US 1608891 A
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Description (OCR text may contain errors)
Nav. 36,1926. y 1,608,891
IGNITION COIL Filed Feb. 5, 1926 ///5 O /O//le /J/s 1F11@ 2.,
Patented Nov. 3G, 19.265.
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2 f SU NIT EDS "STATE irnoivias Lann., or nec-inneren, new volait, .Assieivon ro non rirnasr iinncrrnic ,1. ,COMEANL OF ROCHESTER, NEV YORK, A COREORATEQN 10F NEVI YORK.
' 'IGNITION' COIL.
l Application' filed. February; 1926. Serial Noz'3509.
This invention relates to ignition coils Vsuch as are used in connectionwich internal I combustion engines.
. winding, particularly where this winding isenclosedby insulating material and a sees?.l
upper; and lower casing-members 13 and 14.
In the design of an ignition coil, one of the problems to be metiis the provision for escape of heat generated in the primary ondary .winding` in the... usual manner.
AlVhile. the amount of heat may not be ei:- cessive duringnormal operation or the coil,
it sometimes happensthat the kprimary ciricuit is left constantlyclosed, through failure oit the operator to open the ignition switch.I when operation of the engine is ystopped and in such a case there is 4danger of overheating and injuring the coil, unless effective means are provided for dissipating the heat.-
In the.l manufacture of ignition coils it isl common to use a magnetic core of laminated construction, wind the primary winding upon a stiff sleeve or tube of paper, or other insulating material, and afterwards intro'- duce the core into this sleeve. ln such a serious barrier to the transmission ofheat.
1. The object of the present invention is to avoid the heat insulation resulting froml the construction just described. and;to.pr.ovide a construction in which the heat=may be much more effectively transferred from the primary winding to the magnetic core. this end, itis proposed to substitute a metal sleeve for the sleeveof insulating.material atral member l5 introduced int-o the: metal commonly used, this metal sleeve being in core. provision against the formation of circuits in whicl eddy currents may be generated, and the invention resides particularly in the form and construction of the metal sleeve by which it is engaged non-rotatively with the coil, and is at the .same time so divided and insulated as to provide against the production of such circuits.
In the accompanying drawings, Figi is a vertical Section of a complete ignition coil embodying the present invention. Fig. 2 is a plan view of the core, with the primary winding and the interposed metal sleeve shown partly in section. Figs. 3 and l are sectional views, on an enlarged scale, on the rilo:
`linesl-S ande-fl in: F ig. 2,; and'v F ig. 5 is a plan-view ot one of the-,members of the metal sleeve, seen atitsinnei' side.
4The inventionl is shown asieinbodied in airignition coil having :a priinaryfwinding l() and a secondary winding` ll, surrounding the straight centralwmeinber of'a 4laminated core l2. These-parts are'einbraced.between `The corel isdivided into two halves, for convenience inassembhng itaivith the previouslyA formed` windings. "The central vmember .15 of they core is of'rectangular cross-section, and thelaminae in-iit are secured together by rivets 16. f
The metal sleeve,v in the use of which th present invention particularly residesfcomprises two similar. members IZstampedinto the-form vshown,in cross-section, in Figs. o
and 4l. Preparatory to the 'formation of the primary. winding,
slieet-s of thin, flexible insulating material, such as varnished silk, are
`laid over the outer surfaces of thesemem- -.bers,and one-edge 18 -of veach insulating sheet is, interposed between two of the adjacent edges of the sleeve-members, so .as to provide alongitudinal separation or insulatedjoint. The sleeve-members are held in this position while the primary kwinding is wound directly uponr th'etliin insulating maf terial, the'` metal sleeve thus serving as a support for the winding during its formation. rllhe secondarywinding which has .previously been formed in any `convenient manner, ,is then placed around the primary .winding, and tlietwohalvesv of the core are thenbrought together, with the divided censleeve.
The formi of the sleeveis preferably? such that it has inner reentrant angles which directly engage the salient angles of the rectangular Core, thus providing for eliicient heat conduction at these points. Between the angles mentioned, the sleeve is curved away from the core, particularly at the parts opposite edges of the laminee. In case the core laminae are riveted together, as in the illustrated construction, the sleeve is also preferably curved away to afford space for the heads of the rivets, as shown in the drawings. Even at the parts where the sleeve is not in engagement with the core, however, heat transference by radiation and convection may readily take place; and since only a minimum thickness of insulating material is interposed between the primary winding and the core, it has been found that the escape ot heat from the winding is greatly improved by the substitution of the metal sleeve tor the usual rigid tube of nonmetallic material. Where the core is riveted, it is important that two opposite insulated joints be provided in the metal sleeve, these joints being located between the opposite ends ot the rivets, since otherwise a circuit for eddy currents, passing in part through the rivets, would be produced. The thickness of the laminated core inevitably varies somewhat in manufacture, and allowance must be made for this in the inside dimensions of the metal sleeve. To provide Jfor a secure non-rotative engagement between the parts under these conditions, lugs 19 are formed near the ends of the sleeve-members, by pressing the sheet-metal inwardly at these points, so that a secure engagement results, even though the tit between the top and bottom of the core and the sleeve, respectively, be somewhat loose.
The sleeve is shown in the drawings as being out ot engagement with the heads ot the rivets, but this is not essential provided the sleeve has two longitudinal insulated joints located as shown. The cross-section of the sleeve, as illustrated, shows smoothly curved portions extending vfrom angle to angle. This curved form 'facilitates the win-ding of the primary wire upon the sleeve, but is not essential to the embodiment of the invention. The sleeve may be made of any convenient metal, since even metals having relatively low heat-conductivity are greatly superior, in this respect, to any ot the nonmetallic materials commonly used as supports for the primary winding.
The invention claimed is:
1. In an ignition coil, the combination, with a laminated magnetic core of polygonal cross-section, and a primary winding surrounding the core, of a metal sleeve inter posed between the core and the winding, said sleeve being formed for non-rotative engagement with the core at the salient angles of the core, and having at least one longitudinal insulated joint located between the points ot engagement ot the sleeve with the opposite outermostlaminae ot the core.
2. In an ignition coil, the combination, with a magnetic core comprising laminae and rivets securing the lamin together, and with a primary winding surrounding the core, of a metal sleeve interposed between the core and the winding and formed to en gage the core non-rotatively at opposite salient parts of the core, said sleeve having two opposite longitudinal insulated divisions each located between opposite ends of the said rivets.
3. In an ignition coil, the combination, with a laminated magnetic core ot rectangular cross-section, and a primary winding surrounding the core, of a metal sleeve interposed between the winding and the core and formed with inner angles engaging the angle of the core, the sleeve being curved away from the edees oi' all but the outermost laminas ot the core and having a longitudinal insulated division between its points ot engagement with the two outermost laminee.
el. In an ignition coil, the combination, with a laminated magnetic core oit rectangular cross-section, and a primary winding surrounding the core, ot a metal sleeve interposed between the winding' and the core, engaging the core at its angles and curved away from the core between said angles, the sleeve being provided with inwardly pressed lugs engaging the core adjacent said angles, and comprising two members longitudinally separated and insulated 'from each other.
5. In an ignition coil, the combination, with a laminated magnetic core and a pri.- inary winding surrounding the core, or" a metal sleeve interposed between the winding and the core and engaging the core at a plurality ot opposite points, said sleeve comprising two similar longitudinally divided members; and thin flexible insulating material surrounding the sleeve and extending between the adjacent edges of the sleevemembers.
THOMAS L. LEE.