JP2009264615A - Solar light collector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar light collector capable of being miniaturized by shortening a focal length. <P>SOLUTION: This solar light collector is provided with a collector 1 having a reflecting face formation layer 4 as a reflecting face 5 on one face of a transparent body of which one face has a cross-section of roughly parabolic shape and of which the other face opposite to the face is composed of a straight line or a curved line bulging in the direction separating from the roughly parabolic shape only at its peripheral section, and made of a transparent substance, and having a solar light incidence plane on the other face, the solar light from the incidence plane is reflected by the reflecting face, and the reflected light is refracted from the incidence plane and emitted to the external, thus a focal length of the emitted light can be shortened. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an improvement in a solar light collecting device that can be reduced in size by shortening a focal length.

A conventional reflector-type solar concentrator collects sunlight with a reflector 15 having a substantially parabolic cross section as shown in JP-A-11-502602, and has a structure in which a light receiver 20 is arranged behind the focal point ( FIG. 8) is known.
However, when the light receiving surface has a substantially planar shape like a solar cell, the reflecting surface cannot be disposed behind the light receiving surface in the traveling direction of solar incident light, but further forward in view of the light receiving efficiency of the light receiving surface. Must be placed.
Accordingly, the distance from the geometrical relationship between the size of the reflecting plate and the focal length to the light receiving surface disposed at the substantially focal position is relatively large, about half the size of the reflecting plate, and the thickness of the apparatus is directly collected. There was a problem that it was larger than the optical solar cell.
To prevent this, a method of reducing the size of the reflector and arranging a plurality of small units is conceivable, but the height of the light receiver is required to be about 50 cm even if the size of the reflector is 1 m or less. In order to further reduce this, it is necessary to connect a large number of small solar cells, which is troublesome and complicated, and is not efficient.
On the other hand, in order to shorten the focal length, a substantially parabolic cross section having a large curvature must be used on the reflecting surface, and the reflector plate having a substantially parabolic cross section that is integrally continuous increases in depth and size.
Incidentally, when the focal length is about ½ of the diameter of the reflector, the depth of the reflector is about ½ of the focal length, and when the size of the reflector is about 1 m. The depth is 20 cm or more.
In order to shorten this, as shown in FIG. 9, the reflecting plate 15 may be divided into a large number and the unit plate 16 may be arranged in a substantially flat shape (see Japanese Patent Application No. 2007-31910).
In this case, the unit plate 16 has a stepped portion 17 between a portion close to and far from the optical axis L10, and the stepped portion 17 is closer to the periphery of the reflecting surface that is farther from the optical axis and has a larger normal angle to the optical axis. The reflected light that is reflected from the reflecting surface toward the focal point is inclined twice the inclination angle of the normal line, so that a part of the stepped portion 17 is interrupted.
Special table 11-115022 Japanese Patent Application No. 2007-31010

The present invention has been made in view of the above circumstances, and a main problem thereof is to provide a solar condensing device having a simple structure capable of setting a focal length short with respect to the size of a reflecting surface. .
Another object of the present invention is to provide a solar light collecting device having a reflective surface with a flat divided substantially parabolic cross section with a high concentration of reflected light.

In order to solve the above problem, the invention of claim 1
A cross-section of one surface has a substantially parabolic shape, and a cross-section of the other surface facing the one surface is a straight line or a curved portion bulging in a direction away from the substantially parabolic shape only at the peripheral portion on the one surface of the transparent body. A reflector is provided integrally, and a condenser with the other surface as an incident surface of sunlight is provided.
The incident light is reflected by the reflecting surface, and the reflected light is refracted from the incident surface and emitted to the outside, thereby shortening the focal length of the emitted light.
In the invention of claim 2,
The reflection surface is composed of a unit surface obtained by dividing a substantially parabolic section into a plurality of sections, and a cross section of an incident surface connecting between outer end portions of unit surfaces arranged at both ends is linear,
Each unit surface excluding the lowest unit surface in the substantially parabolic section is displaced downward and connected so as to be aligned with the lowest unit surface through a step portion made of a plane parallel to the optical axis. It is characterized by becoming.
Furthermore, in the invention of claim 3,
The incident surface of sunlight is a flat surface, and the inclination angle of the reflection surface is made smaller than the inclination angle of the substantially parabolic shape of the cross section of the reflection surface as the distance from the optical axis increases.

In this invention, since the sunlight reflected by the reflecting surface is refracted by the transparent incident surface when it is emitted from the incident surface of the transparent body, the focal length can be greatly shortened compared to the case where there is no refraction. The thickness or height of the light collecting device including the vessel can be reduced.
As a result, not only the installation space and cost of the solar concentrator can be saved, but the shape accuracy of the reflecting surface is maintained and reinforced by a transparent material, and the condensing quality on the light receiving surface is stabilized, resulting in earthquakes and typhoons. The influence of etc. also decreases.

  In the present invention, one surface of the transparent body is used as an incident surface, and a reflecting surface is provided on the other surface to reflect incident sunlight, and the reflected light is further bent at the incident surface, thereby shortening the focal length or collecting light. Realized efficiency improvement.

Hereinafter, preferred embodiments of the solar light collecting device of the present invention will be described with reference to the drawings.
As shown in FIG. 1 and FIG. 2, the concentrator 1 included in the solar light concentrator has a cross section of one surface 2 ′ having a substantially parabolic shape, and the other surface 3 facing the one surface 2 ′. A reflecting surface forming layer 4 is provided along the one surface 2 'of the transparent body made of an innocuous transparent substance having a substantially straight cross-section, and the other surface 3' is formed as a reflecting surface 5. The solar light incident surface 3 is used.

The reflective surface forming layer 4 may be formed by bonding or coating a reflective material to one surface 2 ′ of the transparent body.
In the present embodiment, the incident surface 3 is substantially linear, but only the peripheral portion may be a curved curve that swells away from the substantially parabolic shape (not shown).

In the collector 1, sunlight is incident from the flat incident surface 3, the incident light L 1 is reflected by the reflecting surface 5 having a substantially parabolic cross section, and the reflected light L 2 is emitted (radiated) from the incident surface 3.
The reflected light L2 is inclined by the sum of the inclination angle θ1 of the reflecting surface 5 and the angle θ2 equal to that, that is, twice the angle θ1, except for the optical axis portion L0, but the outgoing light L3 is relative to the light incident surface 3. Further, it is discharged with a bending inclination.

In other words, the reflected light L2 is refracted (θ3) in a direction closer to the reflecting surface 5 side than the focal point P1 that arrives without refraction, and reaches the focal point P2.
The distance h2 from the flat incident surface 3 to the focal point P2 varies depending on the refractive index of the transparent body.

When the transparent body is made of a normal lens material such as glass or plastic, the refractive index is about 1.7, and the distance h2 is shortened by about 40% compared to the distance h1 of the conventional structure that is only reflected and is not refracted thereafter. It can be.
Accordingly, the distance of the light receiver (not shown) arranged in the vicinity of the focal point is also shortened by about 40%, so that the size can be reduced.

  As shown in FIG. 1, when the reflecting surface 5 is formed of a reflecting surface having a series of substantially parabolic cross sections, the transparent body has a convex lens shape and a predetermined thickness is required. Shape and weight.

Here, when it is not necessary to shorten the focal length, the inclination angle of the reflection surface 5 is made smaller than the inclination angle of the substantially parabolic shape of the cross section of the reflection surface as the distance from the optical axis is increased in order to obtain the same light collection effect. Can do.
In the case of the reflecting surface 5 having the same area, the depth of the reflecting surface 5, that is, the thickness of the transparent body is only about half that of the conventional one.
Therefore, for example, when the length (or diameter) of the condenser 1 is about 1 m, the depth or thickness may be about 10 cm.

  In the first embodiment, the case where the reflecting surface 5 has a continuous substantially parabolic shape and the incident surface 3 is a flat surface has been described. In this case, the reflected light and the refracting surface are formed around the reflecting surface. The greater the inclination of, the greater the influence of refraction.

In order to make the focal point the same as the reflected light near the optical axis, the peripheral incident surface is brought close to the angle of the reflective surface and the edge is raised, or the incident surface remains flat and the peripheral portion of the reflective surface is substantially parabolic. It may be smaller than the inclination angle.
In the latter case, the thickness of the transparent material can be reduced as the reflecting surface 5 becomes shallower, which has the effect of reducing the material cost and reducing the weight.
In the former case, the depth of the reflecting surface 5 does not change, but the central portion may be recessed instead of raising the edge of the incident surface, and the thickness of the transparent material can be reduced as in the latter case.

  The concentrator 1 of the solar light collecting device shown in FIG. 3 and FIG. 4 or FIG. 7 has a reflection surface 5 formed of a plurality of unit surfaces 6 as a configuration according to the conventional example 2 of FIG. 6 is formed into a polyhedron by rearranging the substantially parabola in which the cross-sectional shape of 6 is divided into straight lines.

In this case, the line segments of the cross section of each unit surface 6 may have a uniform length. However, in the collector 1 of the second embodiment, the lengths D1, D2, D3,. Is arranged so that it gradually becomes shorter from the center of the reflecting surface 5 toward the end side, and the sectional area of the light beam at the focal point of each unit surface 6 is set to be substantially equal to the light receiving surface of the light receiver. As a result, the light receiving efficiency of the light receiving surface can be improved.
Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  Next, the concentrator 1 of Example 3 shown in FIGS. 5 and 6 is similar to the reflective surface 5 of Example 2 in that the incident surface 3 connecting the outer end portions of the unit surfaces 6 arranged at both ends is provided. The cross section is straight, but the thickness is thin.

That is, each unit surface 6 excluding the lowest unit surface of the unit surface 6 constituting the reflecting surface 5 (referred to as 6 'for convenience of explanation) passes through the stepped portion 7 formed of a surface parallel to the optical axis. The unit surface 6 'is displaced and connected to a lower position so as to be substantially aligned with the unit surface 6', and is arranged in a substantially flat plate shape.
And the upper end of the said level | step-difference part 7 can set the thickness of a transparent body as thin as possible and weight reduction by setting it in the position away only a little length from the entrance plane 3. FIG.

  Further, even when the focal length is the same, an area that cannot be used as a reflecting surface by hitting the stepped portion 7 (in the case of the conventional example) compared to the case where the conventional reflecting plate 15 without refraction shown in the right half of the figure is used for comparison. Can be shortened, and the light collection efficiency of the reflected light can be greatly improved.

Although FIG. 6 illustrates the case where the light receiving surface 11 of the light receiver 10 is a flat surface, the shape of the light receiving surface is not particularly limited in the present invention.
For example, as shown in FIG. 7, even when the light receiver 10 has a cylindrical shape and the light receiving surface 11 is a curved surface, the same effect can be obtained.

As described above, the reflecting surface of the condenser 1 may have a spherical shape, a circular arc shape, or a polyhedron.
Furthermore, the unit surface may be configured by combining a plurality of concentric annular bodies having a circular center at the center and gradually increasing in diameter toward the end of the reflecting surface without any gap (not shown).

Further, the reflecting surface is not limited to a substantially spherical surface, but may be a semi-cylindrical shape having a substantially cross-sectional arc shape in which a substantially parabolic cross-section is extended in the depth direction as it is (see FIG. 7).
In addition, it goes without saying that various design changes can be made without departing from the scope of the present invention.

It is a schematic diagram which shows the cross section of the collector of Example 1 of a sunlight condensing device. It is a figure explaining shortening of the focal distance of the collector of FIG. FIG. 6 is a schematic diagram showing a cross section of a concentrator of Example 2. FIG. 4 is a perspective view of the light collector of FIG. 3. It is explanatory drawing which showed the cross section of the collector of Example 3 in the left half, and showed the cross section of the conventional reflecting plate in the right half. It is a perspective view which shows the collector and light receiver of Example 3. It is a perspective view which shows the Example from which a light receiver differs. It is sectional drawing of the prior art example 1 in which a collector | concentrator consists of a reflecting plate. It is sectional drawing of the prior art example 2 which consists of a unit surface where the reflecting plate was divided | segmented.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light collector 2 'One surface 3 of a transparent body Incident surface 3' The other surface 4 of a transparent body 4 Reflecting surface formation layer 5 Reflecting surface 6 Unit surface 7 Step part 10 Light receiver 11 Light receiving surface

Claims (3)

A cross-section of one surface has a substantially parabolic shape, and a cross-section of the other surface facing the one surface is a straight line or a curved portion bulging in a direction away from the substantially parabolic shape only at the peripheral portion on the one surface of the transparent body. A reflector is provided integrally, and a condenser with the other surface as an incident surface of sunlight is provided.
Sunlight incident from the incident surface is reflected by the reflecting surface, and the reflected light is refracted from the incident surface and emitted to the outside, thereby reducing the focal length of the emitted light. Concentrator. The reflecting surface is composed of a unit surface obtained by dividing a substantially parabolic section into a plurality of sections, and the section of the incident surface connecting between the outer ends of the unit surfaces arranged at both ends is linear,
Each unit surface excluding the lowest unit surface in the substantially parabolic section is displaced downward and connected so as to be aligned with the lowest unit surface through a step portion made of a plane parallel to the optical axis. The solar light collecting apparatus according to claim 1, wherein   The solar light collection according to claim 1 or 2, wherein the incident surface of sunlight is a flat surface, and the inclination angle of the reflection surface is made smaller than the inclination angle of the substantially parabolic shape of the cross section of the reflection surface as the distance from the optical axis increases. Optical device.

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