Patent Publication Number: US-6910872-B2

Title: Rotary compressor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of Korean Patent Application No. 2002-29929 filed on May 29, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates, in general, to rotary compressors for refrigeration cycles and, more particularly, to a rotary compressor, a capacity of which is variable as desired. 
   2. Description of the Related Art 
   As is well known to those skilled in the art, rotary compressors have been preferably and widely used as compressors for a variety of refrigeration systems, such as air conditioners or refrigerators operated with refrigerant sequentially and repeatedly flowing through a refrigeration cycle including compression-condensation-expansion-evaporation. In the refrigeration system, the compressor compresses the refrigerant to highly pressurize the refrigerant prior to discharging the highly pressurized refrigerant to a condenser. 
   As shown in  FIG. 1 , a conventional rotary compressor for refrigeration systems comprises a hermetic casing  1  with a drive device  2  and a compressing device  3  installed in the hermetic casing  1 . The drive device  2  generates a rotating force, and the compressing device  3  compresses the refrigerant using the rotating force of the drive device  2 . A rotating shaft  4  is axially arranged in the hermetic casing  1  such that the rotating shaft  4  is rotated by the rotating force of the drive device  2  and transmits the rotating force to the compressing device  3 . 
   The compressing device  3  comprises variable compressing chambers  5  and a roller  6  rotatably set in a bore of the compressing device  3  to define the variable compressing chambers  5  in said bore. The roller  6  of the compressing device  3  is rotated in the bore by the rotating force of the rotating shaft  4 , thus compressing the refrigerant in the chambers  5 . 
   However, the conventional rotary compressors are fixed in capacities thereof, so to change a capacity of the conventional rotary compressor after the conventional rotary compressor is completely assembled is impossible. Therefore, the conventional rotary compressor cannot meet a change in a refrigerating load of refrigeration cycles during a use of the conventional rotary compressor, thus causing the refrigeration systems to sometimes excessively consume electric energy. 
   SUMMARY OF THE INVENTION 
   Accordingly, a rotary compressor is provided, of which a capacity is variable as desired. 
   Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
   In order to accomplish the above and other aspects, a rotary compressor is provided, comprising a drive device generating a rotating force, a rotating shaft connected to the drive device at a first end thereof and rotated by the rotating force of the drive device, and a cylinder through which a second end of the rotating shaft passes, wherein two or more compressing chambers are provided in the cylinder such that the two or more compressing chambers are sequentially arranged along an axial direction of the rotating shaft; a plurality of rollers are eccentrically installed on the rotating shaft such that the rollers are arranged in the compressing chambers, respectively; and a clutch is installed on the rotating shaft to transmit the rotating force of the rotating shaft to at least one of the rollers. 
   In the rotary compressor, the clutch may be a one-way clutch transmitting the rotating force of the rotating shaft to a selected roller only when the rotating shaft is rotated in a predetermined rotating direction. 
   In the rotary compressor, the compressing chambers comprise first and second compressing chambers, the rollers comprise first and second rollers set in the first and second compressing chambers, respectively; and the one-way clutch is installed inside at least one of the first and second rollers. 
   The first roller is provided with a first one-way clutch which exclusively transmits the rotating force of the rotating shaft to the first roller only when the rotating shaft is rotated in a first rotating direction, while the second roller is provided with a second one-way clutch which exclusively transmits the rotating force of the rotating shaft to the second roller only when the rotating shaft is rotated in a second rotating direction. 
   The one-way clutch is a one-way roller clutch comprising: a cylindrical clutch body; a plurality of roller-seating grooves formed on an inner surface of the cylindrical clutch body such that each of the roller-seating grooves is gradually deeper in a direction toward an outer circumferential surface of the cylindrical clutch body; and a roller bearing is seated in each of the roller-seating grooves. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
       FIG. 1  is a sectional view of a conventional rotary compressor; 
       FIG. 2  is a sectional view of a rotary compressor in accordance with an embodiment of the present invention; 
       FIG. 3  is a perspective view showing a rotating shaft and an eccentric cam included in the rotary compressor in  FIG. 2 ; and 
       FIG. 4  is a sectional view of a rotary compressor in accordance with a second embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
   As shown in  FIGS. 2 and 3 , a rotary compressor according to an embodiment of the present invention comprises a hermetic casing  10 , with a drive device  20  and a compressing device  30  installed in the hermetic casing  10 . The drive device  20  generates a rotating force when an electric current is applied to the drive device  20 . The compressing device  30  compresses refrigerant using the rotating force of the drive device  20  while intaking, compressing and discharging the refrigerant. 
   The hermetic casing  10  forms an appearance of the rotary compressor with a refrigerant outlet pipe  11  connected to an upper end of the hermetic casing  10  so as to discharge highly pressurized refrigerant from the rotary compressor and a refrigerant inlet pipe  12  connected to a lower end of the hermetic casing  10  so as to introduce the refrigerant into the rotary compressor. 
   The drive device  20  comprises a stator  21 , a rotor  22  and a rotating shaft  40 . The stator  21  forms an electromagnetic field when an electric current is applied to the stator  21 , while the rotor  22  is rotatably and concentrically set in the stator  21 . The rotating shaft  40  is a longitudinal shaft having a circular cross-section. This rotating shaft  40  is fixed to the rotor  22  at a first end of the rotating shaft  40 , and passes at a second end of the rotating shaft  40  through the compressing device  30 . The rotating shaft  40  is thus rotated along with the rotor  22  to transmit the rotating force of the rotor  22  to the compressing device  30 . 
   The compressing device  30 , which is operated using the rotating force of the drive device  20  transmitted thereto through the rotating shaft  40 , comprises a cylinder  31  with first and second variable compressing chambers  31   a  and  31   b . First and second rollers  32   a  and  32   b  are respectively set in the first and second variable compressing chambers  31   a  and  31   b , and are rotated by the rotating force of the rotating shaft  40 , thus compressing the refrigerant in the first and second variable compressing chambers  31   a  and  31   b.    
   In the compressing device  30 , the first and second variable compressing chambers  31   a  and  31   b  are axially arranged in the cylinder  31  at upper and lower positions such that sidewalls of the first and second variable compressing chambers  31   a  and  31   b  are in parallel to the rotating shaft  40 . The first and second rollers  32   a  and  32   b  are, respectively, set in the first and second variable compressing chambers  31   a  and  31   b . For ease of description, an upper variable compressing chamber  31   a  and an upper roller  32   a  are referred to as a first variable chamber  31   a  and a first roller  32   a , respectively, and a lower variable compressing chamber  31   b  and a lower roller  32   b  are referred to as a second variable compressing chamber  31   b  and a second roller  32   b , respectively. 
   The first and second rollers  32   a  and  32   b  are eccentrically installed on the rotating shaft  40  such that the first and second rollers  32   a  and  32   b  compress the refrigerant in the first and second variable compressing chambers  31   a  and  31   b  during a rotating action in the first and second variable compressing chambers  31   a  and  31   b . To accomplish such an eccentric rotatable arrangement of the first and second rollers  32   a  and  32   b  on the rotating shaft  40 , two eccentric cams  33   a  and  33   b  are, respectively, provided between the rotating shaft  40  and the first roller  32   a  and between the rotating shaft  40  and the second roller  32   b . Due to the eccentric cams  33   a  and  33   b , the first and second rollers  32   a  and  32   b  are, respectively, eccentrically rotated during the rotating action of the rotating shaft  40 . For ease of description, the eccentric cam  33   a  provided adjacent to the first roller  32   a  is referred to as a first cam  33   a , and the eccentric cam  33   b  provided adjacent to the second roller  32   b  is referred to as a second cam  33   b.    
   One-way clutches  50   a  and  50   b  are provided between the rotating shaft  40  and the first and second eccentric cams  33   a  and  33   b , respectively, to exclusively transmit the rotating force of the rotating shaft  40  to an associated cam  33   a  or  33   b  only when the rotating shaft  40  is rotated in either a first selected rotating direction or a second selected rotating direction. The one-way clutch  50   a , provided between the rotating shaft  40  and the first eccentric cam  33   a , is referred to as a first one-way clutch  50   a , and the one-way clutch  50   b , provided between the rotating shaft  40  and the second eccentric cam  33   b , is referred to as a second one-way clutch  50   a.    
   The first rotating direction denotes either a clockwise rotating direction or a counterclockwise rotating direction, and the second rotating direction denotes a remaining rotating direction: either clockwise or counterclockwise. Therefore, the second rotating direction is necessarily opposite the first rotating direction. 
   The first one-way clutch  50   a  is designed such that the first one-way clutch  50   a  exclusively transmits the rotating force of the rotating shaft  40  to the first roller  32   a  through the first eccentric cam  33   a  only when the rotating shaft  40  is rotated in the first direction. The second one-way clutch  50   b  is designed such that the second one-way clutch  50   b  exclusively transmits the rotating force of the rotating shaft  40  to the second roller  32   b  through the second eccentric cam  33   b  only when the rotating shaft  40  is rotated in the second direction. 
   Each of the two one-way clutches  50   a  and  50   b  is a one-way roller clutch, which comprises a cylindrical clutch body  51 , with a plurality of roller-seating grooves  52  axially formed on an inner surface of the cylindrical clutch body  51 . The roller-seating grooves  52  are formed on the inner surface of the clutch body  51  by cutting the inner surface at regularly spaced positions such that each groove  52  becomes gradually deeper in a direction toward the outer circumferential surface of the body  51  as shown in  FIG. 3. A  roller bearing  53  is seated in each of the roller-seating grooves  52 . 
   In this case, one-way roller clutches are used as the one-way clutches  50   a  and  50   b . However, it should be understood that the type of the one-way clutches  50   a  and  50   b  may be changed from that of the roller clutches without affecting a functioning of the present invention. 
   Further, in this case, the compressor is designed such that two one-way clutches  50   a  and  50   b  are installed at the first and second eccentric cams  33   a  and  33   b , respectively. However, it should be understood that the rotary compressor may be designed such that the rotary compressor has only one clutch  50   a  provided at a position associated with the first roller  32   a , as shown in FIG.  4 . 
   The operational of the rotary compressor of the embodiment of the present invention will be described herein below with reference to the accompanying drawings. 
   When the drive device  20  is turned on and the rotating shaft  40  is rotated in the first direction, the rotating force of the rotating shaft  40  is transmitted to the first roller  32   a  through the first one-way clutch  50   a  and the first eccentric cam  33   a , so the first roller  32   a  is rotated to compress the refrigerant in the first variable compressing chamber  31   a.    
   In this case, the second one-way clutch  50   b  is not in a power transmission mode since the second one-way clutch  50   b  is designed to exclusively transmit the rotating force of the rotating shaft  40  to the second roller  32   b  only when the rotating shaft  40  is rotated in the second direction. Therefore, no refrigerant is compressed in the second variable compressing chamber  31   b , but only the first variable compressing chamber  31   a  acts as a refrigerant compressing chamber. 
   Alternatively, when the rotating shaft  40  is rotated in the second direction, the first one-way clutch  50   a  is not in the power transmission mode since the first one-way clutch  50   a  is designed to exclusively transmit the rotating force of the rotating shaft  40  to the first roller  32   a  only when the rotating shaft  40  is rotated in the first direction. Therefore, no refrigerant is compressed in the first variable compressing chamber  31   a.    
   The rotating force of the rotating shaft  40  rotated in the second direction is transmitted to the second roller  32   b  through the second one-way clutch  50   b  and the second eccentric cam  33   b , so that the second roller  32   b  is rotated to compress the refrigerant in the second variable compressing chamber  31   b . That is, during the rotation of the rotating shaft  40  in the second direction, only the second variable compressing chamber  31   b  acts as the refrigerant compressing chamber. 
   As described above, a variable rotary compressor for refrigeration cycles is provided. In the variable rotary compressor, two rollers are installed on a rotating shaft of a drive device through one-way clutches and eccentric cams so as to be rotated by a rotating force of the drive device to compress refrigerant. During operation of the variable rotary compressor, only one of the two rollers is selectively rotated by changing a rotating direction of the rotating shaft, so a capacity of the variable rotary compressor is changeable as desired. 
   Although a few embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.