Noise attenuating friction assembly

Abstract

A brake pad assembly including a molded material affixed to a backing plate which has opposing faces, at least one non-circular opening through its thickness, and tab-like extensions or some other structure for locating and supporting the backing plate in a vehicle brake system. The molded material extends over both opposed faces of the backing plate by extrusion through the openings to provide a unitary structure wherein molded material at one side of the backing plate functions as a friction-generating pad material and the molded material at the opposite side functions as a shim-like noise attenuating element. The number, configuration, and placement of the openings through the thickness of the backing plate is varied to alter the noise attenuating properties of the assembly, further reducing the tendency for modal locking of brake components.

1 . A brake friction pad assembly comprising:
 a rigid backing plate having a thickness between opposed first and second faces, and being capable of transmitting vibrations across said opposed faces, said backing plate including a top edge and bottom edge spaced from said top edge, said top and bottom edges extending lengthwise of said backing plate;   said backing plate including a primary extrusion opening extending between said opposed faces and fully bounded on all edges thereof;   a friction-generating pad element made from a molded material and pressed into contact with said first face of said backing plate such that said molded material fills said primary extrusion opening;   said primary extrusion opening having a non-circular shape whereby vibrations traveling across said backing plate are substantially dampened upon encountering said non-circular shape of said primary extrusion opening, said primary extrusion opening including at least one linear edge, said linear edge oriented non-parallel and non-perpendicular to either of said top and bottom edges of said backing plate, and said primary extrusion opening further including at least one convex corner; and   a noise-damping pad element which overlies and contacts a substantial portion of said second face of said backing plate, said noise-damping pad element being joined to said friction-generating pad element by said molded material contained within said primary extrusion opening.   
     
     
         2 . The brake friction pad assembly of  claim 1 , further including a secondary extrusion opening in said backing plate adjacent said primary extrusion opening and filled with said molded material. 
     
     
         3 . The brake friction pad assembly of  claim 2  wherein said secondary extrusion opening has a non-circular shape. 
     
     
         4 . The brake friction pad assembly of claim wherein said primary extrusion opening comprises a first opening having a primary orientation; and said secondary extrusion opening having a secondary orientation different than said primary orientation. 
     
     
         5 . The brake friction pad assembly of  claim 1  wherein said primary extrusion opening defines an elongated slot. 
     
     
         6 . The brake friction pad assembly of  claim 5 , further including a secondary extrusion opening in said backing plate adjacent said primary extrusion opening and filled with said molded material, said secondary extrusion opening defining an elongated slot oriented generally perpendicular to said primary extrusion opening. 
     
     
         7 . The brake friction pad assembly of  claim 5 , further including a secondary extrusion opening in said backing plate adjacent said primary extrusion opening and filled with said molded material, said secondary extrusion opening defining an elongated slot oriented generally parallel to said primary extrusion opening. 
     
     
         8 . The brake friction pad assembly of  claim 1  wherein said first face of said backing plate is generally planar, and second face of said backing plate is generally planar and parallel to said first face. 
     
     
         9 . The brake friction pad assembly of  claim 1  wherein said primary extrusion opening is generally T-shaped. 
     
     
         10 . The brake friction pad assembly of  claim 1  wherein said primary extrusion opening is generally H-shaped. 
     
     
         11 . The brake friction pad assembly of  claim 1  wherein said molded friction-pad element and said molded noise-damping pad element are fabricated from a common, generally homogenous material mixture formulation. 
     
     
         12 . The brake friction pad assembly of  claim 1  wherein said molded friction-pad element is fabricated from a first material mixture formulation, and said molded material contained within said primary extrusion opening and noise-damping pad element are fabricated from a common, generally homogenous second material mixture formulation having more readily flowable extrusion properties than said first material mixture formulation. 
     
     
         13 . The brake friction pad assembly of  claim 2  wherein said second material mixture formulation is a thermal insulator. 
     
     
         14 . The brake friction pad assembly of  claim 2  wherein said second material mixture formulation is a vibration attenuating material. 
     
     
         15 . A brake friction pad assembly comprising:
 a rigid backing plate having a thickness between opposed first and second faces, and being capable of transmitting vibrations across said opposed faces, said backing plate including a top edge and bottom edge spaced from said top edge, said top and bottom edges extending lengthwise of said backing plate;   said backing plate including a primary extrusion opening extending between said opposed faces and fully bounded on all edges thereof;   a friction-generating pad element made from a molded material and pressed into contact with said first face of said backing plate such that said molded material fills said primary extrusion opening;   said primary extrusion opening having a non-circular shape whereby vibrations traveling across said backing plate are substantially dampened upon encountering said non-circular shape of said primary extrusion opening, said primary extrusion opening including at least one linear edge, said linear edge oriented non-parallel and non-perpendicular to either of said top and bottom edges of said backing plate, and said primary extrusion opening further including at least one convex corner; and   wherein said molded friction-pad element is fabricated from a first material mixture formulation and said molded material contained within said primary extrusion opening is fabricated from a second material mixture formulation having more readily flowable extrusion properties than said first material mixture formulation.   
     
     
         16 . The brake friction pad assembly of  claim 1  wherein said backing plate includes at least two spaced mounting features for operative support within a brake caliper system. 
     
     
         17 . The brake friction pad assembly of  claim 1  wherein said non-circular shape of said primary extrusion opening includes at least two concave corners, said concave corners having a radius of curvature. 
     
     
         18 . The brake friction pad assembly of  claim 1  further including at least one circular opening extending between said opposed faces and filled with said molded material. 
     
     
         19 . A brake friction pad assembly comprising:
 a rigid backing plate having a thickness between opposed first and second faces, and being capable of transmitting vibrations across said opposed faces, said backing plate including a top edge and bottom edge spaced from said top edge, said top and bottom edges extending lengthwise of said backing plate;   said backing plate including a primary extrusion opening fully bounded on all edges thereof and extending between said opposed faces;   a friction-generating pad element made from a molded material and pressed into contact with said first face of said backing plate such that said molded material fills said primary extrusion opening;   a noise-damping pad element which overlies and contacts a substantial portion of said second face of said backing plate, said noise-damping pad element being joined to said friction-generating pad element by said molded material contained within said primary extrusion opening;   said primary extrusion opening having a non-circular shape whereby vibrations traveling across said backing plate are substantially dampened upon encountering said non-circular shape of said primary extrusion opening, said primary extrusion opening including at least one linear edge, said linear edge oriented non-parallel and non-perpendicular to either of said top and bottom edges of said backing plate, and said primary extrusion opening further including at least one convex corner; and   a noise-damping pad element which overlies and contacts a substantial portion of said second face of said backing plate, said noise-damping pad element being joined to said friction-generating pad element by said molded material contained within said primary extrusion opening.   
     
     
         20 . The brake friction pad assembly of  claim 19  wherein said molded friction-pad element and said molded noise-damping pad element are fabricated from a common, generally homogenous material mixture formulation. 
     
     
         21 . The brake friction pad assembly of  claim 19  wherein said molded friction-pad element is fabricated from a first material mixture formulation, and said molded material contained within said primary extrusion opening and noise-damping pad element are fabricated from a common, generally homogenous second material mixture formulation having more readily flowable extrusion properties than said first material mixture formulation. 
     
     
         22 . A brake friction pad assembly for a caliper-type vehicular disc brake system comprising:
 a rigid backing plate having a thickness between opposed first and second faces, and being capable of transmitting vibrations along its length, said backing plate including a top edge and bottom edge spaced from said top edge, said top and bottom edges extending lengthwise of said backing plate;   said backing plate including at least two lengthwise spaced mounting features for operative support within a brake caliper;   said backing plate including a primary extrusion opening extending between said opposed faces and positioned between said spaced mounting features and fully bounded on all edges thereof;   a friction-generating pad element made from a molded material and pressed into contact with said first face of said backing plate such that said molded material fills said primary extrusion opening; and   said primary extrusion opening having a non-circular shape whereby vibrations traveling from one of said mounting features to the other of said mounting features along the length of said backing plate are substantially dampened upon encountering said non-circular shape of said primary extrusion opening, said primary extrusion opening including at least one linear edge, said linear edge oriented non-parallel and non-perpendicular to either of said top and bottom edges of said backing plate, and said primary extrusion opening further including at least one convex corner, wherein   said molded friction-pad element is fabricated from a first material mixture formulation and said molded material contained within said primary extrusion opening is fabricated from a second material mixture formulation having more readily flowable extrusion properties than said first material mixture formulation.   
     
     
         23 . The brake friction pad assembly of  claim 22  wherein said spaced mounting features comprise lug-shaped ears extending in opposite length wise directions from said backing plate. 
     
     
         24 . A method of dampening vibrations traveling lengthwise through a brake friction pad assembly for a caliper-type vehicular disc brake system comprising the steps of:
 forming a rigid backing plate with a primary extrusion opening extending therethrough and at least two lengthwise spaced mounting features on opposing sides of the primary extrusion opening;   pressing a molded material onto a first face of the backing plate to form a friction-generating pad element and simultaneously filling the primary extrusion opening with the molded material;   generating vibrations in the backing plate between the spaced mounting features;   and forcing the vibrations to travel in a non-arcuate path around the periphery of the primary extrusion opening to thereby dampen the vibrations within the friction pad assembly.   
     
     
         25 . A method as set forth in  claim 24 , further including the step of supporting the backing plate within a brake caliper upon the mounting features. 
     
     
         26 . A method as set forth in  claim 24 , further including the step of forming a secondary extrusion opening in the backing plate adjacent the primary extrusion opening and filling the second extrusion opening with the molded material simultaneously with said filling of the primary extrusion opening. 
     
     
         27 . A method as set forth in  claim 26 , wherein said steps of forming the primary and secondary extrusion openings including the step of forming non-circular peripheral edges for each of the extrusion openings. 
     
     
         28 . A method as set forth in  claim 24 , wherein said step of forming the backing plate includes the step of creating a top edge and bottom edge spaced from said top edge, the top and bottom edges extending lengthwise of said backing plate, and said step of forming the primary extrusion opening includes creating at least one linear peripheral edge oriented non-parallel to either of the top and bottom edges of the backing plate. 
     
     
         29 . A method as set forth in  claim 24 , further including the step of forming a noise-damping pad element with the molded material over a substantial portion of a second face of the backing plate simultaneously with said steps of pressing the friction-generating pad element and filling the primary extrusion opening. 
     
     
         30 . A method as set forth in  claim 29 , wherein said step of pressing the friction-generating pad element includes the step of pressing a first material mixture formulation, and said step of forming the noise-damping pad element includes the step of extruding a second material mixture formulation having more readily flowable extrusion properties than the first material mixture formulation through the primary extrusion opening.