US 3307423 A
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March 7, 1967 F. DANS! 3,307,423
- FLY-WHEEL MAGNETO WITH HUB INCORPORATED THEREWITH DU (2 CASTING Filed Marc 0, 1965 INVENTOR Franco Jammy NW n/ ATTORNEY;
United States Patent 3,307,423 FLY-WHEEL MAGNETO WITH HUB INCORPO- RATED THEREWITH DURING CASTING Franco Dansi, Varese, Italy, assignor to Ofiicine Dansi S.p.A., Varese, Italy, a company of Italy Filed Mar. 10, 1965, Ser. No. 438,615 Claims priority, application Italy, Mar. 16, 1964, 5,659/ 64 I 6 Claims. (Cl. 74572) The possibility is known of incorporating with casting, in the body of alloys of aluminium, of zinc, of magnesium, of copper, of silicon etc. pieces of steel, to which is entrusted, owing to their high mechanical strength, the task of connecting them with other mechanical members, by imparting thereto (or receiving therefrom) a movement of any kind.
There is further known the application of that principle also to the rotors of fly-wheel ignition magnetos, which owing to their weight (since they have to act as a fly-wheel mass for the engine) and owing to the mechanical stresses relative to use (inertial forces due to accelerations and decelerations, torsional vibrations, vibrations by upward jerks, etc.), have particular needs of a 'very sturdy connection between the point at which the movement is taken over and said fly-wheel mass; said connecting member is constituted just by a hub partly embedded by means of casting.
That procedure was adopted with various modalities which however have given rise to inconveniences mainly owing to the complex shape of the inserts against which the alloy of the casting, not having been able to cool uniformly, has imprisoned strong internal stresses, which sometimes are higher than the very resistance against compression and against shear of the material; that would cause also shrinking in solidification in a direction different from that to be expected on a cursory examination.
The present invention obviates said inconveniences by suitably shaping the part of the hub that comes to contact the molten part in casting. The shape of that part comprises two regular prisms equal and coaxial to each other, which are displaced angularly with respect to each other by an angle equal to the half of the angle over one side; in that way the isothermal lines during the cooling process are very similar to circles and the cooling is almost uniform and warrants the absence of dangerous internal stresses and a substantially uniform shrinking.
In the accompanying drawing there are illustrated two embodiments of the hub for connection with a fly-wheel magneto. In that drawing:
FIG. 1 is the front view of a hub;
FIG. 2 is an axial section of the hub of FIG. 1 incorporated with the body of a flywheel magneto;
FIG. 3 is the front view of a different embodiment of the hub and V FIG. 4 is a section taken along the line IVIV of the hub illustrated in FIGURE 3.
The hub illustrated in FIGURES l and 2 comprises a cylindrical portion a, a first prismatic portion a, a second prismatic portion 1) and an annular portion c projecting between said prismatic portions. The prisms that confine the two portions 1) and c are octagonal and displaced with respect to each other by an angle equal to and they have strongly rounded edges. In the variant illustrated in FIGURES 3 and 4 there are indicated by the same reference letters already used with FIGURES 1 and 2 the same parts of the hub. As can be seen in said figures, the hub represented therein is without the annular portion present in the embodiment of FIGURES 1 and 2.
In both embodiments the mass of the hub is distributed in a nearly uniform way around the axis of the very hub. When the mass of the fly-wheel magneto diagrammatically illustrated in FIG. 2 where it is indicated by the reference letter e, has been cast over the prismatic parts of the hub (see in particular FIG. 2), the hub results to beafter the solidification of the mass of the fiy-wheel magnetoembedded in the very mass of the fly-wheel magneto, and the surfaces of the prismatic parts oppose a relative rotation between the hub and the fly-wheel magneto, while slipping out between said hub and fly-wheel is prevented, in the case of FIGURES 1 and 2, by the annular part c in particular and, in the case of FIGURES 3 and 4, by the parts of the bases of each one of the two prisms that project radially from the other prism.
1. A rotary device, in particular an ignition fiy-wheel magneto for internal combustion engines, comprising a metallic mass and a hub embedded in said mass by casting thereof, characterized in that the hub has its external surface shaped as two regular prisms equal and coaxial to each other angularly displaced by an angle substantially equal to the half of the angle over one side of the prism.
2. A rotary device according to claim 1, characterized in that the edges of said prisms are joined with one another.
3. A device according to claim 1, characterized in that said hub has an annular projection between said two prism-shaped surfaces.
4. A device according to claim 2, characterized in that said hub has an annular projection between said two prism-shaped surfaces.
5. A rotary device, in particular an ignition fly-Wheel magneto for internal combustion engines, comprising a metallic mass and a hub embedded in said mass by casting thereof, characterized in that the hub has its external surface shaped to include at least two outwardly facing regular prismatic surfaces each composed of fiat surfaces adjacent ones of which are connected through a well rounded juncture, the junctures of the flat surfaces in each said prismatic surface being angularly displaced with relation to the junctures of the flat surfaces of the adjacent prismatic surface.
6. A hub for inclusion through casting in a rotary body such as a fly-Wheel, said hub being shaped to include at least two outwardly facing regular prismatic surfaces each composed of flat surfaces adjacent ones of which are connected through a well rounded juncture, the junctures of the flat surfaces in each said prismatic surface being angularly displaced with relation to the junctures of the fiat surfaces of the adjacent prismatic surface.
References Cited by the Examiner UNITED STATES PATENTS 1,065,733 6/ 1913 Schuppener 22-204 1,601,076 9/1926 Kleckner l23l49 2,607,969 8/1952 Evans et al. 22-203 2,885,873 5/1959 Beeston 19284 FRED C. MATTERN, JR., Primary Examiner.
W. S. RATLIFF, JR., Assistant Examiner.