Scroll compressor

Abstract

A scroll compressor includes a casing, a drive motor arranged in an inner space of the casing, a rotary shaft coupled to the drive motor to rotate, a main frame arranged under the drive motor, a fixed scroll arranged under the main frame, an orbiting scroll engaging with the orbiting scroll to make an orbiting motion, the rotary shaft being inserted into and eccentrically coupled to the orbiting scroll, a first bearing positioned between the main frame and the rotary shaft, and a second bearing positioned between the fixed scroll and the rotary shaft, where a gap between the first and second bearings and the rotary shaft varies with a vertical position. The scroll compressor may prevent the eccentric effect occurring during rotation from deteriorating performance of the bearings, thereby preventing compression performance from being lowered.

What is claimed is: 
     
         1 . A scroll compressor comprising:
 a casing that defines an inner space therein;   a drive motor disposed in the inner space of the casing;   a main frame disposed vertically below the drive motor;   a fixed scroll disposed vertically below the main frame;   an orbiting scroll engaged with the fixed scroll and configured to perform an orbiting motion relative to the fixed scroll;   a rotary shaft that passes through the main frame and the fixed scroll, that is coupled to the drive motor, and that is configured to rotate about a rotation axis, the rotary shaft being inserted into and coupled to the orbiting scroll at a position offset from a center of the orbiting scroll;   a first bearing disposed between the main frame and the rotary shaft, the first bearing defining a first gap between an inner side surface of the first bearing and an outer circumferential surface of the rotary shaft; and   a second bearing disposed between the fixed scroll and the rotary shaft, the second bearing defining a second gap between an inner side surface of the second bearing and the outer circumferential surface of the rotary shaft,   wherein a width of each of the first gap and the second gap is configured to vary based on a vertical position of the rotary shaft.   
     
     
         2 . The scroll compressor of  claim 1 , wherein a center of mass of the rotary shaft is displaced from a center of the scroll compressor in a radial direction of the rotary shaft. 
     
     
         3 . The scroll compressor of  claim 2 , wherein the rotary shaft comprises a middle portion disposed between the first bearing and the second bearing, the middle portion having a shape asymmetric with respect to the rotation axis of the rotary shaft. 
     
     
         4 . The scroll compressor of  claim 1 , wherein the first gap comprises:
 a first lower gap defined between a lower portion of the first bearing and the outer circumferential surface of the rotary shaft; and   an first upper gap defined between an upper portion of the first bearing and the outer circumferential surface of the rotary shaft, and   wherein the first lower gap is wider than the first upper gap.   
     
     
         5 . The scroll compressor of  claim 4 , wherein the second gap comprises:
 a second upper gap defined between an upper portion of the second bearing and the outer circumferential surface of the rotary shaft; and   a second lower gap defined between a lower portion of the second bearing and the outer circumferential surface of the rotary shaft, and   wherein the second upper gap is wider than the second lower gap.   
     
     
         6 . The scroll compressor of  claim 1 , wherein the second gap comprises:
 an upper gap defined between an upper portion of the second bearing and the rotary shaft; and   a lower gap defined between a lower portion of the second bearing and the rotary shaft, and   wherein the upper gap is wider than the lower gap.   
     
     
         7 . The scroll compressor of  claim 1 , wherein at least one of the first bearing or the second bearing comprises:
 a first ring having a first diameter; and   a second ring having a second diameter that is greater than the first diameter, and   wherein the first ring and the second ring are disposed adjacent to each other and arranged along the rotation axis of the rotary shaft.   
     
     
         8 . The scroll compressor of  claim 7 , wherein an inner surface of each of the first ring and the second ring extends parallel to the rotation axis of the rotary shaft. 
     
     
         9 . The scroll compressor of  claim 1 , wherein the first bearing comprises:
 a first ring having a first diameter; and   a second ring disposed vertically below the first ring, the second ring having a second diameter that is greater than the first diameter, and   wherein the second bearing comprises:   a third ring having a third diameter, and   a fourth ring disposed vertically below the third ring, the fourth ring having a fourth diameter that is less than the third diameter.   
     
     
         10 . The scroll compressor of  claim 9 , wherein an inner surface of each of the first ring, the second ring, the third ring, and the fourth ring extends parallel to the rotation axis of the rotary shaft. 
     
     
         11 . The scroll compressor of  claim 1 , wherein at least one of the first bearing or the second bearing comprises:
 an inclined surface that is inclined with respect to the rotation axis of the rotary shaft and that is defined by the inner side surface of the at least one of the first bearing or the second bearing, and   wherein a distance between the inclined surface and the outer circumferential surface of the rotary shaft is configured to vary based on the vertical position of the rotary shaft.   
     
     
         12 . The scroll compressor of  claim 11 , wherein the inner side surface of the first bearing defines a first inclined surface inclined with respect to the rotation axis of the rotary shaft,
 wherein the inner side surface of the second bearing defines a second inclined surface inclined with respect to the rotation axis of the rotary shaft,   wherein a first distance between the first inclined surface and the outer circumferential surface of the rotary shaft increases as the rotary shaft extends downward toward a bottom of the rotary shaft, and   wherein a second distance between the second inclined surface and the outer circumferential surface of the rotary shaft decreases as the rotary shaft extends downward toward the bottom of the rotary shaft.   
     
     
         13 . The scroll compressor of  claim 1 , wherein the rotary shaft comprises:
 a main journal surrounded by the first bearing; and   a sub journal surrounded by the second bearing, and   wherein a diameter of each of the main journal and the sub-journal is configured to vary based on the vertical position of the rotary shaft.   
     
     
         14 . The scroll compressor of  claim 13 , wherein the inner side surface of each of the first bearing and the second bearing extends parallel to the rotation axis of the rotary shaft. 
     
     
         15 . The scroll compressor of  claim 13 , wherein the diameter of the main journal decreases as the rotary shaft extends downward toward a bottom of the rotary shaft, and
 wherein the diameter of the sub-journal increases as the rotary shaft extends downward toward the bottom of the rotary shaft.   
     
     
         16 . The scroll compressor of  claim 15 , wherein the rotary shaft further comprises a middle portion that extends between the main journal and the sub-journal in a direction parallel to the rotation axis of the rotary shaft, and
 wherein the middle portion maintains one diameter as the rotary shaft extends downward toward the second bearing.   
     
     
         17 . The scroll compressor of  claim 13 , wherein the diameter of the main journal is different from the diameter of the sub-journal. 
     
     
         18 . A scroll compressor comprising:
 a casing that defines an inner space therein;   a drive motor disposed in the inner space of the casing;   a main frame disposed vertically below the drive motor;   a fixed scroll disposed vertically below the main frame;   an orbiting scroll engaged with the fixed scroll and configured to perform an orbiting motion relative to the fixed scroll; and   a rotary shaft that passes through the main frame and the fixed scroll, that is coupled to the drive motor, and that is configured to rotate about a rotation axis, the rotary shaft being inserted into and coupled to the orbiting scroll at a position offset from a center of the orbiting scroll,   wherein the main frame defines a first gap between an inner side surface of the main frame and an outer circumferential surface of the rotary shaft,   wherein the fixed scroll defines a second gap between an inner side surface of the fixed scroll and the outer circumferential surface of the rotary shaft, and   wherein a width of each of the first gap and the second gap is configured to vary based on a vertical position of the rotary shaft and a displacement of the rotary shaft from the rotation axis of the rotary shaft.   
     
     
         19 . The scroll compressor of  claim 18 , wherein each of the inner side surface of the main frame and the inner side surface of the fixed scroll is inclined with respect to the rotation axis of the rotary shaft, and
 wherein the outer circumferential surface of the rotary shaft extends parallel to the rotation axis of the rotary shaft.   
     
     
         20 . The scroll compressor of  claim 18 , wherein the rotary shaft comprises:
 a main journal that faces the main frame; and   a sub-journal that faces the fixed scroll,   wherein each of the inner side surface of the main frame and the inner side surface of the fixed scroll extends parallel to the rotation axis of the rotary shaft, and   wherein a diameter of each of the main journal and the sub-journal is configured to vary based on the vertical position of the rotary shaft.