US3025364A - Breaker contact operating mechanism - Google Patents

Description

March 13, 1962 G. CARAMANNA 3,025,364

BREAKER CONTACT OPERATING MECHANISM Filed Nov. 20, 1959 INVEN TOR. George Gamma/m0 c .R. W His A/fomey United States Patent Ofilice 3,025,364 Patented Mar. 13, 1962 3,025,364 BREAKER CONTACT OPERATING MECHANISM George Caramanna, Detroit, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Nov. 20, 1959, Ser. No. 854,397 3 Claims. (Cl. 200-30) This invention relates to distributors for controlling the firing of spark plugs in an internal combustion engine.

In past distributor apparatus, it has been common practice to provide breaker contact mechanism wherein the breaker contacts are opened by an engine driven cam and wherein they are closed by a spring that constantly urges a pivotally mounted breaker lever to a contact closed position. Although this type of apparatus for the most part has been satisfactory, it is vulnerable to highspeed bounce wherein the breaker contacts separate at the Wrong point of time with consequent poor engine timing.

In contrast to the just described breaker contact apparatus, it is an object of this invention to provide a breaker contact mechanism wherein the breaker contacts are both positively opened and closed in synchronism with operation of the engine, thus eliminating breaker contact bounce.

Another object of this invention is to provide a distributor apparatus wherein a breaker lever is provided that has a pair of arms that respectively cooperate with a pair of cam members driven by the engine. In this arrangement, one of the arms and one cam member cause an opening of the breaker contacts while the other arm and cam member cause a closing of the breaker contacts.

Still another object of this invention is to provide a distributor apparatus including a breaker lever having a pair of arms that cooperate with a cam member having axially. spaced cam areas for causing positive opening and closing of the breaker contacts as the cam member is rotatably driven by an engine.

A further object of this invention is to provide a breaker cont-act wherein the breaker arm is formed of metal material having a ductility and shape designed so that it will give to some extent when the contacts close to provide self-adjustment for the breaker contacts.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a plan view with parts broken away illustrating a distributor made in accordance with this invention.

FIGURE 2 is a view taken along line 2-2 of FIG- URE 1.

FIGURE 3 is a View taken along line 33 of FIG URE 1.

FIGURE 4 is a perspective view of a breaker lever made in accordance with this invention.

Referring now to the drawings and more particularly to FIGURE 1, the distributor of this invention includes the usual distributor cap designated by reference numeral having contacts that cooperate with a rotor, not shown. The distributor has a breaker plate 12 which is rotatable and which may be moved by a vacuum advance motor which is not illustrated. A shaft designated by reference numeral 14 is driven by an engine in any conventional fashion and drives a cam member designated in its entirety by reference numeral 16. It is to be understood that the shaft 14 may also drive a suitable centrifugal advance mechanism, not shown, which moves the cam member 16 in relation to the shaft in a manner well-known to those skilled in the art.

The cam member 16 cooperates with a breaker lever designated in its entirety by reference numeral 18 and better illustrated in FIGURE 4 of the drawings. The breaker lever 18 is formed of suitable sheet metal material and has breaker arms 20 and 22. If desired, the lever 18 may be formed as one piece or may be formed as two pieces 20 and 22 which are subsequently joined together. In any event, it is understood that the levers 20 and 22 are rigidly connected so that movement of one of the levers also moves the other.

The lever 18 has a bearing opening which receives a tubular member 24 formed of suitable insulating material which is adapted to be slipped over a post 26 that is supported by the breaker plate 12. It is seen that the arm 20 carries a breaker contact 30 and also carries a rubbing block 32 formed of suitable electrical insulating material. The arm 22 carries another rubbing block 34, the purpose of which is more fully described hereinafter.

The contact 30 carried by breaker lever 18 cooperates with a fixed contact 38 carried by a bracket 36. The bracket 36 is held to breaker plate 12 by a fastener member 40.

The cam member 16 which is driven by the shaft 14 is provided with two separate and distinct 0am areas 44 and 46 which cooperate, respectively, with rubbing blocks 32 and 34. It is seen from the drawings that the cam area 44 is formed as an octagon having flat surfaces forming corners that operate to open the breaker contacts 30 and 38 during rotation of the cam member 16. The cam area 46 is formed with alternate convex and flat areas 48 and 50. In other words, in going around the cam area 46, there will be a convex portion 48 followed by a flat portion 50 and then another convex portion and so on entirely around the cam area.

It is seen from the drawings that the cam area designated by reference numeral 46 cont-acts the rubbing block 34, whereas the cam area 44 contacts the rubbing block 32. It will also be appreciated that the cam areas 44 and 46 are axially spaced as are the rubbing blocks 32 and 34 that cooperate with the cam areas. It is seen that as the cam 16 is rotatably driven by the engine, the cam area 44 in cooperation with rubbing block 32 will cause the breaker points to open. On the other hand, the cam area 46 in cooperation with rubbing block 34 will cause the breaker points to positively close. The cam areas are so designed that the rubbing blocks 32 and 34 are in constant engagement with the cam areas as the cam 16 rotates. Thus, the two cam areas cause the breaker lever 18 to rock around the post 26 in a smooth and positive manner as the cam 16 is rotatably driven.

It can be seen that with the heretofore described distributor apparatus, breaker point bounce is entirely eliminated since the breaker contact 30 is always under positive control of the two cam areas 44 and 46.

In order to provide for self-adjustment of the breaker contacts the arm 18 is formed of metal material which will give slightly when the contacts engage. This metal material may be, for example, a nickel or cadmium plated steel and should take such a form and thickness that it will give or deform slightly when the contacts engage. When the arm is formed as described, the breaker contacts will be self-adjusting both for initial setting and when deposits accumulate on the contacts.

While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In a distributor, the combination comprising, a

relatively rigid breaker lever having a pair of oppositely extending arm members, a breaker contact carried by one of said arm members, a relatively fixed contact adapted to be engaged by the contact carried by said one arm member, a rubbing block carried by each arm member, and a cam member having a pair of axially spaced cam areas cooperating respectively with said rubbing blocks for causing said breaker contacts to be positively opened and closed as said cam rotates, one of said cam areas being formed of alternate convex and flat surfaces.

2. In a distributor, the combination comprising, a breaker lever having a pair of oppositely directed arm members each carrying a rubbing block, a breaker contact carried by one of said arm members and adapted to engage a relatively fixed breaker contact, means pivotally supporting said breaker lever, and a cam member having 0am areas cooperating respectively with said rubbing blocks for causing a positive opening and closing of said breaker contacts, one of said cam areas being formed of adjacent fiat surfaces and the other of said cam areas being formed by alternate convex and flat surfaces.

3. In a distributor, the combination comprising a relatively rigid pivotally mounted breaker lever having a pair of arm members each carrying a rubbing block, said rubbing blocks being axially spaced, a breaker contact carried by one of said arm members for cooperation with a relatively fixed breaker contact, and a cam member having a pair of axially spaced cam areas cooperating respectively with said rubbing blocks for causing a positive opening and closing of said breaker contacts, one of said cam areas being formed of adjacent flat surfaces and the other of said cam areas being formed by alternate convex and flat surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 1,480,546 Cummiskey Jan. 15, 1924 1,497,827 Acker June 17, 1924 1,692,819 Currier Nov. 27, 1928 2,173,828 Doran Sept. 26, 1939 2,306,549 Louis Dec. 29, 1942 2,464,041 Hunsicker Mar. 8, 1949

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