Sunlight concentrating apparatus

Abstract

A sunlight concentrating apparatus includes a plate-like reflecting part, with an upper reflection surface extending in an axial and a width direction, and a lower surface having a central linear region fixed to a main shaft part. A pair of bending mechanisms bend the reflection surface by moving opposite end portions in a central normal direction in accordance with a rotation of the main shaft part. The reflecting part includes a mirror plate and a support plate thereon. In the support plate, the ratio between the distance in the width direction from each end portion in the width direction and the second moment of area at this distance is constant between the end portion and the central linear region, allowing the reflection surface to be bent in an are shape.

1 . A sunlight concentrating apparatus for concentrating sunlight onto a heat collecting part, comprising;
 a main shaft part that is long in a predetermined axial direction;   a plate-like reflecting part having an upper surface that is a reflection surface extending in said axial direction and a width direction perpendicular to said axial direction, and having a lower surface in which a central linear region that extends in said axial direction at approximately a center in said width direction is fixed to said main shaft part;   a main shaft supporter for supporting said main shaft part rotatably about a central axis parallel to said axial direction;   a rotating mechanism for rotating said main shaft part to tilt said reflection surface; and   a pair of bending mechanisms for bending said reflection surface by moving opposite end portions in said width direction of said reflecting part in a similar manner in a central normal direction in accordance with rotation of said main shaft part, said central normal direction being a direction perpendicular to said axial direction and said width direction of said reflection surface,   wherein said reflecting part has a cross-sectional shape that is perpendicular to said width direction and that changes along said width direction to bend said reflection surface in a generally arc shape.   
     
     
         2 . The sunlight concentrating apparatus according to  claim 1 , wherein
 when a mirror plate of said reflecting part or a support plate laid on said mirror plate is taken as a target plate member, a ratio between a distance in said width direction from each end portion of said reflecting part in said width direction and a second moment of area of said target plate member at said distance is constant between said each end portion and said central linear region, or a ratio between said distance and flexural rigidity of said reflecting part at said distance is constant between said each end portion and said central linear region.   
     
     
         3 . The sunlight concentrating apparatus according to  claim 2 , wherein
 said reflecting part includes said mirror plate and said support plate,   said target plate member is said support plate, and   said support plate has a triangular portion between said each end portion and said central linear region, said triangular portion having a base located in said central linear region and a vertex opposing said base and located in the vicinity of said each end portion.   
     
     
         4 . The sunlight concentrating apparatus according to  claim 3 , wherein
 said mirror plate is a rectangular plate having sides parallel to said axial direction and said width direction,   said reflecting part further includes another support plate that is disposed apart in said axial direction from said support plate and that is laid on said mirror plate, and   said another support plate has a triangular portion between said each end portion and said central linear region, said triangular portion having a base located in said central linear region and a vertex opposing said base and located in the vicinity of said each end portion.   
     
     
         5 . The sunlight concentrating apparatus according to  claim 4 , wherein
 said reflecting part further includes a rib member that is connected to said triangular portion of said support plate and said triangular portion of said another support plate and in contact with said mirror plate at a position distanced in said width direction from said central linear region.   
     
     
         6 . The sunlight concentrating apparatus according to  claim 2 , wherein
 said reflecting part includes said mirror plate and said support plate, and   said support plate has a portion whose thickness gradually increases from said each end portion toward said central linear region to make the ratio between said distance and the flexural rigidity of said reflecting part at said distance constant between said each end portion and said central linear region.   
     
     
         7 . The sunlight concentrating apparatus according to  claim 6 , wherein
 said support plate is formed of a material having a lower Young's modulus than said mirror plate.   
     
     
         8 . The sunlight concentrating apparatus according to  claim 2 , wherein
 said reflecting part includes said mirror plate and said support plate, and   said support plate has a portion whose width in said axial direction gradually increases from said each end portion toward said central linear region to make the ratio between said distance and the flexural rigidity of said reflecting part at said distance constant between said each end portion and said central linear region.   
     
     
         9 . The sunlight concentrating apparatus according to  claim 3 , wherein
 with respect to said width direction, opposite end portions of said support plate are located outward of opposite end portions of said mirror plate, and   said pair of bending mechanisms moves said opposite end portions of said support plate in said central normal direction.   
     
     
         10 . The sunlight concentrating apparatus according to  claim 1 , wherein
 said reflecting part includes:   a mirror plate; and   a support beam extending in said width direction and for supporting said mirror plate, and   said support beam has a cross-sectional shape that is perpendicular to said width direction and that changes along said width direction to make a ratio between a distance in said width direction from each end portion of said reflecting part in said width direction and flexural rigidity of said reflecting part at said distance constant between said each end portion and said central linear region.   
     
     
         11 . The sunlight concentrating apparatus according to  claim 10 , wherein
 said support beam has a portion whose height in said central normal direction or whose width in said axial direction gradually increases from said each end portion toward said central linear region.   
     
     
         12 . The sunlight concentrating apparatus according to  claim 1 , wherein
 when a portion of said reflecting part between each end portion in said width direction and said central linear region is divided into a plurality of sections in said width direction, a ratio between a distance in said width direction from said each end portion to each section and an average value of flexural rigidity of said reflecting part in said each section is approximately constant in said plurality of sections.   
     
     
         13 . The sunlight concentrating apparatus according to  claim 4 , wherein
 with respect to said width direction, opposite end portions of said support plate are located outward of opposite end portions of said mirror plate, and   said pair of bending mechanisms moves said opposite end portions of said support plate in said central normal direction.   
     
     
         14 . The sunlight concentrating apparatus according to  claim 5 , wherein
 with respect to said width direction, opposite end portions of said support plate are located outward of opposite end portions of said mirror plate, and   said pair of bending mechanisms moves said opposite end portions of said support plate in said central normal direction.   
     
     
         15 . The sunlight concentrating apparatus according to  claim 6 , wherein
 with respect to said width direction, opposite end portions of said support plate are located outward of opposite end portions of said mirror plate, and   said pair of bending mechanisms moves said opposite end portions of said support plate in said central normal direction.   
     
     
         16 . The sunlight concentrating apparatus according to  claim 7 , wherein
 with respect to said width direction, opposite end portions of said support plate are located outward of opposite end portions of said mirror plate, and   said pair of bending mechanisms moves said opposite end portions of said support plate in said central normal direction.   
     
     
         17 . The sunlight concentrating apparatus according to  claim 8 , wherein
 with respect to said width direction, opposite end portions of said support plate are located outward of opposite end portions of said mirror plate, and   said pair of bending mechanisms moves said opposite end portions of said support plate in said central normal direction.