US1380399A

US1380399A - Spark-plug

Info

Publication number: US1380399A
Application number: US313342A
Authority: US
Inventors: John A Luther
Original assignee: Individual
Current assignee: Individual
Priority date: 1919-07-25
Filing date: 1919-07-25
Publication date: 1921-06-07
Anticipated expiration: 1938-06-07

Description

J. A. LUTHER.

SPARK PLUG.

APPLICATION FILED IuLY 25,19I9.

Patented June 7, 1921.

Z. s .WJ I nF P. 5 H m 3 8 5 i I A lvenCoT John A. Luher .man A. LUTHER, or scnmmc'ranr. NEW vom;

Patented June 7, 19211.

L Application lled July 25, v1911?. Serial No. 313,342.

SPARK-PLUG. 1,380,399 Specication of Letters Patent To all whom t may concern.'

Be it known that .I, JOHN A. LUTHER, a citizen of the United. States, residing at Schenectady, in the countyl of Schenectady, State of New York, havlevinventedcertain new and' useful Improvements in Spark- Flugs, ofvwhich the following isa specificatlon:

The present `invention relates to spark plugs for internal combustion engines and has for its object to improve their construction. My improvements arevdirected prin- /bipally to the means forsupporting the porcelain .or other insulator for the central electrode whereby the breakage thereof bothin -manufacture and use will be decreased to a minimum, and also to the means for insuring airtightv vseals between the porcelain or other insulator and its metal support or K shell and betweenthe central electrode and the surrounding insulator. Additional 'features of my invention are the means for protecting the insulator from injury when the plug'is being screwed into or removed from the engine cylinder, and the arrangement forv conveying heatfaway from'the interior parts of the plug.

Fora consideration of-what I believe to be novel and .my invention, vattention is directed to the accompanying description and claims appended thereto.

In the drawing, Figure 1 is a viewin elevation of a spark plugwith a portion of the casing cut away in quarter section and Fig. 2 is an axial section-of the same.

5 indicatesthe metal shell or casing ofthe plug which is threadedat one end to enable it to be screwed into the engine cylinder or 'othersupport It is provided with the usual flange orshoulder 6 between which and the cylinder or support is located a suitable packing or gasket, not shown. The opposite end of the shell is provided' with a hexagon head 7 to receive a suitable Wrench. y Inside theshell is an annular shoulder 8 upon which the porcelain or other insulator 9 is seated. The head of the shell is also internally threaded to receive the tubular meniber' 10 which has several functions. 'First it acts as an abutment for the shock absorbing' coiled compression spring 11 which Jholds the insulator on its seat;l second it acts ras a guard to prevent injury to the insulator; third it acts as a. guide for the outer portlon of the insulator; and fourth it parts, and hence definitely limits the'tension on the spring to a predetermined. value. It is to'be particularly noted that the inner-end 13 of the member does not contact with the insulator in any way and therefore cannot cause any cracking or undue strains thereon when screwed into place, no matter how careless the assembler may be or how much pressure is employedin securingv the parts together. rIhe shoulder has two flat surfaces to receive a wrench, one of which is indicated' at 14. I l I The outer end of the member is provided with an internal shoulder `15 which acts` as absorbing coiled vcompression spring 11. The spring is preferablymade of Hat stock ince'it permits the desired'sprng tension o be 'obtained without making the diameter unduly large. It is important not only from a manufacturing point of view to make the diameter as small as possible but also to facilitate mounting Lthe plugin the engine. The insulator, it will-be noted, is cylindrical with a shoulder or an enlarged portion 16 which rests on the internal shoulder'on the shell, there being a copper or equivalent gasket 17 to forma seal. The .opposite side of the enlargedportion is also provided with a copper or .the inner end of the spring rests. The spring when mounted in place should be under sufficientcompression to hold the insulator on its seat even when it is subjected' to the .high pressure of the burning charge of combustible in the cylinder. The spring will, however, compensate for changes due to different rates of expansion of the parts L and also absorb shocks to' which the plug is subjected. while in operation.

It is `to f be particularly noted that any shocks to which the insulator is subjected.

due to the firing of the charge in the' cylin-v .der are absorbed by the spring instead of being directly transmitted to the casing, and hence breakage .of the insulator is prevented.

In practicethe springs are cut to the desired' length and their ends properly finished so as to seat squarely on the insulator at equivalent gasket 18 upon which,

' latter being guided the ordinary construction.

-heated andv losing its f- In case the plug gets foul the central elecv occur to the insulator because there are no non-yielding parts which Grip it' as in lhe assembler merely screws the member to its seat an the spring does the rest, the tension ot the latter having been previously determined.` rl`his means that nothing is left to the individual skill of the assembler and the bugbear of loose or cracked insulators is overcome.`

The central electrode 19, is provided With a collar 20 which is seated ona shoulder on the insulator, and betweenv the collar and` and shoulder is a Washer or gasket to maintain an air tight seal. The inner end of the electrode projects beyond the inner part of the shell and standing adjacent to it but separated by a suitable air gap is a second electrode 2l carried by the shell and grounded of course, to the engine. yThe outer end of the center electrode 19 is screwfthreaded and passes through a secondary insulator 22, the or held central by the bore of the internal shoulder on the member. Between the main and secondary insulators there'is or may be a suitable gasket 23 which serves as an additional means to prevent the escape of gas from the cylinder. around the central electrode. 0n the electrode and outside the insulator 22 is a clamping mit 24 which may With advantage be made round and adjusted by a pair of pliers. Under the nut is a lock Washer 25, and below that a copper or other disk. Over the nut 24 is a second nut 25a which acts as a lock-nutv for the irst and also as a seat for the ignition lead which is connected to the plug and to a source of current. 26 indicates the nut for holding the lead in place. By arranging the nut 24 as described there is no danger of a careless person accidentally disturbing the clamping device 24 of the central electrode which would permit air to leak around it into the cylinder.

In order to keep the internal plug from becoming unduly hot,

parts of the the head of the shell is provided With ventilating open.

ings 27 which arev adjacent the enlarged part of the main insulator. Other Ventilating openings 28 are provided in the tubular member and through all of the ogenmgs air is permitted to freely circulate.

preventing the spring from being overtemper.

t'rode can be removed from the under side for cleaning by removing the

nuts

24, 25 and 26. The main insulator is not disturbed because itis held in position by the compression spring and the tubular member.- By

tionary L provided with shoulder and o'rming n particular, the Ventilating arrangement isvuseful in shell Which is screw-t readed externally at 1,3eo,eee

this arrangement the chance of injurying the porcelain or main insulator is reduced to a minimum.

In accordance patent statutes, I ple of operation ofl my with the provisions of the have described the princiinvention, together With the apparatus Which I now consider to -represent by Letters Patent of the United States is -A 1. 1n a spark plug, the combination of a shell adapted to be-attached to a support and provided With an internal shoulder, av

stationary insulator mounted Within the shell and having an enlarged portion Which is seated on the shoulder, a shockabsorbing compression spring which surrounds the insula'tor and forms the means for holding it on its seat against cylinder pressure, an abutment for the outer end di thev spring, a sta- 'electrode Which passes insulator and is adapted to be connected to a source of current, and a second electrode have it understood that the appathrough the coperatingfwith the first and permanently separated therefrom by an air gap.

2. 1n a spark plug, the combination of a shell which is screw-threaded externally for attachment to a support and has an internal shoulder,an insulator which has an enlarged portion on -`the shoulder, a coiled compres-` sion spring which surrounds the, insulator and holds it on its seat against cylinder pres.- sures, a member for the outer-end ofthe spring and is attached to the shell, an electrode Which passes through the insulator, anda second electrode supported by the shell.

3. 1n a spark plug, the combination of a 'shell which is screw-threaded externally at one end and internally` at the other, and is tionary insulator which is seated on the a gas-tight seal, a member which surrounds therinsulator and is screw-seated on the shell at oneend and has an internal flange at they other, a shock absorbing compression spring'which -holds an internal shoulder, astawhich forms an abutment the insulator on its seat against cylinder` pressure and in turn is held'under compression by theflange, and passes through the insulator from end to end and is permanently separated from the shell by an air gap.

4. 1n; a spark plug, the combination of a one end 4and internally at the other, and 1s provided with an internal shoulder, a stationary insulator which is seated on the shoulder,

an electrode which' a member which surrounds the.

insulator and is screw-threaded at one end for attachment to the shell, carries a-sprlng abutment,` and has an, external Shoulder t, displacement and forms a part of an elec-v which is seated on the outer end of the shell, a shock absorbing compression spring which rests on the insulator at one end to hold it on. its seat against cylinder pressure and at the other end engages the abutment, the tension of the springv being determined by said shoulder, and a stationary electrode which passes through the insulator and is permanently separated from the shell by an air gap.

5. In a spark plug, the combination of a screw-threaded shell, having an internal shoulder, an insulator which engages the shoulder, a tubular member screw-threaded to the shell and inclosing the insulator, a coiled compression spring which holds the insulator on its seat against cylinder pressure and is retained under compression by the member, and Ventilating passages formed in the shell and member through which air is free to flow over the spring.

6. In a spark plug, the combination of a screw-threaded shell having an internal shoulder, an insulator mounted on the shoulder, a member which incloses the insulator and is attached to the shell, a spring within the member which holds the insulator on its seat, a secondary insulatorsupported by the first and guided by the member, and an electrode which passes through both insulators, is seated pressure tight in one and forms a means for uniting both.

7. In a spark plug, the combination of a screw-threaded shell having an internal shoulder, an insulator mounted on the shoulder, a member which incloses-the insulator and is attached to the shell, a spring within the member which holds the insulator on its seat, a secondary insulator supported by the first and guided by the member, an electrode which passes through both insulators and is seated pressure tight, a nut on the electrode which clamps the two insulators `together, and a second nut on the electrode which covers the rst to prevent accidental tric terminal.

8. In a spark plug, the combination of a shell adapted to be attached to the engine and which is provided with an internal shoulder, an insulator having an enlarged portion which is seated on the shoulder, a member threaded to the shell which surrounds the insulator and is spaced therea stationary insulator which is provided with an enlargement between its ends, the under surface of which is supported by the shoulder, a tubular member which has screw threads that engage those at the outer end of the shell and also a spring abutment, means for limiting the amount that the member can be screwed downward with respect to the shell, a shock absorbing spring which surrounds the insulator, one Vend of said spring pressing on the enlargement on the insulator, the other end engaging the abutment, an electrode which passes through the insulator, and a second electrode which is supportedl by the shell and separated from the lirst by a permanent air gap.

10. In a spark plug, the combination of a metal shell which is screw-threaded at opposite ends and has an internal shoulder, a gasket which rests on the shoulder, a stationary porcelain insulator which has a shoulder that `is seated on the gasket, a hollow member which surrounds the insulator, has screw threads which engage those on the outer end of the shell and also an internal spring abutment, a shock .absorbing spring which surrounds the outer portion .of the insulator and presses on its shoulder at one end and engages said abutment at the other, means for limiting lthe amount that the member can be screwed downward with respect to the shell, thereby definitely limiting the pressure that the spring can exert on the insulator, and an electrode which extends centrally through the insun lator and is permanently separated from the inner end of the shell by a permanent air gap. p

In witness whereof, I have hereunto set my hand this 23rd day of July, 1919.

JOHN A. LUTHER