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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to devices for harnessing solar energy and
converting same to satisfy household and/or industrial energy requirements
and in particular relates to heliostat construction.
2. Description of the Prior Art
With the advent of the fuel and energy crisis in the past few years, a
re-examination of the prior art and renewed and concentrated endeavors to
harness solar energy have been prime targets of the scientific community.
Exemplifying the prior art devices of the class to which the present
invention appertains are the constructions disclosed in U.S. Pat. Nos.
2,471,954 [Harvey] and 3,466,119 [Francia]. Notwithstanding the existence
of voluminous prior art relevant to solar energy devices, such devices
have not heretofore been put to use on a large scale. Rather it is the
general consensus that the known solar devices are not commercially
feasible for various reasons. The prior art devices of this type have
failed to gain commercial acceptance for reasons such as the exorbitant
initial cost of manufacture of complex systems, the great amount of space
required for such systems, and the low rate of efficiency of such systems
among numerous other reasons. Needless to say, the solar heat
concentrating devices of the Harvey and the Francia patents, mentioned
above, include many linkages, levers and complex arrangements of
mechanical elements, which to say the least may require extensive
maintenance and upkeep.
SUMMARY OF THE INVENTION
The present invention provides a new and improved heliostat apparatus for
concentrating solar energy and comprises a plurality of mirror units
trained to receive incident rays of the sun and to focus reflection
thereof to a desired focal point. The mirror units are mounted on a
support structure in such a manner that each mirror has freedom of
substantial universal articulation. Adjustment structure is provided to
effect conjoint articulation of each mirror unit to thereby conjointly
retrain the mirror units to receive incident rays of the sun and maintain
reflection thereof to the desired focal point over the course of each day.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a new and improved
solar concentrator of sufficiently high efficiency as to gain commercial
acceptance.
It is also an object of the present invention to provide a new and improved
solar concentrator which will require an appreciable lesser amount of
space than the known prior art devices of this type.
It is a further object of the present invention to provide a new and
improved solar concentrator which will require comparatively fewer parts
than the known prior art devices of this type.
It is another object of the present invention to provide a new and improved
solar concentrator which will be simpler in operation than the known prior
art devices of this type.
It is yet another object of the present invention to provide a new and
improved solar concentrator having a generally low profile which will
readily blend in with existing structure in an unobtrusive manner.
It is moreover an object of the present invention to provide a new and
improved solar concentrator suitable for installation in private homes to
supply the heat requirements thereof.
It is yet a further object of the present invention to provide a new and
improved solar concentrator that is readily adaptable to accommodate
obstructions on a roof including line-of-sight obstacles such as chimneys
or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a plan view of a schematic layout of a partially assembled
heliostat apparatus according to one form of the present invention;
FIG. 2 is a sectional view taken along section 2--2 of FIG. 1;
FIG. 3 is an elevational view of several units of FIG. 2 on an enlarged
scale;
FIG. 4 shows an elevational view of an alternative form of the units in
FIG. 3; FIG. 5 is a sectional view taken along section 5--5 in FIG. 4;
FIG. 6 is a sectional view taken along section 6--6 in FIG. 4;
FIG. 7 shows an elevational view of a second alternative form of the units
in FIG. 3;
FIG. 8 is an enlarged view of a sectional view taken along section 8--8 in
FIG. 7;
FIG. 9 is an enlarged view in section of an alternative joint construction
for that which is illustrated in FIGS. 7 and 8;
FIG. 10 is a sectional view taken along section 10--10 in FIG. 9;
FIG. 11 is a view in perspective showing the general location of support
and adjustment portions of the apparatus of FIGS. 1 and 2;
FIG. 12 is a view in perspective showing another alternative embodiment
according to the present invention;
FIG. 13 is a sectional view in elevation taken along section 13--13 in FIG.
12;
FIG. 14 is a sectional view in elevation of an alternative form of the unit
of FIG. 13;
FIG. 15 shows an elevational view of yet another alternative form of the
units in FIG. 3;
FIG. 16 is a plan view of FIG. 15;
FIG. 17 shows an elevational view of an alternative form of the unit in
FIG. 13;
FIG. 18 shows an elevational view of yet another alternative form of the
unit in FIG. 13;
FIG. 19 is a plan view of yet another alternative embodiment according to
the present invention; and
FIG. 20 is a sectional view in elevation taken along section 20--20 in FIG
19.
DETAILED DESCRIPTION OF THE INVENTION
Referring now in particular to the drawings, the reader will readily
appreciate that one form of the present invention is embodied in the
heliostat apparatus 10 depicted in FIGS. 1-3 as comprising a plurality of
groups G.sub.1, G.sub.2, and G.sub.3 of mirror units 12, each of which is
operably connected to a common support structure 14 and a common
adjustment structure 16. While three groups of mirror units 12 are
illustrated, it is clearly within the contemplation of this invention to
have fewer or more groups G.sub.x than as illustrated. As best seen in
FIG. 1 the mirror units 12 of each of the groups G.sub.1, G.sub.2, and
G.sub.3 are arranged in generally arcuate paths. In the completely
assembled form of the heliostat apparatus 10, the mirror units 12 of each
of the groups G.sub.1, G.sub.2, and G.sub.3 may be arranged in closed
arcuate paths, in semi-circular paths, in an array confined by a generally
rectangular outline 18, or in arcuate paths with the portion of outline 18
omitted.
Each mirror unit 12 includes an upper reflection surface 20 trained or
directed in an upwardly facing direction to receive incident rays R of the
sun and to focus the reflection thereof to a focal point or spot F thus
concentrating solar energy thereat. In carrying forth the objectives of
the present invention, each mirror unit 12 is provided with a generally
vertically extending rigid upright 22 extending downwardly from the
underside of reflective surface 20. Each upright 22 has a ball portion 24
extending therearound and secured thereto. Each ball portion 24 is
disposed in a socket 26 formed in the common support structure 14 for
universal movement therein. A slot 28 is formed at the lower end of each
upright 22 and arranged to straddle a pin 30 or like member provided on
common adjustment structure 16. The lower end of each upright 22 is
further secured to common adjustment structure 16 and thus constrained to
be shifted thereby.
According to the present invention the reflective surface 20 of each mirror
unit 12 in a first group G.sub.1 is disposed at one and the same given
angle a.sub.1 with the horizontal so that incident rays R of the sun are
reflected and focused upon a selected point or spot F; and the reflective
surfaces 20 of mirror unit 12 in second and third groups G.sub.2 and
G.sub.3 are disposed at the second and third given angles a.sub.2 and
a.sub.3, respectively, to reflect and focus incident rays R of the sun
upon the same selected focal point F.
Referring to FIG. 11, the reader will readily see that common support
structure 14 is depicted by a plurality of concentric rings at a level
L.sub.1 and the common adjustment structure 16 depicted by a plurality of
concentric rings at a level L.sub.2 parallel to the level L.sub.1.
Referring back to FIG. 1 the concentric rings of common support structure
14 are seen to be structurally connected by rigid spokes 32. It is to be
understood that the concentric rings of common adjustment structure 16 are
rigidly connected to each other in a manner similar to that in which the
concentric rings of common support structure 14 are interconnected.
With the heliostat apparatus 10 constructed as described above, it is clear
that with common support structure 14 fixedly secured in a given plane,
any motion imparted to common adjustment structure 16 will effect conjoint
articulation of each upright 22 of each mirror unit 12 of each of the
groups G.sub.1, G.sub.2, and G.sub.3 and consequently each reflective
surface 20 by the same amount so that the difference between the angles
a.sub.1, a.sub.2, and a.sub.3 will remain constant. Thus as the sun shifts
its position with respect to the earth in the course of the day, each
mirror unit 12 of the heliostat apparatus 10 may be shifted to follow the
sun in such a way that incident rays R of the sun may be continuously
retrained to reflect and focus upon the same selected focal point or spot
F. It is clear that common adjustment structure 16 may be manually shifted
to retrain the reflective surfaces 20 to reflect and focus upon the same
focal point F by applying horizontal forces thereon in the proper
direction; however, it is envisioned that heliostat apparatus 10 be
adapted to be used in combination with motorized actuators and
computerized follower mechanism. For example, fluid motor means may be
secured to common adjustment structure 16 at three or four locations
120.degree. or 90.degree. apart, respectively, so that any horizontal
force applied to common adjustment structure 16 will effect conjoint
pivotal movement of each upright 22 by reason of articulation of ball
portion 24 in the respective socket 26 with common adjustment structure 16
moving toward or away from common support structure 14, but remaining
parallel thereto. From the foregoing it is clear that as each upright 22
is pivoted, reflective surfaces 20 at the upper end of the upright 22 will
also be shifted conjointly.
Because each mirror unit 12 is supported for substantially complete
universal articulation on common support structure 14 by ball and socket
members 24, 26 and is further operably connected to each and every other
mirror unit 12 by common adjustment structure 16, significantly greater
efficiency is attainable with the heliostat apparatus 10 formed thereby
since the entirety of each reflective surface 20 may be continuously
directed to reflect and focus upon one and the same point or spot.
Favorable results are attainable in particular when the reflective
surfaces 20 comprise a great number of small reflective surfaces in
contrast to a smaller number of larger reflective surfaces. Where larger
or elongate reflective units are used, lower efficiency would be obtained
since it would be difficult to provide universal pivot joints for larger
or elongate reflective surfaces of such units.
In a preferred embodiment of the present invention as represented in FIGS.
1-3, the reflective surface 20 of each mirror unit 12 includes an outer
circumferential length C, an inner circumferential length D, and radial
edges having projected length P.sub.x on a horizontal plane of which C is
equal to P.sub.x for all mirror units 12 whether in the same or in
different groups G.sub.1, G.sub.2, G.sub.3 ; D is equal in the case of all
mirror units 12 in the same group, but different from group to group; and
D is less than C for all mirror units 12. The mirror units 12 as described
above need only be spaced at a slight gap from adjacent mirror units 12 in
the same group G.sub.1, G.sub.2, or G.sub.3, which gap is to be only
slightly more than the thickness of the reflective surface 20 at the edge.
Similarly, P.sub.x may be only slightly less than the separation between
centers of support bearings of adjacent groups G.sub.1, G.sub.2, G.sub.3.
The actual length of C should be as great as possible but should be less
than half the minimum linear dimension of the area onto which reflected
rays are focused. In the foregoing arrangement which is adapted to follow
movement of the incident rays of the sun which upon moving through an
angle X, for example, each mirror unit 12 will be moved through an angle
X/2 in the same direction to maintain reflection of focus of incident rays
R upon focal point or spot F. Because each mirror unit 12 is
interconnected to a common support structure 14 and are also conjointly
shiftable by a common adjustment structure 16, movement of one mirror unit
12 to maintain reflection of incident rays R of the sun on focal point or
spot F will be accompanied by movement of all other mirror units 12 in
unison to maintain reflection of incident rays R of all mirror units 12
upon focal spot F.
While common support structure 14 is illustrated as being at upper level
L.sub.1 and common adjustment structure 16 is at lower level L.sub.2, it
is within the concept of the invention that the levels L.sub.1 and L.sub.2
for these structures may be interchanged. Further, while only support
structure 14 is illustrated as including ball and socket members,
adjustment structure 16 may also include articulating ball and socket
members. In light of the foregoing considerations, an alternative form to
mirror unit 12 is illustrated in FIGS. 4-6 as mirror unit 12' which
includes a reflective surface 20' on an upright 22' having a slot 23'
forming two legs 25' of which one leg may be inserted into an opening 15'
in a shiftable common adjustment member 16' at an upper level L.sub.1. At
the lower end of legs 25' is secured a ball 24' disposed in a socket 26'
formed on common support structure 14' fixed at lower level L.sub.2. Ball
24' is disposed in socket 26' for general universal articulation therein.
With support structure 14' fixed at level L.sub.2, any shifting movement
of adjustment member 16' will necessarily be both horizontal and vertical
in nature with tilting of upright 22' and mirror unit 12' and articulation
of ball 24' in socket 26'. Tilting action of upright 22' is further
controlled by confinement of a bevel edge 27' at the crotch 29' of slot
23' with the edge 27' riding on a valley 31' between twin peaks 33' on the
upper surface of adjustment member 16'. To support the weight of common
adjustment member 16' and ensure firm contact between edge 27' and valley
31', a coil spring 35' is disposed around legs 25' and against ball 24'
and the underside of adjustment member 16'. It is also noted that within
the scope and contemplation of the present invention common adjustment
structure 16' may comprise a plurality of interconnected concentric
polygonal members.
As another alternative form of mirror unit 12 and mirror unit 12' FIGS. 7
and 8 depict a mirror unit 12" which includes a reflective surface 20" on
an upright 22" rotatably supported in a common support structure 14" fixed
either at an upper level L.sub.1 or at a lower level L.sub.2, but fixed at
lower level L.sub.2 for purposes of discussion. Consistent with the
options of support structure 14" shiftable common adjustment structure 16"
may be disposed either at a lower level L.sub.2 or at an upper level
L.sub.1, but disposed at upper level L.sub.1 for purposes of discussion.
At the lower end of each upright 22" in the vicinity of level L.sub.2 a
ball 24" is provided in universal articulating relationship within socket
26" of common support structure 14". At the vicinity of the plane of
L.sub.1, a ball 25" is disposed around each upright 22" in articulating
relationship within a socket 27" formed on common adjustment structure
16". A circumferential groove 29" extending in a generally vertical plane
is formed on ball 25" in which one or more projections 31" extend radially
inwardly from socket 27". In this relationship projections 31", which are
conical in shape, cooperate with groove 29" to permit relative rotation
between ball 25" and socket 27" about an axis normal to the plane of
groove 29" and to permit no rotation between ball 25" and socket 27" about
the axis of the mirror unit 22". As clearly seen in FIG. 8 one or more
radial protuberances 33" extend outwardly from upright 22" in a generally
horizontal plane into notches 35" provided in ball 25" whereby relative
rotation between upright 22" and ball 25" about the axis of upright 22" is
precluded. With the relationships between upright 22", ball 25" and socket
27", it is clear that relative rotation between reflective surface 20" and
adjustment structure 16" about the axis of upright 22" is precluded.
An alternative embodiment of the arrangement of ball 25" and socket 27" of
FIGS. 7 and 8 appears on an enlarged scale in FIGS. 9 and 10 in which each
upright 22"' is provided with a ball 25"' therearound at level L.sub.1,
for example. Ball 25"' includes one or more notches 35"' in which radial
protuberances 33"' of upright 22"' are received to preclude relative
rotation between upright 22"' and ball 25"'. Each ball 25"' is rotatably
disposed within a socket 27"' attached to a common support structure 16"'.
A groove 29"' is formed in the surface of ball 25"' as a great circle
thereof in a generally vertical plane. As clearly illustrated in FIG. 10,
groove 29"' is semi-circular in cross section. A member projecting
radially inwardly from socket 27"' into groove 29"' in the form of a
sphere 31"' prevents rotation between socket 27"' and ball 25"' about the
axis of upright 22"', but permits rotation of ball 25"' about an axis
normal to the plane of groove 29"' through which sphere 31"'. With the
foregoing arrangement it is clearly seen that relative rotation between
each upright 22"' and adjustment structure 16"' is precluded about the
axis of upright 22"', but is permitted into any of various positions as
indicated in dotted outline in FIG. 9. Polar bores 37"' and 39"' are
formed at the upper and lower surfaces of socket 27"' to provide clearance
for tilting of upright 22"'.
An alternative embodiment according to the present invention appears in
FIG. 12 in the form of heliostat apparatus 110 which comprises a plurality
of annular groups G.sub.1, G.sub.2, G.sub.3 of mirror units 112 each of
which are in generally block form with inclined reflective surfaces 120 at
the upper end thereof. The grouping of the mirror units 112 and general
arrangement of the respective reflective surfaces 120 thereof are in
accord with those discussed in connection with FIGS. 1 and 2. Each mirror
unit 112 as seen in cross section in FIG. 13 includes a ball portion 113
at the base thereof, a radially inner wall 115, a radially outer wall 117,
along with the upper reflective surface 120. Inner and outer walls 115,
117 are generally concentric to each other and ball portion 113 is adapted
to be rock on or in a support member or surface. Each inner wall 115
according to the arrangement of heliostat apparatus 110 is in contact with
an outer wall 117 of a mirror unit 112 inwardly thereof except, of course,
in the case of mirror units 112 in the innermost group. Similarly, each
outer wall 117 is in contact with an inner wall 115 of a mirror unit 112
outwardly thereof except in the case of mirror units 112 in the outermost
group. Each mirror unit 112 further includes a pair of radial sidewalls in
contact with a radial sidewall of a unit 112 on opposite sides thereof. To
maintain continuous contact between various inner and outer walls 115, 117
as well as the various radial sidewalls of the mirror units 112 a
resilient tensioned band or cable 119 extends around the outer walls 117
of each unit 112 of the outer group G.sub.3. With the reflective surfaces
120 of all mirror units 112 preset at angles as described in connection
with heliostat apparatus 10 of FIGS. 1-3, so that incident rays R of the
sun are reflected to and concentrated at a desired focal point or spot F,
it is clear that movement of any one mirror unit 112 to follow the
incident rays of the sun to maintain reflection thereof on the desired
spot F will necessarily effect movement of all other units 112 due to
motion transmitted between all contacting inner and outer walls 115, 117,
and all contacting sidewalls of all mirror units effected by tensioned
band 119 and tilting movement of all mirror units 112 about the respective
ball portions 113 in or on a support surface that would be fixed. To
maintain stability of band 119, a positioning loop 121 through which band
119 is passed is provided on the outer wall 117 of each mirror unit 112 in
the outer group G.sub.3. In the arrangement of the various mirror units
112 of heliostat apparatus 110, cable or band 119 is at upper level
L.sub.1, whereas ball portions 113 are at lower level L.sub.2 in or on a
fixed surface. To adjust the reflective surface 120 of any one mirror unit
112 and consequently all reflective surfaces 120 of all mirror units 112
of heliostat apparatus 110 and thereby maintain reflection of incident
rays R of the sun continuously focused at spot F, it is only necessary to
apply sufficient force upon the outer wall 117 in the direction in which
the sun has moved therefrom to cause tilting of each unit 112 about ball
portions 113 by half the angle traversed by the sun.
An alternative form of mirror unit 112 appears in FIG. 14 and is designated
by reference number 212. Mirror unit 212 which is generally similar to
mirror unit 112 differs from the latter in that ball portion 213 thereof
is pivotally held in a socket 226, which may be part of a fixed support.
A further alternative form to mirror unit 12 appears in FIGS. 15 and 16 as
mirror unit 312 having an upright 322 with a plurality of reflective
surfaces 320 secured to the upper end thereof. Each reflective surface 320
is arranged at a preset angle from the horizontal. At level L.sub.2
adjustment member 316 may be shifted to effect tilting of upright 322
within socket 326 of support structure 314.
Another embodiment alternative to mirror unit 112 may be seen in FIG. 17 as
a mirror unit 412 formed with a hemisphere base portion 413 and have a
plurality of reflective surfaces 420 arranged at a preset angle to the
horizontal at the upper end thereof.
A further mirror unit 512 may be seen in FIG. 18 as an alternate form of
mirror unit 112. Mirror unit 512 comprises a plurality of inclined
reflective surfaces 520 at the upper end thereof, inner and outer walls
515, 517, and side walls for operation as corresponding walls of mirror
unit 112. Mirror unit 512 further includes an upright 522 having a
yieldable spring portion 523 connected to a fixed support 514 so that any
force applied to any of the walls of unit 512 may be transmitted to
adjacent walls in contact therewith. Because of the resilient connection
provided between upright 522 and fixed support 514 by spring portion 523,
the upper part of mirror unit 512 will have the capacity for tilting
movement about support 514 in a universal motion so that the inner and
outer walls 515, 517, and the side walls of mirror unit 512 function as
adjustment members for adjacent mirror units 512 having wall portions in
contact therewith.
Another embodiment of the invention appears in FIGS. 19 and 20 as an
alternative to those disclosed in FIGS. 1 and 2 and in FIG. 12 in the form
of heliostat 610, which comprises a plurality of mirror units 612. Each
mirror unit 612 includes a head 611 pivotally assembled on a frame 613
secured to a common support structure 614 at an upper level L.sub.1 by
rigid connector elements 615. The head 611 of each mirror unit 612
includes a reflective surface 620 similar in construction and arrangement
as the corresponding reflective surfaces 20 and 120 of the mirror units 12
and 112, respectively, as described above to focus and concentrate
reflections of incident rays of the sun to a desired point or spot F. To
facilitate movement for following the sun, each head 611 has a pair of
gimbals 617 on opposite sides thereof which extend into a rigid
surrounding mounting bracket 618 to provide a pivotal relationship between
head 611 and bracket 618. Frame 613 includes a first set of support rods
619 and a second set of stabilizing rods 621 which are integral with and
cross each of the support rods 619. Each mounting bracket 618 has a pair
of gimbals 623 on opposite sides thereof which are at right angle to
gimbals 617 and extend into frame 613 and/or support rods 619 to provide a
pivotal relationship between head 611 and frame 613. With the foregoing
arrangement, it is clear that each mirror unit head 611 and consequently
each reflective surface 620 is afforded pivotal relationship with respect
to frame 613 along two axes which are at right angle to each other. Each
mirror unit 612 also includes an upright 622 pivotally connected to a
common adjustment structure 616 at a lower level L.sub.2. Rigidly secured
to adjustment structure 616 are a plurality of ram devices 624 each of
which includes an outwardly extending rod 626 with a universally rotatable
ball 628 on the end thereof. The rams devices 624 may be of the fluid
cylinder type, for example, and are so arranged that movement of the rod
626 of one ram device 624 will encounter no interference from the others
and in fact may be coordinated with that of one or more of the other ram
devices 624. For example, the ram devices 624 may be considered in FIG. 19
as being in coordinated pairs in the north-south positions and in the
east-west positions wherein inward movement of the rod 626 of one ram
device 624 of a coordinated pair of ram devices 624 will be accompanied by
outward movement of the rod 626 of the other ram device 624 by the same
magnitude, but with no inward or outward movement of the rods 626 of rams
624 of the other coordinated pair. Coordinated operation of each pair of
ram devices 624 is effected by fluid connection between the supply and
exhaust of one ram device 624 to the exhaust and supply, respectively, of
the other ram device 624, with suitable controls. It is clear that balls
628, which are provided on the end of each rod 626, will because of their
universal action effect independence between one coordinated pair of ram
devices 624 and the other coordinated pair of ram devices 624. In
operation each ball 628 is disposed against an abutting surface of support
structure 614 with the balls 628 of one pair of ram devices 624 being
rolled along the abutting surfaces 614 thereof as the rods 626 of the
other pair of ram devices 624 move in and out, respectively, but with all
balls 628 being maintained in continuous contact with the respective
abutting surfaces 614 thereof.
With the arrangement in FIG. 19 movement of the rods 626 of the north-south
rams 624 will effect conjoint tilting of reflective surfaces 620 of
heliostat apparatus 610 about gimbals 623 whereas movement of the rods 626
of the east-west rams 624 will effect conjoint tilting of reflective
surfaces 620 about gimbals 617. Each upright 622 as assembled with
adjustment structure 616 will be tilted from the vertical position
illustrated in FIG. 20 and adjustment structure 616 will be raised and/or
lowered when rods 626 of at least one coordinated pair of rams 624 are
moved in the cylinders thereof to effect a conjoint corrective or
retraining movement of the reflective surfaces 620 of all mirror units 612
to maintain reflection of the sun's rays at point F. As adjustment
structure 616 is shifted, each ball 628 in effect rides up or down and/or
horizontally on the respective abutment surface 614 with continuous
contact maintained therebetween.
While several embodiments of the present invention have been illustrated
and described herein, numerous other variations or modifications thereof
may occur to those having skill in the art and what is intended to be
covered herein is not only the illustrated forms of the invention, but
also any and all modified forms thereof as may come within the spirit of
said invention.
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