US1848065A

US1848065A - Spark plug

Info

Publication number: US1848065A
Application number: US398665A
Authority: US
Inventors: Rabezzana Hector
Original assignee: AC Spark Plug Co
Current assignee: Delco Electronics LLC
Priority date: 1929-10-10
Filing date: 1929-10-10
Publication date: 1932-03-01
Anticipated expiration: 1949-03-01

Description

Marcm, 1932. H. ABEzzANA 1,848,065

Filed Oct. l0, 1929 (g1/wanton Patnie Mar. 1, 1932 U1\u'l1:nf STATES Pri'rriu'r oFFicE HECTOR RAIBEZZANA, OF FLINT, MICHIGAN, ASSIGNORVTO A C SPAiR/K PLUG COMPANY, F F/LINTAMICHIGAN, A. COMPANY OF MTCHTGALN' SPARK PLUG y Application ledctober 10, 1929. ASerial No. 398,66@

This invention relates to spark plugs of the type commonly used in internal combus tion engines. Such .plugs are usually composed of a metal shell adapted to befthreadedl into the engine, and an insulatingmember of porcelain, mica orother suitable material, 1n which is carried an electrode member. These insulators are necessarily subjected to the very high temperatures developed 1n the combustion chamber, and in order to avoid the possibility of their becoming cracked or otherwise damaged from excessively high temperatures, it is essential that provision be made to .carry away or dissipate as much of theheat as possible. In the usual type of plug, the heat is transferredfrom the'insu-v lator to the shell, and 'from the latter to the engine, by conduction. Due to the fact thatv the threaded connection betwen the shell and` the engine interferes to a considerable extent with the rapid transfer of the heat, the insulator under certain conditions becomes excessively hot and as a result crackstthereby rendering the spark plug inoperatlve.

It is therefore an object of this invention to provide a spark plug construction in which the heat may be more readily and positively ,1' transferred to the combustion chamber wall,

t from which it may be carried away by the 130 liquid in the cooling system. This is accomplished by eliminating the usual spark plug shell, thereb allowing the insulating member to come into direct contactwith the wall of the combustion chamber. A tapered aperture is formed in the Wall and the insulating member'is correspondingly tapered so that it ma be wedged into close contact with the wa l in order to insure a morepositive and rapid transfer of the heat by conduction.

By rotating the insulating member in the tapered aperture at the time of assembly,

with any suitable grinding compound placed between the two, the surfaces may be ground to exactly the same shape, similar to the manner in which valves are ground on their seats. Thus the maximum possible area of contact between the insulator and the com-v A bustion chamber wall is obtained, and the `conduction of heat from the lformer to the 5 latter is facilitated.

. 1, but showing modi-fied forms of spark plugs.

Another object of the invention is to construct a spark plug in which it is not necessary to provide the usual gaskets for preventing leakage of the gases from the cylinder. Such gaskets sometimes permit leakage of gas after the spark plug has been in use, due to the continual expansion and contraction of the shell relative tothe insulating member. Due to the fact that the surfaces of the tapered aperture and the insulator in my improved spark plug are ground together to form a perfect seat, there isno possibility of leakage occurring between the two. By eliminating the gaskets and the usual metal shell, the cost of the plug is materially reduced. Y

Other objects and advantages will be apparent upon referring to the specification and accompanying drawings, in which:

Fig. 1 is a section through a portion of a combustion chamber wall, showing my imlproved spark plug assembled therein.

Fig. 2 is a section taken on the line 2-2 of Fig. 1.

'Figs 3-7 are views corresponding to Fig. 75

The reference numeral 10 indicates a portion of an internal combustion engine which j forms one wall of the combustion chamber. A cooling water jacket 12 is formed between 8o the wall 10 and an outer wall 14. An aperture 16 is formedr throughl both the walls for the purpose of permitting the insertion of a spark plug. This spark plug consists of an insulating member 18 formed o f porcelain, mica or any other suitable material. A portion 20 of this member is tapered and fits into a correspondingly tapered portion 22 formed in a combustion chamber wall. The usual central electrode 24; is supported in the .insulating member. The lower end 2 6 of. this electrode'is bent at a right angleto the main portion and extends quite 4close to a boss 28 formed on the inside of the combustion chamber wall 10.l The distance between the'end 26 of the electrode and the boss 28 is so set as to be exactly the same as the width of the spark gap in the ordinary type of spark plug. f f

-At the time the insulating member 18 is 1 alim mi assembled in the aperture 16, it is pret-erably ground in place with any suitable grinding compound placed between the tapered portions 20 and 22. The insulating member 18 is rotated sufficiently to insure that the sur- 'laces will be ground to exactly the same shapes so that the entire surface ol' the tapered portion 20 will be in contact with the tapered portion 22, thus insuring the maximum possible area ot contact, which will permit a large amount ot heat to be conducted into the combustion chamber wall from which it is removed by the circulation ot th-e cooling water in the jacket 12.

Any suitable means may be provided for holding the insulator in place in the apern ture 18. ln Fig. 1 there is illustrated a quick detachable type of holding means, which consists of a gland nut 3() threaded into the wall 14, and/or which may be permanently secured therein in any suitable lmanner such as by welding. llhis gland nut has -lormed on it a plurality of projections 32 which engage cam surfaces 34 'formed on the insulating member 18. Slots 36 are formed in the body portion ot the insulating member to permit the latter to be inserted through the gland nut 30, the slots being of a sli htly greater width than the projections 32. liter this has been done, the insulating member is rotated and the cam surfaces 34 engage the projections 32 and serve to wedge the tapered portion 20 of the insulating member into firm contact with the tapered portion 22 of the aperture 16. Obviously this wedging action not only serves to bring about a better transfer of heat from the insulating member 18 to the combustion chamber wall, but also provides a tight seal between the two which prevents the escape of any of the explosive gases in the combustion chamber. The result is that no gaskets are needed as is the case in the usual type of spark plug.

In the form of plug shown in Fig. 3, a shoulder 38 is formed on the insulating member 40. The gland nut'42 in this construction bears against a sleeve 44 formed of copper or any other suitable material having a comparatively high coefficient of expansion. The opposite end of the sleeve 44 bears against the shoulder 38, and it will be readily seen that as the parts become heated and tend to expand, the sleeve 44 will expand more rapidly than the gland nut 42 and the combustion chamber wall, and will consequently serve to maintain a firm contact between the tapered portions of the insulator and the combustion chamber wall at all times,'there by preventing leakage of the explosive gases and bringing about a more uniform transfer of heat from the insulating member to the combustion chamber Wall.

In the form shdwn in Fig. 4, the lower end of the central electrode 46 is not bent, but is spaced the desired distance above a ground reagent electrode member 48 secured in a boss till formed on the inside o'l the combustion chamn ber wall. A. slightly diderent form 4oil holding mechanism is shown in connection with this form. This consists or a liulcrum member 52 having an end 54 adapted to bear against the insulator member 56. The opposite end of the Eulerum lmember bears against the wall 14 or it desired against the insulator of another spark plug. A nut 58 threaded on a stud 60 serves to draw the l'i'ulcrum member against the insulator 56, thereby wedging the latter into tirm contact with the tapered aperture in the combustion chamber wall. ln

this term a more rapid transfer oi? heat is provided tor as well as a better seal, due to the increased area oit the tapered surfaces.

ln Fig. 5 is shown an insulating member 52 in which are supported two electrodes 64 and '66. rlhis type oi' plug is more likely to be used in engines ot the type wherein two spark plugs are provided for each cylinder, these plugs being connected in series with each other to insure that a spark will be produced in both plugs. ln this type ot installation the electrode 64 is connected to the distributor and the electrode 66 is connected to the other spark plug.

lnthe form shown in Fig. 6 a central elec trode 68 is spaced the desired distance away from a second electrode l0 which is supported in the insulating member 72 in such a position that it contacts with the wall ot the combustion chamber at "(4. An advantage of this .type of construction is that the widthot` the spark gap may be definitely determined betore the plug is assembled in the aperture.

In Fig. 7 a slightly different form o plug is illustrated, wherein the insulating member 76 is composed of layers of mica, there bein# an axially extending insulating sleeve 7 8 o micasurrounding the central electrode 80. The lower portion 82 of the insulating member is tapered to fit into a tapered aperture 84, while av metal sleeve 86 surrounds the upper portion of the insulating member. Additional mica insulation 88 surrounds the electrode and the axially extending insulation 78 above the sleeve 86. A gland nut 90 threaded into the Wall 14 engages the sleeve 86 and serves to wedge the tapered portion 82 of the insulating member 76 into firm contact with the tapered aperture 84, to eii'ect a. tight seal and a rapid conduction of heat from the insulating member to the combustion chamber wall.

It will be understood of course that in all of the forms of plugs shown and described itis preferable to grind the tapered portions of the insulating members into place in the tapered apertures to insure as large an area of contact as possible, in ord-er that there may be a more satisfactory transfer of heat and at the same time to provide a gas-tight seal. Obviously, any of the securing means shown may be used with any of the types of spark lugs. p Itis thought from the foregoing, taken in connection with the accompanying drawings, that the construction and operation o the spark plug will be apparent to those skilled in the art, and that various changes in size, shape, and proportion may be made without departing from the spirit and scope of the l0 appended claims.

' I claim:

1. In combination, a combustion chamber wall having therein a spark plug receiving opening, at least a portion of which is of conical shape, an insulator body receivable within said opening and having a conicalshaped peripheral surface for engagement with the conical portion of the opening, an inwardly extending tongue at the opening, 9,0 and a cam surface fon said body for engagement with said tongue to move the conical part into tight contact.

2. In combination, a combustion chamber wall having therein a spark plug receiving .5 opening, at least a portion of which is of conical shape, an insulator body receivable within said opening and having a conical-shaped peripheral surface for engagement with the conical portion of the opening, a series of 9,0 inwardly extending tongues at the opening, slidable through axially extending ways in the surface of said body, and a cam surface adjacent each way for engagement with the tongue upon rotation of the body to bring the conical parts into tight contact.

In testimony whereof I affix 1n signature.

HECTORILAB ZZANA.