USRE16159E - Electbical insulatob - Google Patents

Description

Reissued Sept. 8, 19251.

y Mauna Ennemi),- or omesso; ILLINOIS'.

ELECTRICAL INSULATOB.

Original No. 1,369,274, dated February `22, v1921, Serial No. 236,933, filed Hay 27, J1918. Application tor reissue led January 2, 1924. Serial No. 684,175. l

To allwhom z't may concern:

Be it known that I, ALICE MAUDE Fain- CHILD, a` citizen of the United States,' res1d ing at Chicago, in the county of Cook and State of Illinois, have invented -certam new and useful Improvements Ain Electrical Insulators, of which the following'ls a specification. Y

' My invention relates to insulating ma'- 1o terial.

More particularly, my invention relates to material characterized by high electrical insulating and high temperature insulatlng qualities,'which material combines wlth the 1.5 qualities referred to, the advantages of a' high degree of Istrength or sturdiness with a low coefficient of expansion under temperature changes.

As the description rceeds it `will be apparent that the ins ating material constituting the subject-matter of my lnvention has a wide eld of usefulness, belng adapted for use in spark plugs, in burners which are subjected to high temperatures, in crucibles and in lother devices which are subjected to high tension current or to rapid temperature changes. Y l v 1 A11 object of the present invention, therefore, is to provide-.a new insulating material which will withstand high temperatures ywithout breakage. y Y Y A further ob]ect is to provide insulating material having a 'high msulating quality and great strength.

A further obJect is to provide an insulating material'havinga low coeiicient of expansion under temperature changes.

A further object of my invention is to provide an insulating material involving non- 40 metallic oxides.

A further object is to provide an improved spar-k plug well adapted l,to withstand the `heavy duty imposed 1n practical operatlon.

l' As showing'one practical use for the insulating material constituting the subjectmatter of the present invention, I have illustrated a spark plug such as is used in internal combustion engines. l

Referring' to the 'accompanying draw- 'in lgure 1 is a view in cross-section of a an lnsulatlng member spark plu showing mounted t erein; and j ,Figure 2 is a lating member. 'Y The illustrated spark plug includes a sleeve 1 formed to provide a seat for the insulating member carrying the metallic tersectional View of the insuminal 2. The member 1, according to the y vI-have found that zirconium oxide andl zirconium silicate, when constituting from 50 toV 90% of .the mass, forms a ceramic structure having properties which produce an insulating non-metallic structure that has more suitable physical characteristics and desirable properties than any other of the ceramic materials 'such as stone ware, china and porcelain heretofore known or used in spark vplugs and other heat resisting devices.

Zirconia (ZrOz) zirconium oxide has been I well known for many years, having been,

used-lar ely in incandescent mantles of. the

earl I elsbach type and. their immediate Vpre ecessors. It was next largely u-sedas a substitute' for the lime structure in oxyhydrogen or calcium 1i ht and its fire resisting properties are well nown.

The fact that zirconia formed an important constituent in the structure `of the glower in the Nernstlamp might lead to the assumption that it would be unsuitable for use as a heat resisting insulating structure for spark plugs, but I havel found by .numerous tests that it forms amore desirable constituent of a body for a .spark plug insulator than any other ofthe numerous oxides of other compounds with-which I have experimented and that it can be'substituted' with great improvement for china clay, feldspar, silica, magnesium silicate and many of the other constituents heretofore employed in stoneware, chinaor porcelain insulators. l

Of the various processes for forming earthen ware structures, those depending on casting, a` thin si terial formin Water shrinkage such as forming on a Wheel or shaping in a laster of Paris mold or cannotV be. employed where large quantities of zirconia are used on account of its lack of theproperties characteristic of clay, that is, capillary shrinkage into a hard compact mass, but structures containing -a .large lquantity of linely round zirconium silicate such as the minera zircon or finely ground baddeleyite, anatural ore containingjahigh percentage ofzirconium oxide With from 5 1z0/15% plastic-clay, can be readily formed into quite lntricate shapes by what is known as the dry forming process frequently described asipressing a moist dust into steel molds.

moist .ranulated zirconium massv containing as ittle as 5% of clay and about 12% of Water can be placed in a closely litting steel die and sub]ected to a -pressure of from 5 to 8000 pounds to the square inch and formed into a structure that will shrink ver little in air drying oroven drying, and

which may be Yfired to lany high temperature available without danger of undue fusing or shrinkage.

The chemical reaction betweenthe zirco-l nium compound andthe clay will, in the irin processproduce zirconate of alumina, whic is a very refractory material.

It has been -demonstrated that the" mathe subject-matter ofy the present invention maintains its high insulatmg qualities even at very high temperatures.

1.` A spark plu having metallic conducting electrodes an non-metallic wall' form- .ramic structure consisting of zirconia compounds and a clay binder.'I

3. A spark plu having metallic conducting electrodes an non-metallic Wall forming and insulating means consistingof a ceramic structure containing clay and zirconium compound.

4. As a new article manufactured, an insulator for sparkv plugs comprising a ceramic structure of'clay containing zirconia compounds in Varying proportions.

5. An' electric spark plug having a new insulating structure of great mechanical strength and infrangibility under sudden variations' of temperature and high electric insulating resistancey at high temperature consisting of a ceramic structure comprising zirconium compounds as its principal constituent. y

6. An' electrical insulator consistin of a ceramic structure 'composed essentia ly of zirconium compounds. p

`7. An electrical insulator comprising a structure of which zirconium is an essential constituent.

8. A spark plug having anelectrical insulator consistin of a ceramic structure containing zlrcomum compounds and a ceramic binder.

Signed at Chicago, Illinois, this 21st day of November 1923. .ALIE FMRCHILD.

Images