US2722584A - Automotive ignition contact points - Google Patents

Description

Nov. 1, 1955 F. SKAY 2,722,584

AUTOMOTIVE IGNITION CONTACT POINTS Filed July 12, 1952 Frank Shay IN V EN TOR.

BY M4 477O4/VEY Patented Nov. 1, 1955 AUTOMOTIVE IGNITION CONTACT POINTS Frank Skay, Detroit, Mich, assiguor to Holley Carburetor Company, Detroit, Mich., a corporation of Michigan Application July 12, 1952, Serial NO. 298,496

3 Claims. (Cl. 200-166) The object of this invention is to prolong the life of the contact points of a pair of ordinary tungsten contact points on the low tension side of an automotive ignition system.

The characteristic failure of such points is caused by the transfer of metal from the plus to the minus side, which produces the well known pyramid effect and thus shortens the life of the pair of contact points. By distributing the build up around a pre-formed crater in the positive contact, I have gained an improved life.

Figure 1 shows the preferred form of my invention.

Figure 2 shows a cross-sectional elevation on plane 22 of Figure 1.

Figure 3 shows an alternative construction.

Figure 4 shows an enlarged cross section elevation corresponding to Figure 2.

Figure 5 shows the transfer of metal with construction shown in Figure 3.

Figure 6 shows the transfer of metal with construction shown in Figure 2.

In the figures:

A is the moving positive tungsten point having a cavity K mounted on an arm E.

B is the stationary negative tungsten point without any cavity mounted on an upright C of a bracket N.

D is the insulated rubbing block which engages with a cam (not shown) and causes the arm E to move and the contacts A and B to open and shut.

F is the spring which forces the rubbing block D into engagement with the cam (not shown). F is also a conductor leading current from electrical connection M. The stationary contact B and the arm C are all integral with the entire bracket N adjustably mounted on plate S.

R and O are two slots in N to permit the bracket N to be adjusted around its insulated pivot Q which locates on the plate S.

The Figures 3 and 4 show a stationary positive contact H with cavity L mounted on bracket C of entire bracket N. i

I is the negative contact mounted on the breaker arm E.

Figure 5 shows the direction of transfer of the metal when the contact H (stationary) is positive.

Figure 6 shows the direction of transfer of the metal when the moving contact A is positive.

Operation 1. The movement of the arm forces air into the cavity, cushioning the impact of the two contacts; and

2. At the same time provides cooling.

3. Tungsten metal transfer from the cavity side prevents any confined central interference such as a high area within a cavity.

4. Pressure created in the center of the contacts when closed reduces arcing when they break.

What I claim is:

1. A pair of positive and negative contacts for an ignition system for an internal combustion engine comprising a stationary contact point and a moving contact point, one point being plus and the other point being minus, a preformed cavity in the positive contact point the cavity being so formed that it traps air in and expels air from the cavity at the moment of making contact and provides a substantial area of contact, the other contact point being flat and both being unperforated.

2. A combination of contacts as set forth in claim 1 in which the positive contact having the cavity is the moving contact of the pair.

3. A combination of contacts as set forth in claim 1 in which the positive contact having the cavity is the stationary contact of the pair.

References Cited in the file of this patent UNITED STATES PATENTS 1,653,823 Pudelko Dec. 27, 1927 2,072,112 King Mar. 2, 1937 2,339,996 Kight Jan. 25, 1944 2,634,341 Rosen Apr. 7, 1953

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