Radiation Reflection Device

Abstract

A radiation reflection device used to focus radiation from a moving source onto a stationary receiver is disclosed. The primary application of such an invention relates to reflecting the radiation from the sun onto a stationary target. The device orients a reflective surface to a position necessary for imaging using a parallelogram type half-angle system. The device may be used singly or in a ganged array.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a radiation reflection device used to focus radiation from a moving source onto a stationary receiver.

The primary application of such an invention relates to reflecting the radiation from the sun onto a stationary target. In such an application, wherein the device is used to orient a reflective surface to reflect light onto a target, the device may be termed a “heliostat”. In another sunlight reflecting application, wherein the device is implemented in an array used to orient a plurality of reflective surfaces to reflect light onto a target, the device may be termed a “ganged heliostat”. Light concentration achieved by heliostats or ganged heliostats has several uses which include thermal energy conversion, photovoltaic energy conversion, and daylighting.

In other applications, the device may be used to reflect any other type of electromagnetic radiation such as radio signals, sound waves, moonlight, etc.

PRIOR ART

A prior art exists in heliostat devices. Various heliostats of the prior art require complex computer control of encoder type servo or stepper motors such as the device disclosed in U.S. Pat. No. 4,440,150 (Kaehler). Various heliostats of the prior art require a half-angle gearing system such as the devices disclosed in U.S. Pat. No. 5,027,047 (Logan et al.) and U.S. Pat. No. 4,586,488 (Noto). Various heliostats of the prior art require an external sensor feedback system and complicated drive arrangement such as the device disclosed in U.S. Pat. No. 6,899,096 (Nakamura). The present invention, when employed in a heliostat, does not require a complicated external computer control, encoder type motors, or a half-angle gear system.

A prior art exists in ganged heliostats such as devices disclosed in U.S. Pat. No. 4,110,010 (Hilton), U.S. Pat. No. 4,056,313 (Arbogast) and U.S. Pat. No. 3,466,119 (Francia). These devices include a high number of parts and a high complexity of parts. Also, various ganged heliostats of the prior art (e.g. U.S. Pat. No. 4,110,010) require daily adjustment to compensate for the declination of the sun. Such a requirement increases operating cost of the device and the likelihood of focusing errors. The present invention, when employed in a ganged heliostat, does not require continual adjustment to compensate for solar declination and is simpler in construction than ganged heliostats of the prior art.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a radiation reflection device which can be used to orient a mirror to reflect radiation from a moving radiation source to a stationary receiver. The device can be used either singly, or implemented in a ganged array.

The device includes a reflective surface, or mirror and a mirror frame which is attached to the mirror. The device orients the mirror to a position bisecting the incidence vector (i.e.—a vector through the mirror centre and the source of radiation) and the reflection vector (i.e.—a vector through the mirror centre and the stationary receiver), thus achieving the reflection of light from source to target (imaging).

The device includes a linkage that is aligned perpendicular to the incidence vector. This linkage is referred to as the incidence linkage. The device includes a linkage that is aligned perpendicular to the reflection vector. This linkage is referred to as the reflection linkage.

The incidence linkages and reflection linkages are interconnected in a parallelogram pattern. Vertices of the parallelogram pattern define a parallelogram bisecting line that bisects the angle between the incidence and reflection linkages. The device includes traversing bolts that pass through the vertices of the parallelogram bisecting line. The traversing bolts also pass through slots of the mirror frame and indirectly locate the mirror to a position necessary for imaging.

The advantages of the present invention will be more apparent from the following detailed description in reference to the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual elevation view of embodiment ‘1’ of the invention in relation to a source of radiation and a target wherein the device is implemented in a heliostat

FIG. 2 is a top view of the heliostat of FIG. 1 in the neutral position

FIG. 3 is a side view of the heliostat of FIG. 2 taken along the line 3-3

FIG. 4 is a front view of the heliostat of FIG. 3 taken along the line 4-4

FIG. 5 is a side view of the heliostat of FIG. 2 in an alternate position

FIG. 6 is a side view of embodiment ‘2’ of the invention wherein the device is implemented in a heliostat

FIG. 7 is a conceptual elevation view of embodiment ‘3’ of the invention in relation to a source of radiation and a target wherein the invention is implemented in an element of a ganged heliostat

FIG. 8 is a top view of the ganged heliostat element of FIG. 7 in the neutral position

FIG. 9 is a side view of the ganged heliostat element of FIG. 8 in an alternate position

FIG. 10 is a top view of embodiment ‘4’ of the invention in the neutral position wherein the invention is implemented in a heliostat

FIG. 11 is a side view the heliostat of FIG. 10 in an alternate position

FIG. 12 is a top view of embodiment ‘5’ of the invention in the neutral position wherein the invention is implemented in a heliostat

FIG. 13 is a side view of the heliostat of FIG. 12 taken along the line 13-13

FIG. 14 is a side view of the heliostat of FIG. 13 taken along the line 14-14

FIG. 15 is a top view of embodiment ‘6’ of the invention in the neutral position wherein the invention is implemented in a heliostat

FIG. 16 is a side view of the heliostat of FIG. 15 taken along the line 16-16

FIG. 17 is a side view of the heliostat of FIG. 16 taken along the line 17-17

FIG. 18 is a side view of the heliostat of FIG. 15 in an alternate position

FIG. 19 is a side view of a ganged heliostat element of a device employing the wire type reflection aiming means and a half-angle gearing system

DETAILED DESCRIPTION OF USEFUL EMBODIMENTS OF THE INVENTION

Six embodiments of the invention will be described: embodiment ‘1’, embodiment ‘2’, embodiment ‘3’, embodiment ‘4’, embodiment ‘5’, and embodiment ‘6’. The embodiments ‘1’, ‘2’, ‘4’, ‘5’, and ‘6’ are heliostats and embodiment ‘3’ is a ganged heliostat. Each embodiment will be described with respect to a solar reflecting (concentrating) application.

The heliostat of embodiment ‘1’ will now be described with reference to FIGS. 1 through 5. FIG. 1 shows the heliostat reflecting sunlight from source ‘S’ to a receiver ‘R’. To achieve imaging a reflective surface, mirror 1204, mounted on mirror frame 1203 is positioned such that the normal of the mirror (i.e.—a vector perpendicular to the mirror surface coincident with the mirror centre) bisects the angle between the incidence vector (i.e.—a vector from the source to the mirror centre) and the reflection vector (i.e.—a vector from the mirror centre to the receiver). The mirror frame 1203 is positioned indirectly by pan motor 1101 and tilt motor 1102. The mirror, mirror frame, incidence linkages, reflection linkages, motors, and various other parts of the heliostat are mounted on a carriage which is mounted on, and rotates about, a main shaft 1001. During the initial set-up of the heliostat, the main shaft 1001 is fixed to stationary post 1003 using bracket 1002 in such a manner that the central axis of main shaft 1001 is coincident with (i.e.—“pointing at”) the receiver.

FIG. 2 shows the heliostat in the “neutral position”. The heliostat is in the neutral position when the incidence vector and the reflection vector are coincident and opposite. FIG. 2 shows incidence linkages 1301, 1303, 1400, 1402, and 1404, and reflection linkages 1300, 1302, 1304, 1401, and 1403. FIGS. 3 and 4 provide further detail of the heliostat in the neutral position. The linkages and motors are mounted on a carriage consisting of carriage base 1601, carriage posts 1603, pan motor plate 1604, and tilt motor plate 1605. The carriage base 1601 is mounted on, and rotates about, main shaft 1001.

Tilt motor 1102, which is fixed to the carriage at tilt motor plate 1605, is fixed to linkage 1400 at its centre of rotation. Pan motor 1101 is fixed to coupling 1602, which is fixed to main shaft 1001. Pan motor 1101 and tilt motor 1102 are controlled to continually adjust incidence linkage 1400 such that it remains perpendicular to the incidence vector. Reflection linkage 1300 is fixed to the carriage posts 1603 such that it is perpendicular to the main shaft 1001. Since main shaft 1001 is collinear with the receiver, linkage 1300 is always perpendicular to the reflection vector.

Each of the linkages includes three holes; one at the centre and one at either end. The distance between the centre hole and either end-hole is the same for each linkage. Linkage 1401 is connected to linkage 1400 at one end and linkage 1402 at the other end. The joints between linkages 1400 and 1401 and between linkages 1401 and 1402 are rotatable. Similarly, linkage 1301 is connected to linkage 1300 at one end and linkage 1302 at the other end. The joints between linkages 1300 and 1301 and between linkages 1301 and 1302 are rotatable. Traversing bolt 1501 passes through the centre hole of linkages 1301 and 1401 and through the mirror frame guides 1201 and mirror frame guides 1202. Traversing bolt 1502 passes through the centre hole of linkages 1302 and 1402 and through mirror frame guides 1201 and mirror frame guides 1202. A bolt at the centre of linkage 1300 passes through a sleeve fixed to the centre of guides 1201. A bolt at the centre of linkage 1400 passes through a sleeve fixed to the centre of guides 1202.

The function of linkages 1301, 1302, 1401, 1402 is similar to the function of linkages 1303, 1304, 1403, 1404. The function of traversing bolts 1501, 1502 is similar to the function of traversing bolts 1503, 1504.

FIG. 5 shows the heliostat of embodiment ‘1’ in a position other than the neutral position. A line through the traversing bolts 1501, 1502, 1503, 1504 bisects the angle between linkages 1300 and 1400. Note that the incidence linkages and reflection linkages are interconnected in a parallelogram pattern. Therefore, when linkages 1300 and 1400 are perpendicular to the reflection and incidence vectors respectively, a line through the traversing bolts will define the mirror position necessary for imaging. The traversing bolts define the position of the mirror frame guides. The mirror frame guides 1201 and mirror frame guides 1202 are fixed to the mirror frame 1203. The mirror frame 1203 is fixed to the mirror 1204. Therefore the traversing bolts indirectly achieve the mirror position necessary for imaging.

It should be noted that the centre of mass of the rotating parts of the device coincides with the central axis of the shaft of pan motor 1101 and the central axis of the shaft of tilt motor 1102. Therefore, the torque requirement of the motors is minimized.

The heliostat of embodiment ‘2’ is shown in FIG. 6. The heliostat of embodiment ‘2’ functions in a similar manner to that of embodiment ‘1’ with several differences. Embodiment ‘2’ employs 4 interconnection parts and 2 traversing bolts whereas embodiment ‘1’ employs 8 interconnection parts and 4 traversing bolts. Embodiment ‘2’ is unstable in the neutral position. Embodiment ‘2’ is stable and capable of imaging in positions other than the neutral position. Embodiment ‘2’ employs fewer parts than embodiment ‘1’.

Embodiment ‘2’ includes a sensor feedback system used to control pan motor 2101 (analogous to pan motor 1101 of embodiment ‘1’) and tilt motor 2102 (analogous to pan motor 1102 of embodiment ‘1’). Pan sensors 2804 and 2805 are fixed to the carriage posts 2603. Tilt sensors 2802 and 2803 are fixed to the incidence linkage 2400. The sensors are of the photovoltaic type or photoresistor type. The sensors send signals to an electronic control system used to control pan motor 2101 and tilt motor 2102.

Pan motor 2101 rotates the heliostat carriage until the sunlight incident on pan sensors 2804 and 2805 is equal (i.e.—the sensor pair is balanced). Tilt motor 2102 rotates linkage 2400 until the sunlight incident on tilt sensors 2802 and 2803 is equal (i.e. the sensor pair is balanced). When each sensor pair is balanced, linkage 2400 has achieved a position wherein it is perpendicular to the incidence vector. Once this is achieved, the mechanism of the heliostat causes the reflective surface to be oriented for imaging as described above. A sensor feedback system of this type allows non-encoder type motors (e.g.—DC gear motors) to be employed as pan motor 2101 and tilt motor 2102.

It should be noted that initial setup of the heliostat is easily achieved. During setup, the main shaft 2001 is aimed at the receiver. No further calibration is necessary. The device does not require any type of periodic adjustment.

The ganged heliostat of embodiment ‘3’ will now be described with reference to FIGS. 7 through 9. FIG. 7 shows an element of the ganged heliostat reflecting sunlight from source ‘S’ to a receiver ‘R’. A notable difference between the heliostat embodiments ‘1’ and ‘2’ and the ganged heliostat embodiment ‘3’ relates to the main shaft 3001 (analogous to main shaft 1001 of embodiment ‘1’). In the ganged heliostat embodiment, the main shaft 3001 is continually adjusted in such a manner that the central axis of main shaft 3001 is coincident with (i.e.—“pointing at”) the source of radiation. The adjustment of main shaft 3001 is achieved by an aiming means, various types of which are known in the prior art. Wire 3701 is attached at one end to the receiver and at its other end to a reflection linkage of the device. Wire 3701 defines the reflection vector and as such provides a reflection aiming means, main shaft 3001 defines the incidence vector, and the mechanism comprising the linkages, traversing bolts, guides, and frame of the device define the mirror position necessary for imaging.

FIG. 8 shows an element of the ganged heliostat of embodiment ‘3’ in the neutral position. FIG. 9 shows the element of FIG. 8 in a position other than the neutral position. The ganged heliostat element has a very similar form and function to the heliostat of embodiment ‘1’. Reflection linkage 3400 (analogous to incidence linkage 1400 of embodiment ‘1’) is connected to the split ends of wire 3701 at holes 3702 and 3703. The split ends of wire 3701 are equal in length. When wire 3701 is put under tension, linkage 3400 is aligned to a position perpendicular to the reflection vector.

Incidence linkage 3300 (analogous to reflection linkage 1300 of embodiment ‘1’) is mounted on, and rotates about, main shaft 3001 which is adjusted by the incidence aiming means. Therefore, the incidence aiming means indirectly aligns linkage 3300 to a position perpendicular to the incidence vector. When linkages 3300 and 3400 are aligned to positions perpendicular to the incidence and reflection vectors respectively, the mechanism comprising the linkages, guides, and mirror frame achieves a mirror position necessary for imaging.

It should be noted that the centre of mass of the rotating parts of the device lies midway between the split ends of wire 3701. Therefore, the tension requirement of 3701 is minimized.

Optionally, an additional wire 3706 (not shown in the Figures) may be employed in the ganged heliostat element. Wire 3706 would include a plain end and a split end (similar to wire 3701). If employed, the wire 3706 would be connected at its plain end to the receiver, and at its split end to holes 3704 and 3705. When put in tension, wire 3706, together with tensioned wire 3701, adjust and position the reflection linkage.

The novel reflection aiming means achieved by wire 3706 may also be combined with the half-angle gearing method used in heliostats of the prior art as shown in the device of FIG. 19. This device of FIG. 19 will now be described.

A reflection linkage that is positioned using the wire type reflection aiming means is connected to a gear G1. Gear G1 turns gear G2 which turns gear G4 which turns gear G6 which turns gear G8. Gear G1 also turns gear G3 which turns gear G5 which turns gear G7 which turns gear G8. The gear ratio between gear G1 and gear G8 is 2:1.

The heliostat of embodiment ‘4’ will now be described with reference to FIGS. 10 and 11. The linkages and motors of the heliostat are mounted on a carriage similar that that of embodiments ‘1’ and ‘2’.

Tilt motor 4102 is mounted to tilt motor plate 4605. The shaft of tilt motor 4605 is fixed directly to the mirror frame guides 4202. Incidence linkage 4303 is connected at one end to reflection linkage 4606 and fixed to sensor plate 4801 at its other end. Incidence linkage 4403 is connected at one end to reflection linkage 4605 and fixed to sensor plate 4801 at its other end. The joints between linkages 4303 and 4606 and between linkages 4403 and 4605 are rotatable. Traversing bolt 4503 passes through linkages 4303 and 4403 and through mirror frame guides 4201 and 4202.

Sensors 4802, 4803, 4804, and 4805 are located on sensor plate 4801. Pan motor 4101 rotates the heliostat carriage until the sunlight incident on pan sensors 4804 and 4805 is balanced. Tilt motor 4102 rotates the guides 4201 and 4202 until the sunlight incident on tilt sensors 4802 and 4803 is balanced. When each sensor pair is balanced, sensor plate 4801 has achieved a position wherein it is perpendicular to the incidence vector. When sensor plate 4801 is aligned perpendicular to the incidence vector, incidence linkages 4303 and 4403 are perpendicular to the incidence vector.

Reflection linkages 4605 and 4606 are fixed to the carriage posts 4603 such that linkages 4605 and 4606 are perpendicular to the main shaft 4001. Since main shaft 4001 is collinear with the receiver, reflection linkages 4605 and 4606 are always perpendicular to the reflection vector.

When incidence linkages 4303 and 4403 and reflection linkages 4605 and 4606 are aligned to positions perpendicular to the incidence and reflection vectors respectively, the mechanism comprising the linkages, traversing bolts, guides, and mirror frame achieves a mirror position necessary for imaging.

The heliostat of embodiment ‘5’ will now be described with reference to FIGS. 12 through 14. The heliostat of embodiment ‘5’ is similar in form and function to the heliostat of embodiment ‘4’ with the notable difference that the carriage of the heliostat of embodiment ‘5’ is simplified in comparison to the heliostat of embodiment ‘4’. The reflection linkage 5300 is mounted directly on the main shaft 5001. Pan motor 5101 and tilt motor 5102 are mounted directly on the reflection linkage 5300. The main shaft 5001 is keyed to accept a slotted shaft of pan motor 5101.

The heliostat of embodiment ‘6’ will now be described with reference to FIGS. 15 through 18. The heliostat of embodiment ‘6’ is similar in form and function to the heliostat of embodiment ‘5’ with a notable difference. The incidence linkage 6807, reflection linkage 6300, and traversing bolt 6505 operate in a slot in part 6806 that is parallel to the normal of the mirror 6204 (as opposed to a slot that is parallel to the mirror 6204).

Claims

1. A radiation reflection device comprising:

a reflective surface for reflecting incident radiation from a moving radiation source to a receiver;

a mirror frame wherein; said mirror frame is fixed to said reflective surface;

mirror frame guides wherein; said mirror frame guides are fixed to said mirror frame; said mirror frame guides comprise one or more parallel slots;

one or more incidence linkages and one or more reflection linkages wherein; said incidence linkages are aligned perpendicular to the incidence vector; said reflection linkages are aligned perpendicular to the reflection vector; said incidence linkages and said reflection linkages are interconnected in a parallelogram pattern; vertices of said parallelogram pattern define a parallelogram bisecting line that bisects the angle between said incidence linkages and said reflection linkages;

one or more traversing bolts wherein; each of said traversing bolts intersects one of said vertices of said parallelogram bisecting line; each of said traversing bolts passes through one or more incidence linkages, one or more reflection linkages and one or more of said slots of said mirror frame guides;

a main shaft wherein; said mirror, said mirror frame, said incidence linkages, and said reflection linkages, are rotatable about said main shaft; said mirror, said mirror frame, said incidence linkages, and said reflection linkages are mounted, either directly or indirectly, on said main shaft.

2. A device of claim 1 wherein said radiation reflection device is implemented in a heliostat wherein said radiation reflection device comprises:

a tilt motor wherein; one of said incidence linkages is rotated, directly or indirectly, by said tilt motor; one or more of said reflection linkages is mounted, directly or indirectly, to said main shaft wherein said main shaft is aligned along the reflection vector;

a pan motor wherein; said pan motor is connected to said main shaft; said pan motor can cause said mirror, said mirror frame, said incidence linkages, and said reflection linkages to rotate about said main shaft.

3. A device of claim 2 wherein said radiation reflection device further comprises a sensor plate fixed to one or more of said incidence linkages wherein;

said sensor plate includes a pair of pan sensors;

said sensor plate includes a pair of tilt sensors;

said pan sensors produce a control signal which can be used to control said pan motor;

said tilt sensors produce a control signal which can be used to control said tilt motor.

4. A device of claim 1 wherein said radiation reflection device is implemented in a ganged array wherein;

said radiation reflection device comprises a cable wherein: said cable provides a reflection aiming means; said cable is connected at one end to said receiver; said cable is connected at one end to one of said reflection linkages; said cable causes one or more of said reflection linkages to be aligned perpendicular to the reflection vector;

said main shaft is aimed by an incidence aiming means;

said main shaft is continually adjusted by said incidence aiming means to align the central axis of said main shaft with the incidence vector;

one or more of said incidence linkages is mounted, directly or indirectly, to said main shaft causing said incidence linkages to be aligned perpendicular to said incidence vector.