An automatic cleaning machine for wall plates is disclosed. Multiple long axial tracks with the same direction are fixed in a parallel and array pivoted way on the circumference or the plate face of the object to be cleaned. Water-guiding pipes are formed on the long axial tracks which are provided with electric rails, and multiple magnetic valves are provided on the pipe walls of the water-guiding pipes in a spaced way. The long axial tracks are provided with sliding frames. The sliding frames are provided with conducting brackets corresponding to the electric rails, and provided with long axial magnetic-attracted bodies opposed to the magnetic valves to turn on or off the cleaning water with a magnetic force. Brush drive mechanisms are provided on the sliding frames, and the shaft levers of the brush drive mechanisms are arranged in a direction normal to the long axial tracks and combined with long axial brushes to scrub wall plates. Cover plates are provided outside the long axial brushes. The automatic cleaning machine can be used for cleaning the plate faces of external walls, glasses and solar panels.

CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a National Stage of International Application No. PCT/CN2010/000987, filed Jun. 30, 2010, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a cleaning device, and more particularly to a cleaning device for automatically cleaning a wall plate. 
         [0004]    2. Description of the Related Art 
         [0005]    Exterior cleaning is the process of cleaning the exterior walls or windows of a building, thereby maintaining the cleanliness of the building's exterior. A typical method of cleaning a building's exterior is by supporting maintenance personnel on a suspended scaffold as the maintenance personnel manually clean the building's exterior. 
         [0006]    Solar panel cleaning is the process of cleaning a solar panel, thereby maximizing solar panel efficiency. A typical method of cleaning a solar panel is done manually by maintenance personnel. 
         [0007]    However, both the above methods of cleaning a building's exterior and a solar panel are operated manually, which increases labor costs. To overcome the shortcomings, the present invention provides an automatic cleaning machine for wall plates to mitigate or obviate the aforementioned problems. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides an automatic cleaning machine for wall plates that reduces labor costs. 
         [0009]    An automatic cleaning machine for wall plates in accordance with the present invention comprises at least two long axial tracks, at least two sliding frames, at least two bristle drive mechanisms and at least one long axial brush. The long axial tracks are arranged parallel and are secured to a wall plate and each long axial track is an extrusion. The sliding frames are mounted on corresponding long axial tracks and each sliding frame is slid along the long axial track by a main drive mechanism. Each bristle drive mechanism is mounted on one of the sliding frames. Each of the at least one long axial brush is vertical to the long axial tracks, is mounted between two adjacent bristle drive mechanisms and is driven by the two bristle drive mechanisms. Each of the at least one long axial brush includes a plurality of bristles configured to selectively contact the wall plate. 
         [0010]    The automatic cleaning machine for wall plates as above mentioned, wherein each bristle drive mechanism is mounted on a holder and the holder is mounted on one of the sliding frames, each bristle drive mechanism includes two rotating shaft levers being vertical to the long axial tracks, each of the at least one long axial brush is mounted between the rotating shaft levers of the two adjacent bristle drive mechanisms, and the bristles of the at least one long axial brush may be soft bristles. 
         [0011]    The automatic cleaning machine for wall plates as above mentioned further comprises a cover plate covering the at least one long axial brush. 
         [0012]    The automatic cleaning machine for wall plates as above mentioned, wherein each bristle drive mechanism is a linear actuator and includes a longitudinally reciprocating shaft lever being vertical to the long axial tracks, and each of the at least one long axial brush is mounted between the longitudinally reciprocating shaft levers of the two adjacent bristle drive mechanisms. 
         [0013]    The automatic cleaning machine for wall plates as above mentioned, wherein each bristle drive mechanism has a shaft hole formed longitudinally therein and each long axial brush has a shaft hole formed longitudinally therein in alignment with the shaft holes of the bristle drive mechanisms, a shaft is inserted into the shaft holes of the bristle drive mechanisms and the at least one long axial brush, and the bristle drive mechanisms are actuated to move the at least one long axial brush in reciprocating longitudinal movement. 
         [0014]    The automatic cleaning machine for wall plates as above mentioned, wherein a telescopic drive unit has two ends, one end is connected to one of the bristle drive mechanisms and the other end is pivotally connected to one of the sliding frames, and the telescopic drive unit is controlled to make the bristles selectively contact the wall plate. 
         [0015]    The automatic cleaning machine for wall plates as above mentioned further comprises a cover plate covering the at least one long axial brush, a separator mounted between the cover plate and the at least one long axial brush and having a plurality of ventilation holes, and an air duct is formed between the separator and the cover plate. 
         [0016]    The automatic cleaning machine for wall plates as above mentioned, wherein each long axial track includes a longitudinal fastening groove and a nut corresponds to and is received in the fastening groove to secure the long axial track to the wall plate. 
         [0017]    The automatic cleaning machine for wall plates as above mentioned, wherein each long axial track includes a plurality of longitudinal roller rails and a plurality of rollers are rotatably mounted on each sliding frame and slidably mounted in the roller rails. 
         [0018]    The automatic cleaning machine for wall plates as above mentioned, wherein an electric rail is secured to each long axial track and each sliding frame includes a conducting bracket corresponding to the electric rail. 
         [0019]    The automatic cleaning machine for wall plates as above mentioned, wherein each long axial track includes a longitudinal water-guiding pipe and a longitudinal magnet rail, the magnet rail is adjacent to the water-guiding pipe, a plurality of spaced apart magnetic valves are mounted on the long axial tracks, and a long axial magnetic-attracted body is slidably mounted in the magnet rail with one of the sliding frames to control a corresponding magnetic valve. 
         [0020]    The automatic cleaning machine for wall plates as above mentioned, wherein each magnetic valve includes a tube, a magnetic rod, a spring, a sealing gasket and a magnetic plate. The tube has an inner surface, a tubular chamber, a plurality of recesses and a plurality of inflow holes. The tubular chamber has an open end and a closed end. The recesses are formed longitudinally in the inner surface of the tube. The inflow holes are formed radially through the tube and each inflow hole communicates with one of the recesses. The magnetic rod is mounted through the spring and disposed in the tubular chamber. The sealing gasket and the magnetic plate are secured at the open end of the tubular chamber in sequence. The sealing gasket has a hole and the magnetic plate has a hole. The spring biases the magnetic rod to close the holes of the sealing gasket and the magnetic plate. 
         [0021]    The automatic cleaning machine for wall plates as above mentioned, wherein a toothed strip is secured to each long axial track and each main drive mechanism is mounted on one of the sliding frames and has a shaft connected to a gear engaging the toothed strip. 
         [0022]    The automatic cleaning machine for wall plates as above mentioned, wherein two rods are vertical to the long axial tracks and are rotatably disposed at two ends of the long axial track, a plurality of spools are mounted on each rod and each spool corresponds to one end of one of the long axial tracks, a pulling element is mounted between each spool and a corresponding sliding frame, and an auxiliary drive mechanism is connected to and rotates each rod. 
         [0023]    In summary, the present invention is an automatic cleaning machine for wall plates for cleaning a cleaning object such as an exterior wall, a window or a solar panel. The long axial tracks are arranged parallel and are secured to the cleaning object. Each long axial track includes a longitudinal water-guiding pipe. The spaced apart magnetic valves are mounted on the long axial tracks. One electric rail is secured to each long axial track. The sliding frames are mounted on corresponding long axial tracks. Each sliding frame includes one conducting bracket corresponding to the electric rail. One long axial magnetic-attracted body is slidably mounted on one of the long axial tracks to control a corresponding magnetic valve in order to open or close a path for the cleaning water. One bristle drive mechanism is mounted on one of the sliding frames. Each bristle drive mechanism includes a shaft lever being vertical to the long axial tracks and connected to the long axial brush. The long axial brush is used to clean the object to be cleaned. The cover plate covers the long axial brush. Owing to the automatic nature of the cleaning device, labor costs are reduced. 
         [0024]    Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a perspective view of a first embodiment of an automatic cleaning machine for wall plates in accordance with the present invention; 
           [0026]      FIG. 2  is a perspective view of the first embodiment of the automatic cleaning machine for wall plates in  FIG. 1  without a cover plate; 
           [0027]      FIG. 3  is an enlarged partially exploded perspective view of the first embodiment of the automatic cleaning machine for wall plates in  FIG. 1 ; 
           [0028]      FIG. 4  is an enlarged exploded perspective view of a magnetic valve of the first embodiment of the automatic cleaning machine for wall plates in  FIG. 1 ; 
           [0029]      FIG. 5  is an enlarged side view of a long axial track of the first embodiment of the automatic cleaning machine for wall plates in  FIG. 1 ; 
           [0030]      FIG. 6  is an enlarged partial side view of the first embodiment of the automatic cleaning machine for wall plates in  FIG. 1 ; 
           [0031]      FIG. 7  is an enlarged partial perspective view of the first embodiment of the automatic cleaning machine for wall plates in  FIG. 1  showing a connection between a spool and a pulling element; 
           [0032]      FIG. 8  is a perspective view of a second embodiment of an automatic cleaning machine for wall plates in accordance with the present invention; 
           [0033]      FIG. 9  is a perspective view of the second embodiment of the automatic cleaning machine for wall plates in  FIG. 8  without a cover plate; 
           [0034]      FIG. 10  is an enlarged partial exploded perspective view of the second embodiment of the automatic cleaning machine for wall plates in  FIG. 8 ; 
           [0035]      FIG. 11  is an enlarged partial side view of the second embodiment of the automatic cleaning machine for wall plates in  FIG. 8 ; and 
           [0036]      FIG. 12  is an enlarged partial perspective view of the second embodiment of the automatic cleaning machine for wall plates in  FIG. 8  showing that a telescopic drive unit is extended to push a bristle drive mechanism. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    With reference to  FIGS. 1 to 3 , a first embodiment of an automatic cleaning machine for wall plates in accordance with the present invention comprises at least two long axial tracks  10 , a plurality of magnetic valves  30 , at least two sliding frames  20 , at least two bristle drive mechanisms  60 , at least one long axial brush  50  and a cover plate  70 . 
         [0038]    With reference to  FIGS. 3 and 5 , each long axial track  10  is a rectangular aluminum extrusion and includes four side surfaces, a longitudinal water-guiding pipe  101 , three longitudinal roller rails  102 , a longitudinal fastening groove  103 , a longitudinal electric rail mounting groove  104 , a longitudinal magnet rail  105 , a longitudinal magnetic valve mounting groove  106  and a longitudinal toothed strip mounting groove  107 . Each roller rail  102  is formed in one of the side surfaces of the long axial track  10 . An electric rail  1041  is secured in the electric rail mounting groove  104  and has one end electrically connected to a power supply. The magnet rail  105  and the magnetic valve mounting groove  106  are adjacent to the water-guiding pipe  101 . A long axial magnetic-attracted body  1051  is slidably mounted in the magnet rail  105 . The magnetic valve mounting groove  106  communicates with the water-guiding pipe  101  through a plurality of magnetic valve bores  1061 . The magnetic valve bores  1061  are spaced apart from one another by equal distances. A toothed strip  1071  is secured in the toothed strip mounting groove  107  and has a toothed upper surface being exposed. 
         [0039]    With reference to  FIGS. 3 and 4 , the magnetic valves  30  are mounted on the long axial tracks  10 , and each magnetic valve  30  includes a tube  301 , a magnetic rod  302 , a spring  303 , a sealing gasket  304  and a magnetic plate  305 . The tube  301  is inserted through one of the magnetic valve bores  1061  of the long axial tracks  10  and has an inner surface, a tubular chamber  3011 , a plurality of recesses  3012  and a plurality of inflow holes  3013 . The tubular chamber  3011  has an open end, a closed end, a large diameter portion and a small diameter portion. The large diameter portion of the tubular chamber  3011  is formed at the open end. The small diameter portion of the tubular chamber  3011  is formed at the closed end. The recesses  3012  are formed longitudinally in the inner surface of the tube  301 . The inflow holes  3013  are formed radially through the tube  301  and each inflow hole  3013  communicates with one of the recesses  3012 . Screws are mounted through screw holes  3014  of the tube  301  and engage the long axial track  10  to secure the magnetic valve  30  to the long axial track  10 . The magnetic rod  302  undergoes an anti-rust treatment and a hardening treatment and has a large diameter portion and a small diameter portion. The magnetic rod  302  is disposed in the tubular chamber  3011 . The large diameter portion of the magnetic rod  302  has an outer diameter corresponding to an inner diameter of the large diameter portion of the tubular chamber  3011 . The small diameter portion of the magnetic rod  302  has an outer diameter corresponding to an inner diameter of the small diameter portion of the tubular chamber  3011 . The spring  303  has an inner diameter corresponding to the outer diameter of the small diameter portion of the magnetic rod  302 . The spring  303  is mounted around the small diameter portion of the magnetic rod  302  and is disposed in the large diameter portion of the tubular chamber  3011 . The sealing gasket  304  and the magnetic plate  305  are secured at the open end of the tubular chamber  3011  in sequence by screws  306 . The sealing gasket  304  has a central hole  3041 . The magnetic plate  305  has a central hole  3051 . The spring  303  biases the large diameter portion of the magnetic rod  302  to close the central holes  3041 ,  3051  of the sealing gasket  304  and the magnetic plate  305 . 
         [0040]    With reference to  FIG. 3 , the sliding frames  20  are mounted on the long axial tracks  10  and each long axial track  10  has at least one sliding frame  20  thereon. Each sliding frame  20  is slid along the long axial track  10  by a main drive mechanism  207  and includes a bracket  200  and a plurality of rollers  202 . The bracket  200  covers a corresponding long axial track  10  and has a front panel, an upper panel, a lower panel, three pivot holes  203 , two push tabs  206 , a drive mechanism mounting tab  2072  and a gear receiving opening  2073 . The pivot holes  203  are formed through the front panel, upper panel and lower panel respectively and correspond to the roller rails  102  of the long axial track  10 . The two tabs  206  extend from two ends of the front panel of the bracket  200  and correspond to the magnet rail  105  of the long axial track  10 . The long axial magnetic-attracted body  1051  in the magnet rail  105  is disposed between the tabs  206 . Each tab  206  has a pulling element mounting hole  2061 . The drive mechanism mounting tab  2072  extends from the front panel of the bracket  200 . The main drive mechanism  207  is mounted on the drive mechanism mounting tab  2072  and has a shaft connected to a gear  2071 . The gear receiving opening  2073  is formed through the upper panel of the bracket  200  and corresponds to the toothed strip  1071  on the long axial track  10 . The gear  2071  is disposed in the gear receiving opening  2073  and engages the toothed strip  1071 . Each roller  202  is slidably mounted in one of the roller rails  102  of the long axial track  10 . An axle member  204  extends through one of the pivot holes  203  of the bracket  200  and one of the rollers  202  to rotatably mount the roller  202  on the bracket  200 . A conducting bracket  205  is mounted on an inner surface of the lower panel of the bracket  200  and corresponds to the electric rail  1041  on the long axial track  10 . The conducting bracket  205  is electrically connected to the electric rail  1041  to supply power to the main drive mechanism  207  and the bristle drive mechanisms  60 . 
         [0041]    Each bristle drive mechanism  60  is mounted on a holder  201 . The holder  201  is mounted on the bracket  200  of one of the sliding frames  20  and has a back panel, a semi-circular top panel, a semi-circular bottom panel and a plurality of support members  2011 . The back panel is secured to an outer surface of the front panel of the bracket  200 . The semi-circular top panel and the semi-circular bottom panel are separated with a distance by the back panel. Each of the semi-circular top panel and the semi-circular bottom panel has a mounting hole. The support members  2011  are attached between the semi-circular top panel and the semi-circular bottom panel. Each support member  2011  has at least one fastening hole  2012 . Each bristle drive mechanism  60 , which may be cylindrical in shape, is mounted between the semi-circular top panel and the semi-circular bottom panel of the holder  201  of one of the sliding frames  20  and includes two ends and two rotating shaft levers  601 . Each rotating shaft lever  601  extends from one of the ends of the bristle drive mechanism  60  and is mounted through one of the mounting holes of the semi-circular top panel and the semi-circular bottom panel of the holder  201 . The rotating shaft levers  601  are vertical to the long axial tracks  10 . 
         [0042]    With reference to  FIGS. 3 and 6 , each of the at least one long axial brush  50  is vertical to the long axial tracks  10 , is rotatably mounted between two adjacent bristle drive mechanisms  60  and is driven by the two adjacent bristle drive mechanisms  60 . Each of the at least one long axial brush  50  includes a tubular member  501  and a plurality of bristles  503 . The tubular member  501  has an outer surface, two ends and two shaft holes  502 . Each shaft hole  502  is formed longitudinally in one of the ends of the tubular member  501  for receiving one of the rotating shaft levers  601  of one of the two adjacent bristle drive mechanisms  60 . The bristles  503  extend from the outer surface of the tubular member  501  and preferably are soft bristles. 
         [0043]    With reference to  FIG. 3 , the cover plate  70  covers the bristle drive mechanisms  60  and long axial brush  50  and includes a plurality of fastening holes  701  in alignment with the fastening holes  2012  of the support members  2011  of the holders  201  of the sliding frames  20 . Screws  702  extend through the fastening holes  701  of the cover plate  70  and engage the fastening holes  2012  of the sliding frames  20  to secure the cover plate  70  to the holders  201 . The cover plate  70  may be a curved board having a semi-circular cross section and include an inner diameter greater than the rotation diameter of the long axial brush  50 . 
         [0044]    With reference to  FIGS. 1 to 6 , the first embodiment of the automatic cleaning machine for wall plates of the present invention is applied in a building exterior wall plate  90 . The long axial tracks  10  are level and parallel to one another and are secured to the exterior wall plate  90 . A nut  1031  corresponds to and is received in the fastening groove  103  of each long axial track  10 . An elongated connecting piece  1033  has three screw bores  1034  arranged in a line. One screw  1035  extends through the central screw bore  1034  and is screwed into the nut  1031  to secure the connecting piece  1033  to the long axial track  10 . Two screws  1032  extend through the other two screw bores  1034  and engage the exterior wall plate  90  to secure the long axial track  10  to the exterior wall plate  90 . Conduits from a pump or water pipeline are put in communication with the water-guiding pipes  101  of the long axial tracks  10 . The connection between the conduits and the water-guiding pipes  101  is conventional and thus a detailed description thereof will be omitted. In the case illustrated in the drawings, there are three long axial tracks  10  on the exterior wall plate  90 , one sliding frame  20  on each long axial track  10 , one bristle drive mechanism  60  on each sliding frame  20  and one long axial brush  50  between each two adjacent bristle drive mechanisms  60 . The sliding frames  20  and the long axial brushes  50  are arranged in a line, which is vertical to the long axial tracks  10 . In addition, there may be one electric rail  1041  on each long axial track  10  and one conducting bracket  205  on each sliding frame  20 , or only one electric rail  1041  on one of the long axial tracks  10  and only one conducting bracket  205  on one of the sliding frames  20 . The at least one electric rail  1041  and the at least one conducting bracket  205  supply power to the main drive mechanisms  207  and the bristle drive mechanisms  60 . The shaft holes  502  of each long axial brush  50  receive the rotating shaft levers  601  of two adjacent bristle drive mechanisms  60 . Furthermore, two rods  80  are rotatably attached to the exterior wall plate  90  by a plurality of bearing seats  801 . The two rods  80  are vertical to the long axial tracks  10  and are disposed at two ends of the long axial tracks  10 . A plurality of spools  802  are mounted on each rod  80  and each spool  802  corresponds to one end of one of the long axial tracks  10 . With reference to  FIG. 7 , each spool  802  has a helical groove  8021  on its outer surface and an end of a pulling element  803  is wound in the helical groove  8021 . The other end of the pulling element  803  is secured in the pulling element mounting hole  2061  of one of the tabs  206  of the bracket  200  of the sliding frame  20 , which is adjacent to the spool  802 . The pulling element  803  may be a steel rope or chain or the like. An auxiliary drive mechanism  804  is connected to and rotates each rod  80 . The connection of the rod  80  and the auxiliary drive mechanism  804  may be conventional and thus a detailed description thereof will be omitted. 
         [0045]    With reference to  FIGS. 1 to 6 , when the first embodiment of the present invention is in use, the cleaning water is conducted into the water-guiding pipe  101  of each long axial track  10 . The main drive mechanisms  207  or the auxiliary drive mechanisms  804  are then actuated to simultaneously move the sliding frames  20  and the long axial brushes  50  along the long axial tracks  10 . The bristle drive mechanisms  60  can be actuated to rotate the long axial brushes  50 . The rotating long axial brushes  50  create centrifugal force to cause the bristles  503  to contact the exterior wall plate  90 . The push tabs  206  of the bracket  200  of each sliding frame  20  move the long axial magnetic-attracted body  1051  along the magnet rail  105  of the long axial track  10 . When the sliding frame  20  moves the long axial magnetic-attracted body  1051  toward one of the magnetic valves  30 , the long axial magnetic-attracted body  1051  will attract the magnetic rod  302  to open a gap between the magnetic rod  302  and the sealing gasket  304 . The cleaning water in the water-guiding pipe  101  thus flows, in sequence, through the inflow holes  3013 , the recesses  3012  and the central holes  3041 ,  3051  and is then sprayed on the exterior wall plate  90 . When the sliding frame  20  moves the long axial magnetic-attracted body  1051  away from the magnetic valve  30 , the spring  303  will bias the magnetic rod  302  and the magnetic plate  305  will attract the magnetic rod  302  to close the gap between the magnetic rod  302  and the sealing gasket  304 . The cleaning water in the water-guiding pipe  101  thus cannot flow out. The gap between the magnetic rod  302  and the sealing gasket  304  can be closed by either the biasing force of the spring  303  or the attractive force between the magnetic plate  305  and the magnetic rod  302 , or alternatively, the gap between the magnetic rod  302  and the sealing gasket  304  can be closed by both the biasing force of the spring  303  and the attractive force between the magnetic plate  305  and the magnetic rod  302  as shown in the drawings. The attractive force between the long axial magnetic-attracted body  1051  and the magnetic rod  302  is greater than either the attractive force between the magnetic plate  305  and the magnetic rod  302  or the biasing force of the spring  303 , or alternatively, the attractive force between the long axial magnetic-attracted body  1051  and the magnetic rod  302  is greater than the sum of the attractive force between the magnetic plate  305  and the magnetic rod  302  and the biasing force of the spring  303 . In addition, the cover plate  70  can collect the cleaning water during the cleaning process and the collected cleaning water can thus be drained from a bottom of the cover plate  70 . The cover plate  70  also provides a protective effect and aesthetic appearance. With the above-mentioned structure, the exterior wall plate  90  can be easily cleaned. 
         [0046]    With reference to  FIGS. 8 to 10 , same as the first embodiment, a second embodiment of the present invention comprises the parallel long axial tracks  10  attached to an exterior wall plate  90  and the sliding frames  20  slid along the long axial tracks  10 . The second embodiment is different from the first embodiment in that the bristle drive mechanisms  60  of the first embodiment rotate the long axial brushes  50  but the bristle drive mechanisms  60 B of the second embodiment move the long axial brushes  50 B in reciprocating longitudinal movement. The rotating long axial brushes  50  of the first embodiment are applied to cleaning the exterior wall plate  90  with a rough surface. The longitudinally reciprocating long axial brushes  50 B of the second embodiment are applied to cleaning the exterior wall plate  90  with a flat surface and are applied in a situation in which there is a long distance between two adjacent sliding frames  20 . 
         [0047]    The second embodiment of the present invention comprises at least two long axial tracks  10 , a plurality of magnetic valves  30 , at least two sliding frames  20 , at least two bristle drive mechanisms  60 B, at least one long axial brush  50 B and a cover plate  70 B. 
         [0048]    With reference to  FIG. 4 , the magnetic valve  30  of the second embodiment is the same as the magnetic valve  30  of the first embodiment and thus a detailed description thereof will be omitted. 
         [0049]    With reference to  FIGS. 3 ,  5 ,  10  and  11 , the long axial track  10  and the sliding frame  20  of the second embodiment are the same as the long axial track  10  and the sliding frame  20  of the first embodiment and thus detailed descriptions thereof will be omitted. 
         [0050]    With reference to  FIG. 10 , each bristle drive mechanism  60 B, which may be cylindrical in shape, is a pneumatic or electric linear actuator and includes two ends and a longitudinally reciprocating shaft lever  601 B. The longitudinally reciprocating shaft lever  601 B is vertical to the long axial tracks  10  and has a shaft hole  602 B formed longitudinally therein. Two pairs of lugs extend radially from opposite sides of the bristle drive mechanism  60 B. Each pair has two lugs being at a top end and a bottom end of the bristle drive mechanism  60 B. Each lug of one pair has a pivot hole  603 B formed through a distal end thereof. A pivot seat  61 B is secured to the outer surface of the front panel of the bracket  200  by screws. The pivot seat  61 B has a through hole  611 B formed longitudinally therein in alignment with the pivot holes  603 B. A pivot rod  612 B is inserted into the pivot holes  603 B and the through hole  611 B of the pivot seat  61 B to pivotally connect the bristle drive mechanism  60 B to the pivot seat  61 B. A connecting rod  604 B is rotatably mounted between the lugs of the other pair. The connecting rod  604 B has a middle section and a connecting hole  6041 B. The connecting hole  6041 B is formed radially in the middle section of the connecting rod  604 B. A telescopic drive unit  600 B has two ends, one end is inserted into the connecting hole  6041 B and the other end is rotatably connected to the outer surface of the front panel of the bracket  200 . Two support members are mounted on the ends of the bristle drive mechanism  60 B. Each support member has a brace  605 B and a base board  606 B. The base board  606 B is secured to the bristle drive mechanism  60 B and has two ends. One end of the base board  606 B has a hole  6061 B through which the longitudinally reciprocating shaft lever  601 B extends. The brace  605 B is vertical to the base board  606 B and extends from the other end of the base board  606 B toward the long axial brush  50 B. 
         [0051]    Each of the at least one long axial brush  50 B includes a mount  501 B and a bristle structure  502 B. The mount  501 B is elongated and has two side surfaces, two end surfaces, a shaft hole  504 B, a plurality of connecting holes  505 B and two insertion holes  509 B. The shaft hole  504 B is formed longitudinally through the mount  501 B. The connecting holes  505 B are formed in the side surfaces of the mount  501 B. Each insertion hole  509 B is formed longitudinally in one of the end surfaces of the mount  501 B for receiving one of the braces  605 B. The bristle structure  502 B is elongated to correspond to the length of the mount  501 B. The bristle structure  502 B has a front surface, a rear surface, a plurality of bristles  503 B and a plurality of connecting holes  5051 B. The bristles  503 B extend from the rear surface of the bristle structure  502 B. The connecting holes  5051 B are formed in the front surface of the bristle structure  502 B in alignment with the connecting holes  505 B of the mount  501 B. Screws  508 B extend through the connecting holes  505 B of the mount  501 B and engage the connecting holes  5051 B of the bristle structure  502 B to secure the mount  501 B to the bristle structure  502 B. 
         [0052]    The cover plate  70 B is a board having a U-shaped cross section. The cover plate  70 B serves to protect the long axial brush  50 B. A separator  703 B is mounted between the cover plate  70 B and the long axial brush  50 B and has a plurality of ventilation holes  704 B. An air duct  705 B is formed between the separator  703 B and the cover plate  70 B. 
         [0053]    With reference to  FIGS. 5 ,  8 ,  9 ,  10  and  11 , the second embodiment of the automatic cleaning machine for wall plates of the present invention is applied in a building exterior wall plate  90 . The long axial tracks  10  are level and parallel to one another and are secured to the exterior wall plate  90 . The long axial tracks  10  are secured to the exterior wall plate  90  in the same manner as in the first embodiment of the present invention. Conduits from a pump or water pipeline are put in communication with the water-guiding pipes  101  of the long axial tracks  10 . In the case illustrated in the drawings, there are three long axial tracks  10  on the exterior wall plate  90 , one sliding frame  20  on each long axial track  10 , one bristle drive mechanism  60 B on each sliding frame  20  and one long axial brush  50 B between each two adjacent bristle drive mechanisms  60 B. The shaft holes  504 B of the long axial brushes  50 B align with the shaft holes  602 B of the bristle drive mechanisms  60 B. A shaft  22 B is inserted into the shaft holes  602 B,  504 B of the bristle drive mechanisms  60 B and the long axial brushes  50 B for connecting the long axial brushes  50 B and the bristle drive mechanisms  60 B. The shaft  22 B may be a steel rope, round steel bar, flat steel bar or tube or the like. The long axial brushes  50 B and shaft  22 B are secured together by screws  506 B extending through holes  507 B in the long axial brushes  50 B and abutting the shaft  22 B. The bristle drive mechanisms  60 B and shaft  22 B are secured together by screws  6012 B extending through holes  6011 B in the longitudinally reciprocating shaft levers  601 B of the bristle drive mechanisms  60 B and abutting the shaft  22 B. The bristles  503 B of the long axial brushes  50 B face toward the exterior wall plate  90 . 
         [0054]    The long axial brushes  50 B are arranged in a line, which is vertical to the long axial tracks  10 . The cover plate  70 B is secured to the sliding frames  20 . At least one blower  706 B is attached adjacent to the air duct  705 B. Preferably, two blowers  706 B are attached to two opposite ends of the air duct  705 B. The outlets of the blowers  706 B communicate with the air duct  705 B. The attachment method of the blowers  706 B may be conventional and thus a detailed description thereof will be omitted. In addition, two rods  80  are attached to the exterior wall plate  90  and are disposed at two ends of the long axial track  10 . An auxiliary drive mechanism  804  is connected to each rod  80 . The auxiliary drive mechanism  804  can rotate the rod  80  to move the sliding frames  20 . With reference to  FIGS. 2 and 7 , the auxiliary drive mechanism  804  moves the sliding frames  20  in the same manner as in the first embodiment of the present invention. 
         [0055]    With reference to  FIGS. 8 ,  9 ,  10  and  11 , when the second embodiment of the present invention is in use, the cleaning water is conducted into .the water-guiding pipe  101  of each long axial track  10 . The main drive mechanisms  207  or the auxiliary drive mechanisms  804  are then actuated to simultaneously move the sliding frames  20  and the long axial brushes  50 B along the long axial tracks  10 . The telescopic drive unit  600 B can be controlled to make its shaft retracted therewithin such that the bristles  503 B of the long axial brushes  50 B can abut the exterior wall plate  90 . The bristle drive mechanisms  60 B can be actuated to move the long axial brushes  50 B in reciprocating longitudinal movement. The push tabs  206  of the bracket  200  of each sliding frame  20  move the long axial magnetic-attracted body  1051  along the magnet rail  105  of the long axial track  10 . When the sliding frame  20  moves the long axial magnetic-attracted body  1051  toward one of the magnetic valves  30 , the long axial magnetic-attracted body  1051  will attract the magnetic rod  302  to allow the cleaning water to be sprayed on the exterior wall plate  90 . When the sliding frame  20  moves the long axial magnetic-attracted body  1051  away from the magnetic valve  30 , the spring  303  will bias the magnetic rod  302  and the magnetic plate  305  will attract the magnetic rod  302  to stop the cleaning water from flowing out. The cover plate  70 B can collect the cleaning water during the cleaning process. The blowers  706 B can be operated after the cleaning process to blow air through the air duct  705 B and out of the ventilation holes  704 B so as to remove water drops on the exterior wall plate  90 . The cover plate  70 B also provides a protective effect and aesthetic appearance. 
         [0056]    In addition, the long axial tracks  10  are made of oxidation resistant material. The long axial brushes  50 B can be disposed at sides of the building when the cleaning device does not operate. With reference to  FIG. 12 , the shaft of the telescopic drive unit  600 B is extended to push the bristle drive mechanism  60 B such that the bristles  503 B of the long axial brushes  50 B are away from the exterior wall plate  90 , thereby preventing the bristles  503 B from being deformed. 
         [0057]    Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.