Патент USA US2105411код для вставки
Jan. 11, 1938; 2,105,411 1 K. c. DE WALT SPARK PLUG‘ Filed Aug. 1, 1936 ~ ~14. W . ; Inverwtor: Kenneth C. DeWal t, by Hwyafjwlw Hls Attorneg. 2,105,411 Patented Jan. 11, 1938 UNITED STATES PATENT OFFICE 2,105,411 . SPARK PLUG Kenneth C. De Walt, Schenectady, N. Y., assign or to General Electric Company, a corporation of New York . Application August 1, was, Serial No. 93,855 . 4 Claims. v(c1. 1zs_1e9> The present invention comprises an improved spark plug for internal combustion engines. Heretoi'ore it has been common practice to in sulate from one another the oppositely charged 5 parts of a spark plug by an elongated insulator commonly consisting of porcelain. The central conductor is threaded through the insulator which is mechanically clamped by a screw‘ threaded member within the casing of the plug. 10 It is well known that some disadvantages ac company such a construction. For'example, the end of the insulator is subject to carbon deposi tion from the combustion mixture and the- in sulator sometimes is cracked by the compressive 35 forces to which it is subjected, when it consists oi’ opaque material, such as porcelain, the light irom the spark cannot be seen from the exterior and hence the operativeness of the spark plug cannot be ascertained by observing light emitted u by the plug. . ‘ In accordance with the present invention all an engine‘ cylinder. The attached end 01' the conductor 4 is grooved at 8 and is ?rmly gripped by the cap 3, which engages with the groove. The body portion I terminates at the end 0p posite the spark tip 6 in a lip 9 of reduced thick— 5 ness which preferably tapers down to an even smaller rim. The opposite rims of the glass cylinder 2 are sealed by fusion to‘ the rim of the lip 9 and the rim of the cap 3. The seals between ‘ the glass and the metal members are maintained 10 strain-free by so choosing the glass and metal that the thermal expansion characteristics of the glass and metal are substantially coincident at temperatures below the zone of transformation temperatures of the glass, that is, at the zone of 15 temperature at which the thermal expansion characteristics rapidly increase with temperature. Such a seal is described in a copending applica tion, Serial No. 705,250, ?led January 4, 1934 by E. E. Burger and A. W. Hull (see corresponding 20 French Patent 784,164 issued April 23, 1935). such di?iculties are absent and a convenient struc This seal also is described in an article by A. W. ture is provided by making part or the shell or , Hull and E. E. Burger in Physics, Vol. 5, No. 12, outer member of a spark plug oi glass which is pages 384-411. As there explained, a suitable ’ integrally united or welded to adjoining metal parts. No other insulator need be provided be tween the sparking conductors. An internal conductor is joined to a metal portion of the shell at the endof the plug which is remote from the location 01 the terminals between which the spark occurs. If partial obscuration of the light emitted by the spark can be tolerated, a battle is provided between the sparking terminals and the glass insulator, thereby preventing deposition of U carbon or other conductive material upon the inner surface of the‘insulator. . ” - ' ' strain-free seal may be made by sealing a hard glass, sold in the open market by the Corning 25 Glass Co. of Corning under the name “Corning Gill”, to metal members having suitable thermal expansion characteristics, for example, an’ alloy consisting oi’ 54 per cent iron, 28 per cent nickel and 18 per cent cobalt. The above application 30 and article describes various equivalents for this particular glass and this particular metal alloy. vIf desired, the member 1 may be constructed of two parts brazed or otherwise joined to an- 3, other, the thick walled part in consisting of iron 0 The accompanying drawing shows in Fig. 1 a or other inexpensive metal and the lip 5 consist~ longitudinal section of a preferred form of spark ing of alloy suitable for joining to glass. plug embodying my invention; Figs. 2 and 3 are‘ In the spark plug shown in Fig. 1, the space longitudinal sections of modifications; and Fig. 4 between theinner conductor 4 and the outer shell is a perspective enlarged view of a bailie and sup is unobscured so that light from the spark be~ 40 port employed in the modi?cation of Fig. tween-the tips 5 and 6 may be seen‘ through the Referring to Fig. 1, the spark plug illustrated ‘glass member 2. The condition of the spark thus consists of an elongated shell or housing made may be observed and the condition of the plug up of a heavy-walled metal body portion i, a thus may be determined, without the necessity of glass portion '2, and a relatively thin-walled metal using special testing appliances or removing the cap portion 3. An interior conductor 4 is at plug. tached at one end to the cap portion 8 of the Inthe modi?cation shown in Fig. 2, the metal shell. It terminates at the opposite in a spark 'ba?le ii is mounted upon the inner conductor 4, ing tip I, whichlas illustrated, may have a smaller the walls of the shell i being somewhat cut away 50 cross section than the main portion of the con as indicated at H. Particles of metal, carbon, ductor l. The sparking tip I cooperates with a or other conducting material can only reach the similar sparking tip 8 projecting from the screw inner surface of the glass\window 2 through a , ‘threaded portion 1 of the plug which is con sinuous elongated path. Hence the amount of structed to engage with an opening in the wall of such deposition will be greatly decreased. The 1,. 2 2,105,411 battle H, as indicated, consists of a cylindrical portion and an outwardly extending radial ‘por tion, the former making frictional engagement with the conductor i. In the modi?cation shown in Fig. 3, the bailie l4 consists of an insulating .rnateii'al such as alumina, magnesia, porcelain or silica. It is shown somewhat enlarged in Fig. 4 together with the holder i5 whereby it is mounted upon the 10 conductor E. The support 15 makes a frictional engagement, both with battle H and the con“ ductor ‘. The segmental members l5a may be bent outwardly to engage firmly and positively with the baille H. r , What I claim as new and desire to secure by ‘ Letters Patent of the United States is: l. A spark plug for internal combustion ap~ paratus comprising the combination of a hollow casing the wall of which consists of metal and glass having approximately the same thermal co e?icient of expansion, said metal and glass mem bers being fusion-sealed to one another at adjan cent edges and a cooperating conductor located within said‘casing and being connected at one end only with said casing. 2. A spark plug for internal combustion ap paratus comprising the combination of a hollow casing consisting of a plurality of metal members and an intermediate hollow cylindrical glass member which is sealed at opposite ends to said respective metal members and a cooperating con ductor sealed to one of said members and ex tending in sparking relation to another of said metal members. 3. A spark plug for internal combustion ap paratus comprising the combination of a hollow casing consisting of a metal base, a cap and a 10 glass insulator which is fusion-sealed to said base and cap, a conductor sealed to said cap and pro jecting through said casing and a baille mounted on said conductor. 4. A spark plug comprising the combination of 15 a massive, hollow metal base constructed to en gage with an engine cylinder well, said base hav ing a rim of reduced thickness, a hollow glass cylinder sealed at one rim thereof to said base rim, 2. cap closing the opposite rim of said glass cylinder and being fusion-sealed thereto, a con~ ductor extending from said base, and a second conductor joined to said cap, projecting longi tudinally through said casing and extending in sparking relation to said base conductor. KENNETH C. DE WALT.