Scroll compressor

Abstract

A scroll compressor includes a casing with an oil reservoir, fixed and movable scrolls, a crank shaft, and a housing having an upper bearing rotatably supporting the crank shaft. The crank shaft has an oil feed path and the housing has a crank chamber. An outer peripheral surface of the crank shaft has an annular groove, and a spiral groove. The housing has a bearing back-face passage connecting the crank chamber and the annular groove. If no oil is fed from the oil reservoir to the sliding surface of the crank shaft through the oil feed path during rotation of the crank shaft, oil in the crank chamber is fed to the upper bearing from the crank chamber through the bearing back-face passage and the annular groove due to a pump effect of the spiral groove.

1 . A scroll compressor comprising:
 a casing provided with an oil reservoir at a bottom;   a fixed scroll and a movable scroll housed in the casing;   a crank shaft having an upper end portion slidably connected to a boss on a back face of the movable scroll; and   a housing arranged under the movable scroll and having an upper bearing which rotatably supports the crank shaft,   the crank shaft being provided with an oil feed path arranged and configured to feed oil in the oil reservoir to a sliding surface between the boss and the upper bearing,   the housing being provided with a crank chamber formed by a recessed portion of the housing closer to a top surface thereof to house the boss of the movable scroll, the crank chamber being configured to accumulate oil fed to a sliding surface of the crank shaft through the oil feed path,   the crank shaft being provided, on an outer peripheral surface thereof, with
 an annular groove formed at a lower position of a sliding surface with the upper bearing and extending in a circumferential direction of the crank shaft to collect oil fed to the upper bearing, and 
 a spiral groove connecting the crank chamber and the annular groove to transfer oil collected in the annular groove to the crank chamber, 
   the housing being provided with a bearing back-face passage formed at a position closer to a back face of the upper bearing than to a front face, the bearing back-face passage connecting the crank chamber and the annular groove, and   in an event in which no oil is fed from the oil reservoir to the sliding surface of the crank shaft through the oil feed path during rotation of the crank shaft, the oil accumulated in the crank chamber being fed to the upper bearing from the crank chamber through the bearing back-face passage and the annular groove due to a pump effect of the spiral groove.   
     
     
         2 . The scroll compressor of  claim 1 , wherein
 in a normal operation in which the oil is fed from the oil reservoir to the sliding surface of the crank shaft through the oil feed path, the oil collected in the annular groove passes through the spiral groove and the bearing back-face passage to be transferred to the crank chamber.   
     
     
         3 . The scroll compressor of  claim 1 , wherein
 an inner wall surface of the crank chamber is provided with an auxiliary oil reservoir recessed in a radial direction and arranged and configured to accumulate oil together with the crank chamber.   
     
     
         4 . The scroll compressor of  claim 3 , wherein
 the housing is provided with an oil discharge passage having an upstream end open to the inner wall surface of the crank chamber at a position spaced from a bottom surface of the crank chamber by a predetermined distance, and a downstream end open to an outside of the housing, and   the auxiliary oil reservoir is open to the inner wall surface of the crank chamber at a position lower in height than the oil discharge passage.   
     
     
         5 . The scroll compressor of  claim 2 , wherein
 an inner wall surface of the crank chamber is provided with an auxiliary oil reservoir recessed in a radial direction and arranged and configured to accumulate oil together with the crank chamber.   
     
     
         6 . The scroll compressor of  claim 5 , wherein
 the housing is provided with an oil discharge passage having an upstream end open to the inner wall surface of the crank chamber at a position spaced from a bottom surface of the crank chamber by a predetermined distance, and a downstream end open to an outside of the housing, and   the auxiliary oil reservoir is open to the inner wall surface of the crank chamber at a position lower in height than the oil discharge passage.