US2161251A - Ignition distributor - Google Patents

Description

`une 6, 1939. R; H. G|B5ON 2,161,251

IGNITION DISTRIBUTOR INVENTOR. /'f /17' ff. 6/1560/1/ BY Q,... @ad

ATTORNEY,

June 6, 1939. R. H. GIBSON 2,161,251

IGNITION DISTRIBUTOR Filed Nov. 6, 1937 2 Sheets-Sheet 2 INVENTOR. 675601/ ATTORNEY.

Patented June 6, 1939 UNITED STATES PATENT OFFICE American Bosch Corporation,

Springfield,

Mass., acorporation of New York Application November 6, 1937, Serial No. 173,073

1 Claim.

This invention relates to ignition distributors of the sliding contact or brush type for magnetos or the timer distributors of battery ignition systems.

In brush types of distributors it is desirable to use carbon brushes which bear upon a rotating plate. If the carbon is soft the plate necessarily becomes smeared with an annular ring of carbon which forms a conducting path that results in a 1Q short circuit or electrical connection between brushes and thus brings about misring at the spark plugs in some or most of the engine cylinders. If, on the other hand, the brush composition is made hard in order to reduce this carbon 1 5 smearing then the track is scored or cut which results in undue wear of the parts.

It is a primary object of the present invention to obviate the above mentioned difliculties and permit the use of softer carbon brushes than would otherwise be the case, thereby preventing the high rate of cutting of the track upon the rotating disc and at the same time preventing the smear of conducting carbon from accumulating on the surface of the plate to a sufficient extent to short circuit or connect the brushes of the distributor. To this end I provide a means forming a non-cutting scraper to partially or entirely remove the carbon as it is smeared upon the track by the carbon brushes of the distributor connected to the spark plugs. This non-cutting scraper may be in the form of a brush of insulating material placed in a position to Contact the rotating disc and wipe the track where the smear is normally formed. This cleaning operation may also be effected by making alternate brushes of some material other than carbon, such as stainless steel, which forms a good conducting and carbon scraping brush but which does not cut or smear the rotating disc.

In both of the foregoing arrangements the carbon brushes of the distributor connected to the spark plugs can be of softer carbon than would otherwise be the case because even if the brush is so soft that it would ultimately smear the track upon the rotating disc it does no harm in the distributor because the smear is continuously removed and prevented from forming a short circuiting or electrically connecting path on the track. Also the carbon brushes may be of lower grade and therefore less expensive than was formerly the case, and require little or no inspection in assembly for their tendency to smear. Furthermore, the tension of the springs behind 55 the brushes is not so critical, and the metal insert or inserts in the rotating disc of the distributor do not require as smooth a finish as formerly.

The above and other objects and features of the invention will be apparent to` those skilled in the art from a consideration of the following detailed 5 description taken in conjunction with the accompanying drawings, in which:

Fig. lis a section through an electrical distributor constructed in accordance with the invention; Fig. 2 is an inner face view of the distributor 10 plate; Fig. 3 is a plan view of the rotating distributor member thereof; and Fig. 4 is a view similar to Fig. 2 of a modified form of the invention.

Referring to the drawings reference numeral I 15 indicates a distributor cap or plate having a high tension lead 2 embedded therein and which, in the form shown, is adapted to be connected to the high tension terminal of a stationary ignition coil of a magneto by Way of a terminal plug 3 in the 20 upper portion of the distributor cap. The opposite end of the lead 2 is connected to a terminal plug 4, toward the central portion of the cap, in which plug is mounted a brush 5 pressed by a spring 6 into continuous electrical contact with a rotor I mounted on a shaft 8 adjacent the inner edge of the distributor cap I. The rotor I is formed of hard insulating material and, as may be seen in Fig, 3, carries a metallic conducting member 9 embedded therein flush with the surface thereof. This member has a portion I0 positioned toward the center of the rotor 'I forming a central distribution point for the distributor and being adapted for continuous contact with the brush 5, and it also has an outwardly extending portion II. The distributor cap also carries a number of terminal plugsA I2 each of which is adapted for connection to a suitable spark plug lead 20 and each of which contains a brush I3 pressed toward the rotor 1 by a spring I4. The 40 brushes I3 are thus adapted to contact the outwardly extending portion II of the conducting member 9 once during each revolution of the rotor I thus completing the electrical circuit of the spark plugs associated with the particular terminals I2 in a manner Well lmown in the art.

In constructions of the type just described, obviously the brush I3 must be of good conducting material and yet must not be of such a hard composition that it will tend to cut a circular groove in the rotor 1. For this reason such brushes have commonly been formed of soft carbon. However, such soft carbon tends to mark or smear the face of the rotor 1 with a continuous line of lne carbon deposit which during the course of use becomes of sufficient depth and consistency to form an electrically conducting path between the outwardly extending portion II of the conducting member 9 and one or more of the brushes I3. Thus as a brush I3 passes over the conducting portion I I onto the insulating portion of the rotor the circuit is not interrupted but continues from the conducting member through the carbon smear to the brush and thus interferes with the proper ignition in the cylinders of the engine. On the other hand, if soft carbon is not used for the brushes I3 the insulating portion of the rotor 'I becomes scored or cut and since the material of the rotor and the conducting member are of different hardness the scored path is uneven causing one portion thereof to project above another and such projecting portions tend to sheaf oif the tip of the hard brush causing it to wear even more rapidly than if it were soft.

To obviate such difliculties I provide a member for removing the carbon smear substantially as rapidly as it is formed so that the brushes I3 may be of comparatively soft carbon and yet there Will be o conducting smear formed on the face of the rotor. In the form shown in Figs. 1 and 2 this member consists of a brush I5 which is preferably of insulating material, such as bakelized linen, and which is pressed by a spring I5 against the face of the rotor 'I to continuously Wipe the path free from soft carbon deposit. In this form the wiping brush I5 is separate from the electrical system being disposed in the case of a multicylinder engine between two of the electrical conducting brushes I3.

In the form shown in Fig. 4 a similar result is achieved by utilizing one or more of the brushes of the distributor as the wiping member or members. In this form some of the terminal plugs I'I are provided with soft carbon brushes I8. One

or more of the brushes, and preferably alternate brushes I9, are formed of metal, such as stainless steel. In such a construction the metal brush I9 tends to Wipe off the carbon deposited by the preceding carbon brush I8. The soft carbon on the track or gathered by the metal brush tends to lessen the friction thereof upon the track thus preventing this metallic member from cutting or scoring the face of the rotor while at the same time preventing carbon deposit from accumulating upon the surface of the rotor sufficient to form a conducting path thereon.

While I have here described but two embodiments of the invention, other embodiments within the scope of the appended claim will be obvious to those skilled in the art. In the forms Y shown the distributors are of a number of types suitable for use in conjunction with magnetos, but the application of the invention to other forms of distributors and to other types of electrical ignition systems, such as the battery ignition type, Will be obvious from the applications shown.

What is claimed is:

In an electrical distributor, a rotating member of insulating material having a conducting member extending from a central distribution point to a distribution path in registry with a spark plug lead, an' electrical connection continuously in contact with said rotating member, a carbon brush associated with said spark plug lead in continuous engagement with said rotating member for making intermittent electrical contact with said conducting member, and means comprising a stationary non-cutting scraper of insulating material spring-pressed into continuous engagement with the rotatable member and positioned to remove the carbon as it is smeared thereon by the carbon brush.

ROBERT H. GIBSON.

Images