# US 10,767,720 B2 · Method for leaf springs made of fiber-reinforced plastic with integrated eye bushings, and leaf spring made of fiber-reinforced plastic > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,767,720 B2 - Document ID: US10767720B2 - Status: Granted - Kind: B2 - Application number: 16/164,157 - Filed: 2018-10-18 - Published: 2019-04-18 - Granted: 2020-09-08 - Earliest claimed: 2017-10-18 - Assignees: Ford Global Technologies, LLC - Applicants: Ford Global Technologies, LLC - Inventors: Friedrich Peter Wolf-Monheim - Web page: https://patentgrep.com/patent/US10767720B2 ## CPC - F16F 1/3686: {End mountings} - B29C 70/205: {the structure being shaped to form a three-dimensional configuration} - B29C 70/86: Incorporated in coherent impregnated reinforcing layers, {e.g. by winding} - B32B 3/04: characterised by {at least one} layer folded at the edge, e.g. over another layer {; characterised by at least one layer enveloping or enclosing a material} - B32B 5/028: {Net structure, e.g. spaced apart filaments bonded at the crossing points} - B32B 5/12: characterised by the relative arrangement of fibres or filaments of {different layers, e.g. the fibres or filaments being parallel or perpendicular to each other} - B32B 5/26: another layer {next to it} also being fibrous or filamentary {(relative arrangement of fibres or filaments of different layers B32B5/12)} - B32B 15/06: of {natural rubber or synthetic} rubber - B32B 15/14: next to a fibrous or filamentary layer - B29L 2031/774: {Springs} - B32B 2260/021: Fibrous or filamentary layer - B32B 2260/046: Synthetic resin - B32B 2262/02: Synthetic macromolecular fibres - B32B 2605/00: Vehicles - F16F 2224/0241: Fibre-reinforced plastics [FRP] - F16F 2226/04: Assembly or fixing methods; methods to form or fashion parts - F16F 2238/022: leaf-like, e.g. of thin, planar-like metal - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES ## Abstract A fiber-reinforced plastic leaf spring and a method for producing the fiber-reinforced plastic leaf spring are provided, which is suitable in particular for use in a motor vehicle. It has an elongate leaf spring main body which comprises a first eye bushing at a first end and a second eye bushing at a second end. The leaf spring main body and the first and second eye bushings are formed using at least a first layer and a second layer of a composite material. Each of the layers is guided along a centerline of the leaf spring main body to form the leaf spring main body and, to form the first and second eye bushings, is respectively wrapped around a bushing element having a first center axis and around a bushing element having a second center axis. ## Claims ### Claim 1 A method for producing a fiber-reinforced leaf spring for use in a motor vehicle, the method comprising: forming an elongate leaf spring main body with a first eye bushing at a first end and a second eye bushing at a second end using at least a first layer and a second layer of a plastic and/or composite material; guiding each of the layers along a centerline of the leaf spring main body to form the leaf spring main body and to form the first and second eye bushings; wrapping the first layer around a first bushing element having a first center axis in a first circumferential direction and around a second bushing element having a second center axis in the same, first circumferential direction such that a first end region of the first layer terminates adjacent to the first bushing, a second end region of the first layer terminates adjacent to the second bushing and is spaced apart from the first end region of the first layer, and a central region of the first layer between the first and second end regions is guided along only a first side of a curved spring centerline; and wrapping the second layer in a second circumferential direction, counter to the first circumferential direction, around the first bushing element and in the same, second circumferential direction around the second bushing element such that a first end region of the second layer terminates adjacent to the first bushing, a second end region of the second layer terminates adjacent to the second bushing and is spaced apart from the first end region of the second layer, and a central region of the second layer between the first and second end regions is guided along only a second side of the curved spring centerline, the second side of the spring centerline opposite to the first side of the spring centerline. ### Claim 2 (depends on 1) The method of claim 1 further comprising: wrapping a third layer in the first circumferential direction around the first bushing element and, in the same, first circumferential direction, around the second bushing element. ### Claim 3 (depends on 2) The method of claim 2, wherein each of the first, second, and third layers is in one piece. ### Claim 4 (depends on 2) The method of claim 2, wherein the first, second, and third layers are arranged one on top of another at least in a region adjacent to the first and second eye bushing, wherein each of the layers completely surrounds the respective underlying layer, at least in the region adjacent to the first and second eye bushing. ### Claim 5 (depends on 2) The method of claim 2, wherein the centerline forms a curve and the first and third layers are arranged on a first side of the centerline with a first radius of curvature, and the second layer is arranged on a second side of the centerline having a second radius of curvature, the second radius of curvature being greater than the first radius of curvature. ### Claim 6 (depends on 1) The method of claim 1 further comprising wrapping a plurality of additional layers around the first and second bushing elements, wherein the plurality of additional layers are wrapped in alternating first and second circumferential directions around the first and the second bushing element. ### Claim 7 (depends on 6) The method of claim 6, wherein the first layer, the second layer and the plurality of additional layers total an odd number of layers. ### Claim 8 (depends on 1) The method of claim 1, wherein the first layer is wrapped prior to the second layer being wrapped. ### Claim 9 (depends on 1) The method of claim 1, wherein each of the first and second layers are guided only in one ply along the centerline. ### Claim 10 (depends on 1) The method of claim 1, wherein the first and/or the second bushing element has an outer metal sleeve, an inner metal sleeve, and a rubber-like insert positioned therebetween. ### Claim 11 (depends on 1) The method of claim 1, wherein the composite material further comprises prepreg. ### Claim 12 (depends on 1) A fiber-reinforced leaf spring for use in a motor vehicle, the leaf spring comprising: first and second bushing elements; and an elongate leaf spring main body formed by the method of claim 1, the main body with first and second eye bushings extending around the first and second bushing elements, respectively. ### Claim 13 (depends on 1) The method of claim 1, wherein the first layer is wrapped in the first circumferential direction such that the first layer does not cross the curved spring centerline between the first and second bushings; and wherein the second layer is wrapped in the second circumferential direction such that the second layer does not cross the curved spring centerline between the first and second bushings. ### Claim 14 A leaf spring comprising: a first bushing and a second bushing; a first fiber-reinforced composite layer having a central region extending between opposite first and second end regions; and a second second fiber-reinforced composite layer layer having a central region extending between opposite first and second end regions; wherein the first and second end regions of each layer are wrapped about first and second bushings, respectively, such that the first end region of each layer terminates adjacent to the first bushing, and the second end region of the each layer terminates adjacent to the second bushing; wherein each end region of the first layer is positioned between an associated bushing and an associated end region of the second layer; wherein the central region of the first layer extends along only a first side of a curved spring centerline; and wherein the central region of the second layer extends along only a second side of the curved spring centerline. ### Claim 15 (depends on 14) The leaf spring of claim 14, wherein each end region of the first layer terminates on the second side of the spring centerline adjacent to an associated bushing; and wherein each end region of the second layer terminates on the first side of the spring centerline adjacent to an associated bushing. ### Claim 16 (depends on 15) The leaf spring of claim 15, wherein the central regions of each of the first and second layers extend as a single ply between the first and second bushings. ### Claim 17 (depends on 16) The leaf spring of claim 16 further comprising a third fiber-reinforced layer having a central region extending between opposite end regions wrapped about the first and second bushings, respectively, the central region of the third layer extending along only the first side of the spring centerline and in contact with the central region of the first layer; wherein each end region of the second layer is positioned between an associated end region of the first layer and an associated end region of the third layer. ### Claim 18 (depends on 17) The leaf spring of claim 17 further comprising first and second bushings, each bushing having a metal outer wall and a metal inner wall, wherein the leaf spring has a constant wall thickness at the bushings and along the centerline of the spring. ### Claim 19 A fiber-reinforced leaf spring for use in a motor vehicle, the leaf spring comprising: a first bushing element having a first center axis; a second bushing element having a second center axis; and an elongate leaf spring main body with a first eye bushing at a first end and a second eye bushing at a second end, wherein the leaf spring main body and the first and second eye bushings are formed using at least a first layer and a second layer of a plastic and/or composite material, wherein each of the layers runs along a centerline of the leaf spring main body to form the leaf spring main body and, to form the first and second eye bushings, is respectively wrapped around the first bushing element and around the second bushing element; wherein each of the layers runs in only one ply along the centerline; wherein the first layer is wrapped in a first circumferential direction around the first bushing element and in the same first circumferential direction around the second bushing element, such that a first end region of the first layer terminates adjacent to the first bushing element, a second end region of the first layer terminates adjacent to the second bushing element, and a central region of the first layer between the first and second end regions only runs along a first side of the centerline between the first and second bushing elements; wherein the second layer is wrapped in a second circumferential direction, counter to the first circumferential direction, around the first bushing element and in the same second circumferential direction around the second bushing element, such that a first end region of the second layer terminates adjacent to the first bushing element, a second end region of the second layer terminates adjacent to the second bushing element, and a central region of the second layer between the first and second end regions runs only along a second side, opposite the first side, of the centerline between the first and second bushing elements; and wherein the leaf spring main body and the first and the second eye bushing all have a uniform wall thickness. ### Claim 20 (depends on 19) The leaf spring of claim 19, wherein the composite material further comprises prepreg.