Abstract:
A solar tracking device for overcoming the disadvantages of a conventional solar energy system utilizing motors and to lower electricity consumption and decrease cost is provided. The device includes a solar module or solar collector supported by two springs under both ends and two water tanks on both ends. The solar module or solar collector, similar to a heliostat, is adapted to slowly revolve in response to the imbalanced water tanks filled with different amount of water.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The present invention relates to a solar tracking device and, more particularly, to a solar tracking device including a solar module or solar collector supported by two springs under both ends and two water tanks on both ends, wherein the solar module or solar collector, similar to a heliostat, is adapted to slowly revolve in response to the imbalanced water tanks filled with different amounts of water. 
   2. Related Art 
   A conventional heliostat type solar tracker for a solar energy system is adapted to slowly revolve by a motor. In a conventional solar energy system capable of generating 1 KW, its solar module has a weight of about 10 Kg. The solar module and other cooperating components such as a supporter may have a total weight of more than 100 Kg. Also, a solar collector is quite heavy. Thus, the revolving of the solar energy system by a motor may disadvantageously consume much energy and increase cost. This is not desired. Thus, a need for improvement exists. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a solar tracking device for overcoming the disadvantages of conventional solar energy systems utilizing motors and which lowers electricity consumption and decreases cost. 
   It is another object of the present invention to provide a solar tracking device including one or more solar modules or solar collectors adapted to concentrate solar energy, with each of the one or more solar modules or solar collectors having first and second ends. One or more fulcrums enable the solar modules or solar collectors to revolve eastward or westward. One or more first water tanks are mounted on the first end of each of the one or more solar modules or solar collectors and have a first inlet and a first outlet. One or more second water tanks are mounted on the second end of each of the one or more solar modules or solar collectors and have a second inlet and a second outlet. One or more first springs, are secured to and support the underside of the first end of each of the one or more solar modules or solar collectors. One or more second springs are secured to and support the underside of the second end of each of the one or more solar modules or solar collectors. One or more angular movement measuring members are mounted at each of the one or more fulcrums for measuring the present tilt angle. Thus, filing water into the first water tank and/or draining water from the second water tank will compress the first spring and expand the second spring, filing water into the second water tank and/or draining water from the first water tank will compress the second spring and expand the first spring, and compression of the springs will move the solar modules or solar collectors so as to provide a solar tracking device without motors for a solar energy system. 
   The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  schematically depicts a preferred embodiment of a solar tracking device with springs according to the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , a solar tracking device in accordance with a preferred embodiment of the invention comprises a solar module or solar collector  81 , an east spring  85 , a west spring  86 , an east water tank  83  and a west water tank  84 . The solar module or solar collector  81  has a fulcrum  82  and an angular movement measuring member  87 mounted at the fulcrum  82 . Each of the east and west springs  85  and  86  is secured to an underside of either end of the solar module or solar collector  81  as an elastic support. Each of the east and west water tanks  83  and  84  is mounted on either end of solar module or solar collector  81 . The east water tank  83  has a top inlet  831  and a bottom outlet  832 , and the west water tank  84  has a top inlet  841  and a bottom outlet  842 . 
   Provided that there is no water in both of the east water tank  83  and west water tank  84  and that all inlets and outlets  831 ,  832 ,  841 , and  842  are closed, the east spring  85  and the west spring  86  are balanced and the solar module or solar collector  81  is in a state of level. In the night, the inlet  831  of the east water tank  83  is opened to fill water until the east water thank  83  is full. As such, the east spring  85  is fully compressed (i.e., its height is in a lowest point). Also, the solar module or solar collector  81  faces the east. As the sun moves from east to west approximately 15° per hour, a clockwork mechanism (not shown) can be provided to control the amount and period of water flowing from the east water tank  83  so that the solar module or solar collector  81  revolves about the fulcrum  82  at an angle of 15° per hour for precisely tracking the position of the sun. The solar module or solar collector  81  may be adjusted to revolve about the fulcrum  82  at an angle of 7.5° per half-hour, an angle of 3.75° per 15 minutes, or an angle of 2.5° per 10 minutes by controlling the amount and period of water flowing from the east water tank  83 . 
   An embodiment of a solar tracking device according to the invention wherein the solar module or solar collector  81  revolves about the fulcrum  82  at an angle of 2.5° per 10 minutes will be described in detail hereinafter. Ten minutes after sunrise, the outlet  832  of the east water tank  83  is opened to flow off water. In response, the east spring  85  expands upward a small distance. Also, in response, the solar module or solar collector  81  tilts toward the west a small angle by turning about the fulcrum  82 . The water flowing off will stop by shutting off the outlet  832  when the angular movement measuring member  87  measures that the tilt angle reaches 2.5°. 
   After another ten minutes has elapsed, the outlet  832  of the east water tank  83  is opened again to flow off water. In response, the east spring  85  expands upward another small distance. Also in response, the solar module or solar collector  81  further tilts toward the west another small angle by turning about the fulcrum  82 . The water flowing off will stop by shutting off the outlet  832  when the angular movement measuring member  87  measures that the tilt angle reaches another 2.5°. 
   The step discussed in the previous paragraph will continue until there is no water in the east water tank  83 . In this state, no water is in both of the east water tank  83  and west water tank  84 , all inlets and outlets  831 ,  832 ,  841 , and  842  are closed, the east spring  85  and the west spring  86  are balanced again, and thus the solar module or solar collector  81  is disposed in a horizontal position. 
   Next, the inlet  841  of the west water tank  84  is opened to fill water therein. In response, the west spring  86  is compressed gradually and the horizontal solar module or solar collector  81  begins to tilt toward the west a small angle by turning about the fulcrum  82 . The water filling will stop by shutting off the inlet  841  when the angular movement measuring member  87  measures that the tilt angle reaches 2.5°. 
   After ten minutes has elapsed, the inlet  841  of the west water tank  84  is opened to fill water therein again. In response, the west spring  86  is further compressed gradually, the solar module and solar collector  81  further tilts toward the west a small angle by turning about the fulcrum  82 . The water filling will stop by shutting off the inlet  841  when the angular movement measuring member  87  measures that the tilt angle reaches another 2.5°. 
   The step discussed in the previous paragraph will continue until the west water tank  84  is full of water. In this state, the west spring  86  is fully compressed (i.e., its height is in a lowest point). Also, the solar module or solar collector  81  faces the west. 
   Finally, the outlet  842  of the west water tank  84  is opened to flow off water after sundown. This solar tracking cycle is thus completed. 
   Note that all of the above inlet openings for water filling and outlet openings for water flowing off as well as closings associated therewith are done automatically by actuating a clockwork mechanism. 
   By replacing motors with springs, the advantages over the prior art devices described herein include relatively lower cost and significantly lower electricity consumption than conventional devices utilizing motors. Moreover, for precisely tracking the position of the sun, motors of the conventional devices are required to be activated frequently. Thus, electricity consumption increases. In the present invention, the springs  85  and  86  are gradually compressed and the solar module or solar collector  81  therefore revolves gradually to track the position of the sun all the time. 
   Furthermore, since solar altitude angle varies with time, the solar module or solar collector  81  can be modified to be oriented with its longitudinal axis in a north-south direction for north-south tracking so that the tilt angle of the solar module or solar collector  81  changes with solar altitude angle without motors. 
   Also, solar modules or solar collectors respectively oriented with a longitudinal axis in an east-west direction and a north-south direction can be provided simultaneously so that the tilt angles of the solar modules or solar collectors  81  change with solar altitude angle and solar azimuth angle without motors. 
   While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.