Patent Publication Number: US-2013240018-A1

Title: Robotic sunlight tracking apparatus

Description:
BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
     The present invention relates to sunlight tracking apparatuses, and more particularly to a robotic sunlight tracking apparatus which can reduce power consumption and improve efficiency of solar photovoltaic power generation. 
     2. Discussion of the Related Art 
     Currently, as fossil fuel, such as petroleum and coal, is being exhausted, development of substitutional energy is undergoing, and particularly development of technology for utilizing solar energy is undergoing, actively. 
     In power generation technology for producing electricity by utilizing the solar energy, there are solar thermal electric power generation in which a heat engine is driven by using solar heat to generate electricity, and the solar photovoltaic power generation in which a solar cell generates electricity by using sunlight. 
     In this instance, the solar cell used in the solar photovoltaic power generation includes a semiconductor compound device for converting the sunlight into the electricity, directly. 
     Most of the semiconductor compound devices include silicon Si and gallium arsenide GaAs. According to kinds of the semiconductor compounds used in the solar cell, various solar cells, such as dye-sensitized solar cells, CIGS solar cells, CdTe solar cells, and so on are developed and used, currently. 
     In general, a group of the cells put together in parallel and/or series is called as a module, and a structure is used for fixedly securing the modules for the solar photovoltaic power generation. In the structure, there are fixed type, single axis type, and two axes type, wherein the two axes type which generates the power while tracking the sun has the best efficiency. However, since a motor is required for tracking the sun, the two axes type is not used widely due to a drawback of requirement for separate power source. 
     And, though a tracking type solar photovoltaic power generation system uses a sensor for sensing a light, the system has drawbacks in that, since a sensing range of the sensor is limited, the system can not track the sun when the sum is positioned outside of the sensing range if the sun is shaded by cloud for a long time, requires a high cost, and is dependent on sensitivity of the sensor, very much. 
     SUMMARY OF THE DISCLOSURE 
     Accordingly, the present invention is directed to a robotic sunlight tracking apparatus. 
     An object of the present invention is to provide a robotic sunlight tracking apparatus in which a cam type structure is employed for rotating a solar cell module with one motor to move an azimuth angle and an altitude angle of a tracker at a time with small power consumption to improve power generation efficiency. 
     Another object of the present invention is to provide a robotic sunlight tracking apparatus in which a cylindrical cam structure is employed enabling two axes control with single motor for tracking an azimuth angle and an altitude angle of sunlight at a time to improve power generation efficiency. 
     Additional advantages, objects, and features of the disclosure will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a robotic sunlight tracking apparatus includes a solar cell module for converting the sunlight incident thereon into electricity, a rotation shaft connected to a backside of the solar cell module for supporting the solar cell module  110  while rotating, a cylindrical body under the rotation shaft having a cam with a curvature formed as a recess in a surface of the cylindrical body in a preset depth and a motor built therein to rotate in one direction by operation of a timer, and fixing means for supporting and fixing the cylindrical body to ground, wherein the rotation shaft includes a cam follower at one side of the cylindrical body placed in the cam of the cylindrical body for moving following the cam as the motor rotates, and a lift arm connected to the cam follower for moving up/down to adjust an angle of the solar cell module when the cam follower moves following the cam. 
     In another aspect of the present invention, a robotic sunlight tracking apparatus includes a solar cell module for converting the sunlight incident thereon into electricity, a rotation shaft connected to a backside of the solar cell module for supporting the solar cell module while rotating, a cylindrical body under the rotation shaft having a main cam with a curvature formed as a recess in a surface of the cylindrical body in a preset depth and a motor built therein to rotate in one direction by operation of a timer, a supplementary cam with a curvature formed as a recess in a surface of the cylindrical body in a preset depth to have a portion spaced from the main cam and one side and the other side connected to the main cam, and fixing means for supporting and fixing the cylindrical body to ground, wherein the rotation shaft includes a cam follower at one side of the cylindrical body placed in the main cam or the supplementary cam of the cylindrical body for moving following the curve of the cam as the motor rotates, and a lift arm connected to the cam follower for moving up/down to adjust an angle of the solar cell module when the cam follower moves following the main cam or the supplementary cam. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the principle of the disclosure. In the drawings: 
         FIG. 1  illustrates a front side perspective view of a robotic sunlight tracking apparatus in accordance with a first preferred embodiment of the present invention. 
         FIG. 2  illustrates a back side perspective view of a robotic sunlight tracking apparatus in accordance with a first preferred embodiment of the present invention. 
         FIG. 3  illustrates a side view of the rotation shaft in  FIG. 1 . 
         FIG. 4  illustrates a perspective view of the first rotation shaft and the first hinge coupling unit in  FIG. 3  in detail. 
         FIG. 5  illustrates a side view of the second rotation shaft and the second hinge coupling unit in  FIG. 3 , in detail. 
         FIG. 6  illustrates a graph showing a relation between an altitude angle and an azimuth angle measured with a robotic sunlight tracking apparatus of the present invention. 
         FIGS. 7˜9  illustrate diagrams showing rotation angles of a rotation shaft according to the graph in  FIG. 6 . 
         FIG. 10  illustrates a side view of a robotic sunlight tracking apparatus in accordance with a second preferred embodiment of the present invention. 
         FIG. 11  illustrates a back side perspective view of a robotic sunlight tracking apparatus in accordance with a second preferred embodiment of the present invention. 
         FIG. 12  illustrates a side view of the rotation shafts in  FIG. 10 . 
         FIG. 13  illustrates a perspective view of the first rotation shaft and the first hinge coupling unit in  FIG. 12  in detail. 
         FIG. 14  illustrates a side view of the second rotation shaft and the second hinge coupling unit in  FIG. 12 , in detail. 
     
    
    
     DESCRIPTION OF SPECIFIC EMBODIMENTS 
     Reference will now be made in detail to the specific embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIG. 1  illustrates a front side perspective view of a robotic sunlight tracking apparatus in accordance with a first preferred embodiment of the present invention,  FIG. 2  illustrates a back side perspective view of a robotic sunlight tracking apparatus in accordance with a first preferred embodiment of the present invention, and  FIG. 3  illustrates a side view of the rotation shafts in  FIG. 1 . 
     Referring to  FIGS. 1˜3 , the robotic sunlight tracking apparatus includes a solar cell module  110  for converting the sunlight incident thereon into electricity, a rotation shaft  120  connected to a backside of the solar cell module  110  for supporting the solar cell module  110  while rotating, a cylindrical body  130  under the rotation shaft  120  having a cam  131  with a curvature formed as a recess in a surface of the cylindrical body  130  in a preset depth and a motor (Not shown) built therein to rotate in one direction by operation of a timer, and a fixing means  140  for supporting and fixing the cylindrical body  130  to ground, wherein the rotation shaft  120  includes a cam follower  150  at one side of the cylindrical body  130  placed in the cam  131  of the cylindrical body  130  for moving following the cam  131  as the motor rotates, and a lift arm  160  connected to the cam follower  150  for moving up/down to adjust an angle of the solar cell module  110  when the cam follower  150  moves following the cam  131 . 
     In this instance, the rotation shaft  120  supports the solar cell module  110  and has a first rotation shaft  121  for making an angle of the solar cell module  110  to change following the up/down movement of the lift arm  160 . 
     The cell portion of the solar cell module  110  which collects the sunlight has a high heat generation rate of heat reaching to hundreds of degrees of temperature due to the collected light. Since the heat makes the efficiency of the solar cell module  110  poor, a heat dissipation plate (Not shown) is mounted to a backside of the solar cell module  110  for dissipating the heat from the cell portion. 
     Four solar cell modules  110  construe one array, and the rotation shaft  120  includes an “H” shaped securing plate  122  fastened to the backsides of the four solar cell modules  110  for supporting the solar cell modules  110 , a reinforcing plate  123  attached to a backside of the securing plate  122  for reinforcing the securing plate  122 , and a first hinge coupling unit  124  for connecting the reinforcing plate  123  to the first rotation shaft  121 . 
     In order to support the lift arm  160 , formed at one side of the lift arm  160 , there are a lift arm supporting portion  161  for supporting the lift arm  160  when the lift arm  160  moves up/down round the first rotation shaft  121 , a fixed end  162  at one side of the lift arm  160  to slide when the lift arm  160  moves up/down, a fixing bracket  163  for fixing the fixed end  162  to the lift arm supporting portion  161 , and a movable rail  164  formed in conformity with the fixed end  162  for making the lift arm  160  to move up/down following the fixed end  162 . 
     The lift arm  160  has one side connected to the cam follower  150 , and the other side connected to the reinforcing plate  123  on the backside of the solar cell module  110 . 
     Between the connection of the other side of the lift arm  160  to the reinforcing plate  123 , there is a second rotation shaft  165  mounted rotatable with the up/down movement of the lift arm  160  to construe a second hinge coupling unit  166 . 
     There is a roller  151  at an end of the cam follower  150  placed in the cam  131  of the cylindrical body  130  for moving following the cam  131 . 
     Therefore, when the roller  151  moves following the curve of the cam  131 , the movable rail  164  at one side of the lift arm  160  moves up/down following the fixed end  162  by a rolling motion of the roller  151 . 
     In this instance, the one motor in the cylindrical body  130  is programmed with a timer to rotate once the curve of the cam  131  in 24 hours following an azimuth angle and an altitude angle of the sun measured for 24 hours starting from sun rise to sun set. 
       FIG. 4  illustrates a perspective view of the first rotation shaft and the first hinge coupling unit in  FIG. 3  in detail. 
     Referring to  FIG. 4 , over the cylindrical body  130 , there is the first rotation shaft  121  fixed to the reinforcing plate  163  through the rotation shaft  120 . In this instance, the first rotation shaft  121  is placed in a fixing portion  133  coupled to a top of the rotation shaft  120  so that the securing plate  122  rotates in one direction smoothly when the lift arm  160  moves up/down. 
     In the meantime, there is a hollow shaft  134  in the rotation shaft  120  extended through the cylindrical body  130  and the fixing portion  133  for enabling pass of a cable for transmitting electricity from the solar cell module  110 . 
       FIG. 5  illustrates a side view of the second rotation shaft and the second hinge coupling unit in  FIG. 3 , in detail. 
     Referring to  FIG. 5 , the second rotation shaft  165  is on the other side of the lift arm  160  and has a slide bar  167  placed therein for rotating the slide bar  167  of the second hinge coupling unit  166  in left/right directions following the up/down movement of the lift arm  160 . 
     The slide bar  167  has supporting means  168  at both ends of the slide bar  167  for fastening to the reinforcing plate  123  in a state the lift arm  160  is placed between the second rotation shaft  165  for the lift arm  160  to move in left/right directions. 
     In the meantime, though the embodiment suggests the second rotation shaft  165  and the second hinge coupling unit  166 , but the embodiment is not limited to this. In a state the lift arm  160  is connected to the backside of the solar cell module  110  directly, the solar cell module  110  can also be rotated appropriately according to the azimuth angle and the altitude angle of the sun. 
       FIG. 6  illustrates a graph showing a relation between an altitude angle and an azimuth angle measured with a robotic sunlight tracking apparatus of the present invention. 
     Referring to  FIG. 6 , it can be known that the altitude angle of the sun varies with time. 
     Therefore, by tracking the movement of the sun and measuring the azimuth angle and the altitude angle of the sun starting from sun rise to sun set at every hour, and plotting a result of measurement as a graph, averages thereof are calculated, to obtain a cam curve. 
     By tracking the movement of the sun starting from sun rise to sun set, plotting variations of the azimuth angle and the altitude angle of the sun as the graph, averages thereof are calculated, the cam  131  curve is formed in a surface of the cylindrical body  130 , and the altitude angle and the azimuth angle are programmed mechanically such that the solar cell module  110  rotates following the cam  131  curve which describes positional variation of the sun as it is, for the robotic sunlight tracking apparatus to track the sun. 
     Since, by making the roller  151  of the cam follower  150  to move following the cam  131  curve formed in the surface of the cylindrical body  130  according to the variations of the azimuth angle and the altitude angle of the sun, the azimuth angle of the sun is tracked, and the altitude angle of the sun is tracked with the lift arm  160 , power production with the solar cell module  110  can be maximized. 
       FIGS. 7˜9  illustrate diagrams showing rotation angles of a rotation shaft according to the graph in  FIG. 6 . 
       FIG. 7  illustrates the rotation shaft  120  maintained at about 60° at 8˜10 o&#39;clock in the morning, and at 3˜5 o&#39;clock in the afternoon to have the sunlight incident on the solar cell module  110 ,  FIG. 8  illustrates the rotation shaft  120  maintained at about 30˜60° at 10˜11 o&#39;clock in the morning, and at 2˜3 o&#39;clock in the afternoon to have the sunlight incident on the solar cell module  110 , and  FIG. 9  illustrates the rotation shaft  120  maintained at about 30° starting from 11 o&#39;clock in the morning to 2 o&#39;clock in the afternoon to have the sunlight incident on the solar cell module  110 . 
     That is, as the roller  151  of the cam follower  150  rotates following the cam  131  curve for 24 hours, the robotic sunlight tracking apparatus enables to have the sunlight incident thereon while maintaining an angle of 30° in the morning and the afternoon, and 60° in the daytime, permitting to have the sunlight incident thereon to the maximum. 
     According to this, as the rotation shaft  120  maintains an optimum angle to the sun proper to each time band owing to the up/down movement of the lift arm  160  connected to the cam follower  150  which follows the rotation of the cam follower  150  that follows the cam curve  131 , light collecting efficacy of the solar cell module  110  can be improved, further. 
       FIG. 10  illustrates a front side perspective view of a robotic sunlight tracking apparatus in accordance with a second preferred embodiment of the present invention,  FIG. 11  illustrates a back side perspective view of a robotic sunlight tracking apparatus in accordance with a second preferred embodiment of the present invention, and  FIG. 12  illustrates a side view of the rotation shafts in  FIG. 10 . 
     Referring to  FIGS. 10˜12 , the robotic sunlight tracking apparatus includes a solar cell module  110  for converting the sunlight incident thereon into electricity, a rotation shaft  120  connected to a backside of the solar cell module  110  for supporting the solar cell module  110  while rotating, a cylindrical body  130  under the rotation shaft  120  having a main cam  131  with a curvature formed as a recess in a surface of the cylindrical body  130  in a preset depth and a motor (Not shown) built therein to rotate in one direction by operation of a timer, a supplementary cam  132  with a curvature formed as a recess in a surface of the cylindrical body  130  in a preset depth to have a portion spaced from the main cam  131  and to be connected to one side of the main cam  131 , and fixing means  140  for supporting and fixing the cylindrical body  130  to ground, wherein the rotation shaft  120  includes a cam follower  150  at one side of the cylindrical body  130  placed in the main cam  131  or the supplementary cam  132  of the cylindrical body  130  for moving following the main cam  131  or the supplementary cam  132  as the motor rotates, and a lift arm  160  connected to the cam follower  150  for moving up/down to adjust an angle of the solar cell module  110  when the cam follower  150  moves following the main cam  131  or the supplementary cam  132 . 
     In this instance, the rotation shaft  120  supports the solar cell module  110  and has a first rotation shaft  121  for making an angle of the solar cell module  110  to change following the up/down movement of the lift arm  160 . 
     Though two of the main cam  131  and the supplementary cam  132  are formed in the cylindrical body  130  for appropriate dealing with a case when there is seasonal or regional deviation of the altitude angle and the azimuth angle, more than two cams can be formed. 
     Four solar cell modules  110  construe one array, and the rotation shaft  120  includes a securing plate  122  fastened to the backsides of the four solar cell modules  110  for supporting the solar cell modules  110 , a reinforcing plate  123  attached to a backside of the securing plate  122  for reinforcing the securing plate  122 , and a first hinge coupling unit  124  for connecting the reinforcing plate  123  to the first rotation shaft  121 . 
     In order to support the lift arm  160 , formed at one side of the lift arm  160 , there are a lift arm supporting portion  161  for supporting the lift arm  160  when the lift arm  160  moves up/down round the first rotation shaft  121 , a fixed end  162  at one side of the lift arm  160  to slide when the lift arm  160  moves up/down, a fixing bracket  163  for fixing the fixed end  162  to the lift arm supporting portion  161 , and a movable rail  164  formed in conformity with the fixed end  162  for making the lift arm  160  to move up/down following the fixed end  162 . 
     The lift arm  160  has one side connected to the cam follower  150 , and the other side connected to the reinforcing plate  123  on the backside of the solar cell module  110 . 
     Between the connection of the other side of the lift arm  160  to the reinforcing plate  123 , there is a second rotation shaft  165  mounted rotatable with the up/down movement of the lift arm  160  to construe a second hinge coupling unit  166 . 
     There is a roller  151  at an end of the cam follower  150  placed in the main cam  131  or the supplementary cam  132  of the cylindrical body  130  for moving following the main cam  131  or the supplementary cam  132 . 
     Therefore, when the roller  151  moves following the curve of the main cam  131  or the supplementary cam  132 , the movable rail  164  at one side of the lift arm  160  moves up/down following the fixed end  162  by a rolling motion of the roller  151 . 
     In this instance, the one motor in the cylindrical body  130  is programmed with a timer to rotate once the curve of the main cam  131  or the supplementary cam  132  in 24 hours following an azimuth angle and an altitude angle of the sun measured for 24 hours starting from sun rise to sun set. 
     In the meantime, the main cam  131  and the supplementary cam  132  are formed by mechanical programming utilizing average azimuth angles and altitude angles of the sun accumulated for 30 years provided by the meteorological observatory. Therefore, by tracking the sunlight with a fixed program according to the altitude angle and the azimuth angle of the sun, malfunction can be minimized. 
     That is, though, in general, the sunlight is tracked with an additional sensor, such as a pyranometer sensor, when malfunction takes place due to difficulty in measurement caused by shadow and the like, the present invention can minimize malfunction by repetitive tracking of the altitude angle and the azimuth angle of the sun by utilizing the mechanical programming. 
     Moreover, since power is supplied from an outside for driving the motor with power consumption as low as 8 W enabling to reduce the power consumption, and an emergency battery (Not shown) can be provided for operation of the motor when the outside power fails. In this instance, the emergency battery is re-chargeable for supplying power to the motor when the outside power fails. 
     The robotic sunlight tracking apparatus in accordance with the second preferred embodiment of the present invention is programmed to track a position of the sun matched to the present altitude and azimuth angles of the sun automatically when the robotic sunlight tracking apparatus is come into operation again after black out. 
     That is, when the robotic sunlight tracking apparatus is put into operation again after failure of the robotic sunlight tracking apparatus is repaired, the robotic sunlight tracking apparatus can track the position of the sun matched to the present altitude and azimuth angles of the sun automatically by making the robotic sunlight tracking apparatus to be operative with reference to the GPS. 
       FIG. 13  illustrates a perspective view of the first rotation shaft and the first hinge coupling unit in  FIG. 12  in detail. 
     Referring to  FIG. 13 , over the cylindrical body  130 , there is the first rotation shaft  121  fixed to the reinforcing plate  163  through the rotation shaft  120 . In this instance, the first rotation shaft  121  is placed in a fixing portion  133  coupled to a top of the rotation shaft  120  so that the securing plate  122  rotates in one direction smoothly when the lift arm  160  moves up/down. 
     In the meantime, there is a hollow shaft  134  in the rotation shaft  120  extended through the cylindrical body  130  and the fixing portion  133  for enabling pass of a cable for transmitting electricity from the solar cell module  110 . 
     There are extensible supporting members  138  on both sides of an upper side of the cylindrical body  130  extended to the backside of the solar cell module  110 , respectively. Each of the supporting members  138  varies a length thereof when the cam follower  150  moves following the main cam  131  or the supplementary cam  132  of the cylindrical body  130 . 
       FIG. 14  illustrates a side view of the second rotation shaft and the second hinge coupling unit in  FIG. 12 , in detail. 
     Referring to  FIG. 14 , the second rotation shaft  165  is on the other side of the lift arm  160  and has a slide bar  167  placed therein for rotating the slide bar  167  of the second hinge coupling unit  166  in left/right directions following the up/down movement of the lift arm  160 . 
     The slide bar  167  has supporting means  168  at both ends of the slide bar  167  for fastening to the reinforcing plate  123  in a state the lift arm  160  is placed between the second rotation shaft  165  for the lift arm  160  to move in left/right directions. 
     In the meantime, though the embodiment suggests the second rotation shaft  165  and the second hinge coupling unit  166 , but the embodiment is not limited to this. In a state the lift arm  160  is connected to the backside of the solar cell module  110  directly, the solar cell module  110  can be rotated appropriately according to the azimuth angle and the altitude angle of the sun. 
     By tracking the movement of the sun starting from sun rise to sun set, plotting variations of the azimuth angle and the altitude angle of the sun as the graph, averages thereof are calculated, the main cam  131  or the supplementary cam  132  curve is formed in a surface of the cylindrical body  130 , and the altitude angle and the azimuth angle are programmed mechanically such that the solar cell module  110  rotates following the cam  131  curve which describes positional variation of the sun as it is, for the robotic sunlight tracking apparatus to track the sun. 
     Since, by making the roller  151  of the cam follower  150  to move following the main cam  131  or the supplementary cam  132  curve formed in the surface of the cylindrical body  130  according to the variations of the azimuth angle and the altitude angle of the sun, the azimuth angle of the sun is tracked, and the altitude angle of the sun is tracked with the lift arm  160 , power production with the solar cell module  110  can be maximized. 
     As has been described, the robotic sunlight tracking apparatus of the present invention has the following advantages. 
     First, as the solar cell module has the sunlight incident thereon at 60° in the morning and in the evening, and 30° in the daytime while the solar cell module is rotating at a fixed speed following the fixed speed rotation of the motor and moving up/down according to the up/down movement of the lift arm following the cam curve, the robotic sunlight tracking apparatus of the present invention can improve power generation efficiency. 
     Second, the mechanical programming of the variation of the altitude and azimuth angles of the sun with the cam curve permits tracking of the position of the sun without other control functions, thereby providing maximum power generation efficiency. 
     Third, the two axes rotation made available only with one motor permits to track the sunlight only with power in a range of 15 W. 
     Fourth, the 360° rotation following the cam curve for 24 hours permits easy control and no directional control of the motor permits to reduce power consumption. 
     Fifth, the minimized control units and driving units required for tracking the sun permits installation and maintenance easier than other products. 
     Sixth, by providing a mode in which the tracking of the sun is not made in strong wind, snow, rain, a cloudy day, there is no power consumption of the motor. 
     Seventh, the mechanical programming inputted to the cylindrical cam by utilizing average azimuth angles and altitude angles of the sun accumulated for 30 years provided by the meteorological observatory permits the tracking of the sunlight by two axes control by using single motor. 
     Eighth, the cylindrical cam with at least two stages permits to track the sunlight matched to the altitude angle and the azimuth angle of the sun according to a season and a region. 
     Ninth, the synchronized sunlight tracking system permits tracking of the sunlight matched to the present altitude angle and the azimuth angle of the sun in black out or bad weather. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.