US1501491A - Spark plug - Google Patents

Description

`luly 15, 1924.

. c. F. KETTERING SPARK PLUG Filed Jan. 11

kllll Patented July 15, 1924.

UNITED STATES PATENT OFFICE.

CHARLES F. KETTERING, Ol' DAYTON, OHIO, ASSIGNOB TO THE DAYTON ENGINEmING LABORATORIES COIPANY, A (lOllolltA'lloNrl 0F OHIO.

SPARK PLUG.

Application led January 11, 1918. Serial No. 211,425.

ING, a citizen of the United States of' America, residing at Dayton, county of 6 Montgomery, and State of Ohio, have invented certain new and usefulImprovements in Spark Plugs, of which the following is a full clear, and exact description.

This invention relates to spark plugs and has for its object the provision of means for-cooling certain portions thereof which are subjected to a high degree of heat.

Further objects and advantages of the presentinvention will be apparent from the following description, reference being had to the accompanying` drawings, wherein preferred embodiments of the present invention are clearly showns In the drawin Fig. 1 is a longltudinal sectional view of a spark plug embodying the present inventlon; and

Fig. 2 is a bottom plan view thereof.

Referring to the drawing, 20 designates the shell having a lower threaded portion 21, adapting the shell to be attached to the engine cylinder. Within the shell and adjacent its lower end are mounted shell points 22. The shell is threaded internally at 23 and has an annular recess 24 for a purpose to be described. 25 designates the center' electrode having a tube portion 26 extending down into the shell and terminatin in a head portion 27 at its lower end. Said head portion 27 carries a center point 28, a portion of which is located adjacent the shell points. The tube 26 is threaded externally at its upper end at 29. A sleeve of insulating material 30 Surrounds the tube andl extends from the head 27 to apoint slightly below the threaded lportion 29. Surrounding the sleeve 30 andv superimposed in the order named are the insulating spacer 31, the lower packing gland 32 having a flange 33 seating in the recess 24, the upper packinggland 34 having a flange 35, and a bushing 36 of porcelain or other insulating material. A clamping nut 37 ,y centrally boredy to receive the packing glands 32 and 34, has screw-threaded engagement with the threaded portion 23 of the shell, and is provided at its upper end with an annular recess 38 for the reception of the iange 35 of thel upper gland 34. A washer 39 surrounds the tu e 26 and extends over the bushing 36. A radiator nut 40 having fins 41 is centrally tapped for engagement with the threaded portion 29 of the tube 26. A terminal nut 42 is centrally tapped for engagement with the aforesaid threaded portion 29.

The interior wall of the. tube 26 is provided with a coating of amalgam 43 which may be applied by means of a method descrlbed in the co-pending ap lication of Thomas Midgley, Jr., Serial o. 211,224, filed Jan'. 10, 1918. A small quantity of mercury 44 normally occupies a space at the bottom of the tube. A plug 45 welded, or otherwise, permanently connected with the upper end of the tube, seals the chamber containing the mercury. By tightening'up nuts 37 and 40, it will be seen that glands 32 and 34, which are composed of a soft material, will be caused to ow and make a perfect seal between the sleeve 30, the nut 37 and the shell 20. f l The operation of this device is as folows:

When the center contact is heated by the burning gases in the cylinder, the heat therefrom passes into the head 27 and into the mercury 44 which is caused to expand and to boil and evaporate. The vapor from the boiling mercury will transfer its heat in an effective manner to the walls of the tube, and particularly the upper portion of the wall through the medium of the amalgam coating 43. From the vwall of the tube heat-will pass to the radiator nut 40 and be dissipated therefrom into the atmosphere by means of radiator fins 41.

The mercury vapor being cooled, on giving upits heat in the manner described, will condense and return to the bottom of the tube, again to receive heat from the center contact and to transfer said heat in the mgner described, to the upper end of the tu In small spark plu s of the size used generally in automobile engine work, the diameter of the chamber in the center electhere is provided a vent member consisting of several small wires twisted loosely togethei extending from the well of mercury at the'bottom of the chamber to the upper-end thereof. lt has been found that the mercury does not collect in the interstices between thewire strands of member 5t), and therefore the vapor underneath the clogging bod v of mercury has a fiee pasi `sage upwardly through member 5t), whence said vapor may iind its way to a point above the mercury and can force the same downwardly to the bottom of the chamber. This feature, however, is not nl v invention but is described and claimed in the. patent of Thomas l\lidgle v` Jr., No. 1,328,051, patented 1 January lith, 1920.

lt is apparent from the foregoing description that there has been provided a spark plug having a self-contained cooling system which is automatic and thoroughly efficient and reliable in operation. The construction of the spark plug is very simple and therefore conducive to economy in manufacture and easy disassembling for repair.

It has been discovered that the use of mercury as a cooling medium for spark plug electrodes is particularly advantageous for the following reasons: Mercury has a high vaporization point and therefore will not develop such a high vaporization pressure as would be the case in water when subjected to the temperature resulting from the heat of explosion within the gas engine cylinder.

Furthermore, this high vaporization point is, as has been discovered,-ju'st slightly below the spark plug temperature which is present in the operation of explosions of the present type; 4whereas the normal vaporization of water is far below this temperature point.

1n addition to this, mercury has the further advantage in that it is a chemical element instead of a compound, and therefore does not tend to break down into any constituent elements while operating as a cooling medium for a spark plug electrode.

`While the form of mechanism herein shown and described constitutes a preferred form of embodiment of the invention, it is to be understood that other forms might be adopted, all coming Within the scope of the claims which follow.

That is claimed is as follows:

1. In a spark plug, the combination with a plug shell; of an electrode insulated therefrom and having self-contained cooling provisions including a chamberprovided With a chamber lining of metallic amalgam, and a quantity of fluid metal located Within said chamber.

Q. In a spark plug, the combination with a plug shell; of an electrode insulated therefrom and having self-contained cooling provisions including a chamber provided with a chamber lining of metallic amalgam, and a quantity of mercury located within said chamber.

3. ln a spark plug, the combination with a plug shell; of an electrode insulated therefrom and having self-contained cooling provisions including a chamber provided with a chamber lining of metallic amalgam',l a quantity of mercury located within said chamber, and a radiating member carried by the upper cud ot' the electrode.

4. In a spark plug, the combination with a shell carrying a contact; of a center electrode mounted in the shell but insulated tlu-refroin. said electrode comprising a head portion and a tube portion which provides a central chamber extending from the head portion. an amalgam lining for the tube portion; a quantity of mercury in the tube p0rtion, and means for sealing the end of the tube; and a radiating member secured to the tube portion 'adjacent the end opposite the head portion.

5. In a spark plug, the combination with a shell carrying a contact having an annular recess and an interior screw-threaded portion; of a center electrode consisting of a tube portion partially extending down into the` shell and having a threaded upper end portion, and of a head of larger diameter than the tube, closing the lower end of the tube; a center point mounted on the head portion; an insulating sleeve surrounding the tube portion and extending from the head to the threaded portion of the tube; an insulating spacer; a lower packing gland having a flange seated in the annular recess in the shell; an upper packing gland having a flange; an insulating bushing, the spacer, glands and bushing being superimposed in the order named and surrounding the insulating sleeve; a clampinglnut surrounding the glands and located between the flanges of the glands, and having an exterior screw-threaded portion engaging the screw-threaded portion of the shell, and having an annular recess to receive the flange of the upper gland; a Washer surrounding the tube portion and extending over the insulating bushing; a radiator nut, having heat radiating fins, en-

gaging the screw-threaded portion of thetube; a terminal nut 'engagingsaid screwthreaded portion; an amalgam lining for the tube; a quantity of mercury in the tube; and a plug sealing the upper end of the tube.

6. 1n a spark plug, the combination with .a plug shell; of a center electrode supported' by said shell but insulated therefrom, said and arranged to contact with said head pore e ctrode including a hollow stem portion tion of the electrode. 10 1ndaiead potioi; a center plug ploint em- In testimony whereof I aiix my signature.

e e in the ea portion' an cool ing pro- 5 visions contained within said hollow stem CHARLES F' KETTERING' port-ion including a lining of mercury amal- Witnesses: gam for the stem portion, and a quantity of J. W. MCDONALD,

mercury located within said stem portion IRVIN A. GREENWALD.

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