US1248612A - Distributer-arm. - Google Patents

Description

'.l. F. CAVNAGH.

DISTBIBUTER ARM;l APPL'lcAUaN FILED JUNE Il. 1917.

Patented Deo. 4, 1917.

UNITED sTATEs PATENT oEEroE.

.TIN F. CAVANAGH, 0F MERIDEN, CONNECTICUT, A-SSIGNOR TO THE CDNNEGTIGUT TELEPHONE 6b ELECTRIG'CMPANY, 0F MERIDEN,

CNNECTICUT, A CORPORATION DISTRIBUTER-ARM.

'imi-48,612.

Specification of Letters Patent.

Patented nee. 4, 1917.

Application led June l, 1517. Serial No. 174,114.

'tot mz't'may concern.' v it known that I, JOHN F.k CAVANAGH,

rtizenof the United States of Ame1-ica, ding at Meriden, Conn., have .invented anew and useful Distributer-Arm, of which Ai samel time simple and practical connection between the distributer arinf and the uter. shaft.

f Accordingly, my invention consistsin part, in constructing .the distributer arm, which is usually molded in suitable-l insudistriblating material, with a' hore'to tit over the `distribut'er shaftps'aid bore having. radial.

projections at separated 'points therein to,-

engagethe shaft and portions between said bearing projections recessed away from the shaft.4 A further feature is the provision of oppositely disposed driveshoulders within the bore separated from each other' and disposed to engage a .driving tang on the end of the distributershaft.

Other features and details of construction will become apparent as the specification proceeds,

in the accompanying drawing I have illustrated my invention as embodied,- in practical and at present preferred forms, but l would ha've it understood that changes and modifications may be made without despirit and scopeof the invention.

ln this drawing Figure 1 is a broken .sectional view of an ignition distributor having my invention incorporated therein.

Fig. 2 is a bottom plan view of the distributer arm as detached `from the upper end of the distributor shaft, shown also in top plane in this view, illustrating in dotted lines the position of the distributor shaft within the bore of the arm.

Fig. 3 is a bottomplan view of the arm ina slightly modified form.

Referring particularly to Fig. 1, 5 designates the distributor shaft driven from the engineA by suitable gearing and constructed in theillustration, as customary, with one side of the upper end portion thereof out away to (provide a. driving tang 6. This upper 611 dil'erent sides of said bore portion of the shaft is usually substantially cylindrical as illustrated to receive the hub of the distributer arm.

The distributer arm 7, is usually molded to shape in suitable insulating material and in general is'formed with a hub portion 8, fitting over the shaft andan outstanding arm 9, carrying a distributor contact 10, ,the end of this contact in the rotary lnovement -of the armcoming into operative relation y wlth sultable relatively stationary contacts -l1, and current being supplied to the'rotary contact by. a spring brush 12, which bears against a current conducting point 13.

The details of the connection between the shaft and distributor arm will perhaps be `best understood by reference to Fig. 2, wherein it will be seen that the hub portion of the arm is formed with a lgenerally cylindrical bore 14 to receive the end of the shaft and inwardly projecting radial extensions 15 at for engagement with the walls of the shaft.. In practice, the bore is made slightly larger than the diameter of the shaft and the bearing projections 15 project radially inward just far enough to engage with and center the arm upon the shaft. This condition is illustrated by the dotted lines in Fig. 2, which show how the radial projections bear upon the shaft and the portions between said bearing projections are recessed away from the shaft.` The result of this 'construction is that the distributer arm is accurately centered upon the shaft, irrespective of slight irregularities in the molding operations and in spite of certain shrinkages which are likely to occur in molded articles of this character. j

The arm is keyed upon the shaft land caused to rotate therewith'by providing it, in this invention, with drive shoulders 16, projecting inwardly into the .bore at opposite'sides thereof and terminating in abrupt shoulders 17 to engage the driving face of the tang 6, these drive shoulders being disconnected fromeach other as shown in Fig. 2, vso as to engage the tang at separated points. By means of this construction, the bore is substantially symmetrical, so that any shrinkage which may occur will be more or less regular and will not distort the shape of the bore. lThis construction furthermore provides a rm driving engagement at'twq relatively widely separated points` between the driving tang and the arm, causing the arm to move positively therewith. r. l

In the form shown in these first two figures, the distributer arm contacts with the shaft in but four places. Friction is therefore reduced to a minimum, enabling the arm being readily placed upon and removed from the shaft. Also, it will be seen that if the stock'should shrink to a point which would be prohibitive in the old style arm, which is made to contact with the shaft at all points circumferentially, a slight effort merely is required to slip the distributer arm over the end of the shaft, the shaft in somecases having a broachiiig effect on the projections of the bore as the arm is forced in place thereover. Vith my new construction furthermore, any slight distortion from the circular has no ill effect upon the mounting of the -arm on the distributer shaft.

The number and shape of the bearing projections may be varied. For instance, as shown in Fig. 3 there mayl be only three bearing projections disposed equidistantly about the bore, this providing the threepoint support, desirable in mechanisms. The projections in this-case also are shown more in the nature of ribs, as distinguished from the rather flat style of projections shown .in thefrst form;

Another feature of my invention which is of considerable practical importance from a manufacturing standpoint is that the` core or'pin which is used to mold the bore in the distributer armnia be made as a solid pin, except for the s ight depressions in the sides thereof, necessary to form the ribs l or bearing projections, and the relatively small pockets in the end thereof necessary to form the two separated drive shoulders. This practically solid construction of the pin allows for the pin beingk hardened as much as necessary for practical molding purposes without the danger of breaking the pin, due to fragility of any of its parts. This feature will be fully appreciated when it is realized -that this pin or core used in forming the bore should be made quite hard to resist the abrasive action of the molding material and when it is understood further that it has been impractical heretofore to make the pin as hard as desirable because when so made, the rojection or tang on the i end of the pin ha in the mold.

The advantages of the invention will be more fully appreciated when it is realized a tendency to break off that heretofore there has always been considerable waste in moldin articles of this character, because of the yrgact that the concentric or circular seat in the distributer arm had to be molded very close to size so as to accurately 'fit the distributer shaft, and that even a relatively slight4 shrinka "or distortion would make 4these close members unfit for use. As there is practically always some shrinkage in these articles, it can be understood that the percentage of unusable products was relatively high. The present invention makes it possible to mold the ribbed portions of the bore in the distributer arm accurately to size and then, even though some shrinkage does take place, said distributer arms may still be used by simply forcing the arm ove'theend of the distributer shaft, the shaft acting in such cases, as above indicated, in a breaching capacity to mill off the high points on the ribs, producing an accurate andclose fitting ,engagement between the shaft and distributer arm.

What I claim is 1. In combination with a distributer shaft having the end portion cut away at one side thereof to providev a driving tang and a distributer arm of insulatin a shaft-receiving. bore to t the end portion of the shaft, and separated drive shoulders projecting into opposite side portions of said bore to engage the driving tang at separated points thereon.

2. .As an article of manufacture, a disi tributer arm of insulating material arranged to bemountedon a shaft of an igniter mechanism, said Varm having a bore approximately tting the end of said shaft, inward projections on the walls of said bore arranged to be partially cut-away by the shaft upon the application of said arm thereto whereby a. snug fit may be obtained between said parts. u

3. As an article of manufacture, a distributer arm of insulating material -arranged to be mounted on a shaft of an ignter mechanism, said arm having a bore approximately fitting the endv of said shaft, inward projections on the walls of said bore arranged to be partially cut-away by the shaft upon the application of said arm thereto whereby a snu fit may be obtained between said parts, sai inward projections being in the form oflongitudnally arranged spaced ribs.

JH-N F. CAVANAGH.

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