Abstract:
A scroll compressor with a backflow-proof mechanism. The scroll compressor comprises a slider disposed on a scroll couple, forming several enclosed spaces. The slider is raised by the working fluid in the spaces, preventing liquid leakage from a high-pressure chamber to a low-pressure chamber, when the scroll compressor starts. The slider descends when the compression ratio of the scroll compressor is exceeded. Thus, the pressure is released, and the performance of the scroll compressor is improved. The slider of the invention further comprises a floating element to prevent reversal of pressurized fluid and damage to the scroll couple.

Description:
This Non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 092136825 filed in Taiwan, Republic of China on Dec. 25, 2003, the entire contents of which are hereby incorporated by reference. 
   BACKGROUND 
   The present invention relates to a scroll compressor, and in particular to a scroll compressor with mechanisms for adjusting load and preventing damage due to backflow. 
   Presently, scroll compressors must rapidly establish a high pressure when starting, have less backflow when stopped, and provide self-adjustment of operating pressure to prevent damage to scrolls, due to exceeded compression ratio. 
   In U.S. Pat. No. 6,059,549, Tarng, et al. teach a scroll compressor with a sealing arrangement. The scroll compressor comprises a partition dividing the shell thereof into a high-pressure chamber and a low-pressure chamber with a scroll couple therein. A spring and sealing ring are disposed in a hub portion of a fixed scroll, forming a buffer space therebetween. When the scroll compressor starts, the sealing ring is raised by the work flow corresponding to the spring, abutting the bottom surface of a partition. Thus, the sealing ring prevents leakage of the work fluid and achieves required operational pressure rapidly. Due to the additional spring, the sealing ring, however, is forced upwards and unable to descend and release operational pressure in the scroll couple when the compression ratio is exceeded. Therefore, the scroll compressor is unreliable. 
   In the above arrangement, compressed work fluid poured into the high-pressure chamber immediately reverses into the scroll couple when the scroll compressor stops. This backflow problem generates impact, noise and damage to the end portions of each scroll, thus shortening the life of the scroll compressor. 
   Furthermore, conventional scroll compressors must keep running when recycling refrigerant. The space between the scroll couple approaches a vacuum, and gas, or gasiform refrigerant, therein is ionized and discharges electricity, damaging the scroll couple. 
   SUMMARY 
   Accordingly, embodiments of the invention provide a scroll compressor with a pressure adjustment mechanism, capable of releasing load and allowing refrigerant to flow from the high-pressure to the low-pressure chamber when the compression ratio is exceeded. 
   Embodiments of the invention additionally provide a scroll compressor with backflow-proof mechanism, preventing damage due to backflow when the compressor stops. 
   Embodiments of the invention further prevent discharge between the scroll couple when recycling refrigerant. 
   Embodiments of the invention provide a scroll compressor with a backflow-proof mechanism. The scroll compressor comprises a partition, a scroll couple, and a slider disposed thereon. An inner space is defined between a shell of the scroll compressor and a frame therein. A partition with a central hole is disposed in the inner space, forming a high-pressure chamber and a low-pressure chamber. The scroll couple is disposed in the low-pressure chamber on the frame and comprises an orbiting scroll meshed with a non-orbiting scroll. The slider is movably disposed on the non-orbiting scroll and comprises an extending portion with a venting passage therein. The extending portion protrudes into the high-pressure chamber through the central hole, connecting the high-pressure chamber and the scroll couple through the venting passage. A plurality of enclosed spaces are formed between the slider and the non-orbiting scroll, such that the slider can move between a first position and a second position by the pressure variation of the enclosed spaces. 
   Furthermore, the non-orbiting scroll comprises a hub portion, receiving the slider. The hub portion comprises a first cavity and a second cavity beneath the first cavity. The diameter of the first cavity is larger than the diameter of the second cavity. The slider comprises a first portion and a second portion. The diameter of the first portion is larger than that of the extending portion and the second portion. When the slider is disposed in the hub portion, the first portion is received in the first cavity, and the second portion is received in the second cavity, forming the enclosed spaces therebetween. 
   The partition of the scroll compressor comprises a plurality of discharge passages around the side surface of the central hole, allowing communication between the high-pressure chamber and the low-pressure chamber. The slider comprises a circular leak-proof surface surrounding the outer bore of the extending portion, sealing the discharge passages when the slider is in the first position and abuts the partition. The extending portion of the slider comprises a plurality of holes on the side surface of the venting passage, allowing communication between the high-pressure chamber and the venting passage. 
   Embodiments of the invention provide another scroll compressor comprising a slider with a floating element movably disposed in a venting passage. The slider comprises a flange around the side surface of the venting passage, restricting the floating element therein. The floating element comprises a groove and a plurality of perpendicular second holes communicated therewith to balance the pressure difference between the high-pressure and low-pressure chambers. The extending portion comprises a upper hole at the top end and communicated with the venting passage. When the scroll compressor stops, work fluid in the high-pressure chamber reverses into the venting passage through the upper hole and pushes the floating element down to abut the flange. Simultaneously, the floating element blocks the venting passage, preventing damage due to the high-pressure work fluid. 
   The slider comprises a plurality of leak-proof members around the outer bore thereof, abutting the inner surface of the hub portion. The leak-proof members are O-rings or Teflon rings. The non-orbiting scroll further comprises a plurality of bypasses communicated with the first cavity. When the scroll compressor starts, work fluid passing through the bypasses fills the enclosed space in the first cavity, raising the slider. 
   Embodiments of the invention provide another scroll compressor with a backflow-proof mechanism. The scroll compressor comprises a partition, a scroll couple, and a slider disposed thereon. An inner space is defined between a shell of the scroll compressor and a frame therein. A partition with a central hole is disposed in the inner space, forming a high-pressure chamber and a low-pressure chamber. The scroll couple is disposed in the low-pressure chamber on the frame and comprises an orbiting scroll and a non-orbiting scroll with a hub portion. The slider is movably disposed in the hub portion of the non-orbiting scroll and comprises an extending portion with a venting passage therein. 
   The extending portion comprises a plurality of holes on the side surface of the venting passage and protrudes into the high-pressure chamber through the central hole, allowing communication between the high-pressure chamber and the scroll couple through the venting passage when the slider is in a first position. The partition covers the holes on the extending portion when the scroll compressor stops with the slider in a second position. 
   A plurality of enclosed spaces are formed between the slider and the non-orbiting scroll, such that the slider is moved between the first and second positions by the pressure variation of the enclosed spaces. 
   Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the subsequent detailed description and the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
       FIG. 1A  is a partial cross section of a scroll compressor of the first embodiment during operation; 
       FIG. 1B  is an enlarged view of the area a in  FIG. 1A ; 
       FIG. 1C  is a partial cross section of the scroll compressor of the first embodiment when stopped; 
       FIG. 2  is a partial cross section of a scroll compressor of the second embodiment during operation; 
       FIG. 3A  is a partial cross section of a scroll compressor of the third embodiment during operation; 
       FIG. 3B  is a partial cross section of the scroll compressor of the first embodiment when stopped; 
       FIG. 3C  is an enlarged view of the area b in  FIG. 3B ; 
       FIG. 3D  is a top view of a floating element in  FIG. 3B ; 
       FIG. 3E  is a cross section of another floating element; 
       FIG. 3F  is a top view of the floating element in  FIG. 3E ; 
       FIG. 4  is a partial cross section of a scroll compressor of the fourth embodiment during operation; and 
       FIG. 5  is a partial cross section of a scroll compressor of the fifth embodiment during operation. 
   

   DETAILED DESCRIPTION 
   First Embodiment 
     FIG. 1A  shows a scroll compressor of the first embodiment during operation, and  FIG. 1B  shows the enlarged area a in  FIG. 1A . The scroll compressor comprises a shell  10 , a frame  20 , a partition  30 , and scroll couple  40  with a slider  50  disposed thereon. The shell  10  comprises an inlet  12  and outlet  14 . The frame  20  is disposed in the shell  10 , defining an inner space therebetween. The partition  30  with a central hole  38  is disposed in the inner space, forming a high-pressure chamber  32  and a low-pressure chamber  34 . The scroll couple  40  is disposed in the low-pressure chamber  34  on the frame  20  and comprises an orbiting scroll  42  meshed with a non-orbiting scroll  41 . 
   The slider  50  is received in a hub portion  45  in the center on the top of the non-orbiting scroll  41  and movable between a first position and a second position. The slider  50  comprises a cylindrical extending portion  53  with a venting passage  54  therein. The extending portion  53  protrudes into the high-pressure chamber  32  through the central hole  38  of the partition  30 . The extending portion  53  of the slider  50  comprises a plurality of holes  55  on the side surface of the venting passage  54 , thus communicating the discharge port  44  of the scroll couple  40  and the high-pressure chamber  32  through the venting passage  54 . Furthermore, an enclosed space  47  is formed between the slider  50  and the non-orbiting scroll  41 , such that the slider  50  is moved between a higher first position and a lower second position by the pressure variation of the enclosed space  47 . 
   In this embodiment, the slider  50  further comprises a cylindrical first portion  51  with diameter thereof larger than that of the extending portion  53 . The partition  30  of the scroll compressor comprises a plurality of discharge passages  36  around the side surface of the central hole  38 , allowing communication between the high-pressure chamber  32  and the low-pressure chamber  34 . The slider  50  further comprises a circular leak-proof surface  56  surrounding the outer bore of the extending portion  53 . During operation of the scroll compressor, low-pressure work fluid therein passes through the inlet  12  and the intake port  43 , entering the scroll couple  40 , and is compressed thereby. Simultaneously, high-pressure work fluid is discharged through the discharge port  44  into the hub portion  45  of the non-orbiting scroll  41 , raising the slider  50  to the first position as shown in  FIGS. 1A and 1B . The circular leak-proof surface  56  of the slider  50  abuts the bottom surface around the central hole  38  of the partition  30  and seals the discharge passages  36 , preventing leakage of high-pressure work fluid from the high-pressure chamber  32  to the low-pressure chamber  34  through discharge passages  36 . Thus, the required operational pressure can be achieved quickly when the scroll compressor starts. 
   The slider  50  comprises a leak-proof member  70 , such as an O-ring or Teflon ring, disposed around the outer bore of the first portion  51 , abutting the inner surface of the hub portion  45 , to prevent leakage of the work fluid from the gap between the slider  50  and the hub portion  45  to the low-pressure chamber  34 . 
   In  FIG. 1B , when the compression ratio of the scroll compressor exceeds a predetermined limit during operation, the slider  50  descends as the upward force provided by the discharging flow is lower than the downward force provided by the reverse flow corresponding to the weight of the slider  50 . The work fluid in the high-pressure chamber  32  returns the low-pressure chamber  34  through the discharge passages  36  and the gap between the partition  30  and the non-orbiting scroll  41 , such that pressure difference between the high-pressure chamber  32  and the low-pressure chamber  34  can be minimized. 
     FIG. 1C  shows a partial cross section of the scroll compressor of the first embodiment when stopped. In  FIG. 1C , the upward force provided by the discharging flow is eliminated when the scroll compressor stops. Therefore, the slider  50  immediately falls to the second position due to the downward force provided by the reverse flow corresponding to the weight of the slider  50 . The partition  30  covers the holes  55  on the extending portion  53 , thus reducing high-pressure backflow and preventing damage to the scroll couple  40 . Furthermore, after the scroll compressor completely stops, the work fluid in the high-pressure chamber  32  can enter the low-pressure chamber  34  through the discharge passages  36 , gradually balancing the pressure difference therebetween. 
   Second Embodiment 
     FIG. 2  shows a scroll compressor of the second embodiment during operation. In  FIG. 2 , the hub portion  45  of this embodiment comprises a first cavity  46  and a second cavity  48  beneath the first cavity  46 . The diameter of the first cavity  46  is larger than that of the second cavity  48 . The slider  50  comprises a cylindrical first portion  51  and a cylindrical second portion  52 . The diameter of the first portion  51  is larger than that of the extending portion  53  and the second portion  52 . When the slider  50  is disposed in the hub portion  45 , the first portion  51  is received in the first cavity  46 , and the second portion  52  is received in the second cavity  48 . Two leak-proof members  70  and  72 , such as O-rings or Teflon rings, are disposed around the outer bore of the first and second portions  51  and  52 , abutting the inner surface of the hub portion  45 . Therefore, two separated enclosed spaces  47  and  49  are defined between the slider  50  and the hub portion  45  of the non-orbiting scroll  41 . 
   The non-orbiting scroll  41  of this embodiment comprises a plurality of bypasses  471  communicated with the first cavity  46 . When the scroll compressor starts, work fluid passes through the bypasses  471 , filling in the enclosed space  47 , and assists in raising the slider  50  to the first position to rapidly establish required operational pressure. 
   Furthermore, when the compression ratio of the scroll compressor exceeds a predetermined limit during operation, or the scroll compressor stops, the work fluid in the high-pressure chamber  32  can enter the low-pressure chamber  34  through the discharge passages  36  and the gap between the partition  30  and the non-orbiting scroll  41 , such that the pressure difference between the high-pressure chamber  32  and the low-pressure chamber  34  can be gradually balanced. Additionally, the slider  50  of this embodiment falls to the second position with the holes  55  on the extending portion  53  covered by the partition  30  when the scroll compressor stops, thus reducing high-pressure backflow and preventing damage to the scroll couple  40 . 
   Third Embodiment 
     FIG. 3A  shows a scroll compressor of the third embodiment during operation, and  FIG. 3B  shows that when stopped. In  FIGS. 3A and 3B , the movable region of the slider  50  is shorter than that in the first embodiment, such that the holes  55  on the extending portion  53  cannot be completely covered by the partition  30 . Furthermore, the slider  50  of this embodiment comprises a floating element  60  movably disposed in a venting passage  54 , a flange  57  around the side surface of the venting passage  54 , restricting the floating element  60  therein, and a upper hole  58  on the top surface of the extending portion  53 , communicating with the venting passage  54 . 
   In this embodiment, during operation of the scroll compressor, high-pressure work fluid is discharged through the discharge port  44  into the hub portion  45  of the non-orbiting scroll  41  and raises the slider  50  and the floating element  60  to the position as shown in  FIG. 3A . The circular leak-proof surface  56  of the slider  50  abuts the bottom surface around the central hole  38  of the partition  30  and seals the discharge passages  36 , preventing leakage of high-pressure work fluid from the high-pressure chamber  32  to the low-pressure chamber  34  through discharge passages  36 . Thus, the required operational pressure can be achieved quickly when the scroll compressor starts. 
   When the compression ratio of the scroll compressor of this embodiment exceeds a predetermined limit during operation, or the scroll compressor stops, the upward force provided by the discharging flow decreases. Therefore, the slider  50  and the floating element  60  immediately fall to the positions, shown in  FIG. 3B , due to gravity and the downward force provided by the reverse flow. The work fluid in the high-pressure chamber  32  can enter the low-pressure chamber  34  through the discharge passages  36 , gradually balancing the pressure difference therebetween. 
     FIG. 3C  is an enlarged view of the area b in  FIG. 3B , and  FIG. 3D  shows is a top view of the floating element  60  in  FIG. 3B . In  FIGS. 3C and 3D , the floating element  60  comprises a groove  64  and two perpendicular second holes  62  communicated therewith. The floating element  60  is capable of preventing backflow when the scroll compressor stops and balancing the pressure difference between the high-pressure chamber  32  and the low-pressure chamber  34 . Thus, the electrical discharge problems of the scroll couple  40  can be solved when recycling refrigerant. 
   Furthermore, another floating element  60 ′ is provided in  FIGS. 3E and 3F . The floating element  60 ′ comprises a downward protrusion, a groove  64  and two perpendicular second holes  62 . When the scroll compressor stops, the downward protrusion of the floating element  60 ′ directly blocks the discharge port  44  of the scroll couple  40  to prevent electrical discharge and backflow problems. 
   Fourth Embodiment 
     FIG. 4  shows a scroll compressor of the fourth embodiment during operation. Compared with the scroll compressor of the second embodiment in  FIG. 2 , the movable region of the slider  50  is shorter than that in the second embodiment, such that the holes  55  on the extending portion  53  cannot be completely covered by the partition  30 . Furthermore, the slider  50  of this embodiment comprises a floating element  60  movably disposed in a venting passage  54 , a flange  57  around the side surface of the venting passage  54 , restricting the floating element  60  therein, and a upper hole  58  on the top surface of the extending portion  53 , communicating with the venting passage  54 . 
   The hub portion  45  of this embodiment comprises a first cavity  46  and a second cavity  48  beneath the first cavity  46 . The diameter of the first cavity  46  is larger than that of the second cavity  48 . The slider  50  comprises a cylindrical first portion  51  and a cylindrical second portion  52 . The diameter of the first portion  51  is larger than that of the extending portion  53  and the second portion  52 . When the slider  50  is disposed in the hub portion  45 , the first portion  51  is received in the first cavity  46 , and the second portion  52  is received in the second cavity  48 . Two leak-proof members  70  and  72 , such as O-rings or Teflon rings, are disposed around the outer bore of the first and second portions  51  and  52 , abutting the inner surface of the hub portion  45 . Therefore, two separated enclosed spaces  47  and  49  are defined between the slider  50  and the hub portion  45  of the non-orbiting scroll  41 . 
   The non-orbiting scroll  41  of this embodiment comprises a plurality of bypasses  471  communicated with the first cavity  46 . When the scroll compressor starts, work fluid passes through the bypasses  471 , filling in the enclosed space  47 , and assists in raising the slider  50  to the first position to rapidly establish required operational pressure. 
   Similar to the function of the third embodiment, the work fluid in the high-pressure chamber  32  can enter the low-pressure chamber  34  through the discharge passages  36  and the gap between the partition  30  and the non-orbiting scroll  41  when the compression ratio is exceeded during operation, or the scroll compressor stops. Additionally, the floating element  60  is also capable of preventing backflow. 
   Fifth Embodiment 
     FIG. 5  shows a scroll compressor of the fifth embodiment during operation. In  FIG. 5 , the slider  50  of this embodiment comprises a disc-shaped first portion  51  with larger diameter than that of other embodiments. Thus, a larger downward force can be provided by the work fluid in the enclosed space  47 , such that the scroll couple  40  can be tightly meshed during operation. 
   Furthermore, the scroll couple  40  of this embodiment comprises a plurality of gaskets  411 ,  421  on the top ends of each vane thereof, preventing leakage of compressed work fluid during revolution between the non-orbiting scroll  41  and the orbiting scroll  42 . 
   The backflow-proof mechanism in each embodiment of the invention can prevent leakage of compressed work fluid from the high-pressure chamber  32  to the low-pressure chamber  34 , such that the required operational pressure can be rapidly achieved when the scroll compressors start. The backflow-proof mechanisms also block the high-pressure backflow, preventing damage to the scroll couple  40  when the compressors suddenly stop. Furthermore, the backflow-proof mechanisms can balance the pressure difference between the high-pressure and low-pressure chambers  32  and  34  through discharge passages  36 , which prevents electrical discharge between the scroll couple  40  when recycling refrigerant. 
   While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.