US1963714A - Spark plug - Google Patents

Description

June 19, 1934. E, owos LsK 1,963,714

SPARK PLUG Filed Jan. 25, 1932 INVENTOR Edward 5 NowoJ//Jki Patented June 19, 1934 PATENT- OFFICE SPARK PLUG Edward B. NowosielskLBloomfleld, N. J., assignor. by mesne assignments, to Eclipse Aviation Corporation, East Orange, N. J., a corporation of New Jersey 7 Application January 25, 1932, Serial No. 588,759

. I 15. Claims.

This invention relates to spark plugs and particularly to spark plugs of the type capable of producing proper ignition in internal combustion engines of the relatively high compression class.

An object of the invention is to provide a new and improved spark plug of relatively great durability by reason of the incorporation therein of a novel combination and interrelation of parts producing a unit which is capable of withstanding the highest temperatures and compressions encountered under the most trying operating conditions.

Another object of the invention is to provide in a spark plug of the type in which one of the electrodes is in the form of a centrally disposed pin or spindle, novel means for insuring a gastight joint around said spindle.

Another object of the invention is to provide in a spark plug having a centrally disposed electrode as above described, hovel means engageable with said electrode for transferring to the outer shell the stresses set up in the plug as an incident to its assembly and installation, and particularly as an incident to the establishment of the gastight joint above referred to.

These and other objects of the invention will be apparent to those skilled in the art from the following description, taken in connection with the accompanying drawing wherein are illus- 50 trated two embodiments of the invention. It is to be expressly understood, however, that the drawing is for the purpose of illustration only and is not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

Referring to the drawing,

'Figs. 1 and 2 are central longitudinal sections through two embodiments of the invention. Fig. 3 shows in perspective an element of Fig. 2.

Referring first't-o the embodiment disclosed in Fig. 1, the invention is therein shown incorporated in a unitary structure disposed about a center electrode 5 which, as shown, is upset, after assembly, to form a head 6, the under surface of which is tapered to provide a firm seat upon the counter-bored upper surface of metallic cap '7,

the latter being circumferentially grooved, as indicated at 8, for reception of a suitable terminal clip or equivalent conductor (not shown) by which ignition current may be led to the spark plug from the usual current supplying unit.

The center electrode- 5 -is preferably formed with a slight taper and at an appropriate distance above its lower end is provided with a shoulder or ledge 10 forming a support for a multi-layered sleeve 11 of insulating material extending along the surface of the electrode 5 to a point just above the tapered central opening 12 in the lower end of the cap '7. This shoulder or ledge 10, in addition to its function of supporting the insulating sleeve 11, also coacts with the elements yet to be described to provide a novel construction for transferring to the cylinder head, into which the shell 15 of the plug is threaded, the stresses resulting from a tightening of the gas-seal means now to be described.

The novel means for insuring a gas-tight seal around the center electrode 5 comprises the insertion of a metallic sleeve 17 having an externally tapered surface adapted to register with a correspondingly internally tapered bore provided in the surrounding tightening nut 18, the latter having its upper portion 19 cut to form regular polygonal sides facilitating the reception of a wrench by which the assembly may be tightened, and the upper surface of the nut serving as a support for the usual assembly of insulating washers 20 varying in diameter from that of the upper surface of the nut 18 to that of the lower surface of the cap 7 in the usual manner, as indicated. The central portion of the outer surface of the nut 18 is threaded for engagement with the corresponding threads 22 upon the interior bore of the upper portion of the shell 15, the intermediate portion 23 thereof being flanged to constitute a limiting means for engagement with the outer surface of the cylinder head into which the plug is inserted.

The lower surface of the sleeve 17 and the nut 18 are correspondingly beveled, as indicated at 24 and 25, respectively, to register with a similarly inclined upper surface provided on a cooperating sealing member 27 of relatively soft metal adapted to become plastic under pressure and form a gas-tight seal against the sloping ledge or shelf and within an annular ledge 29 on the interior surface of the shell 15. From this ledge 29 the sealing member 27 extends downward to engage a second group of insulating washers 35 of a diameter corresponding to that of the lower section of the bore of the shell 15, the said group of washers being supported upon the annular floor or base 36 of the shell 15. On examination of Fig. 1 it will be seen that at a point a slight distance below the shoulder 10 on the center electrode 5, the washers 35 extend inwardly beneath the said shoulder and provide a seat for a metallic supporting ring 37 on which the said shoulder 10 is adapted to be received as the center electrode is inserted into the shell and washers 35 in the process of amembly.

From the foregoing it is evident that when the parts have been assembled in the indicated man ner, the plug is made gas-tight by turning up on the nut 18, such turning actionoperating upon the sleeve 1'7, through the cooperating wedging surface thereon, to press the said sleeve firmly around the insulating sleeve 11, thus pressing the latter firmly around the electrode 5 and preventing the passage of any gas therebetween. At the same time, the stresses set up in the parts through this tightening action is transferred to the associated engine cylinder by being passed on through the member 2'? and washers 35 to the'shell 15. This transfer of stress to the engine cylinder protects and relieves the plug itself, and every part thereof, of such strain. This is a decided improvement over previous constructions wherein such stresses are transferred to the center electrode and thus operate to weaken either the electrode or the part (usually the upper cap) from which the electrode is suspended. With the present construction, it will be further noted, the electrode is not suspended from its upper end, as in previous construction, but is on the contrary supported on the metal ring 37, near its lower end, the ring being in turn supported on the base 36 of the shell through the intermediary of the washers 35.

The embodiments shown in Fig. 2 is similar in principle to that of Fig. 1, but differs therefrom in the shape of the wedging sleeve 57 and in the provision of an additional wedging member 58 intermediate the tightening nut 19 and the reaction absorbing abutment constituted by the inclined ledge 60 of the shell 15. A further novel feature of this embodiment is the provision of a pair of washers 63 and 64, the former of relatively soft metal adapted to be pressed firmly upon the ledge 60 to form a gas-tight seal therewith, and the latter being of metal hardened and serrated as better shown in Fig. 3 on its outer periphery to bit into the inner bore of the shell 15 and thus maintain the discs 35 firmly packed.

With this embodiment of the invention it is apparent that tightening of the nut 19 acts to produce a wedging effect upon both the upper and lower tapered surfaces of the sleeve 57, thus insuring a more effectively directed lateral pressure on the sleeve 57 and hence an extremely efficient seal around the electrode as well as along the surface of the shells. In this embodiment also, there is provided a limiting means for the tightening action in the form of centrally disposed rim 62 which, by virtue of engaging the nut 19 or the wedging member 58, will act as a stop on the wedging action.

While both embodiments of the invention herein disclosed possess considerable practical merit, it is to be expected that changes may be made in the shape and relative arrangements of the parts within the novel principles herein disclosed; and accordingly such variations are to be considered within the scope of the present invention if fairly included within the language of the appended claims.

What is claimed 1. In a spark plug of the type having an external shell adapted to be inserted in the cylinder wall of an internal combustion engine, the combination with said shell of a conducting spindle centrally mounted therewithin, said spindle having a surrounding sleeve of insulating material and a shoulder extending radially therefrom intermediate its ends, said shoulder constituting the means by which said spindle is supported O said shell, a pair of wedging members surrounding said insulating sleeve and means engageable with said shell for causing one of said wedging members to apply lateral pressure on said insulating sleeve to form a gas-tight seal around said spindle.

2. In a spark plug of the type having an external shell adapted to be inserted in the cylinder wall of an internal combustion engine, the combination with said shell of a conductingspindle centrally mounted therewithin, a sealing member surrounding said spindle, a second sealing member engageable with said shell, a wedging member engageable with both said sealing members, and means interposed between said wedging member and said shell for applying pressure through said wedging member to both said sealing members.

3. In a spark plug of the type having a center electrode and an outer shell attachable to an engine cylinder, a base integral with said shell and centrally apertured to receive the lower end of the center electrode, a plurality of insulating members encircling and supporting said electrode, said members being in turn supported upon said base, a nut threaded to said shell, and a hardened metallic locking member movable into clamping relation to said insulating members in response to tightening of said nut.

4. In a spark plug of the type having an outer shell attachable to an engine cylinder, a base integral with said shell and centrally apertured to receive the lower end of the center electrode, a plurality of insulating members surrounding and supporting said electrode, said members being in turn supported upon said base, a nut threaded to said shell, and a serrated metallic disc movable into clamping relation to said insulating members in response to tightening of said nut.

5. In a spark plug of the type having an external shell adapted to be inserted in the cylinder wall of an internal combustion engine, the combination with said shell of a conducting spindle centrally mounted therewithin, an insulating sleeve wrapped about said spindle, a metallic sleeve fitting closely about said insulating sleeve, said metallic sleeve having a tapered outer surface and a beveled end, and common means for sealing both said shell and spindle comprising an annular gland seated in the shell and having one end beveled to register with the beveled end of said metallic sleeve, and a sealing nut threadedly engaging said shell, said nut also having a beveled end registering with the beveled end of said annular gland, and an internal taper registering with the tapered outer surface of said metallic sleeve, in such a manner as to cause the latter to be pressed firmly against both said insulating sleeve and said annular gland when the nut is screwed into the shell.

6. In a spark plug of the type having an external shell adapted to be inserted in the cylinder wall of an internal combustion engine, the combination with said shell of an electrode centrally mounted therewithin, an insulating member encircling said electrode, a metallic sleeve encircling said insulating member, said metallic seeve having a beveled end, a sealing member having one end beveled to register with the beveled end of said metallic sleeve, and a nut threadedly engaging said shell, said nut having a beveled i end registering with the beveled end of said sealing member and also registering with said metallic sleeve to cause the latter to be pressed firmly 150.

against both said insulating sleeve and said sealing member when the nut is screwed into the shell.

7. In a spark plug of the type having an external shell adapted to be inserted in the cylinder wall of an internal combustion engine, the combination with said shell of a conducting spindle centrally mounted therewithin, an insulating sleeve wrapped about said spindle, a metallic sleeve fitting closely about said insulating sleeve, said metallic sleeve having a tapered outer surface and a beveled end, a sealing member seated in the she I and having one end beveled,,to register with the beveled end of said metallic sleeve, and a nut threadedly engaging said shell, said nut also having a beveled end registering with the beveled end of said sealing member and an internal taper registering with the tapered outer surface of said metallic sleeve in such a manner as to cause the latter to be pressed firmly against both said insulating sleeve and said sealing member when the nut is screwed into the shell.

8. In a spark plug of the type having an outer shell attachable to an engine cylinder and an electrode extending centrally through said shell, a plurality of insulating discs encircling and supporting said electrode, said discs being in turn supported by said shell, a nut threadedly engaging said shell, and a hardened metallic locking member movable into clamping relation to said discs in response to tightening of said nut.

9. In a spark plug of the type having an outer shell attachable to an engine cylinder and an eiectrode extending centrally through said shell, a plurality of insulating discs encircling and supporting said electrode, said discs being in turn supported by said shell, a nut threadedly engaging said shell, and a serrated metallic disc movable into clamping relation to said insulating discs in response to tightening of said nut.

10. In a spark plug of the type having an outer shell attachable to an engine cylinder and an electrode extending centrally through-saidshell, a plurality of insulating members encircling and supporting said electrode, said members being in turn supported by said shell, a nut threadedly engaging said shell, and a hardened metallic looking member movable into clamping relation to said members in response to tightening of said nut.

11. In a spark plug of the type having an outer shell attachable to an engine cylinder and an electrode extending centrally through said shell, a plurality of insulating members encircling and supporting said electrode, said members being in turn supported by said shell, a nut threadedly engaging said shell, and a serrated metallic member movable into clamping relation to said members in response to tightening of said nut.

12. In a spark plug of the type having an external shell adapted-to be inserted in the cylinder wall of an internal combustion engine, the

' combination with said shell of a conducting spindle centrally mounted therewithin, an insulating sleeve encircling said spindle, a metallic sleeve fitting closely about said insulating sleeve, said metallic sleeve having a tapered outer surface,

an annular gland seated in the shell and having its upper end registering with the lower end of said metallic sleeve, and a pressure-applying nut threadedly engaging said shell, said nut having registry with the upper end of said annular gland and a tapered inner surface registering with the tapered outer surface of said metallic sleeve in such a manner as to cause the latter to be pressed firmly against both said insulating sleeve and said annular gland when the nut is screwed into the shell.

13. In a spark plug having a cylinder engaging shell and a center electrode extending therewith, an insulating sleeve encircling said center electrode. a metallic sleeve encircling said insulating sleeve, said metallic sleeve having a tapered outer surface, an annular shelf on the inner surface of said shell, an annular gland having its lower surface registering with said shelf and its upper surface registering with said metallic sleeve, and a pressure-applying nut threadedly engaging said shell, said nut having a tapered inner surface registering with the tapered outer surface of said metallic sleeve to cause the latter to be pressed firmly against both said insulating sleeve and said annular gland when the nut is screwed into the shell.

14. In a spark plug having a cylinder engaging shell and a center electrode, an insulating sleeve encircling said center electrode, a metallic sleeve encircling an intermediate portion of said insulating sleeve, said metallic sleeve having a tapered outer surface, a plurality of insulating washers encircling said insulating sleeve within said shell, annular means having a portion registering with said metallic means, a portion in engagement with said shell, and a portion in engagement with one ofsaid washers, and a pressure-applying nut threadedly engaging said shell and having a tapered inner surface registering with the tapered outer surface of said metallic sleeve to cause the latter to be pressed firmly against said insulating sleeve, to effect a gas sealing engagement between said second named portion of the annular means and the shell, and to cause a compression of said washers through said tht'rd named portion of the annular means when the nut is screwed into the shell.

15. In a spark plug having a cylinder engaging shell and a center electrode, an insulating sleeve encircling said center electrode, a metallic sleeve encircling said insulating sleeve, said metallic sleeve having a tapered outer surface, annular means having a portion registering with said metallic sleeve and a portion in engagement with said shell, and a pressure-applying nut threadedly engaging said shell and having a tapered inner surface registering with the tapered outer surface of said metallic sleeve to cause the latter to be pressed firmly against said insulating sleeve and to effect a gas sealing engagement between said second named portion of the annular means and the shell when the nut is screwed into the latter.

EDWARD B. NOWOSIEISKI.

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