SUNLIGHT CONCENTRATING APPARATUS
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.
The present invention relates to a sunlight concentrating apparatus for concentrating sunlight onto a heat collecting part.
BACKGROUND ARTIn recent years, solar heat collecting systems that collect solar heat energy by concentrating sunlight and heating a heating medium have been put into practical use. It is important for solar heat collecting systems to efficiently collect the solar heat energy. For example, International Publication No. 2011/086825 (Document 1) discloses a technique for, in a sunlight concentrating apparatus that tilts a reflecting mirror in accordance with the movement of the sun, efficiently guiding (reflected light of) sunlight to a heat collecting means by changing the degree of curve of the reflection surface in accordance with the tilting position of the reflecting mirror. More specifically, in the sunlight concentrating apparatus of Document 1, the reflecting mirror is supported at the center, and the degree of curve of the reflection surface is changed by raising and lowering both side edge portions of the reflecting mirror in accordance with the tilting position of the reflecting mirror.
Incidentally, in order to efficiently concentrate sunlight onto the heat collecting part, a sunlight concentrating apparatus that changes the deflection of the reflection surface while rotating (tilting) the reflection surface, as in Document 1, sets the tilt angle and curvature of the reflection surface such that the reflection surface follows a parabola that is focusing on the position of the heat collecting part and whose axis of symmetry is a straight line parallel to sunlight in a plane perpendicular to the rotation axis and passing through the heat collecting part. However, keeping the curvature of the reflection surface substantially constant, i.e., bending the reflection surface in a generally arc shape is not easy, and efficiently guiding the sunlight emitted onto the entire reflection surface to the heat collecting part is difficult. Document 1 discloses a technique for providing the reflecting mirror with a concave portion to change the rigidity of the reflecting mirror in a transverse cross-sectional direction and thereby changing the degree of curve of the reflecting mirror, but even with this technique, it is not easy to bend the reflection surface in a generally arc shape.
SUMMARY OF INVENTIONThe present invention is intended for a sunlight concentrating apparatus for concentrating sunlight onto a heat collecting part, and it is an object of the present invention to bend a reflection surface in a generally arc shape.
The sunlight concentrating apparatus according to the present invention includes 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 the axial direction and a width direction perpendicular to the axial direction, and having a lower surface in which a central linear region that extends in the axial direction at approximately a center in the width direction is fixed to the main shaft part, a main shaft supporter for supporting the main shaft part rotatably about a central axis parallel to the axial direction, a rotating mechanism for rotating the main shaft part to tilt the reflection surface, and a pair of bending mechanisms for bending the reflection surface by moving opposite end portions in the width direction of the reflecting part in a similar manner in a central normal direction in accordance with rotation of the main shaft part, the central normal direction being a direction perpendicular to the axial direction and the width direction of the reflection surface. The reflecting part has a cross-sectional shape that is perpendicular to the width direction and that changes along the width direction to bend the reflection surface in a generally arc shape.
According to the present invention, the reflection surface can easily bend in a generally arc shape. Consequently, sunlight can efficiently be concentrated onto the heat collecting part.
In a preferred embodiment of the present invention, when a mirror plate of the reflecting part or a support plate laid on the mirror plate is taken as a target plate member, a ratio between a distance in the width direction from each end portion of the reflecting part in the width direction and a second moment of area of the target plate member at the distance is constant between the end portion and the central linear region, or a ratio between the distance and flexural rigidity of the reflecting part at the distance is constant between the end portion and the central linear region.
In this case, in one aspect, the reflecting part includes the mirror plate and the support plate, the target plate member is the support plate, and the support plate has a triangular portion between the end portion and the central linear region, the triangular portion having a base located in the central linear region and a vertex opposing the base and located in the vicinity of the end portion. In another aspect, the reflecting part includes the mirror plate and the support plate, and the support plate has a portion whose thickness or width in the axial direction gradually increases from the end portion toward the central linear region to make the ratio between the distance and the flexural rigidity of the reflecting part at the distance constant between the end portion and the central linear region.
In another preferred embodiment of the present invention, the reflecting part includes a mirror plate, and a support beam extending in the width direction and for supporting the mirror plate. The support beam has a cross-sectional shape that is perpendicular to the width direction and that changes along the width direction to make a ratio between a distance in the width direction from each end portion of the reflecting part in the width direction and flexural rigidity of the reflecting part at the distance constant between the end portion and the central linear region.
In yet another preferred embodiment of the present invention, when a portion of the reflecting part between each end portion in the width direction and the central linear region is divided into a plurality of sections in the width direction, a ratio between a distance in the width direction from the end portion to each section and an average value of flexural rigidity of the reflecting part in the section is approximately constant in the plurality of sections.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
The plurality of sunlight concentrating apparatuses 1 are arrayed in the X direction below the heat collecting part 11. Each sunlight concentrating apparatus 1 includes a generally tubular main shaft part 2 that is long in the Y direction, a reflecting part 3 that is fixed to the main shaft part 2 and is long along the length of the main shaft part 2 (i.e., in the Y direction, which is hereinafter referred to as an “axial direction”), and a rotating mechanism 4 that is disposed in the vicinity of the center of the main shaft part 2 in the axial direction. The reflecting part 3 has a plate-like shape and has an upper surface serving as a reflection surface 30. As will be described later, the reflection surface 30 is tilted by the rotating mechanism 4 rotating the main shaft part 2. The following description focuses on one of the sunlight concentrating apparatuses 1, but the other sunlight concentrating apparatuses 1 have the same configuration.
As illustrated in
As illustrated in
In actuality, the cam rail 722 provided on the +Y side of the rotating mechanism 4 and the cam rail 722 provided on the −Y side are symmetric with respect to a plane perpendicular to the axial direction at the center of the main shaft part 2 in the axial direction. Thus, the sliding rod 71 provided on the +Y side of the rotating mechanism 4 and the sliding rod 71 provided on the −Y side slide in opposite axial directions to each other. In other words, reaction forces acting in opposite axial directions and having approximately the same magnitude act respectively on the cam rail 722 on the +Y side and the cam rail 722 on the −Y side from the sliding rod 71 on the +Y side and the sliding rod 71 on the −Y side. Thus, the reaction forces acting on the entire frame 91, which supports both of the cam rails 722, with the movement of both of the sliding rods 71 cancel out each other. This prevents the frame 91 from tilting or falling down due to the reaction forces acting with the movement of the sliding rods 71.
As illustrated in
As described above, the sliding rod 71, the sliding mechanism 72 (see
As described previously, the cam rail 722 on the +Y side of the rotating mechanism 4 and the cam rail 722 on the −Y side in
In the solar heat collecting system 10 in
Here, the curvature of a typical cantilever will be described. For a cantilever with a free end to which a load W perpendicular to the lengthwise direction of the cantilever is applied, Expression 1 is satisfied on the basis of the relationship between the bending moment and the bending stress, where x is the distance from the fixed end at an arbitrary position in the lengthwise direction of the cantilever, R is the radius of curvature at that position, I is the second moment of area (the second moment of area relative to the neutral axis) at that position, E is Young's modulus (modulus of longitudinal elasticity), and L is the entire length of the cantilever in the lengthwise direction.
W·R=E·I/(L−x) (Expression 1)
When a ratio between the distance (L−x) from the free end in the lengthwise direction of the cantilever and the second moment I of area (or flexural rigidity E·I) at the position indicated by the distance in the lengthwise direction of the cantilever is made constant over the entire length of the cantilever, i.e., the second moment I of area is proportional to the distance (L−x), the radius of curvature R is constant over the entire length of the cantilever, irrespective of the magnitude of the load W (or the amount of deflection of the free end), and therefore the cantilever bends in an arc shape.
More specifically, the second moment I of area is expressed as (b·h3/12), where a cross section of the cantilever perpendicular to the lengthwise direction has a rectangular shape, h is the width of the cross section in the direction of the load, and b is the width of the cross section in a direction perpendicular to the direction of the load. When the cantilever is a member having a constant width h in the direction of the load and a constant ratio between the distance (L−x) from the free end in the lengthwise direction of the cantilever and the width b in the direction perpendicular to the direction of the load at this distance, i.e., a plate member having a triangular shape as viewed in the direction of the load, the cantilever bends in an arc shape, irrespective of the magnitude of the load W (or the amount of deflection of the free end).
For example, when the Young's modulus E of this plate member is 205800 megapascals (MPa), the entire length L of the cantilever in the lengthwise direction is 587 millimeters (mm), the width (thickness) of the cantilever in the direction of the load is 3 mm, the width b in the direction perpendicular to the direction of the load (see the longitudinal axis on the right side in
When a portion of each support plate 32 of the reflecting part 3 in
In actuality, the support plate 32, which is bonded to the mirror plates 31, is not identical to the above-described cantilever, but the reflecting part 3 including such support plates 32 can approximate the cross-sectional shape of the reflection surface 30 perpendicular to the axial direction to an arc shape, i.e., can bend the reflection surface 30 in a generally arc shape, as compared to the case where the support plates have a rectangular shape as viewed in the central normal direction. This consequently allows not only the sunlight emitted to the vicinity of the center of the reflection surface 30 in the width direction but also the sunlight emitted to the vicinity of the end portions to be efficiently guided to the heat collecting part 11, thus further improving the performance of concentrating sunlight.
Here, the rib members 33 provided at the end portions of the reflecting part 3 will be described.
As illustrated in
In
As illustrated in
The reflecting part 3 in
The technique for easily bending the reflection surface 30 in a generally arc shape by making the ratio between the distance of each end portion of the support plates 32 in the width direction and the second moment of area at this distance constant between the end portion and the central linear region 39 may be implemented by changing the width h in the direction of the load (the thickness in the central normal direction). As described previously, the second moment I of area of a rectangular cross section is expressed as (b·h3/12). Thus, when a member that has a constant width b in the direction perpendicular to the direction of the load and that has a constant ratio between the distance (L−x) from the free end in the lengthwise direction of the cantilever and the cube of the width h in the direction of the load at this distance is used as a cantilever, this member can bend in an arc shape, irrespective of the magnitude of the load w (or the amount of deflection of the free end).
For example, when the Young's modulus E of this member is 205800 MPa, the entire length L of the cantilever in the lengthwise direction is 587 mm, the width b of the cantilever in the direction perpendicular to the direction of the load is 1000 mm, the width h in the direction of the load (the thickness of the member; see the longitudinal axis on the right side in
Thus, when the support plates having a rectangular shape as viewed in the central normal direction, like the mirror plates 31, are employed and the thickness of the target portions of the support plates in the direction of the load (central normal direction) are changed as indicated by line A3 in
As can be seen from Expression 1, the sunlight concentrating apparatus 1 can approximate the cross-sectional shape of the reflection surface 30 more closely to an arc shape by making the ratio between the distance from each end portion in the width direction and the flexural rigidity (i.e., the product of the second moment I of area and the Young's modulus E) of the reflecting part as a whole at this distance constant between the end portion and the central linear region 39. The following is a description of such a reflecting part.
It is assumed here that when the portion of the reflecting part 3a between the end portion in the width direction and the central linear region 39 is taken as a single cantilever, a cross section of the cantilever taken perpendicular to the axis line (i.e., the axis line extending in the longitudinal direction of the cantilever) remains in a flat plane perpendicular to the axial line even after the reflecting part 3a is bent and deformed by the bending mechanisms 7. At this time, the bending strain c can be expressed as (ε=y/R) because it is proportional to a distance y from the neutral axis J2 (neutral plane) and inversely proportional to the radius of curvature (bend radius) R. The bending stress σg on the mirror plate 31 is obtained as the product of the Young's modulus Eg of the mirror plate 31 and the bending strain ε and thus can be expressed as (σg=Eg·y/R). Similarly, the bending stress σa on the rear plate 35 can be expressed as (σm=Ea·y/R), and the bending stress σc on the support plate 32a can be expressed as (σc=Ec·y/R), where Ea and Ec are respectively the Young's moduli of the rear plate 35 and the support plate 32a.
As described above, the bending stress linearly changes with respect to the distance y from the neutral axis J2. Thus, an integral value of stresses in the entire cross section of each member, including the mirror plate 31, the rear plate 35, and the support plate 32a, can be obtained by multiplying the stress (i.e., average stress) at the center of the member in the thickness direction by the thickness and the axial width of the member. Thus, an integral value of stresses in the entire cross section of the mirror plate 31 can be expressed as (tg·bg·Eg·((tg/2)+ta+tc−y0)/R), an integral value of stresses in the entire cross section of the rear plate 35 can be expressed as (ta·ba·Ea·((ta/2)+tc−y0)/R), and an integral value of stresses in the entire cross section of the support plate 32a can be expressed as (tc·bc·Ec·((tc/2)−y0)/R), by using the thickness tg and width bg of the mirror plate 31, the thickness to and width ba of the rear plate 35, the thickness tc and width be of the support plate 32a, and the distance y0 from the lower end of the support plate 32a to the neutral axis J2. Expression 2 is obtained by setting the sum of these integral values to zero and simplifying the sum with respect to y0. In Expression 2, Kg is (tg·bg·Eg), Ka is (ta·ba·Ea), and Kc is (tc·bc·Ec).
y0={Kg((tg/2)+ta+tc)+Ka((ta/2)+tc)+Kc·tc/2}/(Kg+Ka+Kc) (Expression 2)
Thus, Expression 2 yields the distance y0 from the lower end of the support plate 32a to the neutral axis J2 when the thickness tg and width bg of the mirror plate 31, the thickness ta and the width ba of the rear plate 35, and the thickness tc of the support plate 32a are made constant and the width be of the support plate 32a is an arbitrary value. This distance y0 indicating the position of the neutral axis J2 is then used to obtain the flexural rigidity of the mirror plate 31, the flexural rigidity of the rear plate 35, and the flexural rigidity of the support plate 32a, and the sum of the values of the flexural rigidity is obtained as the flexural rigidity of the reflecting part 3a as a whole. The relationship between the width be of the support plate 32a and the flexural rigidity of the reflecting part 3a as a whole is as illustrated in
When the length of the portion of the reflecting part 3a between the end portion in the width direction and the central linear region 39 is 630 mm and the load W applied to the end portion is 99.9 N, the distribution of the width be of the support plate 32a in order to fix the radius of curvature R of the reflection surface 30 to a constant value of 5400 mm can be obtained on the basis of the relationship expressed by Expression 1 and illustrated in
In the reflecting part 3a illustrated in
As described above, in the sunlight concentrating apparatus 1, the support plates 32a have a portion whose width in the axial direction gradually increases from each end portion of the reflecting part 3a in the width direction toward the central linear region 39 in order to make the ratio between the distance in the width direction from the end portion and the flexural rigidity of the reflecting part 3a at this distance approximately constant between the end portion and the central linear region 39. This allows the reflection surface 30 to be bent to more closely approximate an arc shape. Consequently, the performance of concentrating sunlight onto the heat collecting part 11 can be further improved.
Here, assume the case in which the mirror plate 31 and the rear plate 35 of the reflecting part 3a in
In contrast, for the reflecting part 3a illustrated in
Note that the support plate 32a may have edges on both sides in the axial direction that are asymmetric while having an axial width that satisfies the relationship illustrated in
When, for example, the axial length of the reflecting part 3a is 1 mm, the relationship between the thickness tp of the support plate 32a and the flexural rigidity of the reflecting part 3a as a whole can be obtained in the same manner as in
When, in the reflecting part 3a, the axial length is 1 m, the length of the portion between each end portion in the width direction and the central linear region 39 is 600 mm, and the load W applied to the end portion is approximately 300 N, the distribution of the thickness tp of the support plate 32a in order to fix the radius R of curvature of the reflection surface 30 to a constant value of 6000 mm can be obtained in the same manner as in
Incidentally, in the distribution of thickness indicated by the line A3 in
In the manufacture of the reflecting part 3a, for example, a lower mold having an inner shape that follows the distribution of thickness in
As described above, in the sunlight concentrating apparatus 1, the support plates 32a have a portion whose thickness gradually increases from each end portion of the reflecting part 3a in the width direction toward the central linear region 39 in order to make the ratio between the distance in the width direction from the end portion and the flexural rigidity of the reflecting part 3a at this distance approximately constant between the end portion and the central linear region 39. This allows the reflection surface 30 to be easily bent in a generally arc shape. In addition, the support plates 32a are made of a material having a lower Young's modulus than the mirror plate 31. This increases a change in the thickness of the support plate 32a, thus allowing easy manufacture of the support plate 32a.
Note that, depending on the design of the reflecting part 3a, the linear relationship between the distance in the width direction from each end portion and the flexural rigidity of the reflecting part at this distance may be satisfied by further changing the thicknesses of the mirror plate 31 and the auxiliary plate 34 (i.e., changing the thicknesses of some or all of the plate members of the reflecting part 3a). In addition to the above change in thickness, the axial width of the support plates 32a or the auxiliary plate 34 may be changed. Moreover, the auxiliary plate 34 may be omitted from the reflecting part 3a, and the reflecting part 3a may be formed of four or more layers.
While the above-described sunlight concentrating apparatus 1 uses the support plates 32 or 32a, support beams that extend in the width direction may be used instead of the support plates 32 or 32a.
The reflecting part 3b includes a mirror plate 31, a rear plate 35, the support beams 32b, and the rib members 33. The rear plate 35, the support beams 32b, and the rib members 33 are made of aluminum or steel, for example. The cross sections of the mirror plate 31 and the rear plate 35 perpendicular to the width direction have a rectangular shape. The cross section of the support beams 32b perpendicular to the width direction has a C shape that opens downward, and the support beams 32b are so-called C-shaped beams. In the reflecting part 3b, only the height of the support beams 32b in the central normal direction (height in the direction indicated by an arrow V2 in
For convenience of description, it is assumed here that the axial length of the reflecting part 3b is 1 m and the reflecting part 3b is provided with two support beams 32b arrayed in the axial direction. In this case, the relationship between the height h of the support beams 32b (the height excluding the plate thickness is as illustrated in
Thus, when, in the reflecting part 3b, the length of the portion between each end portion in the width direction and the central linear region 39 is 600 mm and the load W applied to the end portion per one meter of the axial length is approximately 200 N (20.4 kgf), the distribution of the height h of the support beams 32b in order to set the radius R of curvature of the reflection surface 30 to a constant value of 5400 mm is as illustrated in
As described above, the reflecting part 3b is provided with the support beams 32b for supporting the mirror plate 31 from the underside, and the support beams 32b has a cross-sectional shape that is perpendicular to the width direction and that gradually changes along the width direction so that the ratio between the distance in the width direction from each end portion of the reflecting part 3b in the width direction and the flexural rigidity of the reflecting part 3b at this distance remains constant between the end portion and the central linear region 39. This allows the reflection surface 30 to be bent in a generally arc shape. By using the support beams 32b having a C-shaped cross-section, it is possible to achieve high rigidity with a small cross-sectional area and to reduce the weight of the reflecting part 3b as compared to the case of using the support plates (e.g., the weight of the reflecting part is one- to three-tenths of the weight in the case of using the triangular support plates). In addition, C-shaped beams having a constant height are readily available in the market and are relatively low cost. The support beams 32b can thus be manufactured easily at low cost by applying a simple process on such C-shaped beams (for example, the manufacturing cost can be reduced one-third in the case of manufacturing triangular support plates), and therefore, the manufacturing cost of the sunlight concentrating apparatus 1 can be reduced. In the region of the reflecting part 3b where the support beams 32 are not present, the mirror plate 31 is supported by the rib members 33. This suppresses deflection of the mirror plate 31 under its own weight between the plurality of support beams 32b.
The cross-sectional shape of the support beams 32b is not limited to the shape illustrated in
While, in the case of the support plates 32 and 32a and the support beams 32b described above, the cross-sectional shape changes smoothly and continuously along the width direction, the cross-sectional shape of the support plates 32 and 32a and the support beams 32b may change roughly (in stages) along the width direction.
The support beams 32b in
For the reflecting parts 3b including the support beams 32b in
As described above, in the sunlight concentrating apparatus 1, the reflecting part having a cross-sectional shape that is perpendicular to the width direction and that changes along the width direction (preferably, approximately over the width direction) so that the reflection surface 30 can be bent in a generally arc shape can be achieved in various forms.
The above-described sunlight concentrating apparatus 1 can be modified in various ways. For example, the ratio between the distance from each end portion in the width direction and the second moment of area at this distance may be made constant between the end portion and the central linear region 39, by changing the thickness in the central normal direction in one range of a target portion of the support plate in the width direction (e.g., an approximately 80% range of the entire length from the fixed end) and changing the axial width in the other range. Alternatively, both of the thickness in the central normal direction and the width of the axial direction may be changed as necessary. For example, it is possible to employ a support plate whose target portion as viewed in the central normal direction has a generally triangular shape having a blunt vertex in the end portions and whose thickness in the central normal direction changes only in the vicinity of the end portions. As described above, the support plates in which 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 39 can be implemented in various forms (the same applies to the case where the ratio between the distance in the width direction from each end portion of the reflecting part in the width direction and the flexural rigidity of the reflection part at this distance is constant).
The support plates 32 of the reflecting part 3 may be omitted. In this case, the mirror plate 31 is configured such that 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 39.
The sunlight concentrating apparatus 1 may include the rotating mechanism 4 having a motor and rotate the main shaft part 2 via a speed-reduction mechanism. Alternatively, the sliding mechanism 72 may use mechanical elements (e.g., gears) other than cams to slide the sliding rods 71 in the axial direction in accordance with the rotation of the main shaft part 2. Moreover, in the motion transmission mechanism 73, the sliding rods 71 and the end portions of the reflecting part 3 may be mechanically coupled to each other by a link mechanism, for example, so that the end portions of the reflecting part 3 are moved in the central normal direction along with the sliding of the sliding rods 71.
Depending on the design of the sunlight concentrating apparatus 1, a bending mechanism that uses power independent of that of the rotating mechanism 4 may be employed. For example, a bending mechanism having a motor may be disposed below the end portions of the reflecting part 3, and the end portions of the reflecting part 3 may be moved in the central normal direction by the power of the motor. In this case, the drive of the bending mechanism is controlled by the control part in accordance with the rotation of the main shaft part 2 by the rotating mechanism 4.
The heating medium in the heat collecting part 11 of the solar heat collecting system 10 may be used in applications other than electric power generation. The sunlight concentrating apparatus 1 having the reflection surface 30 that is a variable curved surface may be installed in facilities other than the solar heat collecting system 10.
The configurations of the above-described preferred embodiments and variations may be appropriately combined as long as there are no mutual inconsistencies.
While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore to be understood that numerous modifications and variations can be devised without departing from the scope of the invention.
REFERENCE SIGNS LIST
-
- 1 Sunlight concentrating apparatus
- 2 Main shaft part
- 3, 3a, 3b Reflecting part
- 4 Rotating mechanism
- 5 Main shaft supporter
- 7 Bending mechanism
- 11 Heat collecting part
- 30 Reflection surface
- 31 Mirror plate
- 32, 32a Support plate
- 32b Support beam
- 33, 33a Rib member
- 39 Central linear region
- 321 End portion (of support plate)
- J1 Central axis
Claims
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.
Type: Application
Filed: Mar 14, 2014
Publication Date: Feb 11, 2016
Inventors: Satoshi ASHIDA (Osaka), Donghui MA (Osaka)
Application Number: 14/780,229