Patent Application
20140102838
The present invention relates to drum brakes for vehicles, and in particular to a brake drum having turbo-style vanes configured to reduce mechanical and/or thermal stresses on the drum.
Drum brakes operate on the principles of converting kinetic energy into heat by creating friction when a set of brake shoes or pads press against an inner surface of a rotating brake drum. However, a common problem with such drum brakes is that uneven mechanical and thermal stresses and uneven cooling tends to cause premature drum cracking (heat cracks) and elevated brake temperatures tend to reduce lining life on brake shoes.
With respect to temperature, it is known that the larger the temperature gradient over a short space, the higher the resulting tension in the material. To combat this, some drums have incorporated narrow cooling fins along the outside of the drum to mitigate this effect, although this has been met with only modest results.
With respect to the mechanical stresses, excess stress is caused when the drum begins to exhibit what is called ‘bell mouthing,’ which occurs when the open end of the drum experiences a greater degree of expansion than does the hub end of the drum. Such uneven drum expansion places a tremendous amount of mechanical stress on the drum, which again tends to cause cracking and a general reduction of useful life.
Therefore, what is needed is a drum design which alleviates the aforementioned mechanical and thermal stresses that are experienced by the drum of a drum brake.
Disclosed and claimed herein is a drum brake assembly, a drum for a brake assembly and a method of operating the same. In one embodiment, the drum includes an annular drum wall having an open end and an attachment end. The drum wall further includes an outer drum surface and an inner braking surface, each of which extends between the open end and the attachment end. The drum includes a hub attachment section that is attachable to an associated wheel hub. Finally, the drum has a drum wall connection section extending between the attachment end of the drum wall and the hub attachment section, where the drum wall connection section comprises a plurality of radially angled vanes interspersed with a corresponding plurality of air openings.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein:
As described in more detail below, the present disclosure relates generally to a drum brake assembly and a drum having an annular drum wall with an open end and an attachment end. More particularly, the present disclosure relates to a turbo-style drum having a drum wall connection section extending between the attachment end of the drum wall and a hub attachment section, where the drum wall connection section has a plurality of radially angled vanes interspersed with a corresponding plurality of air openings. Additional details of the preferred embodiments are set forth below with reference to the figures.
As used herein, the terms “a” or “an” shall mean one or more than one. The term “plurality” shall mean two or more than two. The term “another” is defined as a second or more. The terms “including” and/or “having” are open ended (e.g., comprising). The term “or” as used herein is to be interpreted as inclusive or meaning any one or any combination. Therefore, A, B or C means any of the following: A; B; C; A and B; A and C; B and C; A, B and C. An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive. Reference throughout this document to “one embodiment”, “certain embodiments”, “an embodiment” or similar term means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of such phrases in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner on one or more embodiments without limitation.
Referring now to
The drum of
In order to reduce the aforementioned mechanical stresses and ‘bell mouthing’ effect, the drum wall connection section 140 is further configured with a plurality of radially angled vanes 145 interspersed with a corresponding plurality of air openings 150. It should be appreciated that the radially angled vanes 145 may be curved in a radially concave or a radially convex manner.
In certain embodiments, the plurality of radially angled vanes 145 are oriented at an angle of between 20 degrees and 50 degrees as measured from an edge of the drum wall (i.e., attachment end 125) from which the plurality of radially angled vanes 145 extend. In certain embodiments, the particular angle may be selected based, at least in part, on the type of material used and/or the amount of desired cooling. In this fashion, the plurality of radially angled vanes 145 facilitate a radial expansion of the attachment end 125 of the drum wall 105 during operational rotation of the drum 100. This radial expansion thereby serves to minimize a difference between a radial expansion of the attachment end 125 of the drum wall 105 and a radial expansion of the open end 120 of the drum wall 105, thereby reducing or eliminating the undesired ‘bell mouthing’ effect.
While it should be appreciated that the plurality of radially angled vanes 145 may comprises at least two, in certain embodiment it may be preferable to have between 3 and 30 individual values encircling the hub attachment section 130, as shown in
It should further be appreciated that the plurality of radially angled vanes 145 may preferably be curved such that their respective lengths are greater than a radial width of the drum wall connection section 140, thereby enabling additional expansion capacity during operational rotation of the drum 100 without creating large stresses due to differential in temperature from the hub mounting interface (e.g., hub attachment section 130) and high frictional areas (e.g., inner braking surface 115). As a result, the design of drum 100 tends to provide a longer drum life and lining life, as well as provide a lighter weight drum.
Additionally, the air openings 150 serve to facilitate air flow along the inner braking surface 115 of the drum 100, thereby providing a desirable cooling effect as well. As described in more detail below with reference to
Continuing to refer to
The drum of
Referring now to
Also depicted in
The above-mentioned squealer band 155 circumferentially positioned around the outer surface of the drum 100 is also depicted in
Referring now to
While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.
