JP2009139761A - Sun tracing light condensing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sun tracing light condensing device whose condensing performance is improved though it is a spherical mirror. <P>SOLUTION: Reflected light R' from a reflection mirror 2a at the periphery on the outside far from the optical axis K of a spherical mirror M causing a spherical aberration is parallelly transported by required dimensions d to the optical axis direction from the state of being matched with the spherical mirror M. Concretely, only the reflection mirror 2a in which a spherical aberration lies in the range outside a prescribed range is parallelly transported. Thus the reflected light R' from the reflection mirror 2a at the periphery on the outside passes through the vicinity of the focal position F on the optical axis K, and its condensing performance is improved. Then, owing to the spherical mirror M, the production of the respective reflection mirrors 2, 2a is facilitated, and the inspection regulation of the spherical degree after the parallel arrangement of the reflection mirrors 2, 2a is also facilitated. Instead of parallelly transporting the reflection mirror 2a in the periphery on the outside, it may be rotated by a required angle θ to the outward direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solar tracking condensing device.

  A plurality of reflecting mirrors are arranged side by side to form a concave mirror, tracking control is performed so that the optical axis of the concave mirror always faces the sun, a Stirling engine is supported at the focal point on the optical axis, There is known a solar tracking concentrator that is intended to be used.

  This type of solar tracking concentrator is generally a parabolic mirror as a concave mirror composed of a plurality of reflecting mirrors. This is because all the reflected light gathers at one point (focal point) on the optical axis in the case of a parabolic mirror, and the heat receiving portion of the Stirling engine can be heated evenly (see, for example, Patent Documents 1 and 2).

US Pat. No. 4,463,749 JP-A-9-280664

  However, in such a conventional technique, each of the reflecting mirrors has a curved surface that forms a part of the parabolic mirror because of the structure in which a plurality of reflecting mirrors form one parabolic mirror. Furthermore, it is necessary to arrange the reflecting mirrors side by side in a parabolic shape. Therefore, the manufacturing of the individual reflecting mirrors is troublesome, and the inspection adjustment of the parabolic surface after arranging the reflecting mirrors is troublesome.

  Therefore, it is conceivable to use a spherical mirror that can be easily manufactured and inspected and adjusted instead of a parabolic mirror. Was avoided.

  The present invention has been made paying attention to such a conventional technique, and provides a solar tracking condensing device with improved condensing performance while being a spherical mirror.

  According to a first aspect of the present invention, there is provided a solar tracking condensing device that tracks a plurality of mirror elements defining one spherical mirror in a state where the optical axis of the spherical mirror is directed to the sun, the spherical aberration being predetermined. Only a specific mirror element exceeding the permissible range is changed in attitude with respect to the spherical mirror so that the spherical aberration falls within the permissible range.

  According to a second aspect of the present invention, the posture change is characterized in that the specific mirror element is moved a predetermined distance parallel to the optical axis.

  According to a third aspect of the present invention, the posture change is characterized in that the inclination is changed by a predetermined angle so that the spherical aberration of the specific mirror element falls within the allowable range.

  According to a fourth aspect of the present invention, the specific mirror element is a reflection mirror through which a predetermined inscribed circle centered on an optical axis in a spherical mirror passes and a reflection mirror outside the reflection mirror, the inner mirror The radius of the tangent circle is determined based on the predetermined allowable range.

  According to the first feature of the present invention, since only the specific mirror element whose spherical aberration is outside the predetermined allowable range is changed with respect to the spherical mirror so that the spherical aberration is within the allowable range, the light collecting performance is improved. Greatly improved. Further, since a spherical mirror is used, it is easy to manufacture individual mirror elements, and it is easy to check and adjust the sphericity after the mirror elements are arranged.

  According to the second feature of the present invention, the posture is changed so that the specific mirror element is moved by a predetermined distance parallel to the optical axis, so that the light collecting performance can be improved by a simple change operation.

  According to the third aspect of the present invention, since the posture of the specific mirror element is changed so as to change the angle, the light collecting performance can be improved by a simple change operation.

  According to the fourth aspect of the present invention, the range of mirror elements whose posture is changed can be bounded by a predetermined inscribed circle, so that design and manufacture are easy.

(First embodiment)
FIGS. 1-10 is a figure which shows 1st Example of this invention. The solar tracking concentrating device 1 of this embodiment is a graticule type that rotates in an azimuth direction H and an altitude direction V, and is a type that always tracks an optical device straight toward the sun S.

  The reflection mirrors 2 and 2a used in the solar tracking condensing device 1 are quadrangular or round and have a spherical shape forming a part of one large spherical mirror M described later. The reflecting mirrors 2 and 2a are attached to a large rectangular support panel 3 via support shafts 4 having different lengths. The support shaft 4 is perpendicular to the support panel 3, and the reflection mirrors 2 and 2a are attached to the tip of the support shaft 4 at a predetermined angle. The plurality of reflecting mirrors 2 and 2a attached to the support panel 3 in this way define one large virtual spherical mirror M as a whole. The spherical mirror M also has a substantially quadrangular outer shape and an optical axis K at the center. Although the reflecting mirrors 2 and 2a are preferably spherical, the spherical mirror M can be configured as a whole even if the reflecting mirrors 2 and 2a are planar.

  By rotating the spherical mirror M in the azimuth direction H and the altitude direction V, the optical axis K of the spherical mirror M is controlled so as to always face the sun S. A structure for rotating the spherical mirror M in the azimuth direction H and the altitude direction V will be described below.

  A pipe frame part 5 is integrated under the support panel 3, and the support panel 3 to which the reflection mirrors 2 and 2 a are attached and the pipe frame part 5 constitute a mirror structure 6. The mirror structure 6 is installed on a frame body 7 made of a structural material. The mirror structure 6 is rotatable as a whole about a hinge 8, and the opposite side of the mirror structure 6 from the hinge 8 is connected to an arm portion 9 whose lower end is rotatably supported by a frame body 7. ing. The arm portion 9 is provided with a loop-shaped chain 12 that is movable between the driven pulley 10 and the rotating block 11, and a connecting ring 13 on the opposite side of the mirror structure 6 is coupled to a part of the chain 12. Yes.

  Since the rotational driving force of the altitude side motor 14 is transmitted to the rotary block 11 via the worm gear 15 and the worm wheel 16, the chain 12 engaged with the rotary block 11 moves up and down. Accordingly, since the connecting ring 13 of the mirror structure 6 is coupled to the chain 12, the mirror structure 6 rotates up and down around the hinge 8 in accordance with the chain 12, and the mirror structure 6 in the altitude direction. The angle changes.

  The frame body 7 on which such a mirror structure 6 is placed is installed on the upper portion of the base portion 17 formed on the ground G. A cylindrical portion 18 is formed in the base portion 17, and the frame body 7 rotates in the azimuth direction H around a shaft portion 19 formed at the upper end thereof. Three caster portions 20 are formed in the frame body 7, and the caster portion 20 rolls on the upper surface of the base portion 17, whereby the frame body 7 rotates in the azimuth direction H together with the mirror constituent body 6.

  A chain 21 is wound around the cylindrical portion 18. The chain 21 is hung around with both ends 21a and 21b overlapped at an angle range of 90 °, and a rotating block 22 that engages the chain 21 is provided on a part of the chain 21. The rotating block 22 is supported on the frame body 7 side, and rotates by transmitting the rotational driving force of the azimuth side motor 23 attached to the frame body 7 side via the worm gear 24 and the worm wheel 25. Then, it rotates around the cylindrical portion 18 along the chain 22. Accordingly, the frame body 7 rotates in the azimuth direction H together with the rotating block 11.

  The rotation of the mirror structure 6 in the altitude direction V and the rotation of the frame body 7 in the azimuth direction H are controlled by the altitude sensor 26 and the azimuth sensor 27 detecting the direction of the sunlight L. That is, a feedback signal from the altitude sensor 26 and the azimuth sensor 27 to the altitude side motor 14 and the azimuth side motor 23 so that the optical axis K of the spherical mirror M formed by the plurality of reflecting mirrors 2 and 2a always faces the sun S. Is output.

  The focal point F on the optical axis K of the spherical mirror M is at a position moved from the spherical center toward the spherical surface (pole) by 1/2 of the distance between the spherical center and the pole, that is, 1/2 of the spherical radius of the spherical mirror M. The light receiving portion (heat receiving portion) of the Stirling engine 28 is supported on the support panel 3 by a support pipe 29 in the vicinity of the focal point F. When the heat receiving portion is heated by the sunlight L, the Stirling engine 28 generates about 1 to 3 kW.

<Spherical aberration>
In FIG. 8, sunlight rays I, II, and III are incident on the spherical mirror M at a predetermined distance from the optical axis parallel to the optical axis K. A virtual spherical mirror M having a predetermined curvature as a whole is defined by the individual reflecting surfaces of the plurality of reflecting mirrors 2 and 2a. Light rays I and II having a small distance from the optical axis are reflected by the spherical mirror M and pass near the focal point F on the optical axis K. On the other hand, as the distance from the optical axis K increases with respect to the radius of curvature, the position crossing the optical axis moves away from the focal point F. That is, the light beam III incident on the mirror 2a passes through a position offset by a significant distance D from the focal point F on the optical axis. If this position deviates from the heat receiving portion of the Stirling engine 28, the light beam III cannot contribute to heating.

  FIG. 9 shows a characteristic curve representing the relationship between the distance of the incident light beam L from the optical axis K and the position where the reflected light crosses the optical axis K. The vertical axis Z displays the position where the reflected light crosses the optical axis K with respect to the focal point F, that is, the deviation as positive below, and the spherical aberration of each reflected light is expressed by the deviation of the intersection of the reflected light and the optical axis K. Is. Therefore, the vertical axis corresponds to the distance from the optical axis K at the position where the reflected light crosses the virtual plane perpendicular to the optical axis at the focal point F. In the vertical axis, Z = 0 corresponds to the focal point F. When the reflection position of the incident light beam L is relatively close to the optical axis K (I, II), the spherical aberration is small. However, the farther the reflection position is, the larger the spherical aberration is. For example, in this embodiment, when the range of spherical aberration allowed based on the shape, size and position of the heat receiving portion of the Stirling engine 28 is in the range of Z = 0 to A, the optical axis K in FIG. The sunlight III incident on the distant position is out of the above range and passes through the position f (D> A) greatly deviated from the focal point F, and thus cannot contribute to the heating of the Stirling engine.

<Correction of spherical aberration>
Thus, when the allowable range ΔA of spherical aberration is determined, the range outside the allowable range of the reflected light is an area where X ≧ Xa at the reflection position of the incident light, and this is referred to as “outer area”. In this case, if only the mirror element in the outer region of the spherical mirror M is moved a predetermined distance toward the sun parallel to the optical axis K direction, the curved region Ra in FIG. 9 is translated into the region Rb. As a result, the sun rays reflected by the moved mirror element in the outer region fall within the allowable range of spherical aberration, so that all the mirror elements can contribute to the heating of the Stirling engine.

  Therefore, in order to improve the light condensing degree of the spherical mirror M, it is only necessary to determine the range of allowable spherical aberration, specify the outer region accordingly, and translate the mirror elements related to the outer region. The allowable spherical aberration range ΔA (A1 ≦ Z ≦ A2) can be determined based on the distribution of the heat receiving area (light receiving area), that is, the shape, size, position, etc. of the heat receiving section. In general, the light receiving surface or the heat receiving surface is distributed in a space near the focal point F, and the allowable range ΔA can be determined in consideration of the distribution density of reflected light.

  Since the characteristic curve of FIG. 9 is calculated mainly based on the spherical radius of the spherical mirror M, when the allowable range ΔA is determined, the corresponding range of the incident light beam L is obtained. In the example of FIG. 9, since the allowable range ΔA is 0 ≦ Z ≦ A, the boundary is X = Xa, and the range farther from the optical axis K is the outer region (X> Xa). The movement distance can be set so that each mirror element (reflection mirror) related to the outer region is included in the range of ΔA by parallel movement. In FIG. 9, the spherical aberration can be within the allowable range ΔA by translating the specular element in the region of the curve Ra to the position of Ra ′ by the correction C. Normally, the allowable range of spherical aberration is set in the vicinity of the focal point F.

  Next, the spherical mirror M will be described. As indicated by hatching in FIG. 6, a virtual circle N set corresponding to the boundary (X = Xa) with the outer region of the spherical mirror M passes, or the reflecting mirror 2a on the outer side is the target of the correction C It is. A spherical mirror M having a predetermined curvature as a whole is formed by the individual reflecting surfaces of the plurality of reflecting mirrors 2 and 2a. However, as shown in FIGS. Since the mirror 2a is included in the outer region, the mirror 2a is translated to the reflection side along the direction of the optical axis K by a predetermined dimension d. For example, when the allowable range ΔA is set to −A / 2 ≦ Z ≦ A / 2 depending on the position and distribution of the heat receiving region (light receiving region), the dimension d can be determined so that the reflected light is substantially directed to the focal point F. .

  If the spherical mirror M is left as it is, the focal length of the reflecting mirror 2a in the outer region is larger than the focal length of the reflecting mirror 2 near the optical axis K, as shown in FIGS. This is because the aberration (deviation) D occurs between the focal points F and f on the optical axis K, and the light condensing performance decreases. Therefore, in order to reduce the aberration D, the reflecting mirror 2a related to the outer region is translated along the direction of the optical axis K by the dimension d. The translation distance d is appropriately set based on the allowable spherical aberration range ΔA.

  As a result, the reflected light R ′ from the reflection mirror 2a in the outer region passes through the vicinity of the focal point F together with the reflected light R from the inner reflection mirror 2, so that the Stirling engine is heated by the reflected light from all the reflection mirrors. Can do. Therefore, the reflected light R and R ′ can be condensed in the vicinity of the focal point F while the spherical mirror M as a whole, and the light condensing performance is improved. Therefore, the heat receiving portion of the Stirling engine 28 can be heated without unevenness, and the power generation performance of the Stirling engine 28 can be maximized.

  In addition, since each of the reflection mirrors 2 and 2a is a spherical surface that forms a part of the spherical mirror M, the reflection mirrors 2 and 2a can be easily manufactured, and basically, one spherical mirror M is basically configured. In addition, inspection adjustment of the sphericity is easy. Furthermore, the degree of condensing can be greatly improved by the correction C in which only the specific reflecting mirror 2a is translated instead of correcting all the reflecting mirrors so that the reflected light is directed to one specific point.

  In the present embodiment, an example in which the Stirling engine is fixed to the support panel 3 as an example of a solar power utilization device is shown, but the present invention is not limited to this. The solar-powered device includes an optical element such as a reflecting mirror. In this case, the reflecting mirror itself becomes the light receiving unit.

(Second Embodiment)
11 and 12 are views showing a second embodiment of the present invention. This embodiment includes the same components as those in the first embodiment. Therefore, the same constituent elements are denoted by common reference numerals, and redundant description is omitted.

  Also in this embodiment, the spherical aberration is improved only for the specular element included in the outer region shown in FIG. The method for determining the spherical aberration tolerance ΔA and the outer region is the same as in the first embodiment. In the present embodiment, the inclination of the mirror element in the outer region of the spherical mirror M is changed so that the reflected light L passes through the allowable range ΔA on the optical axis K. As a result, since the spherical aberration about the sunlight reflected by the mirror element in the outer region whose inclination is corrected falls within the allowable range, it can contribute to the heating of the Stirling engine.

  Therefore, in order to improve the light condensing degree of the spherical mirror M, it is only necessary to determine the range of allowable spherical aberration, set the outer region accordingly, and correct the inclination of the mirror element related to the outer region. Each corrected inclination angle can be determined mainly by the reflection position of the light beam L on the spherical mirror M and the allowable range ΔA. The inclination angle to be corrected can be set so that the reflected light R ′ is included in the range of ΔA for each specular element (reflection mirror) related to the outer region. By such correction, the Ra area of the curve in FIG. 9 is deformed and moved to the Ra ′ area included in the allowable range ΔA by correction C.

  More specifically, the reflection mirror 2a in the outer region far from the optical axis K is rotated outward by a predetermined angle θ. By doing so, the reflected light R ′ from the outer reflecting mirror 2 a also passes in the vicinity of the same focal point F as the reflected light R from the inner reflecting mirror 2. Therefore, the reflected light R and R ′ can be condensed within the allowable range of spherical aberration, that is, in the vicinity of the focal point F, although the spherical mirror M as a whole, and the condensing performance is improved. In other words, not all the reflection mirrors are corrected so that the reflected light is directed to one specific point, but the degree of light collection can be greatly improved by the correction C that changes the inclination of only the specific reflection mirror 2a.

  In each of the above embodiments, the amount by which the outer reflecting mirror 2a is translated or rotated is shown large so that it can be clearly understood from the drawings. Is.

1 is an overall perspective view showing a solar tracking light concentrating device according to a first embodiment of the present invention. The disassembled perspective view which shows a solar tracking condensing device. The side view which shows a solar tracking condensing device. The side view of the sun tracking condensing device which shows the state which the mirror structure body tilted. Sectional drawing which shows the internal structure of an arm part. The front view which shows a spherical mirror. The side view which shows the state which translated the reflective mirror of the outer periphery. The optical path figure of the reflected light in the spherical mirror which does not translate the reflective mirror of an outer periphery. A characteristic curve representing the relationship between incident light and spherical aberration. The optical path figure of the reflected light by the spherical mirror which translated the reflective mirror of the outer periphery. The side view which shows the state which rotated the reflective mirror of the outer periphery which concerns on 2nd Embodiment of this invention. The optical path figure of the reflected light by the spherical mirror which rotated the reflective mirror of the outer periphery.

Explanation of symbols

1 Sun tracking condensing device 2 Reflecting mirror 2a Reflecting mirror (outside periphery)
M Spherical mirror K Optical axis H Azimuth direction V Altitude direction G Ground L Sun rays S Sun F Focus f Focus (short)
A Allowable aberration d Translation amount D Aberration θ Rotation amount N Virtual circle (inscribed circle)
R Reflected light R 'Reflected light (outer periphery)

Claims (6)

A solar tracking condensing device that tracks a plurality of mirror elements defining one spherical mirror with the optical axis of the spherical mirror facing the sun,
The solar tracking condensing device, wherein only a specific mirror element whose spherical aberration is out of a predetermined allowable range is changed in attitude with respect to the spherical mirror so that the spherical aberration is within the allowable range. The solar light utilization device is fixed to the spherical mirror, the light receiving unit of the solar light utilization device is positioned near the focal point of the spherical mirror,
The solar tracking concentrating device according to claim 1, wherein the predetermined allowable range is determined based on a distribution of a light receiving region of the solar light utilizing device.   The solar tracking condensing device according to claim 1 or 2, wherein the posture change moves the specific mirror element by a predetermined distance parallel to the optical axis.   3. The solar tracking condensing device according to claim 1, wherein the posture change is performed by changing the inclination of the specific mirror element by a predetermined angle so that the spherical aberration of the specific mirror element falls within the allowable range. .   The solar tracking concentrator according to claim 1, wherein the plurality of mirror elements are spherical mirrors. The specific mirror element is a reflecting mirror through which an inscribed circle of the spherical mirror centered on the optical axis of the spherical mirror passes and a reflecting mirror outside the reflecting mirror,
The solar tracking concentrator according to any one of claims 1 to 5, wherein a radius of the inscribed circle is determined based on the predetermined allowable range.

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