making an electrode device in which a wire electrode is secured in a hollow elongate ceramic insulator having a bore of non-circular longitudinally grooved form and having attached thereto a shaped metal mounting member;
wherein the wire electrode is formed by severing a
straight piece of wire of predetermined length
from a supply of wire, deforming the piece to form
a holding portion having a part which is thinner,
and wider than the diameter of the piece and to
form transverse edges on the piece at or adjacent
to the ends of the holding portion and, before, at
the same time as, or after the formation of the
holding portion, forming a terminal end portion at
one end of the piece, the deforming and forming
being such that the holding portion is nearer to
said one end than to the other end of the piece, is
disposed at a predetermined angular relationship
to the terminal end portion and is an interference
fit in the insulator; wherein the other end of the
piece is inserted into the insulator; wherein an
axial thrust is applied to the terminal end portion
to drive the holding portion into the insulator so
that the holding portion is disposed in a
predetermined position relative to the mounting
member, engages said grooves and thrusts the
edges into engagement with the bore; and
wherein a transverse thrust is applied to the other
end to form a spark tip projecting from the
insulator.
In one embodiment the grooves and the
holding portion are offset from the longitudinal
centre line of the bore and the axis of the body by
approximately equal amounts, and the grooves are
linked by an abutment ridge in the bore, which
ridge thrusts and bends a central longitudinal part of the holding portion towards said axis whilst the
longitudinal margins of the holding portion are supported by the grooves.
In other embodiments either the grooves or the
holding portion are offset from the centreline of
the bore or the axis of the body, or the grooves
and the holding portion are offset by different
amounts, so that the engagement of the
longitudinal margins of the holding portion in the grooves urges or thrusts the axis of the body away from the longitudinal centreline of the bore, or
towards said centreline.
The longitudinal margins preferably have
shoulders or ends which are tapered or shaped to facilitate entry of the margins into the grooves during assembly of the device.
The invention will be described further, by way of example, with reference to the accompanying
diagrammatic drawings, wherein: - Figure 1 shows a first embodiment of electrode
device of the invention, in longitudinal crosssection;
Figures 2 and 3 show transverse cross-sections through the device on the lines Il-Il and Ill-Ill of
Figure 1 respectively;
Figures 4 and 5 show, in side elevation and
plan, holding and terminal portions of an electrode
of the device prior to assembly of the device;
Figure 6 shows a transverse cross-section of the holding portion on the line VI--VI of Figure 4;
Figure 7 shows a transverse cross-section through a second embodiment of electrode device of the invention, showing a hotding portion of the electrode;;
Figures 8 and 9 show the sections of the electrode and insulator shown in Figure 7 prior to the assembly of the device;
Figure 10 shows the holding portion shown in
Figure 8 in side elevation;
Figure 11 is a cross-section, similar to Figure 7, of a third embodiment of the invention;
Figures 12 and 13 are sections similar to
Figures 8 and 9 of the electrode and insulator of the third embodiment, and
Figures 14 shows a holding portion of the electrode of the third embodiment in side elevation.
Referring generally to the drawings each of the electrode devices generally comprises a wire electrode 10, a ceramic insulator 11 and a metal mounting member 12.
Each wire electrode 10 is formed from 72 thou.
diameter wire, as hereinafter described, so as to comprise a shaped spark tip 13 at one end of a body and a terminal portion 14 at the other end of the body. The body includes a straight hot end portion 15 (i.e. a portion which in use receives heat from the spark tip) disposed between a holding portion and the spark tip; and a cold end portion 16 between the holding portion and the terminal portion 14. The form of the holding portion varies.
In the first embodiment shown in Figures 1 to 6, the holding portion 20 is of flat form; has a central longitudinal part 21 which is offset from the body axis 22 so as to have an external surface (shown in Figure 5) which is level with (as shown in Figure 4), or slightly proud of, the adjacent peripheral parts of the surfaces of the portions 1 5 and 16 (as shown in Figures 1 and 2); has longitudinal marginal parts 23 which project, when the electrode is first formed, tangentially from the line of the circumference of the wire and extend between transverse holding edges 24; has a transverse width greater than the wire diameter; and has a thickness substantially less than said diameter.
The holding portion 20 is formed so as to leave retaining edges 25 on the adjacent ends of the portions 15 and 16, which edges 25 may be flush with the wire circumference (as shown in Figures 4 and 6) or stand proud of said circumference (as shown in Figures 1 and 2).
The insulator 11 has a bore which is part circular on a radius greater than that of the wire, and is shaped to include longitudinal grooves 27 (Figure 3) which are nearly tangential to a circle at said radius, and to include between said grooves an abutment ridge 28 which protrudes towards the axis of the part circular portion of the bore.
The bore is dimensioned so that, as shown diagrammatically in Figures 2 and 3, most of the body is freely slidably accommodated in the bore, except for the holding portion which is deformed by the abutment ridge 28 thrusting the central part 21 towards the axis, whilst the marginal parts 23 and the holding edges 24 engage the grooves 27, whereby also to thrust the retaining edges 25 into engagement with the part circular part of the bore, so as to secure the electrode against working loads applied axially and rotationally to the terminal portion 14.
The relative dimensions of the wire and the bore may be varied or may vary due to manufacturing tolerances, so that the wire is a close or tight fit in the bore. In such instances the holding portion 20 can be varied from the form shown in Figure 1 to the form shown in Figures 4, 5 and 6, by lessening the flattening and displacement of the holding portion; and since the body is confined by the bore the marginal parts 23 are deformed more relative to the central part 21.
Furthermore, the marginal parts 23 and the holding edges 24 are thicker to engage the grooves sufficiently to compensate for any reduction of the thrust applied to the retaining edges 25 or any reduction of the engagement of the bore by the retaining edges 25.
In the second embodiment shown in Figures 7 to 10 the holding portion 20A is similar to the holding portion 20, except in that the holding edges 24 are replaced by curved shoulders 30 which slope relative to the axis so as to merge with the hot end and cold end portions 15 and 16.
The insulator 11, in this embodiment, is of known form and has a bore which in cross-section has the shape of an 80 thou. diameter circle combined with a 110 by 50 thou. rectangle so as to have grooves 27A and two pairs of internal shoulders 31,31 and 32, 32 defining edges running longitudinally of the bore, as shown in Figures 7 and 9. (The rectangle was dimensioned to allow the terminal portion to be inserted into the bore as was necessary in known methods of constructing the cemented devices hereinbefore mentioned.)
Prior to assembly of the device the holding portion is offset from the axis by an amount which is fractionally greater than a plane joining one shoulder 31 with one shoulder 32, so that after assembly the marginal parts 23 engage in the grooves 27A so that the holding portion is thrust towards said axis whereby to force the retaining edges 25 into engagement with the bore.
The third embodiment, shown in Figures 11 and 14 has a basic difference, as compared with the second embodiment, in that the holding portion 20B is not displaced bodily from the wire axis when the electrode is formed, whereas the grooves 378 are displaced from the axis of the bore. In the assembled device, the marginal parts 23 are thrust away from the axis of the bore so as to force two of the four holding edges 24 into engagement with a common wall 33 of the bore between the grooves 27B.
In all embodiments the insulator has a hot end 34 (i.e. an end which is heated in use) and a cold end 35 (Figure 1).
The mounting member 12 is of known form and comprises a cylindrical collar 1 7 having a shaped planar flange 18.
During manufacture, the electrode 10 is formed by cutting a straight piece of wire of predetermined iength from a supply of wire.
The piece is then worked to form the holding portion 20, 20A or 20B and the terminal portion
14, the latter being made to British standard No:
BS 5057 and being disposed at one end of the piece, so that a predetermined angular relationship exists between said portions 14 and 20,20Aor20B.
Said holding and terminal portions may be made, at least partially, by a single pressing operation if they are disposed in parallel planes or the same plane, instead of planes at right angles as shown in Figures 1, 4 and 5.
The other end of the piece is inserted into the cold end 35 of the insulator which is then located in a support with its hot end 34 abutting a former and with the flange 18 located in a locating recess shaped to hold the insulator assembly in a particular orientation; and so that the terminal portion 14 projects towards a slotted locator mounted on a first hydraulic or pneumatic ram which, upon being actuated, thrusts the piece into the bore until a first predetermined position is reached. The slotted locator is shaped to engage the portion 14 so as to ensure that the portion 14 is held at a predetermined angular orientation relative to the locating recess.
When said first predetermined position is reached the other end of the piece protrudes from said hot end 34 and the ram actuates a limit switch which in turn actuates a transverse ram.
The transverse ram has a forming head which is moved to bend the other end against the former to form the spark tip 13, and thereafter to actuate a further limit switch which causes the rams to retract, so that the electrode device can be removed from the apparatus.
The apparatus is constructed so as to permit variation of the strokes of the rams, the positions of the limit switches, the location of the locating recess and the locator, and the shape of the former, to enable variations to be made in the forms of devices produced.
The invention is not confined to the precise details of the foregoing examples, and many variations are possible within the scope of the invention. For example the shape and the position of the holding portion may be varied provided that it is nearer to the cold end than the hot end of the insulator. The position of the mounting member may be varied, but it is preferred to locate the holding portion either partially within the mounting member or between the latter and said cold end.
The shape of the bore may be varied, but a bore partially defined by substantial robust shoulders, e.g. shoulders having a large included acute angle or an obtuse angle, providing sharp or blunt edges, is preferred. The amount of interference between the bore and the holding portion may be varied to suit the nature of the bore and to avoid cracking the insulator as the holding portion is inserted during assembly or becomes warmed in use.
Claims (10)
1. An electrode device comprising a wire electrode, a hollow elongate ceramic insulator, and a shaped metal mounting member, wherein: (a) the wire electrode has an elongate body formed from wire of substantially constant diameter, which body is disposed between a spark tip and a cold terminal end portion of the electrode;
(b) part of the body is deformed to form a holding portion which has a width which is greater than the wire diameter and a thickness which is less than the wire diameter, and to form transverse edges on the body at or adjacent the ends of the holding portion;
(c) the insulator has a bore of a non-circular transverse cross-section which is grooved longitudinally of the bore to accept longitudinal margins of the holding portion;;
(d) the body has a hot end portion between the holding portion and the spark tip, which hot end portion is a sliding fit in said bore; and
(e) said deformation is such that the holding portion is a non-rotatable press-in interference fit in said bore and serves to thrust said edges against the bore.
2. A device as claimed in claim 1, wherein the grooves and the holding portion are offset from the longitudinal centre line of the bore and the axis of the body by approximately equal amounts, and the grooves are linked by an abutment ridge in the bore, which ridge thrusts and bends a central longitudinal part of the holding portion towards said axis whilst the longitudinal margins of the holding portion are supported by the grooves.
3. A device as claimed in claim 1, wherein either the grooves or the holding portion are offset from the centreline of the bore or the axis of the body, or the grooves and the holding portion are offset by different amounts, so that the engagement of the longitudinal margins of the holding portion in the grooves urges or thrusts the axis of the body away from the longitudinal centreline of the bore, or towards said centreline.
4. A device as claimed in claims 1,2 or 3, wherein the longitudinal margins have shoulders or ends which are tapered or shaped to facilitate entry of the margins into the grooves during assembly of the device.
5. A device as claimed in claims 1, 2, 3 or 4, wherein the mounting or an extension of the mounting surrounds and grips an internally loaded portion of the insulator around said holding portion, or a separate collar is provided around said internally loaded portion.
6. A device as claimed in claim 5, wherein the mounting or a part of the mounting is disposed between the hot end portion and said loaded portion.
7. An electrode device substantially as hereinbefore described with reference to Figures 1 to 6, Figures 7 to 10, or Figures 11 to 14 of the accompanying drawings.
8. A method of making an electrode device in which a wire electrode is secured in a hollow elongate ceramic insulator having a bore of noncircular longitudinally grooved form and having attached thereto a shaped metal mounting member; wherein the wire electrode is formed by severing a straight piece of wire of predetermined length from a supply of wire, deforming the piece to form a holding portion having a part which is thinner and wider than the diameter of the piece and to form transverse edges on the piece at or adjacent to the ends of the holding portion and, before, at the same time as, or after the formation of the holding portion, forming a terminal end portion at one end of the piece, the deforming and forming being such that the hollow portion is nearer to said one end than to the other end of the piece, is disposed at a predetermined angular relationship to the terminal end portion and is an interference fit in the insulator; wherein the other end of the piece is inserted into the insulator; wherein an axial thrust is applied to the terminal end portion to drive the holding portion into the insulator so that the holding portion is disposed in a predetermined position relative to the mounting member, engages said grooves and thrusts the edges into engagement with the bore; and wherein a transverse thrust is applied to the other end to form a spark tip projecting from the insulator.
9. A method as claimed in claim 8 and substantially as hereinbefore described.
10. An electrode device made by the method claimed in claims 8 or 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7933550A GB2060151A (en) | 1979-09-27 | 1979-09-27 | Spark ignition electrode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7933550A GB2060151A (en) | 1979-09-27 | 1979-09-27 | Spark ignition electrode |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2060151A true GB2060151A (en) | 1981-04-29 |
Family
ID=10508110
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7933550A Withdrawn GB2060151A (en) | 1979-09-27 | 1979-09-27 | Spark ignition electrode |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2060151A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19539516A1 (en) * | 1995-10-25 | 1997-04-30 | Rauschert Gmbh & Co Kg Paul | Mounting for ceramic firing/ignition electrode of burner |
| FR2746553A1 (en) * | 1996-03-20 | 1997-09-26 | Sapco | Spark plug with improved fixing of electrode in insulator |
| AU720740B3 (en) * | 1999-02-26 | 2000-06-08 | Tyco Electronics Pty Limited | Improved gas igniter |
| WO2000052391A1 (en) * | 1999-02-26 | 2000-09-08 | Utilux Pty. Limited | Improved gas igniter |
| DE102006058284A1 (en) * | 2006-12-08 | 2008-06-12 | Viessmann Werke Gmbh & Co Kg | electrode |
| DE19906032B4 (en) * | 1999-02-12 | 2016-06-09 | Federal-Mogul Ignition Gmbh | Current feedthrough element for a gas or oil burner |
-
1979
- 1979-09-27 GB GB7933550A patent/GB2060151A/en not_active Withdrawn
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19539516A1 (en) * | 1995-10-25 | 1997-04-30 | Rauschert Gmbh & Co Kg Paul | Mounting for ceramic firing/ignition electrode of burner |
| FR2746553A1 (en) * | 1996-03-20 | 1997-09-26 | Sapco | Spark plug with improved fixing of electrode in insulator |
| DE19906032B4 (en) * | 1999-02-12 | 2016-06-09 | Federal-Mogul Ignition Gmbh | Current feedthrough element for a gas or oil burner |
| AU720740B3 (en) * | 1999-02-26 | 2000-06-08 | Tyco Electronics Pty Limited | Improved gas igniter |
| WO2000052391A1 (en) * | 1999-02-26 | 2000-09-08 | Utilux Pty. Limited | Improved gas igniter |
| DE102006058284A1 (en) * | 2006-12-08 | 2008-06-12 | Viessmann Werke Gmbh & Co Kg | electrode |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |