US1996421A

US1996421A - Spark plug

Info

Publication number: US1996421A
Application number: US435461A
Authority: US
Inventors: Roy T Hurley
Original assignee: HURLEY TOWNSEND CORP
Current assignee: HURLEY TOWNSEND CORP; HURLEY-TOWNSEND Corp
Priority date: 1930-03-13
Filing date: 1930-03-13
Publication date: 1935-04-02
Anticipated expiration: 1952-04-02

Description

R. T. HURLEY April 2, 1935.

SPARK PLUG Filed March 13, 1930 IN VENT 0R fioy Z Hur/ey w W-% ATTORNEYS Patented Apr. 2, 1935 1,996,421

UNITED STATES PATENT OFFICE- sraax rnuc Roy '1. Hurley, Dobbs Ferry, N. Y., alalgnor to Hurley-Townsend Corporation, New York, N. Y., a corporation of Delaware Application March 13, 1930, Serial No. 435,461

' 10 Claims. (Cl. 123-169) This invention relates to spark plugs and has A sheet of compressible, heat-resisting, insufor an important object the provision of a spark lating material, such as mica, is next snugly plug which will be well sealed at all times against wrapped around the sleeve 6 in the form of a the escape of gases through it and which will, as multiple-pLv tube 9. Upon this tube 9 the lower a consequence, be well adapted to avoid overend iii of the insulator is built up of washers 5 heating evenunder the exacting conditions imof suitable insulating material, such as mica. posed in heavy duty engines, such as those em- The nut 4 is then impaled upon the tube and the ployed in airplanes and in racing automobiles. pp r nd II 0! h insulator is built p y p Other objects and advantages will hereinafter ing upon the tube further washers of mica or I0 appear. other suitable material. As thus assembled, the

In the drawing forming part f thi in nut 4 does not bind upon the tube 9 but fits it tion, rather snugly.

Figure 1 is a vertical sectional view taken cen- The Cali-r81 electrode 18 next inserted in e trally through a spark plug embodying feat sleeve 8 from the lower end thereof. The cen- I5 of the invention. tral electrode comprises a shank l2 and a nose Figure 2 is a vertical, sectional, damn i It, the nose being larger than the shank, but through an expandible sleeve employed in t of such small mass that the heat absorbed by it spark plug of Figure 1; may be rapidly and efliciently conducted away, Figure 3 is a plan view of the sleeve of Figprincipally by the shank I! and the sleeve 6. ure 2; The central electrode is desirably made of steel 20 Figure 4' is a sectional view t k n on t line or other suitable material that will resist oxidal-l of Figure 2, looking in the direction of the tion by the combustion in the engine. The nose arrows; and I3 carries a sparking tip it of suitable material,

Figure 5 is a vertical, sectional view through a such s ic an a ese wi modified form of expandlble sleeve hi may be Prior to the insertion of the central electrode, 25 employed. the sleeve, insulator and nut assembly is longi- The illustrative spark plug comprises an tudinally compressed, and this pressure is-maintemally threaded shell I adapted to be thread d tained throughout the insertion of the electrode. into a motor. The shell I carries a spark eiee- The shank I2 of the central electrode is of a trode 2 which forms one terminal of the spark diameter to 8 mi Within the ungmoved 30 Ban. An insulator and central electrode assemlower end of the sleeve It may he s r in bly 3 comprises an externally threaded u; 4 the sleeve readily therefore, but when it reaches which is screwed t ghtly into the shell I to cothe internal ribs formed by grooving of the act with the shell in firmly clamping an int r. exterior of the sleeve, it must be driven. This posed gasket 5 to form a tight seal. The nut driving of the electrode through the sleeve elimi- 35 4 serves as a retaining and supporting memb nates the grooves and expands the grooved porfor the central assembly 3. tion of the sleeve to the diameter of the un- The central assembly 3 also comprises an exmo p t on. Such expans on of the s e panded sleeve 6, (see Figures 2 and 3) of malsimultaneously applies circumferential tension 40 leable metal having high heat conductivity, such fi "41131 W to the tube W811 9 30 that 40 as copper. This sleeve is provided with a flange the tube wall is pressed with considerable force I' at the lower end thereof. It is upon this sleeve between thelsleeve and the nut The Shank that the central assembly is built up. The leeve and the sleeve 8 have at least as high coeflit may be initially a cylindrical tube provided cients of heat expansion as the nut 4, so that with the flange I, but before the steps of incor-' this pressure is not relieved when the spark plug 45 porating it in a spark plug are begun, longibecomes heated in use. tudinally extending grooves I are formed in the After the insertion of the central electrode, outer face of the tube. The grooves l terminate the conductive terminal II is placed upon the a short distance above the lower end of the upper end of the shank 42 and the upper end 60 sleeve. Since the formation of the grooves (115- of the shank is upset, as shown at it, to hold places some of the metal inward, the outside the parts in assembled relation and under presdiameter 0! that length of the sleeve in which sure the grooves have been formed is reduced by the The described construction is efficient under formation'of the grooves and is less than that all operating conditions and is especially eflicient of the \mEI ved lower end Po tion. under heavy duty conditions of operation because and a radially e member portant that the shank be protected against the circulation of hot gasm around it, since the absorption of heat by the shank from any source other than the electrode nose will necessarily reduce the temperature gradient of the shank. It is of especial importance that the circulation of gases between the shank and the nut be avoided because the mass of metal forming the nut serves as an efiective means of withdrawing heat from the shank at the point where the insulation is of minimum thickness. The described construction is efiective to maintain the shank and sleeve in as intimate heat-transferring relationship with the nut i as is consistent with maintaining good electrical insulation between the shank'and the nut.

In Figure 5 a modified sleeve 6A is illustrated. This sleeve is not grooved like the sleeve 8 but includes a portion 5 I of reduced diameter. The sleeve is assembled with the insulator and nut eieinents in the same manner as the sleeve 6 already described. It would not be practicable to drive the electrode rod directly into this sleeve for the purpose of expanding it. Such expansion may be accomplished, however, by introducing a steel ball N in advance of the electrode I2 and driving it through the reduced portion of the sleeve in advance oi the electrode 02. The construction and operation of the finished assembly is the same as that illustrated in Figure 1.

While I have illustrated and described in detail certain preferred forms oi my invention, it is to be understood that ches may be made therein and the invention embodied in other structures. I do, not. therefore, desire to limit myself to the specific constructions illustrated, but intend to cover my invention broadly in whatever form its principle may be utilized.

1 claim:

1. In a spark plug the combination with a shell, of a nut threaded in the shell, a central electrode, a tube oi insulating material interposed between the central electrode and the nut, snugly fitting the electrode and =1 sulating tube against the nut.

2. In a spark plug, a central electrode, a tub of insulating material sm'rounding the same, a metallic retaining member surrounding the tube of insulating material, and an expansible sleeve interposed between the central electrode and the insulating tube and expanding the said sleeve into firmly sealed engagement with the metallic retaining member.

3. In a spark plug, the combination with a central electrode 0! a tube of insulating material surroimding the a metallic retaining mem-' ber surrounding the tube of ting material,

and means including an expansible metal sleeve member cooperating with the electrode simultaneously to stretch the insulating tube circumferentially and to compress it radially against the metallic retaining member to form an eflective seal.

4. In a spark plug, the combination with a central electrode and a metallic retaining member surrounding the same, of an insulating tube interposed between the electrode and therevtaining member and an expansible sleeve member positioned within said tube and maintained under circumferential tension and under radial compression for forming a seal.

5. In a spark plug, the combination with a central electrode, 01' a retaining member surrounding the electrode, and a sealing tube interposed between the electrode and the retaining member and an expanding sleeve interposed between the sealing sleeve and the electrode and maintaining the tube under circumferential tension and under radial compression for forming a seal.

6. In a spark plug, in combination, a central electrode having a cylindrical shank, an expand-. ing sleeve surrounding the shank, an insulating tube on the sleeve, and a heat conductive retaining member surrounding the tube, the tube being expanded by the sleeve and pressed by it into sealing engagement with the retaining member.

7. In a spark plug, in combination, a central electrode having a cylindrical shank and a nose larger than the shank, an expanding sleeve surrounding the shank, an insulating tube on the sleeve, and a heat conductive retaining member surrounding the tube, having no greater coeflicient of expansion than the electrode, the tube being expanded by the sleeve and pressed by it into sealing engagement with the retaining member.

8. An expanding sleeve for use in spark plugs having a circumferential flange portion at one of its ends and a tubular portion, the end of the tubular portion adjacent the 'flange being ungrooyed and the remainder oi the lengthoi' the tubular portion being externally, longitudinally grooved.

9. An expanding sleeve for use in spark plugs having a circumferential flange portion at one of its ends and a tubular portion, the end of the tubular portion adjacent the flange being cylindrical and of a diameter to receive the spark plug electrode snugly, and the remainder oi the length 01' the tubular portion being of less diameter, so that it will be expanded by the driving of the electrode into'it.

10. In a spark-plug, the. combination of a body piece having a central opening, a metallic quill through said opening, an insulating sleeve surroimding the quill, and a central lmetallic spindle driven into the quill so as to expmd the same to grip the insulating sleeve against the surrounding surface of the opening in the body piece. ROY 'i'. HURLEY.