Abstract
The invention concerns a brake drum for a drum brake of a motor vehicle, the brake drum having: a ring section extending concentrically about a rotation axis; and a circular wall section extending at an angle to the rotation axis; wherein in the brake drum has at least one portion that deviates from at least one of: a) a rotation symmetric configuration of the brake drum with respect to the rotation axis; b) a material comprised by at least one other portion of the brake drum.
Claims
1. A brake drum for a drum brake of a motor vehicle, the brake drum having: a ring section extending concentrically about a rotation axis; and a circular wall section extending at an angle to the rotation axis; wherein in the brake drum has at least one portion that deviates from at least one of: a) a rotation symmetric configuration of the brake drum with respect to the rotation axis; b) a material comprised by at least one other portion of the brake drum.
2. The brake drum according to claim 1, according to the option a), wherein the at least one portion is comprised by one of the ring section and the wall section, wherein the respective other one of the ring section and wall section is rotation symmetric.
3. The brake drum according claim 1, according to the option a) wherein both of the ring section and the wall section each have a portion according to option a), said portions being different from one another in terms of at least one dimension and/or in terms of their circumferential position.
4. The brake drum according to claim 1, according to the option a), wherein, by way of the rotation asymmetry, a difference in eigenfrequencies is defined and/or is increased between the ring section and wall section.
5. The brake drum according to claim 1, according to the option a), wherein the deviation from the rotation symmetry is defined by at least one local structural deviation, in particular a recess, a cavity, an added mass or a change in material strength.
6. The brake drum according to claim 5, wherein at least three local structural deviations are provided that are non-uniformly distributed in a circumferential direction.
7. The brake drum according to claim 5, wherein the deviation from the rotation symmetry is defined by a plurality of local structural deviations, the local structural deviations being different from one another.
8. The brake drum according to claim 1, according to the option b), wherein the portion comprises one of the wall section or ring section.
9. The brake drum according to claim 1, according to the option b), wherein the portion comprises at least one layer attached to at least one of the wall section or ring section.
10. The brake drum according to claim 9, wherein the layer comprises at least one cavity.
11. Method for producing brake drum for a drum brake of a motor vehicle, the brake drum having: a ring section extending concentrically about a rotation axis; and a circular wall section extending at an angle to the rotation axis; wherein in the method includes producing at least one portion of the brake drum that deviates from at least one of: a) a rotation symmetric configuration of the brake drum with respect to the rotation axis; b) a material comprised by at least one other portion of the brake drum.
12. Method according to claim 11, including: producing the at least one portion by an additive manufacturing technology.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0045] Embodiments of the invention are discussed below with respect to the attached schematic figures. Throughout the figures, same features may be marked with same reference signs.
[0046] FIGS. 1-2 show a cross-sectional view (1) and front view (2) of a brake drum according to a first embodiment of the invention.
[0047] FIGS. 3-4 show a cross-sectional view (3) and front view (4) of a brake drum according to a second embodiment of the invention.
[0048] FIGS. 5-6 show a cross-sectional view (5) and front view (6) of a brake drum according to a third embodiment of the invention.
[0049] FIGS. 7-8 show a cross-sectional view (7) and front view (8) of a brake drum according to a fourth embodiment of the invention.
[0050] FIGS. 9-10 show a cross-sectional view (9) and front view (10) of a brake drum according to a fifth embodiment of the invention.
[0051] FIGS. 11-12 show a cross-sectional view (11) and front view (12) of a brake drum according to a sixth embodiment of the invention.
[0052] FIGS. 13-14 show a cross-sectional view (13) and front view (14) of a brake drum according to a seventh embodiment of the invention.
[0053] FIGS. 15-16 show a cross-sectional view (15) and front view (16) of a brake drum according to a eighth embodiment of the invention.
[0054] FIGS. 17-18 show a cross-sectional view (17) and front view (18) of a brake drum according to a ninth embodiment of the invention.
[0055] FIGS. 19-20 show a cross-sectional view (19) and front view (20) of a brake drum according to a tenth embodiment of the invention.
[0056] FIGS. 21-22 show a cross-sectional view (21) and front view (222) of a brake drum according to a eleventh embodiment of the invention.
[0057] FIGS. 23-24 show a cross-sectional view (23) and front view (24) of a brake drum according to a twelfth embodiment of the invention.
DETAILED DESCRIPTION
[0058] FIGS. 1 and 2 show a brake drum 10 according to a first embodiment of the invention. The brake drum 10 is configured to rotate about a rotation axis R. FIG. 1 a is a cross-sectional view of the brake drum 10 with the cross sectional plane including the rotation axis R. FIG. 2 is a front view of the brake drum 10 with the rotation axis R extending orthogonally to the image plane. The brake drum 10 is configured as a one-piece member having an homogeneous material structure.
[0059] The brake drum 10 comprises a circular wall section 12 that is a plate shaped an extends at an angle to the rotation axis R. For example, the wall section 12 extends at an angle of more than 60° or more than 80° to the rotation axis R and may substantially extend orthogonally to the rotation axis R.
[0060] At its geometric centre that is intersected by the rotation axis R, the wall section 12 comprises a connection portion 14 for connecting to an axle component. As an optional feature, the connection portion 14 comprises a number of off-centre through holes 18 for receiving mechanical fixing elements, such as bolts, for being secured to the axle component and/or to a vehicle wheel.
[0061] The brake drum 10 also comprises a ring section 20. The ring section is configured as a section of a cylinder mantle surface that is concentrically positioned with respect to and extends about the rotation axis R. The wall section 12 merges with the ring section 20 and extends at an angle thereto. Said angle may e.g. amount to at least 60° or more than 80° and/or the wall section 12 may substantially extend orthogonally relative to the ring section 20. The ring section 20 extends substantially axially.
[0062] At its inner circumferential face 22, the ring section 20 has an e.g. metallic contact surface for being contacted by a non-illustrated brake shoe to generate a braking effect. In a generally known manner, the brake shoe may be configured to carry a ring-shaped and non-illustrated friction lining that comprises a friction material.
[0063] The brake drum 10 comprises recesses 24 positioned in the ring section and extending axially inward from an axial end face 16 of the ring section 20. The recesses 24 each form a structural deviation from respectively adjacent or surrounding areas of the ring section 20 which are free of recesses (i.e. are massive).
[0064] As shown in FIGS. 1-2, the brake drum 10 is generally rotation symmetric with respect to the rotation axis R. This, however, does not apply to the recesses 24. Each of them thus forms a rotation asymmetric portion of the brake drum 10 that contributes to the overall rotationally non-symmetric design of the brake drum 10. Alternatively, the recesses 24 may be regarded jointly form a respective rotation asymmetric portion or pattern.
[0065] In more detail, the angular distances between the recesses 24 are nonuniform. For example, between the upper recesses 24 in FIG. 2, the angular distance is approximately 90°, wherein between the lower recess 24 and each of the upper recesses 24, the angular distance is about 135°.
[0066] Therefore, the brake drum 20 can only resemble or restore its shape and/or orientation of FIG. 2 if rotated by a full turn of the 360°. Any partial return of less than 360° results in the recesses 24 being distributed differently from and thus not reproducing the configuration in FIG. 2.
[0067] The recesses 24 are produced by an additive manufacturing technology. Yet, they could also be produced by metal casting or by a machining operation.
[0068] In the embodiment of FIGS. 1-2, the recesses 24 are only provided in the ring section 20. Therefore, only said ring section 20 is marked by a rotation asymmetry, whereas the wall portion 12 is rotation symmetric. As a result, the eigenfrequencies of the ring section 20 and of the wall portion 12 are reliably kept apart.
[0069] FIGS. 3-4 show an alternative embodiment in which the rotation asymmetry of the ring section 20 is achieved by positioning additional masses 26 at the ring section 20. These additional masses 26 form radial projections or radial protrusions of the brake drum 10.
[0070] Again, the additional masses 26 are distributed at irregular angular distances from one another. The uppermost and left additional mass 26 have an angular distance of 90° to one another and about 135° to the right additional mass 26. The additional masses 26 thus each form a rotation asymmetric portion 25 of the brake drum 10. As an exemplary option, the additional masses 26 are located at an outer circumferential face of the ring section 20. They may be joined thereto or integrally formed with the brake drum 10, in particular by an additive manufacturing technology.
[0071] In FIGS. 5-6, the ring section 20 is rotation symmetric, but the wall section 12 is not. Specifically, the wall section 20 comprises a number of cavities 13 which, again, are nonuniformly spaced apart from one another in a circumferential direction. Accordingly, they each form a rotation asymmetric portion 25 of the brake drum 10.
[0072] In FIGS. 7-8, the ring section 20 is rotation symmetric, but the wall section 12 is not due to comprising additional masses 26 at a rear face of the wall section 12. As shown in FIG. 8, the at least three additional masses 26 are irregularly spaced apart from one another by 90° and 180°. Accordingly, they each form a rotation asymmetric portion 25 of the brake drum 10.
[0073] Generally, any of the depicted embodiments may be combined with one another. FIGS. 9-10 show an embodiment in which a configuration similar to FIGS. 7-8, FIGS. 1-2 and FIGS. 3-4 are combined. Accordingly, non-regularly distributed additional masses 26 at the wall section 12 are combined with a single additional masses 26 (or alternatively a non-regularly distributed plurality) at the ring section 20. Also, a single recess 24 (or alternatively a non-regularly distributed plurality) is provided at the ring section 20.
[0074] FIGS. 9-10 show an embodiment comprising a different combination of rotation asymmetric portions 25. Specifically, a number of non-uniformly shaped and distributed recesses 24 is provided at the ring section 20. Also, a single additional mass 26 (or alternatively a non-regularly distributed plurality) is provided at the ring section 20. Further, the wall section 12 comprises a number of irregularly distributed and/or irregularly sized cavities 30.
[0075] The embodiment of FIGS. 13-14 and FIGS. 15-16 (which may also be combined with one another or with any other embodiment disclosed herein) comprises portions 25 defining a rotational asymmetry by way of a varying material strength (or differently put a varying material thickness or wall thickness).
[0076] In case of FIGS. 13-14, the ring section 20 has a first reduced material strength t0 and a second enlarged material strength t1. These define a rotation asymmetry due to the ring section 20 thus having a respectively varying material strength along its circumferential direction, see FIG. 14. The wall section 12 has a continuous or at least not rotation asymmetrically distributed material strength. According to the illustration FIG. 14, the variation can be continuous, but does not have to be continuous. It could also be stepwise. For example, the upper and lower portions having the different strengths t1, t0 could be connected by a circumferential portion having a constant material strength.
[0077] In FIGS. 15-16, the variation of material strengths is provided in the wall section 12. Again, this variation may occur continuously in a circumferential direction or in a stepwise manner. The ring section 20 has a continuous or at least a not rotation asymmetrically distributed material strength.
[0078] FIGS. 17-18, 19-20, 21-22, 23-24 each show brake drum designs having deviations with respect to material. Specifically, each of these embodiments comprises at least one portion 33 whose material differs from a material of at least one other portion of the brake drum 10 (e.g. a main portion in terms of weight or volume). In a particular, the material of said portion 33 may differ from the material of both of the wall section 12 and ring section 20. The embodiments of FIGS. 17-18, 19-20, 21-22, 23-24 may be combined with any of the previous embodiments or with one another.
[0079] In FIGS. 17-18, 19-20, 21-22, the material of deviation is provided by attaching a vibration dampening and noise absorbing layer 32 that is in particular made of a flexible and/or more elastic material compared to the wall section 12 and ring section 20. For example, the noise absorbing layer 32 may comprise a flexible foam material, whereas the remainder of the brake drum 10 comprises a metallic material. As an additional optional feature, said flexible layer 32 comprises cavities 30. These may be angularly distributed regularly or irregularly, the latter case thus defining a rotation asymmetric portion 25 as discussed above.
[0080] In FIGS. 17-18, the layer 32 is ring-shaped and attached to an outer circumferential face of the ring section 20. In FIG. 18 a circumferential position of selected cavities 32 is indicated.
[0081] In FIGS. 19-20, the layer 32 is plate-shaped and attached to a rear face of the wall section 12. At its geometric centre portion, the layer 32 optionally receives the connection portion 14. As a mere example, the layer 32 comprises cavities 30, an arrangement thereof being indicated in FIG. 2.
[0082] In FIGS. 21-22, the embodiments of FIGS. 17-18 and FIGS. 21-22 are combined.
[0083] In FIGS. 23-24, the material deviation includes that the wall section 12 and the ring section 12 are configured of a different material and joined along a joining face 41.
