Abstract:
A cam-type pump structure for a refrigerant recycling machine includes a cam device driven by a motor for pistons to be reciprocated in conjunction with cylinders and valve bodies so as to pump liquid. The pump apparatus is compact in size and has high efficiency for the demand of recycling refrigerant.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a cam-type pump structure for a refrigerant recycling machine. In particular, a pump apparatus uses a cam-type structure for pistons to be reciprocated in the same direction or in opposite directions so as to pump refrigerant. 
         [0003]    2. Description of the Prior Art 
         [0004]    Refrigerant is widely used in our daily living, such as domestic refrigerators, air conditioners, refrigerating equipment or car air conditioners. When refrigerators or air conditioners need maintenance, it is required to drain out the refrigerant. This not only pollutes the ambient air but also brings poisonous substances to harm the human body when the refrigerant is burned at a high temperature. Recently, there is a refrigerant recycling machine on the market to pump the refrigerant or the like into a specific container, which conforms to the operation safety and protects the global environment. 
         [0005]    The existing refrigerant recycling machine doesn&#39;t have a proper design for its inside construction. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to improve the existing products. 
       SUMMARY OF THE INVENTION 
       [0006]    The primary object of the present invention is to provide a cam-type pump structure for a refrigerant recycling machine, which comprises two pairs of pistons and cylinders. The two pistons are driven by a cam device. When the cam device is activated, the two pistons are reciprocated synchronously. The pistons are reciprocated in the same direction or in opposite directions. By the motion of the pistons, the present invention provides a high efficiency and is compact in size. 
         [0007]    In order to achieve the object, the present invention comprises a main body. The main body comprises a motor at one end thereof. The motor has an output end which is a shaft. The main body has a space therein. The shaft of the motor is disposed in the space. A cam device is inserted on the shaft. The cam device comprises a central rotating body and two eccentric rotating bodies at two sides of the central rotating body. A bearing is provided at an outer end of each of the eccentric rotating bodies. An outer sleeve is provided at an outer end of the bearing. The outer sleeve has a protrusion at one end thereof and a piston at a distal end of the protrusion. The main body has a pair of openings at two sides thereof. Each opening is connected with a cylinder. The cylinder has a chamber therein to receive the piston for reciprocation. 
         [0008]    Preferably, a fan is provided at an outer end of the motor to lower the temperature and dissipate the heat when in operation. 
         [0009]    Preferably, the main body has a ring portion at an outer edge of the space. The ring portion is covered with a plate to seal the space. 
         [0010]    Preferably, each cylinder is connected with a valve body. The inside of the cylinder communicates with the inside of the valve body. The valve body has an inlet and an outlet. The piston is reciprocated in the cylinder to form pressure for the valve body to provide a pump function. 
         [0011]    Preferably, the center of the central rotating body of the cam device is formed with an axial hole for insertion of the shaft of the motor. The axial hole penetrates each eccentric rotating body and isn&#39;t located at the center of each eccentric rotating body. 
         [0012]    Preferably, the centers of the two eccentric rotating bodies are located at different axes. When the shaft is turned to drive the central rotating body, the two eccentric rotating bodies will be turned eccentrically at different angles and the two pistons at the two sides of the cam device will be reciprocated in opposite directions. In this way, the two valve bodies are to pump synchronously, providing a better pump function. 
         [0013]    Alternatively, the centers of the two eccentric rotating bodies are located at the same axis. When the shaft is turned to drive the central rotating body, the two eccentric rotating bodies will be turned eccentrically at the same angle and the two pistons at the two sides of the cam device are reciprocated in the same direction. In this way, the two valve bodies are to pump in turn, providing a smooth operation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of the present invention; 
           [0015]      FIG. 2  is an exploded view of the present invention; 
           [0016]      FIG. 3  is an exploded view of a cam device of the present invention; 
           [0017]      FIG. 4  is a cross-sectional showing the cam device of the present invention in an operating status; 
           [0018]      FIG. 5  is another cross-sectional showing the cam device of the present invention in an operating status; 
           [0019]      FIG. 6  is an exploded view of a cam device according to another embodiment of the present invention; and 
           [0020]      FIG. 7  is a cross-sectional view of  FIG. 6  showing the cam device of the present invention in an operating status. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. 
         [0022]    As shown in  FIGS. 1 to 4 , a cam-type pump structure for a refrigerant recycling machine according to a first preferred embodiment of the present invention comprises a main body  1 , a cam device  2 , a cylinder  3  and a valve body  4 . 
         [0023]    The main body  1  has a casing shape and comprises a motor  11  at one end thereof. A fan  12  is provided at an outer side of the motor  11 . The motor  11  has an output end which is a shaft  14 . The main body  1  has a space  13  therein. The shaft  14  of the motor  11  is disposed in the space  13 . The cam device  2  is inserted on the shaft  14 . A distal end of the shaft  14  is provided with a shaft bearing  141 . The main body  1  has a pair of openings  15  at two sides thereof to receive the cylinder  3 . The main body  1  has a ring portion  16  at an outer edge of the space  13 . The main body  1  further comprises a plate  17  and a rubber washer  171  associated with an oil seal ring  161  to seal the space  13 . The plate  17  and the rubber washer  171  are connected to the ring portion  16  with screws  172 . 
         [0024]    The cam device  2  comprises a central rotating body  21 , a pair of eccentric rotating bodies  22  at two sides of the central rotating body  21 , a pair of bearings  24  next to the pair of eccentric rotating bodies  22  and a pair of outer sleeves  25  next to the pair of the bearings  24 . Each outer sleeve  25  has a protrusion  26  at one end thereof and a piston  27  at a distal end of the protrusion  26 . The cam device  2  has an axial hole  23  along a central axis thereof. In this embodiment, the axial hole  23  penetrates through the center of the central rotating body  21 , but not through the center of each eccentric rotating body  22 . 
         [0025]    The cylinder  3  is coupled to the opening  15  of the main body  1 . The cylinder  3  has a chamber  31  therein to receive the piston  27  for reciprocating motion. Preferably, there are two openings  15  in this embodiment, so the cylinder  3  corresponds in number to the opening  15 . 
         [0026]    The valve body  4  is mounted on the cylinder  3 . The inside of the cylinder  3  communicates with the inside of the valve body  4 . The valve body  4  has an inlet  41  and an outlet  42 . The piston  27  is reciprocated in the cylinder  3  to form pressure for the valve body  4  to provide a pump function. 
         [0027]    When the motor  11  is started, the shaft  14  will be driven to turn the cam device  2  on the shaft  14 . The central rotating body  21  and the two eccentric rotating bodies  22  are turned synchronously. Because the axial hole  23  is not disposed at the center of each eccentric rotating body  22 , the cam device  2  is turned eccentrically. As shown in  FIG. 4  and  FIG. 5 , the two eccentric rotating bodies  22  are in an eccentric motion, and the two pistons  27  at the two sides of the cam device  2  are reciprocated in opposite directions, namely, they are synchronously turned inward or outward, such that the two valve bodies  4  are to pump synchronously. In this motion way, the two valve bodies  4  provide more efficiency to pump than a single piston with a single valve. 
         [0028]      FIG. 6  shows a second embodiment of the present invention, which is substantially similar to the first embodiment with the exceptions described hereinafter. A cam device  5  comprises a central rotating body  51 , a pair of eccentric rotating bodies  52  at two sides of the central rotating body  51 , a pair of bearings  54  next to the pair of eccentric rotating bodies  52  and a pair of outer sleeves  55  next to the pair of the bearings  54 . Each outer sleeve  55  has a protrusion  56  at one end thereof and a piston  57  at a distal end of the protrusion  56 . The cam device  5  has an axial hole  53  along a central axis thereof. In this embodiment, the axial hole  53  penetrates through the center of the central rotating body  51 , but not through the center of each eccentric rotating body  52 . In particular, the centers of the two eccentric rotating bodies  52  are located at the same axis, namely, the two eccentric rotating bodies  52  are eccentric toward the same side relative to the axial hole  53  simultaneously. In addition, the central rotating body  51  has an engaging groove  511  on one side thereof and a threaded hole  512  in the engaging groove  511 . The engaging groove  511  is adapted to receive a rib  581  of a counterweight block  58 . The counterweight block  58  has a hole  582  thereon for insertion of a screw  583 , such that the counterweight block  58  is coupled to the central rotating body  51 . Because the two eccentric rotating bodies  52  are eccentric toward the same side relative to the axial hole  53  simultaneously, the two eccentric rotating bodies  52  will be turned eccentrically when the shaft  14  is turned. In order to solve this problem, in this embodiment the counterweight block  58  is located at an opposite side relative to the eccentric rotating bodies  52  for balance. 
         [0029]    When the motor  11  is started, the shaft  14  will be driven to turn the cam device  5  on the shaft  14 . The central rotating body  51  and the two eccentric rotating bodies  52  are turned synchronously. Because the axial hole  53  is not disposed at the center of each eccentric rotating body  52 , the cam device  5  is turned eccentrically. As shown in  FIG. 7 , the centers of the two eccentric rotating bodies  52  are located at the same axis, and the two pistons  57  at the two sides of the cam device  5  are reciprocated in the same direction, namely, one piston  57  is turned inward and the other piston  57  is turned outward, such that the two valve bodies  4  are to pump in turn. In this motion way, the motion directions of the cam device  5  and the piston  57  are the same, providing a smooth operation. 
         [0030]    Although particular embodiments of the present invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the present invention. Accordingly, the present invention is not to be limited except as by the appended claims.