GB2387485A

GB2387485A - Arrangement for attaching or removing a magnetic device to or from a spark plug

Info

Publication number: GB2387485A
Application number: GB0208086A
Authority: GB
Inventors: Joseph Gibson Dawson
Original assignee: MAGTRIX CONNECTORS Ltd
Current assignee: MAGTRIX CONNECTORS LIMITED
Priority date: 2002-04-09
Filing date: 2002-04-09
Publication date: 2003-10-15
Also published as: GB0208086D0

Abstract

A tool 24, 22, for attaching or removing a magnetic device 1 to or from a spark plug 7 installed in an engine, comprises, in use, a level of magnetic attraction between the tool and the magnetic device which is less than or greater than that between the magnetic device 1 and a spark plug 7, respectively. The magnetic device 1 may be an annular Neodymium Iron and Boron permanent magnet which fits around the ceramic insulated portion of the spark plug. The tool is used to install or remove the magnetic device in a manner which avoids the magnetic device from being damaged during the process. The tool 24, 22 may be a cylindrical tube made of magnetic material such as steel and it may have dimensions which make maximum use of the recess space provided around the spark plug 7 or it may have a width which is less than the maximum width of the spark plug. A non-magnetic polymeric spacer element 36 may be used to reduce the magnetic attraction of the tool 24 to a desired level below that between the magnetic device 1 and a spark plug 7. Methods of attaching and removing a magnetic device to or from a spark plug are also disclosed.

Description

-" '1 A TOOL FOR USE WITH MAGNETS

The present invention relates to a tool for attaching an annular magnet to a spark plug installed in an engine and/or removing said magnet and the manufacture and use of such tools. Attaching annular magnets to spark plugs may be used to improve the performance of internal combustion engines. Such devices are described in co-pending GB application Number 0122533.3. Inserting such strong magnets over a spark plug in an environment, such as an engine, comprising large magnetically attractable bodies and accurately seating the magnet on a spark plug can be difficult. This difficulty is increased as, in many modern engines, spark plugs are recessed in deep narrow recesses in an engine block or cylinder head. When such magnetic devices have to be removed further difficulties ensue, particularly where spark plugs may need to be changed in a hot engine as in, for example, racing use.

Whilst the handling of magnetic attachments to spark plugs during attachment and removal may be troublesome, further and compounding difficulties arise due to the brittle nature of such magnetic attachments. Ultra high strength magnets, such as those composed of neodymium iron and boron, are typically manufactured using a sintering process. Such sintered products can be both brittle and highly magnetised. Hence, it has been found that the unaided attraction of such magnets, even over a short distance, to a large metal object such as an installed spark plug can generate enough kinetic energy to break a magnet on any resulting impact. In addition even low energy impact can be sufficient to damage any magnet coating, thus exposing a magnet to rapid oxidization. Neodymium iron and boron magnets are particularly susceptible to such oxidisation.

The user of magnetic attachments to spark plugs therefore has a delicate task of installing and removing such magnets, often in a hot environment, where a mistake can easily result in these expensive devices being destroyed. This is exacerbated in modern engines where spark plugs are often deeply recessed into a cylinder head.

The present invention provides a tool for at least one of attaching or removing a magnetic device associated with a spark plug installed in an engine, the magnetic device being of generally annular form being disposed about an insulator portion of a spark plug, the tool being adapted in use to have a greater magnetic attraction for the magnetic device when removing the device and a lesser magnetic attraction to the magnetic device when attaching the device to the spark plug.

The tool is primarily intended for use in conjunction with a conventional spark plug. Such plugs consist of a steel body having a machine screw thread to engage in a cylinder block or head. The body houses a central cathode electrode surrounded by a ceramic insulator.

The body also includes one or more anodes to form a spark gap with an end of the central electrode. On the body above the thread, a contiguous steel shoulder region is typically present having a hexagonal portion used for tightening the spark plug in the engine. The topmost portion of the metal body is typically swaged over to retain the ceramic portion.

Magnetic devices suitable for use with the tool are releasably attachable to a spark plug.

Their attachment may be by a magnetic attractive force only. The magnetic devices are those preferably attached to at least part of the metal body of a spark plug left exposed after the spark plug has been secured in an engine by, for example, being screwed into an engine block or cylinder head. The exposed metal portion of the spark plug on which the tool can facilitate attachment or removal of the magnetic device is preferably the swaged portion of the spark plug.

Tools of the invention are preferably adapted for use with annular magnetic devices.

Attachment or removal of such magnetic devices will typically require a high-tension lead to be detached from the electrical contact of a spark plug. More preferably magnetic devices for use with the tool may be predominantly flat annular discs having two faces. Even more preferably the flat discs have a recess or bevel on one face on the rim of a central aperture.

The recess on the flat disc may conform generally to the shape of the swaged portion of the spark plugs outer surface. Tools of the invention may be used to contact the face of such discs away from the face with the recess.

l Tools of the invention are adapted in use to have a greater magnetic attraction to the magnetic device than the magnetic device has to a spark plug when used for removing the device. Tools of the invention are adapted in use to have a lesser magnetic attraction to the magnetic device than the device has for a spark plug when attaching the device to the spark plug.

Tools of the invention may be attracted to magnetic devices by the magnetic attraction due to the device alone or may have attraction for as well as attraction to the magnetic device, by means of magnetism in the tool itself.

Tools of the invention may facilitate the attachment and / or removal of magnets from spark plugs and reduce the potential for breakage of fragile magnets by uncontrolled magnetic attraction generating high levels of kinetic energy which is dissipated by breakage of a magnet on impact with a surface. These benefits of the tool are particularly apparent when installing or removing magnets from spark plugs installed in a recess in an engine.

Tools of the invention, particularly when used, configured or intended for use as an applicator or installation tool for attaching a magnet or magnets to a spark plug may comprise a distancing means. Distancing means for use with the invention reduce the potential for magnetic attraction to a part of the tool. The tool may therefore have a lesser magnetic attraction from and/or magnetic attraction to a magnetic device, on closest approach, than the magnetic device will have for a spark plug, on closest approach, thereby forming an attachment tool. In particular when a magnetic device is in contact with the tool and also with a spark plug and the tool and spark plug are moved apart the magnetic device will therefore remain preferentially attached to the spark plug. The distancing means may be achieved by offsetting the closest approach of a magnet to a magnetically attractable part of the tool by means of a non- magnetically attractable material. The bulk of magnetically attractable material may be reduced in the distancing means. The distancing means or offset may comprise a solid material, a coil spring or a series of posts or pins such as metal pins.

Materials comprising the distancing means may have a cushioning effect on a magnet attracted to and impacting upon the tool in the region where the distancing means is

present. Materials for the distancing means may be resilient. The distancing means preferably comprises a plastics or polymeric material. Suitable polymeric materials include polyesters and polyolefins, nylons and rubbers and polytetrafluoroethylene.

The distancing means may be retained in the tool by an interference or push fit or may be adhered to the tool. The distancing means may comprise a short tube with a first portion with a diameter to allow a push fit into the tubular member so as to retain the short tube in the tubular member and a second portion of a larger diameter so as to form the distancing means function at the end of said tubular portion wherein the short tube has an internal diameter sufficient to allow it to be inserted over the porcelain portion of a spark plug to the level of the swaged portion of the spark plug.

A distancing means for use in tools of the invention may be releasably attached to a portion of the tool. Attaching or detaching the distancing means modifies the potential for magnetic attraction of a magnet to the tool. By attaching a distancing means, a removal tool, with higher magnetic attraction for a magnet, may be converted to an attachment tool by the consequential reduction in magnetic attraction to a relevant part of the tool. Distancing means suitable for use with the invention may offset a magnet from a magnetically attractable part of the tool by 2 to 5mm, more preferably by 4mm for use with an annular magnet of strength above 1,500 Gauss.

Tools of the invention include an inter-convertible tool for attaching and removing a magnetic device associated with a spark plug installed in an engine, the magnetic device being of generally annular form being disposed about an insulator portion of a spark plug, wherein the tool is inter-convertible by the attachment or removal of a non-magnetisable distancing means wherein the tool is adapted in use to have a greater magnetic attraction for the magnetic device than the magnetic attraction of the device for a spark plug, by removal of the distancing means when used for removing the device and a lesser magnetic attraction to the magnetic device than the magnetic attraction of the device for a spark plug, by attaching the distancing means when used for attaching the device to the spark plug.

- l A tool of the invention may comprise an elongate member capable of insertion into a recess of similar dimensions to a spark plug, such as a recess in an engine wherein a spark plug is located. A maximum width of the tool for attracting and holding the magnetic device may be of smaller dimensions than a maximum width, perpendicular to a principal longitudinal axis, of the corresponding size of spark plug.

The whole tool may comprise an elongate member. An end or ends of a tool of the invention may comprise portions adapted for attaching or removing a magnet releasably attached to a spark plug. A tool of the invention may comprise a portion for attaching and another portion for removing the magnetic device wherein said portions comprise the ends of a substantially elongate member. The portion of a tool for attaching may comprise a tubular member suitable for placing over the porcelain portion of a spark plug but only up to the level of the swaged portion of the spark plug.

A tool of the invention is preferably in the form of a substantially elongate rectilinear of between 15 and 30 centimetres in length. Modern engines often having spark plugs recessed by some 12cm or more, Vauxhall_ Astra_ and Vectram models being of such depth and of diameter 3cm. Spark plugs cannot be removed from such engines without first removal of any inserted magnetic device.

An inventive security system, is also disclosed, comprising a distancing means similar to that hereinbefore described, but just enough to enable attachment of an annular magnetic device, as hereinbefore described, to a removal tool as hereinbefore described, such that said tool comprises substantially a maximum bulk of magnetically attractable material insertable in an engine recess for receiving a spark plug when a spark plug is present and said distancing means is permanently attached to the upper side of the magnetic device as magnetically releasably attached to a spark plug by a lower side wherein access, particularly to the hexagonal portion but excluding the upper ceramic portion and associated outer electrode, to said installed spark plug can only be obtained by use of such a security removal tool to remove said magnetic device by said magnetic device being preferentially magnetically attached to said removal tool when removal tool, magnetic device and spark plug are substantially in mutual contact in a removal operation as herein described. Said removal tool preferably comprises a magnetic member. Said inventive

security system by virtue of requiring said removal tool stops users without access to said tool accessing a spark plug for removal as tools of lesser magnetically attractable material or magnetic attraction cannot sufficiently attract said magnetic device to effect removal and enable access to said spark plug. The magnetic device of such a security system preferably nearly conforms (i.e. is slightly less than) in its outer radial dimensions to the inner radial dimensions of the engine recess at the height of the location of said magnetic device when seated on an install spark plug.

The utility of a tool of the invention as a tool for removing magnetic devices is greatly improved by a rapid cooling of magnets by heat conduction and the choice of an optimal bore for a part of the tool intended to be disposed about an insulator portion of a spark plug. Magnetic devices in a recently stopped engine can be at a temperature well in excess of 90 C. Removal and subsequent manual handling of such magnetic devices requires a rapid reduction in temperature of a magnet upon removal. Removal tools of the invention therefore preferably contact more than 60% of the surface area of a face of a magnet, preferably to the outer face of a magnet as present when attached to a spark plug. Tools of the invention may be 5 times or greater in mass, more preferably 10 times or greater, most preferably 20 times or greater in mass than a magnet suitable for affecting the performance of a spark plug. Removal tools of the invention may combine a high surface contact area and a high mass relative to a magnetic device to be removed. Such tools may be capable of reducing the temperature of a magnet in a recently stopped engine on removal to that capable of manual handling, and thereby additionally reducing any potential dangers due to contact with flammable materials, within 2 seconds, such as may be important particularly in racing use.

Spark plugs are conventionally manufactured in two sizes with, a 16mm hexagonal portion and a 20mm hexagonal portion. A plug spanner for a '16mm' spark plug cannot be disposed fully about an insulator portion of a '20mm' spark plug and 16mm spark plugs can be recessed in channels of 20mm diameter. A tool suitable for removing annular magnets from spark plugs of both conventional sizes, accurately, quickly and with minimal risk of

- breakage and skin burns has been found to comprise a cylindrical tube of approximately 20mm outside diameter and approximately 1 3mm inside diameter.

Tools of the invention may additionally comprise supplementary sizes of installation and /or removal tool.

Tools of the invention may comprise a waisted central portion for an easier handling and to enable a tool to be conveniently secured by resilient tool clips for storage. Such storage may preferably be mounted inside a vehicle, for example, in an engine compartment for ready access when maintaining an engine.

Tools of the invention comprise a magnetically attractable material. Suitable materials include various types of steel, including; high carbon steel; chrome-vanadium steels; and mild steel. Tools of the invention preferably comprise magnetically attractable stainless steel. Any metal having adequate magnetic properties may be used.

Tools of the invention may be coated. Suitable coatings include metal plating, painting and coating with plastics. Such tool coatings are not per se considered to constitute a distancing means within the scope of the invention, unless the maximum potential magnetic attraction by a strong magnet is thereby significantly attenuated. Coatings may be used to introduce a cushioning means for a tool used as a removal tool. Such coatings are particularly advantageous as protection against abrasion or chipping of a magnetic device coating, such as metal plating is thereby avoidable.

A metal magnetically attractable, preferably elongate, tool of the invention may comprise two ends, the ends differing in the thickness of a plastics/polymeric coating, such as a polyolefin, such that the maximum attractive attachment force of a magnet on closest approach to a tool end is modified so as to give an attachment tool function at one end, thick coating and a removal tool function at the other end, thin coating due to consequent modification of the degree of attraction.

A tool of the invention comprising a polymeric distancing means may be manufactured wherein the polymeric distancing means is formed by placing a heat shrinkable polymer

tube over and overlapping the end of a tubular metal inside portion of the tool wherein the polymer is then shrunk to contact the inside portion and is thereby secured thereto wherein the polymer thereby overlaps the inside portion so as to form the polymeric distancing means. A tool of the invention comprising a polymeric distancing means may be manufactured wherein a polymeric distancing means is formed by at least partially immersing an end of the tool wherein the distancing means is to be formed in a polymer melt and withdrawing the tool with a polymer coating thereupon.

A tool of the invention may comprise a member comprising a predominantly polymeric material with a magnetically attractable insert or integrally moulded component to confer the aforementioned properties of tools of the invention.

The tool may comprise part of a kit of parts comprising a tool as described above and one or more annular magnetic attachments for a spark plug.

A tool as hereinbefore described may be used in a method of releasably attaching an annular magnetic device to a spark plug installed in an engine comprising magnetically attaching the annular magnetic device to an end of a magnetically attractable tool with apertures of the magnetic device and the tool disposed substantially coaxially, placing said tube and magnet over an insulator portion of the spark plug until the magnet is magnetically secured to the spark plug and removing said tool thus leaving the magnet attached. The tool may be in the form of a tube.

A tool as hereinbefore described may be used in a method of removing an annular magnetic device releasably attached to a spark plug installed in an engine comprising placing a magnetically attractable tool over an insulator portion of the spark plug until the releasably attached magnet is magnetically secured to the tool and removing said tool thus removing the magnet attached to the tool. The tool may be in the form of a tube.

In order that the present invention may be more fully understood, examples will now be described by way of illustration only with reference to the accompanying drawings, in which: Figure 1 shows a cross section through an annular magnetic device with which a tool of the invention is intended to operate; Figure 2 shows a view of the underside of the annular magnetic device of Figure 1 with which a tool of the invention is intended to operate; Figure 3 shows a conventional spark plug in association with an annular magnetic device shown in Figures 1 and 2 positioned in manner as facilitated by a tool of the invention.

Figure 4 shows a side elevation of a tool of the invention; Figure 5 shows an end view of the tool of the invention shown in Figure 4; Figure 6 shows a cross section of an attachment portion of the tool of the invention shown in Figure 4; Figure 7 shows a schematic representation of a tool of the invention applying an annular magnet to a conventional spark plug located in a recess; and Figure 8, which shows a schematic representation of a tool of the invention removing an annular magnet from a conventional spark plug.

Referring now to the figures where the same features are denoted by common reference numerals. Figures 1 to 3 show an annular magnet 1 with which tools of the invention are intended to operate. The magnet 1 is in the form of an annulus with a central aperture 3 through which the ceramic portion 5 of a conventional spark plug 7 is inserted. The annular magnet has a

recess 9 which co-operates with a swaged portion 11 of the spark plug when the magnet is correctly applied to the spark plug.

An elongate, steel tool 20 of one embodiment of the invention is shown in Figures 4, 5 and 6 and comprises two end portions 22, 24 joined to a central portion 26 by shoulder regions 28, 30. Central portion 26 is of a lower diameter than the end portions 22,24 to aid visibility of the end of the tool, particularly when used in a recess of an engine. The two end portions 22, 24 are in the fomm of cylindrical tubes. One end portion comprises a distancing means 34. The distancing means comprises an annular Polyterafluoroethylene (PTFE) distancing part 36 attached to the steel end 38 of the tool. Distancing means 34 comprises a tube with a stepped outer surface. This is formed from a portion with a small radius 37 and an adjoining portion 36 of larger radius, forming a shoulder 44 between the two portions. Portion 37 has an outer dimension substantially the same as the inner dimension of tubular portion 24. Insertion of portion 37 of the distancing means 34 into the bore 40 of the tool 20 retains the distancing unit in place by an interference fit. The distancing unit is prevented from entering the bore too far by means of a shoulder 44 of the distancing means 34. The height of the shoulder part 36 defines a distance for offsetting the closest approach of a magnet to the end of the tool thus reducing a maximum magnetic attraction force by a magnet to the end portion 38 of the tool 20.

In alternative embodiments of the tool the distancing means 34 may extend over a portion of the outside or the tool. Alternatively the distancing means 34 may extend over both a portion of the outside of the tool and also into an aperture 40 of the tool.

Figures 7 and 8 are purely schematic representations to illustrate the use of the tool. In practice a magnet is usually not present unattached to either the spark plug or the tool, during use of the tool, and the change over in attachment of the magnet from tool to spark plug and visa versa typically occurs when the magnet is in physical contact, by magnetic adhesion to both spark plug and tool. It is a preferred that the magnet is never in 'free flight' between the tool and spark plug, unless momentarily, as a benefit of the tool is the avoidance of such movement which may result in an impact that shatters a magnet.

Figure 7 is a schematic representation of a tool of the invention 20 installing a magnet 1 to a spark plug 7 itself installed in a recess 48 in a cylinder head portion 46 (shown in cross section). In use, Figure 7, the tool 20 may be used to apply an annular magnet 1 using an end portion 24 of the tool. The magnet is placed against the distancing portion 34, with apertures 3, 40 co-terminus. Wherein the magnet remains attached by virtue of its own magnetic attraction to the end portion of the tool 24 as mediated by the distancing means 34. Holding another portion of the tool, for example, end 22 or middle portion 26, the tool 20 with the attached magnet 1, is placed over a spark plug 7 such that a ceramic portion of the spark plug 5 enters the apertures 3, 40. On close approach of the magnet 1 to the spark plug 7, particularly the swaged portion 11 of the spark plug, the magnet 1 becomes preferentially attached to the steel swaged portion 11. Withdrawing the tool from the spark plug leaves the magnet 1 in place.

The other end 22 of the tool 20 may be used for removing the annular magnet 2 as shown schematically in Figure 8. The end 22 of the tool 20, on which an annular magnet 1 is seated, is placed over a spark plug 7 and the ceramic portion of the spark plug 5 entered into aperture 50 of the tool. On lowering the tool further the end face 52 of the tool contacts the magnet over more than 90% of the upper face of the magnet and the magnet is more strongly attracted to the tool than to the spark plug. The tool thereby rapidly extracts heat from the magnet cooling the magnet to a safe handleable temperature. The tool is then removed from the spark plug and the magnet is withdrawn attached to the tool.

Claims

1. A tool for at least one of attaching or removing a magnetic device associated with a spark plug installed in an engine, the magnetic device being of generally annular form being disposed about an insulator portion of a spark plug, the tool being adapted in use to have a greater magnetic attraction to the magnetic device when removing the device and a lesser magnetic attraction to the magnetic device when attaching the device to the spark plug.

2. A tool as described in claim 1 for both attaching and removing the magnetic device.

3. A tool as described in either claim 1 or claim 2 comprising a distancing means for reducing the attraction of the magnetic device to a part of the tool wherein the distancing means comprises part of the tool for engaging the magnetic device.

4. A tool as described in claim 3 wherein the distancing means is releasably attached to a portion of the tool such that detachment of the distancing feature converts that portion from an attaching to a removing function.

5. A tool as described in either claim 3 or claim 4 wherein the distancing means has a cushioning effect on the impact of a magnetic device attracted to a portion of the tool.

6. A tool as described in any one of claims 3 to 5 wherein the distancing means comprises a polymeric material.

7. A tool as described in any previous claim wherein a maximum width of the tool for attracting and holding the magnetic device is of smaller dimensions than a niaximum width, perpendicular to a principal longitudinal axis, of the spark plug.

8. A tool as described in any of claims 2 to 7 comprising a portion for attaching and another portion for removing the magnetic device wherein said portions comprise the ends of a substantially elongate member.

9. A tool as described in any previous claim wherein a portion for attaching a magnetic device comprises a tubular member suitable for placing over the porcelain portion of a spark plug down to the level of a swaged portion of the spark plug.

10.A tool as described in both claim 6 and claim 9 wherein the distancing means comprises a short tube with a first portion with a diameter to allow a push fit into the tubular member so as to retain the short tube in the tubular member and a second portion of a larger diameter so as to form the distancing means function at the end of said tubular portion wherein the short tube has an internal diameter sufficient to allow it to be inserted over the porcelain portion of a spark plug to the level of the swaged portion of the spark plug.

11.A tool as described in any previous claim wherein the tool comprises steel.

12.A tool as described in claim 11 wherein the steel is chrome vanadium steel or magnetic stainless steel.

13.A kit of parts comprising a tool as described in any one of claims 1 to 12 and one or more annular magnetic attachments for a spark plug.

14.A method of releasably attaching an annular magnetic device to a spark plug installed in an engine comprising magnetically attaching the annular magnetic device to an end of a magnetically attractable tool with apertures of the magnetic device and the tool disposed substantially coaxially, placing said tool and magnet over an insulator portion of the spark plug until the magnet is magnetically secured to the spark plug and removing said tool thus leaving the magnet attached.

15.A method of removing an annular magnetic device releasably attached to a spark plug installed in an engine comprising placing a magnetically attractable tool over an insulator portion of the spark plug until the releasably attached magnet is magnetically secured to the tool and removing said tool thus removing the magnet attached to the tool.

16.A method of manufacture of a tool according to claim 6 wherein a polymeric distancing means is formed by placing a heat shrinkable polymer tube over and overlapping the end of a tubular metal inside portion of the tool wherein the polymer is then shrunk to contact the inside portion and is thereby secured thereto wherein the polymer thereby overlaps the inside portion so as to form the polymeric distancing means.

17.A method of manufacture of a tool according to claim 6 wherein a polymeric distancing means is formed by at least partially immersing an end of the tool wherein the distancing means is to be formed in a polymer melt and withdrawing the tool with a polymer coating thereupon.

18.A tool as hereinbefore described with reference to the accompanying description and

Figures 4 and 5 of the drawings.

(a-) A- i INVESTOR IN PEOPLE (I/. TW

Application No: GB 0208086.9 l5 Examiner: John Watt Claims searched: 1 18 Date of search: 8 October 2002 Patents Act 1977 Search Report under Section 17 Databases searched: UK Patent Office collections, including GB, EP, WO & US patent specifications, in:

UK Cl (Ed.T): HIP (PGXC, PGZ, PT) Int Cl (Ed.7): HOlF (7/02); HOlT (13/00, 13/40) Other: Online: EPODOC, JAPIO, WPI Documents considered to be relevant: Category Identity of document and relevant passage Relevant E, A GB 2373293 A (DAWSON) see whole document A US 6374709 B1 (VASICHEK) see whole document A US 6182537 B1 (VASICHEK) see whole document X Document indicating lack of novelty or inventive step A Document indicating technological background and/or state of the art.

Y Document indicating lack of inventive step if combined with P Document published on or after the declared priority date but before the one or more other documents of same category. filing date of this invention.

E Patent document published on or after, but with priority date earlier than, & Member of the same patent family the f lima date of this application.

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