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EP-4491522-B1 - EXTENSION BOOM, SOLAR PADDLE, AND METHOD FOR MANUFACTURING EXTENSION BOOM

EP4491522B1EP 4491522 B1EP4491522 B1EP 4491522B1EP-4491522-B1

Inventors

  • KOYAMA, TATSUYA
  • KOBAYASHI, HIROKI
  • TAKAGAKI, Kazunori

Dates

Publication Date
20260506
Application Date
20220311

Claims (9)

  1. An extensible boom (120) to be extended from a retracted state of being rolled in a cylindrical form, wherein - the extensible boom (120) is made of a fiber-reinforced composite material, - when the extended extensible boom (120) is deployed, - in a first area, directions of fiber contained in the fiber-reinforced composite material are a first low-angle direction forming a negative angle to a clockwise direction with respect to an extending direction of the extensible boom (120) and a second low-angle direction forming a positive angle to the clockwise direction with respect to the extending direction, - in a second area a position of which in the extending direction is different from a position of the first area in the extending direction, directions of fiber contained in the fiber-reinforced composite material are a first high-angle direction forming a negative angle to a clockwise direction with respect to the extending direction and a second high-angle direction forming a positive angle to the clockwise direction with respect to the extending direction, - the first low-angle direction is closer to the extending direction than the first high-angle direction, and - the second low-angle direction is closer to the extending direction than the second high-angle direction.
  2. The extensible boom (120) according to claim 1, wherein each of an angle formed by the first low-angle direction and the extending direction and an angle formed by the second low-angle direction and the extending direction is an angle smaller than 45°.
  3. The extensible boom (120) according to claim 1 or 2, wherein the first area is a center portion (121) of the extended extensible boom (120) in the extending direction, and the second area is at least one end portion (122) of the extended extensible boom (120) in the extending direction.
  4. The extensible boom (120) according to claim 3, wherein an angle formed by the first low-angle direction and the extending direction and an angle formed by the second low-angle direction and the extending direction are each 10° or more and 40° or less.
  5. The extensible boom (120) according to claim 3 or 4, wherein an angle formed by the first high-angle direction and the extending direction and an angle formed by the second high-angle direction and the extending direction are each 40° or more and 75° or less.
  6. The extensible boom (120) according to any one of claims 3 to 5, wherein when the extensible boom (120) is extended, the extensible boom (120) has a cylindrical shape with an axis parallel to the extending direction as a center axis, the shape having an opening continuously from one end to another end of the extensible boom (120) along the extending direction, - the opening corresponds to part of an outer perimeter of the cylindrical shape and is an area where the fiber-reinforced composite material is not present, and - a size of the opening in the at least one end portion (122) is smaller than a size of the opening in the center portion (121).
  7. The extensible boom (120) according to any one of claims 3 to 6, wherein a percentage of fiber content of the fiber-reinforced composite material in the at least one end portion (122) is higher than a percentage of fiber content of the fiber-reinforced composite material in the center potion.
  8. A solar cell paddle (100) for use in an artificial satellite, the solar cell paddle (100) comprising: the extensible boom (120) according to any one of claims 1 to 7.
  9. A manufacturing method for the extensible boom (120) according to any one of claims 1 to 7, the manufacturing method comprising: - stretching a center portion (121) in an extending direction of a woven prepreg along the extending direction, the woven prepreg being made of a plurality of fibers; and - forming the stretched woven prepreg into a cylindrical shape with an axis parallel to the extending direction as a center axis, wherein - when the extended extensible boom (120) is deployed, - in a first area, directions of fiber contained in the fiber-reinforced composite material are a first low-angle direction forming a negative angle to a clockwise direction with respect to an extending direction of the extensible boom (120) and a second low-angle direction forming a positive angle to the clockwise direction with respect to the extending direction, - in a second area a position of which in the extending direction is different from a position of the first area in the extending direction, directions of fiber contained in the fiber-reinforced composite material are a first high-angle direction forming a negative angle to a clockwise direction with respect to the extending direction and a second high-angle direction forming a positive angle to the clockwise direction with respect to the extending direction, - the angle formed by the first low-angle direction to the clockwise direction with respect to the extending direction is an angle larger than -45° and is larger than the angle formed by the first high-angle direction to the clockwise direction with respect to the extending direction, the first low-angle direction being a direction along which the fiber arranged in the center portion (121) of the stretched woven prepreg goes, and - the angle formed by the second low-angle direction to the clockwise direction with respect to the extending direction is an angle smaller than 45° and is smaller than the angle formed by the second high-angle direction to the clockwise direction with respect to the extending direction, the second low-angle direction being a direction along which the fiber arranged in the center portion (121) of the stretched woven prepreg goes.

Description

Technical Field The present invention relates to an extensible boom, a solar cell paddle, and an extensible boom manufacturing method. Background Art To keep up with increasing power consumption on artificial satellites, upsizing of photovoltaic power generation panels is desired. For accommodating upsizing of photovoltaic power generation panels, a scheme of retracting a photovoltaic power generation panel in a cylindrical shape has been developed as a scheme of a retracting photovoltaic power generation panels. In the scheme, the photovoltaic power generation panel is deployed by extending a mast. The scheme also provides high efficiency in retraction of photovoltaic power generation panels, compared with a conventional scheme of retracting a photovoltaic power generation panel by alternately folding the photovoltaic power generation panel. In the scheme of retracting a photovoltaic power generation panel in a cylindrical shape, an extensible boom using a member with bidirectional stability is used as a mast. Here, the member with bidirectional stability is a member that can maintain each of a shape at the time of retraction and a shape at the time of extension even without external force. An extensible boom assumes a cylindrical shape when it is retracted and becomes a mast when it is extended. Also, when the extensible boom is deformed, an extending force is generated, which is a force for deploying a solar cell paddle. In the extensible boom, as the size is larger and as the thickness is larger, the extending force becomes larger. However, a large size and a large thickness make the weight of the extensible boom heavy. Thus, in the extensible boom, a technique has been desired to obtain a necessary extending force while reducing an increase in weight. Further prior art related to the invention is given in Patent Literature 2 to 6 Citation List Patent Literature Patent Literature 1: JP 6 525 272 B2Patent Literature 2 : US 2016/226126Patent Literature 3 : WO 03/062565Patent Literature 4 : JP 2021 066188Patent Literature 5 : JP 2018 001601Patent Literature 6 : JP 7 012908 Summary of Invention Technical Problem In the technology disclosed in Patent Literature 1, an improvement in extending force is achieved by assisting the extensible boom by using a metal-made plate material. However, an increase in weight of the extensible boom poses a problem. Also, in the technology, fabric with orthogonal fibers is used as a material configuring the extensible boom. However, to improve the extending force by utilizing fiber orientation, the fiber angle is limited in normal fabric, and therefore it is required to improve the extending force by laminating unidirectional materials. Here, when unidirectional materials are laminated for the technology, the weight increases because it is required to ensure many number of laminations to ensure symmetry of lamination. In addition, if an improvement in the extending force with fiber orientation is simply sought, the shape in a retracted state becomes unstable. Thus, the technology has a problem in which stability in a retracted state decreases. Patent Literature 2 discloses - according to its abstract - an antenna assembly which comprises an extendible mast constructed and arranged so as to be configurable between a coiled form and an extended form. The extended mast is resiliently biased in the form of an elongate tube having a slit along its length. The coiled mast is wound about an axis extending transversely to the longitudinal extent of the mast. An antenna is integrally coupled to the mast such that when extended, the mast supports and positions the antenna, and when coiled, the mast and antenna are coiled together. An object of the present invention is to provide an extensible boom in which a relatively high extending force can be obtained without an increase in weight and stability in a retracted state is relatively high. Solution to the Problem An extensible boom according to the present invention is given in claim 1 and is an extensible boom to be extended from a retracted state of being rolled in a cylindrical form, wherein the extensible boom is made of a fiber-reinforced composite material,when the extended extensible boom is deployed, in a first area, directions of fiber contained in the fiber-reinforced composite material are a first low-angle direction forming a negative angle to a clockwise direction with respect to an extending direction of the extensible boom and a second low-angle direction forming a positive angle to the clockwise direction with respect to the extending direction,in a second area a position of which in the extending direction is different from a position of the first area in the extending direction, directions of fiber contained in the fiber-reinforced composite material are a first high-angle direction forming a negative angle to a clockwise direction with respect to the extending direction and a second high-angle direction forming a posi