Patent Publication Number: US-9850899-B2

Title: Brushless DC compressor in micro-miniature form

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a compressor, particularly to one that is operated by a brushless DC motor, abreast of a compression device, achieving a brushless DC compressor in micro-miniature form with stronger torque and greater efficiency in compression with the speed-change function of a driving mechanism. 
     2. Description of the Related Art 
     Conventional air-conditioners usually have a reciprocating compressor or one with rolling piston to operate with refrigerant. Such compressors have large volume and would distribute heat; therefore they are more suitable to be installed outdoors instead of indoors or in small space. 
     The air-conditioning compressors used in cars are mostly driven by the engines, but when the engines are turned off, the air-conditioning compressors would not be able to operate, causing the temperature in the cars rising and the people sitting in would not be able to stand the hot. On the other hand, if the engine is kept running to operate the air-conditioning compressors for the people in the car when the car is parked, it would be a waste of energy and the carbon dioxide emission would cause environmental pollution as well. Also, idling for over certain period would break the law. 
     There are some other air-conditioning compressors have a DC motor to drive the motor to operate the compression and recycling of the refrigerant to cool down the air in the cars. However, such structure has a design of eccentric shaft in the DC motors which would cause the unbalanced driving force of the motors, producing more shakings and louder noises during the operation. Also, there are problems of the sparks due to the operation of the brushes and the electromagnetic interference when the DC motors with brushes are operating. Besides, most DC compressors have the axis of the motor sharing the same axis with the operation axis of the compressor. Since the compressor and the motor both have high rotation speed, the torque would be too weak and the machine would not be able to change the speed, resulting in poor compression efficiency. 
     With the problems disclosed above, there is still room for improvements. 
     SUMMARY OF THE INVENTION 
     A primary object of the present invention is to provide a brushless DC compressor in micro-miniature form that has a small volume for indoors or small space installment. 
     Another object of the present invention is to provide a brushless DC compressor in micro-miniature form that has a driving mechanism with speed-change function to achieve stronger torque and greater efficiency in compression. 
     Yet another object of the present invention is to provide a brushless DC compressor in micro-miniature form that is stable in operation with less shaking and lower noises. 
     To achieve the objects mentioned above, the present invention comprises a casing which is hollow and has openings at both sides, including a left room, a right room, and a lower room; a first tubular passage and a first shaft hole being arranged through the lower room and the left room; a second tubular passage and a second shaft hole being arranged through the lower room and the right room; a brushless DC motor disposed in the left room, including a stator with a surrounding coil group having a lead and an axial groove, and a rotor to be engaged and rotate in the stator having a permanent magnet arranged thereon, an upper shaft at an end and a lower shaft at the other end and having the lower shaft stretching into the lower room; a compression device disposed in the right room, including a compression space, a refrigerant inflow hole, a body with a radial trench, and a hollow shaft with a rotary element for eccentrically rotation in the compression space; a movable block disposed in the radial trench for the spring to push for displacement; a radial refrigerant intake hole arranged on the inner side of the compression space to connect to the refrigerant inflow hole; a refrigerant discharge hole arranged on the side wall of the redial trench; a lower cover fixed at the bottom of the body, having a first axial hole connecting the refrigerant discharge hole of the compression space and being pressed by a first oblong depression with a free end, and a fourth shaft hole to be engaged through by the second end of the hollow shaft which then stretches into the lower room; a driving mechanism disposed in the lower room of the casing, including a driver engaged around the end of the lower shaft, and a driven element engaged around the second end of the hollow shaft, where the driven element would be driven to rotate by the driver; a top cover arranged on the top of the casing for the rotor of the brushless DC motor to be disposed in the left room, and for the compression device to be disposed in the right room; a set of electrical connector arranged through the top cover and connected to the lead of the brushless DC motor with the inner end thereof; a bottom cover arranged at the bottom of the casing; a refrigerant intake tube connecting the refrigerant intake hole through the entry hole of the top cover; and a refrigerant discharge tube connecting the exit hole of the top cover; 
     whereby the rotor would be driven by the magnetic force from the stator when refrigerant flows into the compression space via the refrigerant intake hole, driving the driver and the driven element of the driving mechanism, and then the rotary element to rotate eccentrically, to force the refrigerant in the compression space to flow out via the refrigerant discharge hole on the radial trench and push the free end of the first elastic oblong piece with high pressure when the refrigerant flows through the first axial hole of the lower cover so that the refrigerant would flow through the lower room and the axial groove of the stator, and then be discharged to the inner wall of the top cover and flow out through the refrigerant discharge tube, so as to form a brushless DC compressor in micro-miniature form. 
     Furthermore, the driver of the driving mechanism is a driving gear and the driven element of the driving mechanism is a driven gear, where the cogs of the driving gear are less than the one of the driven gear; a set of speed-change gears is further arranged between the driving gear and the driven gear and has a larger gear with more cogs and a smaller gear with less cogs, where the larger gear is meshing with the driving gear and the smaller gear is meshing with the driven gear. And the driving gear, driven gear, larger gear, and the smaller gear are all helical gears. 
     In addition, the hollow shaft has a plurality of small holes radially arranged thereon and a helical element arranged therein. The first elastic oblong piece has the inner end thereof fixed with an end of a first fixed oblong piece by a screw, so as to define the space for the free end of the first elastic oblong piece to spring. 
     The body of the present invention further has an axially through bypass hole arranged thereon, a second oblong depression arranged on the upper cover with an end having a through second axial hole connecting the refrigerant discharge hole of the compression space, a second elastic oblong piece and a second fixed oblong piece with an inner end of both being fixed in the second oblong depression by a screw and the free end thereof pressing the second axial hole to spring; a fixing cover fixed above the upper cover, allowing the refrigerant from the second axial hole to flow through the bypass hole of the body and then flow into the lower room. 
     The present invention further includes a housing for placing the brushless DC compressor in micro-miniature form, a lid arranged on the top of the housing with an electrode to be connected to the electrical connector on the top cover, and two openings for the refrigerant intake tube and the refrigerant discharge tube to stretch out the lid; and the housing has liquids and a water absorbing buffer filled therein, as so to form a sealed brushless DC compressor. 
     The housing further includes a base arranged at the bottom thereof and a plurality of buffer cushions arranged on the base. And the liquids is made of coolant, oil, water, or any of the combination; and the water absorbing buffer is made of sponges, clothes, fibers or any of the combination. 
     With structures disclosed above, the present invention has a smaller volume for application in indoors and small space. Also, with the abreast brushless DC motor and compression device, the present invention has stronger torque and greater efficiency in compression by the speed-change function of the driving device. Further, the present invention has buffer filled inside the sealed housing, keeping a stable status in operation with less shaking and lower noises, so as to achieve greater efficiency with power saving function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the present invention in a preferred embodiment; 
         FIG. 2  is an exploded view of a sealed brushless DC compressor of the present invention in a preferred embodiment; 
         FIG. 3  is a perspective view of a sealed brushless DC compressor of the present invention in a preferred embodiment; 
         FIG. 4  is a sectional view along ling  4 - 4  in  FIG. 3 ; 
         FIG. 5  is an exploded view of a brushless DC motor of the present invention in a preferred embodiment; 
         FIG. 6  is a an exploded view of a compression device of the present invention in a preferred embodiment; 
         FIG. 6A  is a schematic diagram of the flow of the refrigerant in the compression device; 
         FIG. 7A  is an exploded view along line  7 A- 7 A in  FIG. 4 , illustrating the operation of the present invention in a preferred embodiment; and 
         FIG. 7B  is an exploded view illustrating another operation of the present invention in a preferred embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIGS. 1 and 4 , a preferred embodiment of the present invention mainly comprises a casing  10 , a top cover  50 , a bottom cover  60 , a brushless DC motor  20 , a compression device  30 , a driving mechanism  40 , a set of electrical connector  55 , a refrigerant intake tube  61 , and a refrigerant discharge tube  62 . 
     The casing  10  is a hollow tube with openings at both sides, having a divider board  11  therein to define a left room  12 , a right room  13 , and a lower room  14 . The left room  12  has a first tubular passage  15  and a first shaft hole  16  connecting the lower room  14 . The right room  13  has a second tubular passage  17  and a second shaft hole  18  connecting the lower room  14 . 
     The top cover  50  is arranged on the top of the casing  10  to seal the left and the right room  12 ,  13  and the bottom cover  60  is arranged at the bottom of the casing  10  to seal the lower room  14 . 
     The DC brushless motor  20  includes a stator  21  and a rotor  22 . The stator  21  is fixed inside the left room  12  of the casing  10 , formed by an annular body  211  and a surrounding coil group  212  with an axial groove  215  arranged on the stator and the surrounding coil group  212  having a lead  213  for connecting with the external DC circuit. The rotor  22  is formed by a column  221  and a permanent magnet  222  arranged on the column  221  with the column  221  having an upper shaft  223  and a lower shaft  224  sharing the same axis. The upper shaft  223  is rotating in a first positioning hole  51  on the top cover  50  with a third bearing  23  engaging around and the lower shaft  224  has a first bearing  23  engaging around and is stretching through the first shaft hole  16  into the lower room  14  for the rotor  22  to be engaged and rotate inside the stator  21 . 
     Referring to  FIG. 6A , the compression device  30  includes a body  31 , a spring  32 , a movable block  33 , a refrigerant discharge hole  315 , an upper cover  34 , a second elastic oblong piece  345 , a rotary element  35 , a hollow shaft  36 , a lower cover  37 , and a first elastic oblong piece  375 . 
     The body  31  is disposed inside the right room  13  of the casing  10  with the middle thereof having a round compression space  311  for a through refrigerant inflow hole  31   6 , an axial bypass hole  319 , and a radial trench  312  to be arranged on the inner wall of the compression space  311 . The radial trench  312  is connecting the compression space  311  on the inner side and has a radial hole  313  on the outer wall. The compression space  311  further has a radial refrigerant intake hole  314  arranged on the inner wall to connect the refrigerant inflow hole  316 . The spring  32  is disposed in the radial hole  313 . The movable block  33  is disposed inside the radial trench  312  for the spring  32  to push for displacement. The refrigerant discharge hole  315  is arranged on the inner side of the radial trench  312 . The upper cover  34  is fixed on the top of the body  31 , having a third shaft hole  341  arranged at the center which has a shorter diameter than the one of the compression space  311 ; in this embodiment, the upper cover  34  further has a second oblong depression  342  arranged thereon with an end having a through second axial hole  343  connecting the refrigerant discharge hole  315  of the compression space  311 , and the other end having a second screw hole. The second elastic oblong piece  345  is fixed in the second oblong depression  342  by a screw  347  that fixes an end thereof in the second screw hole, and has a second fixed hole  348  arranged on the other farther end from the second axial hole  343  to be able to spring as a free end to define a space for springing. In this embodiment, the present invention further includes a fixing cover  39  fixed above the upper cover  34  for defining the space for the second elastic oblong piece  345  to spring, allowing the refrigerant from the second axial hole  343  to flow through the bypass hole  319  of the body  31  and then flow into the lower room  14  below the lower cover  37 . 
     The rotary element  35  has a shorter diameter than the one of the compression space  311  to be disposed inside for rotation. The hollow shaft  36  has a first end  361  and a second end  362 , and an eccentric convexity body  363  is formed in the middle thereof to be engaged through the rotary element  35 . The first end  361  is engaged through the third shaft hole  341  and rotates with a fifth bearing  381  in the second positioning hole  52  on the top cover  50 . In the embodiment, the hollow shaft  36  has a plurality of small holes  364  radially arranged thereon and a helical element  365  arranged therein. 
     The lower cover  37  is fixed at the bottom of the body  31 , having a fourth shaft hole  371  sharing the same axis as the third shaft hole  341  for the second end  362  of the hollow shaft  36  to stretch through the fourth shaft hole  371  and the second shaft hole  18 , into the lower room  14 ; a second bearing is arranged around the hollow shaft  36  to fix the position in the middle of the body  31 , and the eccentric convexity body  363  at the middle of the hollow shaft  36  is able to rotate the rotary element  35  eccentrically in the compression space  311 . Furthermore, a first oblong depression  372  is arranged on the lower part of the lower cover  37  with an end thereof having a first axial hole  373  connecting the refrigerant discharge hole  315  of the compression space  311  and the other end having a first screw hole  374  arranged thereon. Referring to  FIG. 6 , the first elastic oblong piece  375  is fixed in the first oblong depression  372  with an end farther from the first axial hole  373  being screwed in the first screw hole  374  to fix the position in the first oblong depression  372 , allowing the other end to elastically press the first axial hole  373  as a free end and being able to spring. In this embodiment, the first elastic oblong piece  375  has the inner end thereof fixed with an end of a first fixed oblong piece  376  by screwing, so as to define the space for the other free end to spring. 
     The driving mechanism  40  is disposed in the lower room  14  of the casing  10 , including a driver  41  engaged around the end of the lower shaft  224 , and a driven element  42  engaged around the second end  362  of the hollow shaft  36 ; the driven element  42  would actuate when driven by the driver  41 . In this embodiment, the driver  41  is a driving gear and the driven element  42  is a driven gear, and a set of speed-change gears  43  is further arranged between the driving gear  41  and the driven gear  42  with a larger gear  431  having more cogs, a smaller gear  432  having less cogs, and a gear shaft  433  having an end thereof fixed by a fourth bearing  44  to rotate in the lower room  14  of the casing  10 . Besides, the cogs of the driving gear  41  are much less than the one of the driven gear  42  so that the hollow shaft  36  of the compression device  30  has stronger torque for operation, and the driving gear  41  is meshing with the larger gear  431  and the driven gear  42  is meshing with the smaller gear  432 . Also, for greater operation efficiency, the driving gear  41 , driven gear  42 , larger gear  431 , and the smaller gear  432  are all helical gears. 
     The top cover  50  also has an entry hole  53  and an exit hole  54  arranged thereon; the electrical connector set  55  is arranged through the top cover  50  and the inner end thereof is connected to the lead  213  of the brushless DC motor  20 . The refrigerant intake tube  61  is connecting the refrigerant inflow hole  316  through the entry hole  53  of the top cover  50 . The refrigerant discharge tube  62  is connecting the exit hole  54  of the top cover  50 ; 
     whereby the rotor  22  would be driven by the magnetic force from the stator  21  when refrigerant flows into the compression space  311  via the refrigerant inflow hole  316  and the refrigerant intake hole  314 , driving the driving gear  41 , the speed-change gears set  43  and the driven gear  42  of the driving mechanism  40  to rotate the rotary element  35  eccentrically and force the refrigerant in the compression space  311  to flow out via the refrigerant discharge hole  315  and then flow into the first axial hole  373  on the lower cover  37  or the second axial hole  343  on the upper cover  34 , either would push the free end of the first elastic oblong piece  375  or the second elastic oblong piece  345  with high pressure, resulting the refrigerant eventually flowing below the lower cover  37  and being discharged to the inner wall of the top cover  50  via the second tubular passage  17 , the lower room  14 , the first tubular passage  15  and the axial groove  215  of the stator  21 ; then the refrigerant would flow out from the refrigerant discharge tube  62 , forming the present invention as a brushless DC compressor in micro-miniature form  100 . 
     In another applicable embodiment, the present invention could be a sealed brushless DC compressor  200 . Referring to  FIG. 4 , the sealed brushless DC compressor  200  includes a housing  71  for placing the brushless DC compressor in micro-miniature form  100 , a lid  73 , and two openings  731 . The housing has a base  72  arranged at the bottom thereof and a plurality of buffer cushions  721  arranged on the base. The lid  73  is arranged on the top of the housing  71  with an electrode  74  to be connected to the electrical connector  55  on the top cover  50 . The openings  731  allow the refrigerant intake tube  61  and the refrigerant discharge tube  62  to stretch out the lid  73  and allow the housing  71  to have liquids  81  and a water absorbing buffer  82  filled therein, so as to form a sealed brushless DC compressor  200 . 
     In this embodiment, the liquids  81  is made of coolant, oil, water, of any of the combination, and the water absorbing buffer  82  is made of sponges, clothes, fibers or any of the combination. In addition, the sealed brushless DC compressor  200  not only has the features of the brushless DC compressor in micro-miniature form  100 , but also has lower noises, making it suitable for the design of air-conditioner indoors. 
     With the structure disclosed above, the present invention has the features and function as described in the following. 
     1. The abreast brushless DC motor  20  and the compression device  30  can obtain the compressed torque by the design of the driving gear  41 , the driven gear  42 , the larger gear  431 , and the small gear  432  of the driving mechanism  40 . In other words, the cogs of the mentioned gears can be adjusted to obtain the compressed torque needed. 
     2. The hollow shaft  36  has a plurality of small holes  364  radially arranged thereon and a helical element  365  arranged therein. As shown in  FIG. 4 , when the hollow shaft  36  is rotating, the helical element  365  would draw in the liquid refrigerant from the lower room  14 , and the refrigerant would flow through the third shaft hole  341 , the fourth shaft hole  371  and the rotary element  35  via the small holes  364 , functioning as a lubrication and coolant to prevent the entire machine from overheating. 
     3. The refrigerant inflow hole  316  can be filled with filtering materials  317 . As shown in  FIG. 4 , before the refrigerant enters into the compression space  311  from the refrigerant intake tube  61 , the impurities can be filtered by the filtering materials  317 , to make sure the components in the compression space  311  would not be damaged and therefore extend the durability of the device. 
     4. The brushless DC motor  20  of the present invention includes a stator  21  with a surrounding coil group  212  and a rotor  22  with a permanent magnet  222 . As shown in  FIG. 5 , the surrounding coil group  212  has a lead  213  for connecting with external DC circuit by the electrical connector  55  on the top cover  50 . When connected to the external DC circuit, the stator  21  would drive the rotor  22  therein to rotate. Since there is no carbon brushes fractioning with the rotor  22 , the brushless DC motor  20  is power saving and quiet in operation. 
     5. The moving block  33  is disposed in the radial trench  312  for the spring  32  to push for radial displacement. As shown in  FIGS. 7A and 7B , when the hollow shaft  36  drives the rotary element  35  to eccentrically rotate in the compression space  311 , the place of the moving block  33  would be adjusted in accordance with the displacement of the rotary element  35  and the pushing of the spring  32 .  FIG. 7A , illustrates the moving block  33  being pushed to the extreme by the spring  32 ; the refrigerant is drawn into the compression space  311  via the refrigerant intake hole  314 .  FIG. 7B  illustrates the moving block  33  being pushed to the extreme by the rotary element  36  due to the rotation of the hollow shaft  36 ; the refrigerant in the compression space  311  is forced to flow out from the refrigerant discharge hole  315  by the compression of the rotary element  36 . Further referring to  FIG. 6A , the refrigerant would flow through the first axial hole  373  on the lower cover  37  and push the free end of the first elastic oblong piece  375  with high pressure, then flow out from the compression device  30 . In this embodiment, the first elastic oblong piece  375  has the inner end thereof fixed with an end of a first fixed oblong piece  376  by screwing, so as to define the space S for the free end of the first elastic oblong piece  375  to spring, allowing the high-pressured refrigerant to be discharged and preventing from elastic fatigue and deformation due to long-term operation. In the embodiment, the refrigerant can also flow through the second axial hole  343  of the upper cover  34  from the refrigerant discharge hole  315  and push the free end of the second elastic oblong piece  345  to enter through the lower cover  37  through the bypass hole  319  of the body  32 ; and the second elastic oblong piece  345  also has the inner end thereof fixed with an end of a second fixed oblong piece  346  by a screw  347 , so as to define the space S for the free end of the second elastic oblong piece  345  to spring, 
     In summary, the present invention has a smaller volume to be applied in the design in indoors or small space, and it has stronger torque and greater compression efficiency with the speed-change function of the driving mechanism  40  by the abreast arrangement of the brushless DC motor  20  and the compression device  30 . Also, the present invention has liquids  81  and water absorbing buffer  82  to be filled in the housing  71  to completely seal the device, providing a stable machine with less shaking and lower noises to achieve greater efficiency with power saving function. 
     Although particular embodiments of the 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 invention. Accordingly, the invention is not to be limited except by the appended claims.