# US 2021/0340947 A1 · A wind turbine blade with multiple spar caps > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0340947 A1 - Document ID: US20210340947A1 - Status: Published application - Kind: A1 - Application number: 17/281,019 - Filed: 2019-10-23 - Published: 2021-11-04 - Earliest claimed: 2018-10-25 - Assignees: Lm Wind Power A/S - Applicants: Lm Wind Power A/S - Inventors: Klavs JESPERSEN; Lars NIELSEN - Web page: https://patentgrep.com/patent/US20210340947A1 ## CPC - F03D 1/0633: {of the blades} - F03D 1/0675: {of the blades} - F03D 13/10: Assembly of wind motors; Arrangements for erecting wind motors - F05B 2220/30: in turbines - F05B 2230/23: by permanently joining parts together - F05B 2240/221: with horizontal axis - F05B 2280/6003: Composites; e.g. fibre-reinforced - Y02E 10/72: Wind turbines with rotation axis in wind direction - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - F03D: WIND MOTORS - F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract The present invention relates to wind turbine blade and a method of manufacturing the wind turbine blade. An aerodynamic shell is provided with a recess (70) at its inner surface, the recess (70) extending with-in the shell along a spanwise direction of the blade. A first region of the recess (70) has a first width and a second region of the recess (70) has a second width exceeding the first width. A transition region is provided between the first region and the second region of the re-cess. A first and a second spar cap (80, 82) are arranged within the shell. ## Claims ### Claim 1 A wind turbine blade comprising: an aerodynamic shell (62) having an outer surface (64) forming at least part of an exterior surface of the wind turbine blade and an inner surface (66), a recess (70) at the inner surface (66) of the aerodynamic shell, the recess (70) extending within the shell along a spanwise direction of the blade, wherein the recess (70) comprises a first region (72) having a first width, a second region (74) having a second width exceeding the first width, and a transition region (73) connecting the first region (72) with the second region (74) of the recess (70), and a load carrying structure comprising a first and a second spar cap (80, 82) extending within the shell (62) along a spanwise direction of the blade, wherein the first spar cap (80) is arranged at least partly in the recess (70) of the aerodynamic shell, and wherein the second spar cap (82) is arranged on top of at least part of the first spar cap (80). ### Claim 2 (depends on 1) A wind turbine blade according to claim 1, wherein the second spar cap (82) is wider than the first spar cap (80). ### Claim 3 (depends on 1) A wind turbine blade according to claim 1, wherein the shell comprises a pressure side shell half and a suction side shell half, each of the shell halves comprising a recess (70) and a load carrying structure according to claim 1. ### Claim 4 (depends on 1) A wind turbine blade according to claim 1, wherein the first and second spar caps (80, 82) each comprise a fabric, wherein the fabric of the first spar cap (80) is different from the fabric of the second spar cap (82). ### Claim 5 (depends on 1) A wind turbine blade according to claim 1, wherein the first width of the first region is within a range of 35-90% of the second width of the second region. ### Claim 6 (depends on 1) A wind turbine blade according to claim 1, wherein the difference between the first width of the first region and the second width of the second region is in a range of 50-800 mm. ### Claim 7 (depends on 1) A wind turbine blade according to claim 1, wherein the spanwise extent of the transition region is 0.5-5 meters. ### Claim 8 (depends on 1) A wind turbine blade according to claim 1, wherein the first and/or second spar cap (80, 82) comprise a hybrid carbon/glass fibre material. ### Claim 9 (depends on 1) A wind turbine blade according to claim 1, wherein the recess (70) is substantially bottle-shaped. ### Claim 10 (depends on 1) A wind turbine blade according to claim 1, wherein the aerodynamic shell comprises a first thickened portion laterally adjoining the recess (70) at a first side of the recess (70) and a second thickened portion laterally adjoining the recess (70) at a second side of the recess (70). ### Claim 11 (depends on 10) A wind turbine blade according to claim 10, wherein the first thickened portion and/or the second thickened portion are formed as a sandwich structure comprising a number of outer skin layers, a number of inner skin layers, and an intermediate sandwich core material. ### Claim 12 (depends on 1) A wind turbine blade according to claim 1, wherein the recess (70) has a base (71) and two opposing side walls (76a, 76b), each side wall having a respective upper edge (76a, 76b), wherein the transition region (73) of the recess has a proximal end and a distal end, seen in the spanwise direction, wherein an angle (□) is formed between the base (71) of the recess (70) and a line extending from the upper edge (76a) of a side wall (70a) at the proximal end of the transition region to an intersection between the base (71) and the respective sidewall (70a) at the distal end of the transition region (73), wherein said angle is between 0.2-20 degrees. ### Claim 13 (depends on 12) A wind turbine blade according to claim 12, wherein the side walls (76a, 76b) of the recess (70) are chamfered. ### Claim 14 (depends on 1) A wind turbine blade according to claim 1, wherein the first spar cap (80) and the second spar cap (82) each are pre-manufactured as a fibre-reinforced object comprising a fibre reinforcement material and a matrix material. ### Claim 15 A method of manufacturing a wind turbine blade, wherein the method comprises the steps of: manufacturing an aerodynamic shell comprising a recess (70) at the inner surface of the aerodynamic shell, the recess (70) extending within the shell along a spanwise direction of the blade, wherein the recess (70) comprises a first region having a first width, a second region having a second width exceeding the first width, and a transition region connecting the first region with the second region of the recess (70), and arranging a first spar cap (80) in the shell such that it extends within the shell along a spanwise direction of the blade, wherein the first spar cap (80) is arranged at least partly in the recess (70) of the aerodynamic shell, bonding the first spar cap (80) to the shell, arranging a second spar cap (82) on top of at least part of the first spar cap (80), bonding the second spar cap (82) to the first spar cap (80) and optionally to the aerodynamic shell.