US1740515A - Chusetts - Google Patents

Description

Dec. 24, 1929. G LOUIS 1,740,515

BREAKER POINT MECHANISM Filed sept. 12,` 1927 'I rlll grill/ller:

A TTORNEYS.

` INVENTQR.

Patented Dec. 24, 1929 UNITED STATES PATENT OFFICE TERRENCE G. LOUIS, OF SPRINGFIELD, MASSACHUSETTS, ASSGNOR TO WICO ELECTRIC COMPANY, OF WEST SPRINGFIELD, MASSACHUSETTS, ACORPORATION OF MASSA- cHUsETTs BREAKER-POIN T MECHANISM Application led September 12, 192'?.` Serial No. 219,116.

patent, lends itself nicely tothe requirements of a magneto of the reciprocating armature type and is commonly used therewith, yas shown for example in my prior U. S. Letters Patent No.,1,517,997, granted December 2, 1924.

This particular type of breaker point mechanism includes a plunger for `moving one of the breaker points and a guide in which the plunger slides. This plunger and guide have heretofore been made of metal and the relatively slidable bearing surfaces thereof require lubrication. While provisions are readily made for lubricating these parts, it is not so easy to control the lubrication within close limits to just the amount necessary. If lubrication .is excessive or deficient, undesirable conditions are created. For example, if the relatively slidable parts donot receive enough oil, cutting of the bearing surfaces results and the small metal particles worn oft may eventually reach and lodge between the cooperating breaker points. Onthe other hand, if these parts receive the least bit too much oil, the excess oil may reach andlodge between `the breaker points. `With either of these conditions there is an increase in the disruptive effect of the arc between the contacting faces of the breaker pointsk and an increased disturbance of the metal particles in such contacting faces. While by the use of the invention of said first named patent, which is likewise embodied in the breaker point mechanism of the present invention, the points are redressed on'each engagement by bringing them together with a percussive blow, kthe force of which is carefully gauged so as to put back into place the disturbed parthe source. yThat is, while excessive or decient lubrication results in damage to the points which can be repaired, it is better to prevent, or at least substantially reduce, the

damage and thereby reduce the repair work which needs to be done by the redressing action of the percussive blow. The force of such blow must be adapted to the work in hand and will vary according to the amount of redressing necessary. The variation in force is secured by varying the speed and/or mass of the plunger. By reducing the amount of redressing to be done, one can use a lighter blow and is not restricted to such close limits as to the force of the blow. This means greater freedom as to the choice of the mass and speed of the plunger.

This invention is concerned, among other things, with the solution of the special lubrication problem above set forth and, to this end is directed to the provision of a breaker point plunger and a guide in which the same slides, wherein no lubrication is required for the bearing surfaces and wherein the undesirable conditions heretofore arising from excessive or deficient lubrication are avoided. The construction is also such as to protect the breaker points from oil which is used for lubricating other parts of the magneto. That is, the construction not only requires no lubrication but it also tends to exclude oil from any source from passing up the breaker point tube and reaching the breaker points.

To this end, at least one of the two cooperating bearing surfaces is made of felt or some material having similar characteristics. Usually, the plunger is constructed with a bearing surface of felt although it is possible to so construct the guide, It is sufficient that one of the two bearing surfaces be so constructed and the other may he of metal, bakelite or any other of many materials which will work withthe felt.` The particular material used for the bearing surface, with which the felt bearing surface is engaged for relative sliding movement, is ordinarily not material although l prefer, tor certain other reasons to use bakelite or thelike. The felt bearing surface slides nicely over its opposing bearing surface without requiring any provision for lubrication. Moreover, the

felt, in itseli' ltends to exclude the oil `which might `fin some cases enter the base vof the breaker point tube from other parts of the magneto which have to be lubricated.

"The invention also has for an additional objectto provide abreaker point construction which is not only simple in form and adapted for manufacture at low cost but which is also durable, eiective, eiicient and substantially fool prooi.

Infmanycases,tlie'magneto includes-Ia body ofbakelitefor similar material, which Vhouses the vcoils Aof the magneto, -and the breaker point mechanism 'is so located with respect to other lYpartsofithe magneto that it has to be 'housed :in this body of bakelite. lVith the 4prior construction of the Vbreaker point'mech- -anism, afmetal guide tube had to 'be set `into the bakelite to receive the metallic breaker `point plunger :and these relatively fslidable parts hadfto iitwithin close tolerances. lith the present construction, the `breaker-point .guide can consist simply of a hole in the bakelite body, whereby the expense or the "metal insert issaved lT he felt plunger then slides `on Ythe bakelite wall ot this `hole and works nicely in cooperationtherewith, Aforni- 4ing a lguide i'or the movable breaker point and requiring no lubrication. The liormer necessity for working to close tolerances 4in finishing the breaker point plunger and its guiding v-tube no longer exists. The felt plunger Lwill woik in a hole which is undersize as well as one Vwhich is oversize within relatively wide itolerances.

@ther objects and advantages ywill appear `inthefollovvingdescription and will bepointed outin the appended claims.

Theinventioirwill be disclosed with refer- Aence to `the accompanying drawings, in Which:-

iF ig. il is a front elevational view partly in section, of a magneto showing a breaker point mechanism,einbodyiiig the invention applied thereto;

Fig@ isI an end velevational view, partly in section, showing the breaker point mechanism -and its relation with'the magneto and Fig. 3 is a fragmentary sectional view, taken 4similarly to Fig. l and showing the constructional -det-ails ot the'breaker point lunfrer.

{n 'these drawings I have shown the invention as applied to afniagneto of aitype in 'which it would ordinarily be easy for .oil-t0 -enterthe breaker point guide tubeand reach the breaker points. However, Vthe breaker pointmechanism of this invention has worked Lsatisfactorily in a magneto suchasvshown.

That is, it has eifectivelystoppedy the entrance `of the magneto.

loosely ythrough an abutment 10 onarmature a. Fixed to stem 9 andfa'tazpoint below abut- ,29, .represented by the lower end faces of a pair of cores-c, is periodically moved Yaway irom said-polestogeneratean ignition spark in an electrical winding (not shown). The `functional Operation of the magneto and the general type of construction, including the mechanism 4for operating the armature, are substantially the same as disclosed in my copending application rSeizial No. 133,493, iiled lSeptember 3, 1926.

Particularly, the breaker lpoint mechanism of'this inventionhasitliesame function and is operated in the saine manner =as disclosed in said application. The breaker `.points are shown at 'and 6,?the former in ,tliiscase bcing fixed-and insulated andthe latter movable and yin `electrical `connection with `the Iframe The lmovablefpoint 6 is cari'ied by the -veitically rreciprocable plunger shown which slides :in'a xhole 7 :formed Vin a body S of bakelite, or `.the like. The breaker point plunger has a `stem 39, which passes ment d0 is a 'collar l1 which constitutesan abutment adapted to be engaged by the .ffirst named abutmentduring the'downward iight oi' the armature. A spring l2, actiiigfagainst collar 1l, tends toholdtlie'breaker points v*in contact. The-armaturen, whenimoved away fronipoles p sufficiently -so thatabutment l() Aengages abutment 1-l,willino ve steni9 downwardly against tliestress ofspring 'l2 yand separate.the'breaker points. The latter are subsequently yreengaged byspring 12 onthe return'strokeofarmature'a as the abutments 10 Aand 11 eventually become disengaged. The described arrangement ,is substantially the same as disclosed in said'application.

The breaker point :plunger is, however,- of novel construction. yIt includes'one orimore bodies of `felt f, or likeimaterial, which slide in bearing engagement with .the walls ofhole i A7. The latter forms thezguide forthe plunger.

This guide, as shown, lis formed of bakelite but this isinot essential to the -successful use ofthe felt plunger notwithstanding that it is desirable `for thespecial 'reasons 120 abovefpointed out. Theplunger-and vguide are usually, lalthough not necessarily, .cylindrical and Athe `plunger may 4consist simply of one cylindrical body of felt, as -shown in vF ig. 3, orit may and desirably does, consist Iof a plurality (twoas-sliown'inFigal) 'orion- `gitudinally spaced cylindricalbodies or Stelt.

Theuse of more-than onebodyiof feltfmakes it'more diiiicult foroil to `reach `the'breaker points, especially -if :these 1 bodies :are` axially 130 separated by a distance in excess of the stroke of the breaker point plunger, as shown. If oil creeps up past one of the felt bodies, it will lodge in the space betweeny the bodies and will remain in contact with the lower body without getting an opportunity to reach the other body on account of the space being longer than the stroke of the plunger. That is, the lower end of the upper body never descends in hole 7 as low as the uppermost level to which oil can be raised by the upper face of the lower body.

As a convenient way of formin the bodies f, I construct them of a series of elt washers 'w mounted in a vertical stack on stem 9 and clamped together under axially applied pressure. Conveniently, stem 9 has a 'flange 14 near its lower end on which the base of the stack of washers fw rest. Stem 9 terminates short of the stack of washers and is bored out and threaded, as at 15, to receive a threaded stem 16 which carries a nut 17 and, above this nut, the breaker point 6. A washer 18 en compassing stem 16 below nut 17 presses against the top of the stack of washers fw. By turning nut 17 and thereby threading stem 16 into hole 15, the stacked washersw may be placed under sufficient pressure and clamped together. This pressure is a moderate one, such as can be obtained wholly with the means shown, as distinguished from heavy pressures which would compress the felt material to so high a degree that it would lose all its resiliency and become virtually like metal and would then require lubrication as much as metal. The compression is purposely moderate so that the felt material retains a certain amount of its resiliency. In the case where two bodies of felt are used, as in Figs. 1 and 2, the construction is the same except that a spacing collar 19 is applied between the two stacks of washers. These two stacks are clamped together'under pressure by the single means above described.

IVhile the felt bodies may be otherwise constructed, according to some features of the invention, the described construction will be found simple and well adapted to practical rmanufacture and is therefore desirable, im-

portant and preferred.

The most important characteristic of the felt is its ability to slide in bearing engagement with a guiding surface without receiving lubrication. Doubtless this characteristie is due to its inherent qualities of non abrasiveness, non-friability and elasticity or resiliency. Other materials, possessing these inherent qualities or the aforesaid characteristie, may be used and I intend, by the use of the term felt, to cover substances of an equivalent nature. As a matter of oreference, felt is used and I have found it important to use a high grade of left, such as woven felt used on tennis balls. While ordinary pressed felt can be used, it tends to frazzle out and liberate small whiskerdike fibers, which may find their way to and lodge between the breaker points and thereby create an obviously undesirable condition. ,y

The important consideration is to have one of the two cooperating bearing surfaces of felt or equivalent material. The nature or the other bearing ksurface is ordinarily immaterial.r It follows that either the guide or the plunger `may be offelt. As a practical matter it will usually be found more feasible to construct the plunger of felt rather than the guide but the latter is nevertheless possible and considered to lie within the scope of this invention.

Ihile various materials may be used for the bearing surface, which cooperates with the felt, bakelite has been found to work in an ideal manner. In the particular magneto shown, the bakelite housing 8 exists and is so located and disposed that the interrupter mechanism must be, for the most part, housed therein. According to prior practice, a metal guide tube would have to be secured in the bakelite to receive the metallic breaker-point plunger. According to this invention, such a tube is unnecessary because a satisfactory guide is had simply by forming a hole in the bakelite itself. Since the felt plunger enables one to dispense with the metal guide tube and use a guide tube which is in itself an insulator, there is no longer any necessity for ,providing the insulation, formerly required,

for the upper breaker point 5. There are then substantial advantages relating to economy in manufacture in the exact arrangement disclosed, wherefore such arrangement is important and preferred although not necessarily essential so far as the broader aspects of the invention are concerned.

In the magneto shown, the housing 8 rests upon a lower housing 20, which is somewhat similarr to the crankcase of an automobile in that it contains the supply of lubricant. A thick felt pad 21 saturated with oil lies in the bottom of housing 2O and oil is conducted from the pad by wicks 22 to various bearings of the magneto. The point is that the lower housing contains oil and the lower end of the breaker point plunger is very close to the oil supply. The space limitations are so close that the armature almost touches the pad 2l.

The spring 12 also passes through the felt pad 21 and, as it works up and down,oil tends to creep up the same. These points are mentioned as factors which would ordinarily make it easy for oil to reach the breaker points. The conditions here are such that it would be exceedingly diflicult with the former types of breaker point mchanisms to prevent oil from reaching the breaker points. The problem of excluding oil from the breaker points of the illustrated magneto is therefore a diiiicult one. Nevertheless, this prob- 4 mamma lem `'has been adequately 4and satisfactorily solved by ltheeonstruetiondisclosed.

The invention has been disclosed herein, in an embodiment at presentfpreferred, for .illus- `5 trative purposes but the scope of the invention is defined by the appendedelaims rather than lby fthe foregoing description.

7h at 'I claim is l. In breaker point mechanism, areciprolo cable plunger for moving one-of the breaker points and a guide therefor, said plunger and guide having cooperating bearing surfaces one of which is composed of 'felt-like anaterial.

y15 2. In breaker point mechanism, a reciprocable plunger for moving one of the breaker Ypoints and a guide therefor constructed of bakelite or `the like, that portion of the plunger which is slidably engaged with said guide 20 being composed of felt-like material.

3. Breaker point mechanism, comprising. a reciprocable plunger, a breaker point carried thereby, a guide for the plunger composed Iof bakelite or the like, and a breaker ,25 point mounted in and insulated by said bakelite guide and so positioned as to be engaged by said vfirst named breaker point, said plunger having a sur-face of felt-like material `in bearing engagement with said guide.

13o 4T. ln -breaker point mechanism, a lreciprocable plunger for moving one of vthe breaker points and a guide -With which said plunger `is slidably engaged, said plunger including a central stem, a series of superimposed felt 35 washersmounted on said stem, and means for forcing themftogether axially underpressure, said ffelt Washers forming a cylindrical body the periphery of which vis lin bearing engagement with said guide.

lo 5. In breaker point mechanism, a `reciprocable plunger for moving one of the breaker points and a-guide with which the plunger is slidably engaged, said plunger having-a p'luralityof axially spaced vbodies of felt in bear- Axi ingengagement Withsaid guide.

6. In breaker point mechanism, a reciproeable plunger vfor moving one `of the breaker points and a guide `with whiehthe plunger is slidablyengaged, said plu-nger lievi-nga plu- .U fl'ality of axially spaced Ibodies of felt in :bearing` engagement with said guide, said bodies being spacedone fromethe other ybyafdistance greater than the stroke oflsaid plunger.

In testimonywhereof flhave affixed my sig- 55 nature.

TERRENO/E G. LOUIS.

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