USRE21550E - Shielded spark plug - Google Patents

Description

Rel 21,550

Sept. 3, 1940. A. HYLAND SHIELDED SPARK PLUG INVENTOR Lawrence A.

Hyland ATTORNEY UNITED STATES PATENT OFFICE 21,550 I I A snmman SPARK PLU Lawrence A. Hyland, Washington, D. 0., assignor,

by mesne alignments, to Bendix Aviation Corporation, South Bend, Ind, a corporation of Delaware Original 1v.'1,950,40a, dated We. 1:, 1934, Serial No. 558,291, August 20, 1931, which is a a1- vision Serial No. 375,241, July 1, 1929. Application for reissue February 26, 1935, Serial 8'Claims. (01. 123-169) (Granted under the .act of March 3, 1883, as amended April 30, 1928; 370,0. G. 757) This invention relates to a shielded spark plug like that shown in my co-pending application Serial No. 375,241, July 1, 1929, of which this application is a division.

Theobjects of this invention are to provide a spark plug that will not interfere with radio re-, ceiving apparatus and to provide a sparkplug the parts of which will remain tly assembled and prevent the escape of fuel on compression fromthe cylinders of an internal combustion engine, in

spite of the vibration and the linear and volumetric changes due to temperature diflerences met in practice. I

The single figure of the drawing is a longitudill nal axial section through the present invention.

spark plugs of such engines be prevented from interiering with the reception of radio signals.

The body I has a substantially cylindrical, ex-

,temally threaded portion 2 that screws into the usual spark plug aperture in the cylinder wall of the engine wherein this device is used and an ex panded portion 3, internally threaded at I to engage a co-acting threaded portion on the gland 5. Portion 3 is formed internally to act as a seat 6 for packing element 7, which insures a. tight joint" between gland 5 and body I.

The electrode 8 is grounded to the engine block through body I.-

Gland Shas a frusto-conical recess 9 formed therein, and in said recess is seated a like shaped member II with an axial bore ll therethrough.

The recess 9 communicates with a cylindrical reoess I2 in said gland, which recess is extended by tubular sleeve [3 which projects from said gland,

a the cross sectional area of the bore in said sleeve being the same as that of said recess- The base 101' recess 9 forms a shoulder It on which are I is substantiatlly enclosed in mica insulating ele- 55 shoulder 23 and the end 01! stem II is upset over ment l9. Immediately adjacent electrode II stem II is expanded at 28. and a shoulder 21 is i'ormed thereon. Element l9 and the series of mica washers 22 are seated on said shoulder, the washers 5 being compressed between the shoulder and the base of irusto-conical member Ill.

The upper end of stem I9 is reduced, forming a shoulder 23, and has an axially extending bore 24 therein. A metal washer 25 is'seated on the the washer 25, as shown at 26, compressing mica washers. l5 and 22, and securing the stem, mica washers, and frusto-conical member 10 in tight assembly with gland 5. metal parts of this assembly due to temperature differences will be taken up by thecompressed mica washers, so there will be no relaxation 'or loosening of the parts thereof due to such changes or to vibration.

Connection to a wire is made by inserting in here 24 a suitable contact element carried by such wire. 7

While mica has been mentioned as the insulating material in the present construction, it is to be understood that it is by way of description Any changes in the only, and not of limitation, as any substance hav- I ing the requisite properties of limited compressibility, heat resistance, and electrical insulation -will serve.

It is apparent that inasmuch as the electrode 8 is directly grounded to the engine block through body I, and the metal. parts directly connected to central electrode I! are substantially enclosed in metal parts such as sleeve l3 and gland 5, that the electrodes are efl'ectively shielded so that radia-' tion of oscillations from discharges between said electrodes is prevented.

The herein described invention may be manulectured and used by or for the Government of the United States of America. for governmental purposes without the payment of any royalties thereonor therefor.

I claim: V

1. A spark plug, comprising a body member adapted to engage the wall of an engine cylinder, an'electrode carried thereby, a gland engaged with said body member, said gland having.a recess in one face th'ereol, an interfltting member disposed in said recess, said interfitting member having a passage therethrough, 'a tubular sleeve extending from the other face of said gland, a lining of in- I sulating material within said sleeve extendin 'into the recess in said gland, a stem extending through said interfltting member andinto said sleeve, a sheath of insulating material around said stem extending substantitally to the upper end of said stem, heat resistant compressible insulating material disposed on each side of said member around said stem, means co-acting with said stem to place said material under compression, and an electrode carried by said stem adjacent the aforesaid electrode.

2. A spark plug, comprising a body member adapted to engage the wall of anengine cylinder, said body having an expanded interiorly threaded portion and a seat for a packing element adjacent the inner end of said threaded portion, a packing element on said seat, a. gland engaged with said said recess, a tubular sleeve extending from the j said other face of said gland concentricwith the said annular recess, a stem having an enlarged portion at one end with a shoulder formed on the inner face theretof, said stem extending through the bore in said trust-conical member and havin the other end reduced to form a, shoulder, an in-' sulating sheath around said stem, heat resistant compressible insulating material around said stem on each side of said frusto-conicalmember, an insulating lining in said tubular sleeve extendlng into-the annular recess in said gland, an axial bore in said stem at the reduced end thereof, a washer seated on the shoulder at the said reduced end and said reduced end upset over saidwasher, and an electrode on the enlarged portion of said stem disposed adjacent the aforesaid electrode.

3. A spark plug, comprising a body member adaptedto engage the wall of an engine cylinder,

an electrode carried thereby, a, gland engaged with said body member, a stem passing through said gland, an electrode carried on said stem adjacent the aforesaid electrode, heat resistant compressible insulating material on each side of said gland around said stem, a sleeve extending outwardly from said gland beyond the outer end of said stem, and means coacting with said stem to place said material under com pression.

4. A spark plug, comprising a body member adapted to engage the wall of an engine cylinder, an electrode carried thereby,- a gland engaged with said body member, a stem passing through the said gland, said stem having a substantially cylindrical recess at its outer end adapted to receive a connection to a wire, an electrode carried on said stem adjacent the aforesaid electrode, heat resistant compressible insulating material on each side of said gland around said stem, a sleeve internally insulated throughout its length extending outwardly from said gland beyond'the outer end of said stem, and means coactlng with said stem to place said material under compression.

5. A spark plug, comprising a central. electrode. a stem whereby said electrode is carried, said stem being adapted to have a conductor connected thereto and having a shoulder adjacent said electrode, a second electrode operatively disposed adjacent the'aforesaid electrode, an insulating sheath around said stem, an axially bored frusto-conical member through which said stem and sheath extend, insulating means around said stem on each side of said member, means coacting with said shoulder to place said insulating means under compression, a body in which said member is mounted and to which said second electrode is connected and which is adapted to be connected to an engine block, an outwardly extending sleeve connected to said body, and an insulating liner in said sleeve, said sleeve and said body enclosing said electrodes and.forming I a grounded electrical shield therearound.

6. A spark plug, comprising a central electrode, a stem whereby said electrode is carried, said stem being adapted to have a conductor in ternally connected thereto and-having a shoulder adjacent said electrode, a second electrode operatively disposed adjacent the aforesaid electrode, an insulating sheath around said stem, an

axially bored frusto-conic'al member through which said stem and sheath extend, insulating means around said stem on each side of said member, means coacting with said shoulder to place said insulating meansunder compression, a body in which said member is mounted and to which said second electrode is connected and which is adapted to be connected to an engine ductor, a mica sleeve lining said barrel, a stack of mica washers occupying the space between said mica sleeves and bearing on a shoulder of the body, and means on the upper end of the spindle confining said stack.

8. A spark-plug comprising the combination of a central spindle, a mica sleeve about said spindle, a body in which the spindle and its mica sleeve are fixed, a barrel extending upward from said body above the spindle to form a socket for the insertion of an insulated high-tension conductor, a mica sleeve lining said barrel, a stack of mica washers occupying the space between said mica sleeves and bearing on a shoulder of the body, and a confining element bearing on the top of said stack, the upper end of the spindle passing through said confining element and being upset thereon.

LAWRENCE A. HYLAND.

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