Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S30/00—Arrangements for moving or orienting solar heat collector modules
  • F24S30/40—Arrangements for moving or orienting solar heat collector modules for rotary movement
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
  • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S40/00—Safety or protection arrangements of solar heat collectors; Preventing malfunction of solar heat collectors
  • F24S40/80—Accommodating differential expansion of solar collector elements
  • F24S40/85—Arrangements for protecting solar collectors against adverse weather conditions
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S50/00—Arrangements for controlling solar heat collectors
  • F24S50/20—Arrangements for controlling solar heat collectors for tracking
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S80/00—Details, accessories or component parts of solar heat collectors not provided for in groups F24S10/00-F24S70/00
  • F24S80/50—Elements for transmitting incoming solar rays and preventing outgoing heat radiation; Transparent coverings
  • F24S80/56—Elements for transmitting incoming solar rays and preventing outgoing heat radiation; Transparent coverings characterised by means for preventing heat loss
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S80/00—Details, accessories or component parts of solar heat collectors not provided for in groups F24S10/00-F24S70/00
  • F24S80/50—Elements for transmitting incoming solar rays and preventing outgoing heat radiation; Transparent coverings
  • F24S80/52—Elements for transmitting incoming solar rays and preventing outgoing heat radiation; Transparent coverings characterised by the material
  • F24S80/525—Elements for transmitting incoming solar rays and preventing outgoing heat radiation; Transparent coverings characterised by the material made of plastics
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
  • Y02B10/00—Integration of renewable energy sources in buildings
  • Y02B10/20—Solar thermal
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/40—Solar thermal energy, e.g. solar towers
  • Y02E10/47—Mountings or tracking

Definitions

• the present invention relates generally to the field of heliostats and solar arrays. More specifically, the present invention pertains to a heliostat protected by a mechanical enclosure that renders it optimized tor domestic lighting use.
• a heliostat is a device used to follow the Sun's route during the span of the day, usually to orient the light thereof towards a precise target thanks to the help of one or more mirrors.
• heliostats arc mostly used in industrial thermodynamic processes to increase the temperature of thermal devices on towers, by the simultaneous use of several heliostats pointing at the same target, which are indispensable to obtain the necessary temperatures for devices that convert heat into electricity.
• heliostats may include light-redirection for domestic and city uses, in which the heliostat redirects sunlight towards an object, room, street, monument or piazza to iUuminate, brighten and/or warm.
• a heliostat as a domestic device to place indoors (on a window sill, kitchen-island, desk, nightstand, wall or ceiling to name a few options) or outdoors (balcony railing or garden for example) in order for such domestic device to be in direct contact with the sun that it then is able to redirect where sunlight is most needed, which could be indoors (on the ceiling to obtain a diffuse lighting effect thanks to the scattering provided by the ceiling material or in specific parts of the building to obtain a task-based lighting effect such as to illuminate a specific area of the building like a desk or a plant) or outdoors (on patios or backyards that are in the shade and require sunlight), the heliostat systems in use today would prove to be rather inadequate.
• heliostats in fact, focus on emphasizing and optimizing the features that are fundamental in industrial applications, such as pointing accuracy, planarity of the mirror, stability and robustness of the mechanics. But other features become important when developing a heliostat for domestic applications, such as but not limited to compactness, portability, self-powered autonomy, lightness, low maintenance times, low-cost of the entire system and protection from outside weather.
• US Patent No. 4,192,583 to Horton defines a heliostat assembled within a protective enclosure supported by a foundation mounted in the ground. While this is a means of protection from weather elements, such an enclosure does not allow for the portability required of a heliostat for residential indoor as well as outdoor use.
• U.S. Pat. No. 4,870,949 to Butler teaches a wind resistant, two axis tracker that is used to direct a solar reflector, heliostat, or dish antenna.
• An elevation drive ring is supported in a vertical orientation by dolly wheels rotatably attached to a base.
• the reflector is attached at two points along the circumference of the elevation drive ring.
• a reflector having a diameter slightly less than the inside diameter of the elevation drive ring is mounted to the elevation drive ring.
• a number of support members, such as cables, extend from the elevation drive ring to the periphery of the reflector.
• Azimuth adjustment is either provided by mcorporatirig a horizontal turntable or drive ring as part of the base, or by pivoting the reflector within the elevation drive ring by adjusting the respective lengths of the support cables extending laterally from the elevation drive ring to the periphery of the reflector.
• Drawbacks with this type of heliostat device is that it does not include an enclosure to protect the heliostat device and is primarily concerned with using a centerless elevation drive combined with a turntable azimuth drive for reflectors in order to reduce the structure/weight of materials for wind resistance. This may be suitable under extreme conditions, such a design would be impractical and ineffective for the domestic use of a scaled down heliostat device.
• US Patent No. 8,132,928 to Bronstein et al. describes an improved solar reflector utilizing a tensioned reflective membrane, further including a membrane attached to the outer surface of a metal strap that is positioned on an end form by means of a curved-face tensioning block. While Linear tensioned membrane reflectors have some advantages over more rigid structures, such membranes present a variety of problems compared to those reflector technologies using more rigid frames. For example, most membranes utilize certain laminates, such as films, as a substrate for the membrane. Mylar (Biaxially-oriented polyethylene terephthalate boPET polyester film) is a dimensionally stable material that reacts in undesirable ways when the film is placed under compression.
• Mylar Biaxially-oriented polyethylene terephthalate boPET polyester film
• a typical means of mounting the membrane is to adhere it to the underside of a metal strap with a structural adhesive, such as epoxy.
• the strap is then wrapped around the end form and clamped in place.
• wrinkles are produced.
• Such defects are then crushed and locked in place as the strap is tightened on the end form.
• the present invention provides a mechanical enclosure for a heliostat that renders it optimized for domestic lighting use in accordance with the claims of the present invention.
• the present invention provides for a domestic heliostat that encompasses all the characteristics of a domestic object in one compact device, those characteristics being portability, light-weight, self-powering, wireless, sleek design, low maintenance, and resistance to outdoor weather. It is also designed to have a low cost of manufacture.
• the deleterious effects of weather on the functional components of the heliostat are minimized
• the design of the present invention greatly reduces the effects of wind-loading on the mirror. These aspects are achieved by enclosing the steerable mirror and its electromechanical control systems inside a transparent enclosure. In a preferred embodiment, the mirror and control system are completely sealed from the outside.
• the present invention provides for a domestic heliostat including: a steerable mirror, a mechanical mirror-steering mechanism, a steering control- system, a steering-control sensor, all contained within a mechanical enclosure wherein the mechanical enclosure has a break-line or joint about which the enclosure may be separated into two or more parts.
• this embodiment is further characterized in that: at least one portion of the mechanical enclosure is in the shape of a portion of a spherical-shell and such portion is made of optically transparent material, further wherein the transparent spherical-shell shaped portion of the enclosure subtends a solid angle at center of the sphere of more than 2 pi steradians.
• the trajectory of the joint that divides the mechanical enclosure in two parts is optimized to allow the insertion of the largest possible mirror inside the mechanical enclosure so as to maximize the solar energy and illumination reflected on the target, with this optimization being saddle shaped or elliptical.
• the steerable mirror is preferably circular in order to maximize the reflective area that will fit inside the mechanical enclosure, which is preferably spherical in shape, and the steerable mirror has a radius that is smaller than the inner radius of the spherical portion of the mechanical enclosure.
• the steerable mirror is rotatably mounted about two axes that intersect at or near the geometric spherical center of the spherical portion of the mechanical enclosure, hi a further aspect, the steerable mirror is mounted such mat its reflective surface over a major portion of its steerable rotatable position range, faces the spherical portion of enclosure made of optically transparent, material.
• the steering-control sensor is fixed to the inner surface of the mechanical enclosure.
• the heliostat is electrically self-powered.
• Another embodiment of the present invention describes a mechanical enclosure for a heliostat characterized in that the spherical portion of the mechanical enclosure of the heliostat is greater in solid angular extent than a hemisphere and preferably greater in solid angular extent than five-fourths of a hemisphere and, preferably, in at least one dimension that subtends an angle of as much as 270 degrees at the center of the sphere.
• the joint trajectory that divides the mechanical enclosure in two parts additionally allows for the insertion of a mechanical mirror-steering mechanism and steering control-system into the enclosure whereas the joint trajectory is elliptical, or is saddle shaped and it does not intersect the portion of the mechanical enclosure which is substantially spherical in shape and is made of optically transparent material.
• the joint trajectory is chosen such as to leave as great an area as possible, and possibly all, of the substantially spherical portion of transparent enclosure unbroken.
• the electrical self-power that powers the mirror steering mechanism and control system of the heliostat is provided by one or more first photovoltaic cells, wherein the first photovoltaic cell(s) are located within the mechanical enclosure, which is provided with a transparent window wherein the first photovoltaic cell(s) are positioned so as to be visible to the outside through the transparent window.
• this window may be partly or wholly provided by the spherical portion of the mechanical enclosure that is made of optically transparent material.
• these first photovoltaic cell(s) are mounted co- moving with the steerable mirror such that their optically sensitive surface(s) face substantially in the same direction as the reflective surface of the steerable mirror.
• the steering-control sensor is fixed to the inner surface of the mechanical enclosure and is positioned such as to minimize its obstruction to the passage of light from the sun to the heliostat' s target, and preferably below the horizontal midline plane of the mechanical enclosure.
• the steering-control sensor may be powered by the first photovoltaic cells, but is preferably self-powered independently of the heliostat.' s electrical self-power, and is preferably self-powered by one or more second photovoltaic cells co-mounted with the steering-control sensor. In another aspect, these second photovoltaic cell(s) are mounted such that their optically sensitive surfaces face towards the center of the steerable mirror or towards the zenith.
• the steering-control sensor preferably communicates with the steering control-system wirelessly via an infra-red (IR) link or a radio link.
• the steering control sensor communicates with the control system via a wired connection.
• the mechanical mirror-steering mechanism and the steering control-system are both mechanically mounted on the rear (non-reflective side) of the steerable mirror and are substantially hidden from sight of external viewers by the non-transparent sections of the heliostat's mechanical enclosure and/or by the steerable mirror.
• the mechanical mirror-steering mechanism is preferably attached to the mechanical enclosure at substantially one position only on a non-transparent portion of the mechanical enclosure.
• the steering control mechanism is remotely controllable from outside of the mechanical enclosure preferably without a wired link, via a radio link, an infra-red (IR) link, a wireless link (ie. WiFi) or an acoustic link that is preferably ultrasonic.
• IR infra-red
• WiFi wireless link
• acoustic link that is preferably ultrasonic.
• the mechanical enclosure is substantially rigid, is substantially sealed from the external environment and is preferably hermetically sealed, is preferably provided with a desiccator element, such as silica gel, and is made of material(s) that is substantially shatter-proof and preferably a category of plastics materials, e.g. methacrylate polymers or polycarbonate.
• the overall size of the mechanical enclosure is optimized for domestic lighting use; the largest dimension of the mechanical enclosure is preferably not less than 20cm and preferably not more than 100cm, and more preferably not more than 60cm.
• all of the internal components to the mechanical enclosure are preferably chosen to be of lighter construction than would be required to withstand normal outdoor wind loading in the absence of the enclosure, and the thickness of the steerable mirror is preferably chosen to be substantially less than the minimum thickness of the mirror that would be required to avoid substantial bending were the mirror to be exposed directly to normal outdoor wind loading.
• the mechanical miiror-steering-mechanism is chosen to have substantially smaller holding torque than would otherwise be required were the steerable mirror to be exposed directly to normal outdoor wind loading. In this way, much lighter and cheaper components may be used to build a well-functioning heliostat by minimizing their strength or torque specifications through shielding of the components from wind loading by the mechanical enclosure.
• the external shape of the mechanical enclosure is such as to provide low wind-loading torque on the mechanical enclosure when exposed to winds coming from any horizontal direction.
• the external shape of the mechanical enclosure is preferably an ellipsoid with one axis in the vertical direction or more preferably is a spheroid or sphere.
• the material of the transparent portion of the mechanical enclosure is thin enough to prevent significant refraction errors of pointing and is not more than 10mm thick, and preferably not more than 5mm thick, and most preferably not more than 2mm thick.
• the material of the transparent section of the mechanical enclosure is sufficiently optically smooth to prevent optical aberrations from significantly degrading the heliostat pointing precision and is preferably optically smooth to at least 10 micro.meter, and more preferably to 5 micro.meter, and even more preferably equal to or better than 1 micro.meter.
• the steerable mirror is selected from the group consisting of a plane mirror, a concave mirror and a convex mirror.
• Figure 1 depicts a side view of the mechanical enclosure containing the heliostat of the present invention.
• Figure 2 depicts a variety of lateral views of the inside of the rear shell and steering mirror, (a) an internal side view of the rear shell with steering mirror; (b) a rear perspective view of the rear shell of the mechanical enclosure with steering mirror; (c) a top perspective view of the rear shell with steering mirror.
• Figure 3 depicts a variety of view of the front transparent hard shell, (a) side view of the front transparent hard shell with break-line being centered in view; (b) an alternative perspective view of the front transparent hard shell.
• Figure 4 shows the central mirror having chord defined segments, (a) mirror having chord defined segments removed from two edges where x ⁇ 2r or x is smaller than the diameter of the circular mirror; (b) bottom view of transparent hard shell with break-line.
• the present invention provides for a domestic heliostat providing for all the benefits of a full scale version without the ensuing disadvantages of same.
• the present invention provides for the steerable mirror and its electromechanical control systems being inside a transparent enclosure, preferably completely sealed from the outside.
• the heliostat of the present invention To allow the heliostat of the present invention to track the sun across the greatest possible angle (e.g. from sunrise to sunset) it is important to maintain a clear, unobstructed and continuous optical path through the enclosure both for the sun's rays to enter, be reflected off the mirror, and exit to the target of the heliostat. It is also important that the optical sun-sensor component that allows automatic steering of the heliostat as the sun moves has a continuous and unobstructed view of the sun through the enclosure over its full steering angle.
• a spherical-shell transparent enclosure as providing for the optimal design. Since the steering angle can be as much as 90 degrees, and since the mirror itself subtends nearly 180 degrees of such a spherical housing, it is preferred that a nearly 270 degree, unobstructed section of spherical-shell housing is desirable. To maximize the reflective capability of the mirror within the heliostat of the present invention, it is desirable to make the size of the mirror as large as possible, and for a spherical housing, such a maximum mirror size corresponds to a circular mirror of diameter just less than the inner-diameter of the spherical-shell (to allow clearance when the mirror moves within the shell).
• one proposed solution provides for a division of the spherical shell into two hemispheres, which allows the mirror to then be assembled to its mountings within the shell, after which the two halves of the shell can be closed.
• the trajectory of the joint that divides the mechanical enclosure in two parts is optimized to allow the insertion of the largest possible mirror inside the mechanical enclosure so as to maximize the solar energy and illumination reflected on the target, to allow clearance of any components (e.g. for sensing and/or steering fixed to the front or rear of the mirror while inserting the mirror), and to allow adequate access for assembly of the internal components of the heliostat.
• This optimized shape essentially forms a slot in the spherical-shell housing and two preferred embodiments of the near-optimized shape for the aperture are saddle shaped or elliptical shaped.
• the present invention provides for a domestic heliostat in a mechanical enclosure 100, a substantially spherical and transparent front hard shell 1, and a not necessarily spherical and preferably not transparent rear shell 2, joined together by a joint or break-line 9 in the shape of a saddle in this particular embodiment.
• Fig. 1 further indicates a steering control sensor 8 sited on the inside of the front hard shell 1, and that the rear shell 2 rests on a stand 7 and supports internally a rigid circular steering mirror 3 with two attached photovoltaic cells 4a and 4b.
• ⁇ mechanical mirror-steering mechanism 5 and a steering control system 6 can also be preferably mounted to the rear of the mirror.
• the present invention provides for a rear shell 2 of mechanical enclosure 100 comprised of a steering mirror 3, a housing 10 where mechanical mirror-steering mechanism S (not shown) and steering control system 6 (not shown) are housed, and stand 7.
• Fig 2b shows a rear view of the rear shell 2 of mechanical enclosure 100 comprised of the steering mirror 3, the housing 10 and the stand 7.
• Fig 2c shows a top perspective view of the rear shell 2 comprised of the steering mirror 3, the housing 10 and the stand 7.
• the saddle shaped break-line 9 defines the perimeter of rear shell 2.
• Joint or break-line 9 allows this particular embodiment to maximize the optically smooth area of front transparent hard shell 1 available in front of the steering mirror 3 by retaining a saddle shape that at the same time is able to maximize the size of the steering mirror 3 that may be fitted within it.
• the front transparent hard shell 1 of mechanical enclosure 100 is extended enough so as to allow the unobstructed entrance of sunlight through the front transparent hard shell 1 towards the steering mirror 3 and its ensuing exit via reflection of sunlight from the steering mirror 3 through the front hard shell 1 towards the target (not shown), over a very wide range of mirror steered positions.
• the steering mirror 3 will have a clear view of the sky through the transparent front hard shell 1 , unhindered by the joint or break-line 9 that must necessarily be present in order for the steering mirror 3 to be fitted inside the mechanical enclosure 100 during manufacture and for maintenance.
• the steering control sensor 8 is situated on the front transparent hard shell 1 in front of steering mirror 3 so as to receive the reflected sunlight from the steering mirror 3 (outbound light) and hide as little as possible of the steering mirror 3 reflective surface from the target.
• Steering control sensor 8 is, in this particular embodiment, wirelessly connected to steering control system 6 through a pulsed-iR system (not shown) and powered by separate co-located photovoltaic cell(s) (not shown).
• steering control sensor 8 is wirelessly connected to steering control system 6 by means of a radio transmitter at the sensor and a radio receiver at the mirror steering motor controller. This radio system could be a WiFi- or Bluetooth-enabled module, or something much simpler and cheaper, as the data rate required is very low.
• the radio transmitter and receiver are each powered by separate co-located photovoltaic cells.
• WiFi or Bluetooth modules are fitted within the heliostat of the present invention, whether or not they are used for communication internally within the heliostat, they can be used to transmit data generated by but not limited to the steering control sensor 8, steering control system 6 and mechanical mirror-steering mechanism 5, to an external server or smartphone.
• the present invention provides for the reception by the heliostat of control instructions and data from an external device such as a smartphone.
• steering control sensor 8 could be physically connected to steering control system 6 by means of a wired connection. While this direct wired approach is simple and potentially very low cost, there are mechanical problems to be overcome with relative movement between the two ends of the connecting cable, as well as aesthetic issues with the visible wires, which makes the wireless approach more preferred.
• the mechanical mirror-steering mechanism 5 contains all the gears and motors (not shown) capable of directing and moving the stecrable mirror 3.
• the steering control- system 6 contains all the electronics that dictate the movement of the steerable mirror 3 through the mechanical mirror-steering mechanism 5.
• the steering control system 6 is wirelessly connected to the steering control sensor 8 so as to accurately guide the movement of the steering mirror 3.
• the connection between steering control system 6 and steering control sensor 8 is made wirelessly by means of a radio transmitter and receiver, which may be, for example, a WiFi- or Bluetooth-enabled module or a very simple low-data-rate radio system, or physically by means of one or more wired connections).
• Such a WiFi or Bluetooth module allows data collected by but not limited to the steering control sensor 8, steering control system 6 and mechanical mirror-steering mechanism 5, to be transmitted to an external server or a smartphone, as well as to allow the reception by the heliostat of control instructions and data, from an external device such as a smartphone.
• the circular steerable mirror 3 is mounted on two axes around which it is rotatably mounted, that intersect at or near the geometric spherical center of the transparent front hard shell 1. This allows the steering mirror 3 to be able to rotate freely without impacting the transparent front hard shell 1 , the rear shell 2, or the stand 7.
• housing 10 is not limited to a hemisphere, as represented in the present embodiment, but could be any geometrical shape or combination of shapes, including but not limited to, two hemispheres.
• Housing 10, the mechanical mirror-steering mechanism S and the steering control system 6, are connected to the mechanical enclosure 100 through a single point of contact that lies on one of the two axes of rotation.
• Two photovoltaic cells 4a and 4b that accumulate the power for the steering control system 6 to move the steerable mirror 3 through the mechanical mirror-steering mechanism 5, are fixed to the surface of the steerable mirror 3, or onto an outer frame around the mirror that extends beyond the perimeter of the mirror's reflective surface. This location allows the photovoltaic cells 4a and 4b to always move jointly with the steerable mirror 3, which avoids shadowing of the steerable mirror 3 by the photovoltaic cells 4a and 4b and, at the same time, enables the photovoltaic cells 4a and 4b to always be oriented towards the sun, because the steering mirror 3 is oriented towards the sun automatically by the steering control system 6.
• the mechanical enclosure 100 includes a stand 7, which can have different shapes according to its installation including, but not limited to, a flat foot for desk mounting, or a railing clasp for mounting on a balcony.
• the trajectory of joint or break-line 9 that divides in two the mechanical enclosure 100 is saddle shaped so as to minimize the optical aberrations experienced by the sunlight coming into and going out of after being reflected off of the steering mirror 3, the mechanical enclosure 100, while maximizing the size of the steerable mirror 3 and thus the solar energy and illumination delivered to the target.
• Fig 3a shows a side view of the transparent front hard shell 1 of the mechanical enclosure 100, whereby the joint or break-line 9 is central and part of the internal surface of the transparent front hard shell 1 can be seen as well.
• Fig 3b shows a rotated side view of the transparent front hard shell 1 of the mechanical enclosure 100, whereby the joint or break-line 9 is clearly defined and again part of the internal surface of the transparent front hard shell 1 can be seen.
• Fig 4a shows mirror 3 as being circular with center C and radius r where the mirror 3 has chord-defined segments removed from two edges where the chords are parallel and distance X apart, where X ⁇ 2r, or equivalently, X is smaller than the diameter of the circular mirror 3.
• Fig 4b shows a bottom view of the substantially spherical and transparent front hard shell 1 with break- line 9 characterized by a width greater than chord separation X to allow passage through of the mirror with segments removed, and height y equal to the length necessary for the mechanism to fit through.
• the heliostat of the present invention is comprised of a steerable mirror, a mechanical rnirror-steering mechanism, a steering control-system, a steering-control sensor, all contained within a mechanical enclosure wherein the mechanical enclosure has a break-line or joint about which the enclosure is separable into two or more parts, characterized in that at least one portion of the mechanical enclosure is in the shape of a portion of a spherical- shell, the spherical-shell shaped portion of enclosure is made of optically transparent material and the transparent spherical-shell shaped portion of enclosure subtends a solid angle at center of the sphere of more than 2 pi steradians.
• the steerable mirror is either circular in shape or circular with one or more segments removed from the edge defined by chords, and where two such segments are removed with their respective chords being parallel, with an aperture in the spherical-shell formed by the break-line or joint having an extent in a first direction across the spherical-shell of greater than or equal to the diameter of the mirror where the mirror is circular and less than a mirror diameter where the mirror has one or more chord- segments removed from its edge, and in a second direction orthogonal to the first direction, the aperture so formed extends far enough to at. least allow clearance for the thickness of the mirror.
• steerable mirror being circular with radius smaller than the inner radius of the spherical portion of enclosure with the steerable mirror being rotatably mounted about two axes, further wherein the two axes intersect at or near the geometric spherical center of the spherical portion of enclosure and the steerable mirror is mounted such that its reflective surface over a substantial portion of its steerable rotatable position range, faces the spherical portion of enclosure made of optically transparent material.
• the steering-control sensor is fixed to the inner surface of the mechanical enclosure, wherein the heliostat is electrically self- powered and is able to transmit and receive wirelessly control-instructions and data to and from an external device such as a smartphone or external server.
• the spherical portion of the enclosure is greater in solid angular extent as viewed from the center of the sphere than a hemisphere.
• the spherical portion of the enclosure is greater in solid angular extent as viewed from the center of the sphere than five fourths of a hemisphere.
• the aperture in the spherical shell enclosure formed by the joint trajectory has dimensions greater than the outline dimensions of the mechanical mirror-steering mechanism and steering control.
• the joint trajectory is elliptical or saddle shaped and does not intersect the one portion of the mechanical enclosure which is spherical in shape and which is made of optically transparent material.
• the joint trajectory is chosen such as to leave as great an area as possible, and possibly all, of the spherical portion of the transparent enclosure unbroken.
• the heliostat of the present invention is self-powered, with such power provided by one or more first photovoltaic cells.
• the first photovoltaic cell(s) are located within the mechanical enclosure, with the mechanical enclosure provided with a transparent window and the first photovoltaic cell(s) being positioned within the mechanical enclosure such as to be visible through the window from outside.
• the transparent window is partly or wholly provided by the spherical portion of enclosure made of optically transparent material.
• the first photovoltaic cell(s) are mounted in a fashion that moves with the steerable mirror.
• the first photovoltaic cell(s) are mounted such that their optically sensitive surface(s) face in the same direction as the reflective surface of the steerable mirror.
• the steering-control sensor fixed to the inner surface of the mechanical enclosure is positioned such as to minimize its obstruction to the passage of light from the sun to the heliostat's target, further wherein the steering-control sensor is positioned below the horizontal midline plane of the mechanical enclosure.
• the steering-control sensor is self-powered independently of the heliostat electrical self-power and, more preferably, the steering-control sensor is self-powered by one or more second photovoltaic cells co-mounted with the steering-control sensor, with the second photovoltaic cell(s) being mounted such that their optically sensitive surface(s) face towards the center of the steerable mirror.
• the second photovoltaic cell(s) are mounted such that their optically sensitive surfaces) face towards the zenith.
• the steering-control sensor communicates wirelcssly with the steering control-system.
• the wireless communication is selected from the group consisting of infra-red (IR) link, radio link and WiFi link.
• the mechanical mirror-steering mechanism and the steering control-system are both mechanically mounted on the rear (non-reflective side) of the steerable mirror.
• the mechanical mirror-steering mechanism is attached to the mechanical enclosure at one position only.
• the one mechanical attachment position on the enclosure is situated on a non-transparent portion of the enclosure.
• the mechanical mirror-steering mechanism and the steering control-system are hidden from sight of external viewers by the non-transparent sections of the enclosure and/or by the steerable mirror.
• the steering control mechanism is remotely controllable from outside the enclosure with a member selected from the group consisting of a wireless link, a radio link, an infra-red (IR) link and an acoustic link.
• the wireless link may be ultrasonic.
• the mechanical enclosure is sealed from the external environment, with such seal being optionally hermetic.
• the mechanical enclosure further comprises a desiccator, wherein the desiccator is comprised of silica gel.
• the mechanical enclosure is made of material(s) that are shatter-proof and constructed of plastics materials.
• the plastics materials may be selected from the group consisting of methacrylate polymers and polycarbonate.
• the overall size of the mechanical enclosure is optimized for domestic lighting use, wherein the largest dimension of the mechanical enclosure is not less than 20cm or not more than 100cm, or not more than 60cm.
• the mechanical enclosure is rigid and the mechanical strengths of any or all of the components internal to the mechanical enclosure are chosen with no regard to direct wind loading.
• the thickness of the steerable mirror is chosen with regard to gravitational distortion due to its weight, but with no regard to wind loading.
• the holding torque of the mechanical mirror-steering mechanism is chosen with regard to gravitational loading due to the weight of supported components but with no regard to wind- loading.
• the external shape of the mechanical enclosure may be an ellipsoid with one axis in the vertical direction.
• the material of the transparent section of the mechanical enclosure is thin enough to prevent significant refraction errors of pointing.
• the thickness of material of the transparent section of the mechanical enclosure is not more than 10mm, or not more than 5mm, or not more than 2mm.
• the material of the transparent section of the mechanical enclosure is sufficiently optically smooth to prevent optical aberrations from significantly degrading the heliostat pointing precision.
• the material of the transparent portion of the mechanical enclosure is optically smooth to at least 10um, or to 5um, or to better than 1um.
• the steerable mirror is selected from the group consisting of a plane mirror, a concave mirror and a convex mirror.

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• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Mounting And Adjusting Of Optical Elements (AREA)
• Optical Elements Other Than Lenses (AREA)

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• 2015
  • 2015-10-05 WO PCT/US2015/054059 patent/WO2016054653A1/en not_active Ceased
  • 2015-10-05 CN CN201580065004.0A patent/CN107003593B/zh not_active Expired - Fee Related
  • 2015-10-05 EP EP15846623.5A patent/EP3201689A1/de not_active Withdrawn

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