BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description given here below, the appended claims, and the accompanying drawings in which:
FIG. 1 is a front-view of a rotor according to one embodiment of the present invention,
FIG. 2 is a side-view of the rotor of FIG. 1,
FIG. 3 is a cross-sectional view of the rotor of FIG. 2 along line 3-3,
FIG. 4 is an interior view of a hat assembly according to one embodiment of the present invention,
FIG. 5 is a cross-sectional view of the hat assembly of FIG. 4 along line 5-5,
FIG. 6 is side-view of a hat assembly according to one embodiment of the present invention,
FIG. 7 is a cross-sectional view of the hat assembly of FIG. 6 along line 7-7,
FIG. 8 is a rear view of a brake disc assembly according to one embodiment of the present invention,
FIG. 8A is a zoom view of one portion of the brake disc assembly of FIG. 8, and
FIG. 9 is a side-view of the brake disc assembly of FIG. 8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, a rotor portion 10 of a brake disc assembly 100 according to one embodiment of the present invention is disclosed. The rotor 10 includes an opening 12 disposed in its interior. This opening 12 is capable of receiving and securing a hat assembly 50, as described more fully below. The opening 12 includes a plurality of radial recesses 14 extending in an outwardly direction from the center of the rotor 10. These radial recesses 14 include first and second sides or side portions 14a and 14b. In a preferred embodiment, these side portions have the shape of an involute with respect to the curved projections of the hat assembly, as described more fully below. Between each of the radial recesses 14 is a rotor tooth 10t.
FIG. 2 is a side-view of rotor 10. Rotor 10 is comprised of two annular portions 10a and 10b with a plurality of ribs or vanes 10c that connect the two annular portions 10a and 10b, as is well known in the art. While the discussion below is directed to this traditional construction of rotor 10, the invention is not limited to such a construction and encompasses rotors of different configurations, for example, a rotor 10 made of one solid piece of material. The arrangement of the annular portions 10a and 10b and the connecting vanes 10c in rotor 10 of FIG. 2 form a plurality of cooling ducts or passageways 10d. In a preferred embodiment, these passageways 10d are aligned with the radial recesses 14 of the rotor. These passageways 10d allow for circulation of air behind the annular portions 10a and 10b to cool the rotor 10, as is well known in the art. FIG. 3 is a cross-sectional view of rotor 10 along line 3-3 and illustrates more completely the passageways 10d and connecting vanes 10c. In a preferred embodiment, the rotor 10 is composed of carbon-fiber reinforced silicon carbide, although any other suitable material may be used (e.g., cast iron, steel, metal matrix composite, carbon fiber reinforced ceramic, carbon-carbon, titanium and titanium alloys).
The hat assembly 50 of the brake disc assembly 100 according to one embodiment of the present invention is illustrated in FIGS. 4-7. FIG. 4 shows the completed hat assembly 50 with first hat portion 51 nested within second hat portion 52. The hat assembly is preferably constructed of stainless steel, although any other suitable material may be used. The two hat portions 51 and 52 are preferably attached to each other, most preferably by welding their respective bowl-shaped body portions 51b and 52b together when nested and properly aligned, as described more fully below. FIG. 5 is a cross-sectional view of the hat assembly 50 along line 5-5. Each of the first and second hat portions 51 and 52 includes an opening 55 in their center. This hat opening 55 is designed to receive a pilot on the end of an axle or similar member. The hat opening 55 in the first hat portion 51 preferably includes a chamfered edge 55a to assist in the insertion of the pilot axle or similar member through the hat opening 55. Curved projections 51c and 52c, respectively, of the first and second hat portions 51 and 52 extend radially outwardly from the center of the hat assembly 50. These curved projections 51c and 52c are designed to interact with the radial recesses 14 of the rotor 10, as described more fully below.
The hat assembly 50 is further described with respect to FIG. 6. In FIG. 6, the bowl-shaped body 52b of the second hat portion 52 is shown. Preferably, curved projections 52c extend outwardly from the bowl-shaped body 52b in both the axial and radial direction of the second hat portion 52. In a preferred embodiment, these curved projections 52c include curved tabs 56 that provide a more secure attachment of the hat assembly 50 to the rotor 10, as described more fully below. These tabs 56 can take any shape including, but not limited to, the preferred C-shaped cross-section illustrated in FIGS. 5 and 6. Alternatively, the tabs 56 may be straight, angled or even replaced by projections or similar structures. The first hat portion 51 has a similar, but complementary, construction to that of the second hat portion 52.
As illustrated in FIG. 7, which is a cross-sectional view of the hat assembly 50 of FIGS. 4-6, in a preferred embodiment the curved projections 51c and 52c of the hat portions 51 and 52 have a substantially check-mark shaped construction, with one leg of the check mark being aligned with the circumference of the bowl-shaped body 52b and 51b and the other leg extending outwardly therefrom. The exact shape of the curved projections 51c and 52c is unimportant, and other shapes besides the preferred check-mark shape are within the scope of the invention, e.g., U-, V-, or C-shapes. Both hat portions 51 and 52 further comprise bolt openings 58 that allow for the hat assembly 50 to be bolted to an axle or other member.
The complete brake disc assembly 100 is illustrated in FIGS. 8 and 9 and comprises the hat assembly 50 and rotor 10. The brake disc assembly 100 is preferably constructed according to the following method. In a preferred embodiment illustrated, the first hat portion 51 is inserted through the rotor opening 12 by aligning the curved projections 51c with the radial recesses 14 and moving the hat assembly through the rotor opening 12 (in the FIG. 8 illustration, the direction is outwardly from the page). The first hat portion 51 is then rotated with respect to the rotor 10 in the clockwise direction of the illustration, such that the tabs 56 of the first hat portion extend partially over the face of the rotor 10. Then, the second hat portion 52 is inserted in a similar manner to that of the first hat portion 51, such that the bowl-shaped body 52b of the second hat portion 52 envelopes the bowl-shaped body portion 51b of the first hat portion 51 in a nesting configuration. The second hat portion 52 is then rotated in a counter-clockwise direction with respect to the rotor 10 and first hat portion 51. As illustrated in the zoom view of FIG. 8, this method arranges the rotor 10, the first hat portion 51 and second hat portion 52 such that the curved projections 51c of the first hat portion 51 contact the first side portions 14a of the radial recesses 14, the curved projections 52c of the second hat portions 52 contact the second side portions 14b of the radial recesses 14 and the tabs 56 project over the face of the rotor 10. In another embodiment, the first hat portions 51 is engaged with the rotor 10 by insertion in one direction and the second hat portion 52 is inserted in the opposite direction such that the first and second hat portions 51 and 52 are nested. Other assembly methods are within the scope of the invention so long as the first and second hat portions 51 and 52 are nested together and secured to the rotor 10.
In a preferred embodiment, the hat portions 51 and 52 are rotated as described with forces sufficient to pre-load the curved projections 51c and 52c such that contact is maintained between the curved projections and the radial recesses over a wide range of operating conditions. In a preferred embodiment, the curved projections 51c and first side portions 14a, and the curved projections 52c and the second side portions 14b, have the shape of an involute when the hat assembly 50 is in the assembled and preloaded condition. This involute relationship provides for the best complementary mating between the hat assembly 50 and the rotor 10. As the rotor 10 temperature increases, the radial recesses 14 will increase in size due to thermal expansion. By preloading the curved projections 51c and 52c with a sufficient force, the hat assembly 50 may compensate for this size increase and ensure sufficient contact between the hat assembly 50 and rotor 10. In order to maintain the preloaded force, the hat portions 51 and 52 are rotated independently in opposite directions and then securely attached together, preferably by welding as described above.
In the side view of the brake disc assembly 100 in FIG. 9, the bowl-shaped bodies 51b and 52b of the hat assembly 50 extend outwardly from one side of the rotor 10 and the tabs 56 extend from the other side of the rotor 10. In order to prevent the rotor 10 from detaching from the hat assembly 50, the rotor 10 is secured between the top portion 52p of the bowl-shaped body 52c of the second hat portion 52 and the tabs 56, as is most clearly illustrated in the zoom view of FIG. 8. The tabs 56 prevent the rotor 10 from detaching from the hat assembly 50 in one direction (in FIG. 9, the tabs 56 prevent the rotor 10 from moving to the right and detaching from the hat assembly). To prevent the rotor 10 from detaching from the hat assembly 50 in the opposite direction, the rotor 10 is arranged such that the rotor teeth 10t contact the top portion 52p of the bowl-shaped body 52b. In this construction, the rotor 10 is secured from movement in the axial direction of the hat assembly 50 because it is secured between tabs 56 and the top portion 52p of the bowl-shaped body 52b of the second hat portion 52. In this manner, the rotor 10 and hat assembly 50 are fastened together to complete the brake disc assembly 100. In an alternative embodiment, the rotor teeth 10t contact both the top portion 52p of the bowl-shaped body 52b as well as the side of the bowl-shaped body 51b of the first hat portion 51. In yet another alternative embodiment, which is not illustrated, the rotor teeth 10t contact the top portion of the bowl-shaped body 51c (similar to that described above with respect to the top portion 52p of the bowl shaped body 52b) and the rotor 10 is secured from movement in the axial direction of the hat assembly 50 by being secured between tabs 56 and the top portion of the bowl-shaped body 51b of the first hat portion 51.
The foregoing discussion discloses and describes an exemplary embodiment of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the true spirit and fair scope of the invention as defined by the following claims.