CA1105720A - Solar powered engine and tracking system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A solar powered engine and tracking system comprises a piston working within a cylinder for turning a drive shaft for driving an electrical generator or performing other useful work, a solar concentrator comprising a plurality of mirrors, each reflecting Sun light on a common focal point on the end of the cylinder for heating a flash boiler located thereon, preheated water from a source is injected into the flash boiler by a pump powered by the drive shaft timed according to piston movement after operating the piston, the steam is then vented from the boiler by valve means operated from the drive shaft. A
starter motor is provided to initially start the engine operating by rotating the drive shaft until the piston movement is self sustaining. The entire device is enclosed in a solar energy collector panel for elevating the temperature of the system so as to maintain the water at a sufficient temperature with a minimum of external heating. The collector may also be utilized for separate external heating purposes. Sensor controlled motors track the relative movement of the Sun and Earth and continually position the collector for maximum solar energy concentration.

Description

BACKGROUND OF THE INVENTION
The present invention relates to a system for tracking the re]ative movement of the sun and earth for use with a flash boiler operated steam engine where the principal heat is supplied by a solar concentrator confined within a solar energy collector.
There are several prior art devices that utilize solar heat to operate steam engine devices.
United States Patent No. 1,4~4,932 teaches the use of a steam engine boiler positioned at the apex of a parabolic reflector system. This system teaches the forming of a parabolic surface and a plurality of different focal points around the surface of the steam boiler.
There is no means provided for positioning of the device to ensure maximum heat from the Sun during Sun/Earth relative movement.
United States Patent No. 1,386,781 teaches a solar con-_entrator device where Sun tracking is performed by a 20 clock motor mechanism~ -United States Patent No. 3,8~2,433 teaches a plurality of curved reflectors positioned to direct solar energy to a plurality of focal points on a steam generator. The positioning of the reflectors requires an equal plurality of optical sensors and sensor-servo mechanisms.
These prior art systems are complicated, inefficient and economically expensive to produce.
SUMMARY OF T~E INVENTION
The present invention provides a system for tracking the relative movement of the sun and earth comprising: a base memberî a positionable platform carried by said base ~, member; a plurality of light sensors, each light sensor providing a control signal when exposed to the direct rays of the sun, said sensors being positioned in a spaced apart relationship about the periphery of said positionable platform provicling a first and second pair of diagonally opposed light sellsors; shieldincJ means pos:itioned adjacent each of said plurality of light sensors for preventing -the direct rays of the sun from s-triking more than one light sensor of each pair of ligh-t sensors at any given time; a first positioning means responsive to said control signals from said first pair of light sensors for providing directional rotation of said positionable platform with respect to said base member along a first path of travel between physical restraints; and a second positioning means responsive to the control signals from said second pair of light sensors for providing directional rotation of said positionable platform with respect to said base member along a second path of travel between the physical restraints; said first and second positioning means include control signal interruption means for stopping the movements of said positionable platform along said first and second paths of travel prior to reaching said physical restraints.

- - la -DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a partially cutaway side view of the apparatus of the invention;
FIGl]RE 2 is a plan view o:E the reElective surface of the solar concentrator of the invention;
~ IG[JRE 3 :is a partial:l.y cutaway v:iew o:E the apparatus o:E the inventioJI taken along lines 3-3 of Figure 2;
FIGURE 4 is a diagrammatic view o:E the electrical wiring of the solar tracking mechanism of the invention;
FIGUR.E 5 is a plan view, partially in phantom~ of the injector pumps and their operating mechanism; and

- 2 -FIGURE 6 is a side view of the Figure 5 showing further including the valves and their operating mechanism.
Description of the Preferred Embodimen-t The same reference numerals are used throughout the Figures and specifications to depict the same element or part.
ReferL~ing now specifically to E'igures 1, 2 and 3, a combination solar light energy collector and concentra-tor 10 is shown. The apparatus is suppor-ted by as base 12, 12a at-tached to a surface positioned on the Earth 13, an example would be a support member buried in the ground to a sufficient depth and having sufficient mass to easily support the apparatus 10. The base 12a supports a motor 14 which drives a gear 16 attached to the motor shaft. Gear 16 drives a larger semi-circular gear 18.
The gear 18 is fixedly attached to shaEt 20 which is fixedly attached to the collector bracketry 22. Shaft 20 is rotatably attached to the base member 12 thus allowing the base free rotational movement relative thereto.
Pivotly attached to bracketry 22 is the collector bottom member 24. The bottom member 24 is allowed to pivot with respect to base member 12, 12a at its pivotal attachment points 26, 28. The collector further includes side members 30 and end members 32. The lid 34 of the collector is constructed of a light admitting material, such as, but not limited to, glass or plexi-glass. The lid, sides, ends and bottom make up an enclosure for the collection of solar energy. Insulation (not shown) is used to contain the heat within the collector.
A bracket 36 fixedly secured to shaft 20 supports a second motor 38. The rotation of motor 38 drives a gear 40.
A gear rack 42 is pivotly attached at its upper end 39 to the collector bottom 24. The opposite end of the rack 42 is held in sliding engagement by bracket 45 which is free to pivot with respect to gear 40 and allows rack 42 to freely move therein when the gear 40 i5 caused to rotatate. It can be readily seen ~ h ~

that when the motor rotates, the rack will translate causing the co:Llector to tilt downwardly from its Figure 1 and 3 position. Along arrow 43 within the limits of the length of -the gear rack 42.
Posi-tioned within the upper portion of the collector are two cyllncle:r~ 44 which contain pistons 46 sli.dably engaged thereln. The pi.stons ~re each connected to a connec~ing rod 48 by a conventional pis-ton pin ~9 (see Figure 5) so that the connectiny rod is Eree to move laterally with respect to the longitudinal movement of the piston. The ends of the connecting rods remote from their piston attached ends are pivotly connec-ted to a central disk 50 (see the various figures). The disk 50, in some instances, will be required to have sufficient mass to act in the manner of a fly wheel.
It can be readily seen that as the pistons move wi-thin their respective cylinders, the disk S0 will rotate.
The disk 50 is secured to the end of a drive sha:Et 52 which passes through a 51ip guide 53 and is attached to a generator 55 for the production of electricity as the pistons 20 move. It should be understood that drive shaft 52 may be util-ized.to perform any type of useful wor~ and is not limlted to the production of electricity.
The cylinders are supported by the lower surface 24 by any convenient manner so as to block as little of the Sun's rays striking the reflective surfaces as practical. Brackets 51 are an example of how this may be accomplished.
The generator 55 is secured either to the bracketry 22, -the bottom 24 of the collector or through a supporting bearing on shaft 52, so that it can tilt or turn with the collector panel when motors 38 and 14 are ener~ized.

At one end of cylinders 44 is positioned flash steam boiler 54. A pump 56 for pumping the pre-heated water or any suitable expandable fluid through the injectors 41 (shown in one variation~ is interconnected to each of the two flash -steam boilers throu~h high pressure condui-t 58,60. The inlet to the pump 56 is connected to a source of preheated water (herein~
after discussed) through conduit 62. The output of the pump supplies water under increased pressure to a conventional injector ~11, such as those used in the diesel encJine ar-t, which injects this wa-ter :into the Elash steam boiler 5~.
A plurallty oE f:la-t rec-ti-linear reflective surfaces 6~ are supported by and cover the inner surEace of bottom 2~.
The reflective surfaces are positioned and held in place so that each will reflect the light of the Sun shining thereon to a single focal point 66 on the lower surface of the flash steam boiler 54. It sllould be noted that the reflective surfaces shown are of sufficient area quantity to be equally divided between two focal points to operate two flash steam boilers 54.
The reflective surface may be glass mirrors, however, the invention is not limited in this manner as any suitahle re-flective surface may be utilized equally as well to practice the invention.
The source of preheated water supplied to the pump 56 may be provided by the coil of conduit 68 positioned within the aforementioned collector, from any external heating means (not shown) or from a combination of the coil of conduit 68 and additional heat from an external source. It should be apparent that the heated water from the coil of conduit 68 may be used to supply heat requirements separate from the engine, a~ a conventional solar heater. The engine exhaust steam may be vented to atmosphere through condui-t 70 in an open cycle system where the input to the coil of conduit 68 is supplied from an external source of water. Ideally, the engine steam exhaust is utilized in a closed system wherein the steam passes through an external heat exchanger where it is used for the heating of building, operating refrigeration apparatus or the - 5~

like. The removal of heat from the steam in this manner acts as a condenser to cool the steam back to a water which is then returned to one end of -the coil conduit 68, is re-heated, and again supplied to pump 56 through conduit 62 (see Figure 3).
If, in a closed system, the use o:E the exhaust heat is - 5a -2~
not desired, a sufficiently long conduit 70 would be requiredto lower the steam temperature or a conventional condesner may be employed, in series between the engine exhaust and the coil of conduit 6~.
Referring now to Figures 1-~, on each side 30, eAYternal o:f the collector, are positioned light sens:ing elemcnts 72a, 72b, on each end 32 are positioned a pa.ir of sensors 72c and 72d, in some appli.cations a pair of sensors 72c and 72d may be be required (see Figure 4). These sensors may take many forms, such as~ but not limited to, selenium photo cells, catalog number 276-115 and light activated silicon controlled recitfiers, catalog number 276-1095, both are manufactured by Archer for Radio Shack Inc., or tlle like. ~eferring now speci:Eically to Figure 1, a shield 74 is positioned ad-jacent to the sensors 72c and 72d preventing direct Sun light from the opposite side of the collector from stri~ïng their light sensitive surface; A protrusion or lïp 71 is posit.ioned aro~nd the upper sur:Eace of the collector panel for shielding the various sensors 72a, 72b, 72c and 72d which are adjacent thereto. The protrusion or lip has sufficient width to aid in shielding the Sun t S light rays from its adjacent sensor when the collector is properly positioned with respect to reflecting the Sun's light rays from reflectors 64 to focal point 66.
The sensors 72c3 72d are interconnected to motor 1~ so that when light strikes the sensors, t~e motor will be activated in a rotational dîrection to turn the collector until the light no longer strikes that sensor. The sensors 72a and 72b are positioned so that when they receive light rays from the Sun, they cause mo~or 38 to operate and tilt the collector until that sensor no longer receives t~e - 6 ~

.

: . .

light rays.
Both motors operate in either rotational direction depending upon thei.r requirement and hold their last activated posit:ion. Tlle motors are eithcr very slow rotating, such as a clock motor, or are .

- ~a -.~ ~

.

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connected to a speed step down gear box (no-t shown) to reduce their speed to that suitable for the above requirement.
A pair of normally closed switches 77, 79 are wired in series with sensors 72a, 72b respectively, which are in series with moto~ 38 and hatter~ 98. The sensors have separate series circui.ts. Switch 77 is depressed when the bottom 2~} is rotated to i~:s maximum downward position causlng the switch to enyacJe braclcet 83 attached -to base 12. When contac-t is made, switch 77 opens the series circuit between sensor 72a and the motor causing the motor to be inoperative. When the bottom 24 is ln its Figure 1 and 3 position, swi-tch 79 engages bracke-t 85 and causes motor 38 to be inoperative in the opposite direction.
This is a safety feature to prevent burn out of the motor. A
similar pair of series circuits are provided with switches 74a and 74b that engage brackets 75a and 75b respectively to serve the same purpose as switch 77, 79 for apparatus rotating motor 14.
It should be obvious that when conduit 70 i.s connected ~ external of the collecto.r that a flexible conduit must be attached to its end to allow freedom of rotational and tilting movement with the collector as required. When operating as a closed system as hereinbefore mentioned, the conduit 70 may be a flexible conduit.
Referring now specifically to Figures 5 and 6, the - valves 78 are ac-tuated by the operation of their associated push rods 80. Push rods 80 bear against cam lobe 82 secured to drive shaft 52 for rotation therewith. Springs 81 return the valves to a normally closed position. The valves 78 are operable in a conventional manner to open at the required time so as to ven-t each flash steam boiler 54 when its associated piston reaches the end of its power stroke. The first showing of pump 56 was a block showing of a single conventional device well known in the diesel engine art or the like. Separate , . . . . ' ' ' - . . ..
.

single pumps 56a are shown in Figures 5 and 6 as another example of a pump system tha-t may be utilized equally as wel] to practice khe invention. The two pumps ~6a as 56 may be supported by the cylinder through bracket 84 as an example, however, support means from the bottom 24 (not shown) may be utilized equally as well to practice the invention. The pumps 56a are actuated by means of cam 86 operating push rods 57. The pump actuators are internally biased to bear against the cam 86 at all times.
Referrlng now specifically to Figure 1, in some circumstances a starter system will be required to initially turn shaft 52 so as -to provide rotation of cam 86 to actuate the pumps 56a. The starter system includes a starter motor 88 having its rotor coaxial and attached with drive shat 52.
~ctuation of the starter motor will turn shaft 52 at sufficient speed to properl~ actuate the pumps 56a.
The circuit for the starter motor includes a temper-ature sensitive switch 90 positioned preferably adjacent one of the flash steam boilers and a second switch comprising an electrical conductive slip ring 94 positioned above a centri-fugal ~ly weight g6 which is attached to the drive shaft 52.When drive shaft 52 turns the fly weight 96 at sufficient speed/ it is caused to move away frorn slip ring 9~ which in turn opens the starter motor circuit. Switch 90 and slip ring switch 94 are wired in series with the starter 88 and the battery 98 so that both are required to close to enable the starter motor to operate. Therefore, the starter motor will run only when the engine operation does not rotate shaft 52 at a speed that opens slip ring switch 94 and the tempera-ture is su~icient to close switch 90. If either do not occur, in the absence of the Sun, the starter motor will remain inoperative. The power to operate the starter motor is supplied, for example, by battery 98. It shoulcl be under~
stood that in some instances, it will be advan~ageous to combine the starter motor and generator into a single devicein a known manner.
It should be understood that although two steam engine piston and cylinder combinations are shown and discussed, that a single piston and cylinder steam engine or more than -two piston atld cylincler combinations may be connectecl to the same drLve shaft 52 dependincJ on power requlrem~nts ancl space available. Each steam engine would re~uire a separate concen-trator.
Operation of the Preferred Embodiment The apparatus, as described, is positioned with its side 30 having motor 38 in a generally southerly direction and ends 32 in an east/west direction.
With the apparatus properly positioned with respect to the Sun, the rays will be reflected by each of the mirror segments 64 to their appropriate focal point 66 on the bottom surface of the flash steam boiler 54.
Assume that at a given time the Sun has no-t been visible for a period of time, and now reappears, the tempera-ture of the collector is reduced below a pre-determined level and the Sun's rays will not be directed to focal point 66 because of relative movement between the Sun and Earth. The Sun's light rays will strike sensors 72a, 72b, 72c and 72d that are exposed to direct Sun light, activating the motors 38 and 14 to position the panel to focus on focal point 66.
In the afternoon, the sensors on the North and West would likely be exposed and in the morning/ likely the South and East sensors would be e~posed. The sensor or sensors receiving the Sun's light rays will cause their associated motor to operate sensors 72a and 72b in a rotational direc-,, :
tion in which that sensor is directed away from direct contactwith the Sun's rays and sensor 72c will cause counterclockwise rokation whiIe 72d will cause clockwise rotation of motor 14.

_ g _ When the sensor is shielded from the Sun's rays, then its associated motor will stop and maintain its last rotational position. If a second sensor 72 has been activated, a similar operation will occur. When both of the motors are stopped, then the rays o~ the Sun will again be clirected from the reflectors to the Eocal point 66 on the bottom surface of the Elash steam boiler 5~.
When the flash steam boiler 5~ reaches a predeter-mined temperature that is sufficient to maintain piston displacement and drive shaEt rotation switch 90 will energize the starter motor 88. The speed of rotation of the starter motor is suficient to cause the pistons to translate at an operable speed taking in consideration the load of the generator, pumps, and valves, but not sufEicient to turn the fly weight 96 fast enough to disengage slip ring 94. When the normal operation of the device increases the speed of the pistons and drive shaft, the fly weight 96 will then rise and disengage the slip ring 94 and the starter motor circuit will then be de-eneryized.
As relative movement between the Sun and Earth is directed by the Sun's rays again striking the sensor or sensors, the positioning motors will be activated to re-position the collector so that the reflective surface will ~ maintain their same focal point on the lower surface 66 to ; provide maximum heat collection.
As is well known for servo-systems, some hunting between the motors directional rotation may occur, but a slightly enlarged focal surface will allow the reflectlon to be positioned on the lower surface during normal hunting of the positioning system.
~ The positioning o~ the collector will continue to occur as Iong as Sun light is present. Absence of Sun light will cause the positioning to stop. When the Sun light is again present, a similar sequence of events will occur bringing the positioning apparatus into operation.
When the flash boiler tempera-ture is such that the pistons wi].l cease to operate, the switch 90 circuit is open preven-ting operation of the starter ci.rcuit as wi-th -the positioninc3 apparatus, returll o:E Sun light will provlde a proper sequenee o:E events bringincJ the encjine into operation.
The invention may be embodied :in other specifie forms without departing from the spirit or essential charaeter-istics thereof. The present embodiment is, therefore, to beeonsidered in all aspeets as illustrative and not restrieting, the seope of the invention being indieated by the appended claims rather than by the foregoing description, and all ehanges whieh eome within the meaniny and range of equivaleney of the elaims are therefore int.ended to be embraeed -therein.

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Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A system for tracking the relative movement of the sun and earth comprising:
a base member;
a positionable platform carried by said base member;
a plurality of light sensors, each light sensor providing a control signal when exposed to the direct rays of the sun, said sensors being positioned in a spaced apart relationship about the periphery of said position-able platform providing a first and second pair of diagonally opposed light sensors;
shielding means positioned adjacent each of said plurality of light sensors for preventing the direct rays of the sun from striking more than one light sensor of each pair of light sensors at any given time;
a first positioning means responsive to said control signals from said first pair of light sensors for providing directional rotation of said positionable platform with respect to said base member along a first path of travel between physical restraints; and a second positioning means responsive to the control signals from said second pair of light sensors for providing directional rotation of said positionable platform with respect to said base member along a second path of travel between the physical restraints;
said first and second positioning means include control signal interruption means for stopping the movements of said positionable platform along said first and second paths of travel prior to reaching said physical restraints.

2. The invention as defined in claim 1, wherein said positioning means comprises two motors interconnected to said positionable platform for moving said platform along its first and second paths of travel, the rotational direction of each of said motors being determined by the control signal from its light sensor exposed to the direct rays of the sun.