Scroll type compressor having curved surface portions between the shaft and bearing means

Abstract

A scroll type compressor comprising: a crankshaft having an eccentric shaft portion formed thereon; an orbiting scroll which is given torque by the crankshaft through the eccentric shaft portion; and bearing means for rotatably supporting the crankshaft; wherein at least one of the eccentric shaft portion and the bearing means is constituted by a rotatably engaged bushing and a curved surface portion.

We claim: 
     
       1. A scroll type compressor comprising: a rotatable crankshaft having an eccentric shaft portion formed thereon;   a fixed scroll;   an orbiting scroll cooperable with said fixed scroll to compress gas; and   bearing means rotatably connecting said orbiting scroll to said eccentric shaft portion so as to orbitally drive said orbiting scroll, wherein said bearing means comprises:   a) a bushing having an outer periphery fitted in said orbiting scroll, and   b) a non-rotatable connection between said bushing and said eccentric shaft portion, said non-rotatable connection including a portion curved in the direction of the axis of rotation of the crankshaft.   
     
     
       2. The scroll type compressor of claim 1 wherein said non-rotatable connection further comprises cooperating flat surfaces on said bushing and said eccentric shaft portion. 
     
     
       3. A scroll type compressor according to claim 2, .Iadd.wherein said crankshaft further comprises a main shaft portion and a sub shaft portion, .Iaddend.further comprising:   an upper balance weight and a lower balance weight placed on the opposite ends of .[.the.]. .Iadd.a .Iaddend.rotor to be balanced against a centrifugal force which is generated by an orbiting movement of the orbiting scroll; and   .[.a.]. .Iadd.the .Iaddend.rotor coupled to said crankshaft for driving said crankshaft;   .[.the bearing means comprising.]. bearing devices which are provided in a main frame and a sub frame to support the crankshaft at .[.its.]. .Iadd.said .Iaddend.main shaft portion and .Iadd.said .Iaddend.sub shaft portion via further bushings;   wherein in order to prevent partial contact from occurring due to flexture-deformation of the crankshaft in the bearing .[.parts for supporting the main shaft and sub shaft portions of the crankshaft.]. .Iadd.devices.Iaddend., at least one of the main shaft portion and the sub shaft portion has a central portion provided with a barrel shaped band portion to present a convex surface in the entire peripheral direction, the band portion has a peripheral portion engaged with the further bushings through a minute gap.   
     
     
       4. A scroll type compressor according to claim 2, .Iadd.wherein said crankshaft further comprises a main shaft portion and a sub shaft portion, .Iaddend.further comprising: an upper balance weight and a lower balance weight placed on the opposite ends of .[.the.]. .Iadd.a .Iaddend.rotor to be balanced against a centrifugal force which is generated by an orbiting movement of the orbiting scroll; and   .[.the bearing means comprising.]. bearing devices which are provided in a main frame and a sub frame to support the crankshaft at .[.its.]. .Iadd.said .Iaddend.main shaft portion .Iadd.via a bushing .Iaddend.and .Iadd.at said .Iaddend.sub shaft portion .[.via further bushings.].;   wherein in order to prevent partial contact from occurring due to flexture-deformation of the crankshaft .[.in the bearing devices.]. .Iadd.at said main shaft portion.Iaddend., the main shaft portion has a central portion provided with a barrel shaped band portion to present a convex surface in the entire peripheral direction, the band portion has a peripheral portion engaged with the .[.further.]. bushing .Iadd.at said main shaft portion .Iaddend.through a minute gap, and the .[.further.]. bushing .Iadd.of said main shaft portion .Iaddend.is coupled to the crankshaft by a pin in terms of a rotational direction; and   wherein the bearing device for supporting the sub shaft portion of the crankshaft is constructed by a rolling bearing to prevent partial contact from occurring in the bearing device due to flexture-deformation of the crankshaft.   
     
     
       5. A scroll type compressor comprising: a main frame;   a sub frame.Iadd.; .Iaddend.   a crankshaft rotatably mounted in said main frame and said sub frame via bushings, said crankshaft having an eccentric shaft portion formed thereon, wherein the main frame and sub frame are mutually spaced along the axis of the crankshaft;   a fixed scroll;   an orbiting scroll cooperable with the fixed scroll to compress gas, said orbiting scroll being drivingly mounted on said eccentric shaft portion;   .[.a.]. .Iadd.an .Iaddend.electric motor mounted between said main frame and said sub frame and having a rotor coupled to said crankshaft for driving said crankshaft; upper and lower balance weights placed at opposite ends of said rotor for balancing orbiting movement of said orbiting scroll;   a pin rotatably coupling at least one of the bushings to .[.a respective one of the main frame and.]. the .[.sub frame.]. .Iadd.crankshaft.Iaddend.; and   a circumferentially continuous barrel shaped band portion presenting a convex surface and formed on said crankshaft to engage at least one of the bushings through a minute gap.   
     
     
       6. A scroll type compressor comprising: a main frame;   a sub frame;   a crankshaft rotatably mounted in said main frame and said sub frame via bushings, said crankshaft having an eccentric shaft portion formed thereon, wherein the main frame and sub frame are spaced along the axis of the crankshaft;   a fixed scroll;   an orbiting scroll operable with the fixed scroll to compress gas, said orbiting scroll being drivingly mounted on said eccentric shaft portion;   .[.a.]. .Iadd.an .Iaddend.electric motor mounted between said main frame and said sub frame and having a rotor coupled to said crankshaft for driving said crankshaft;   upper and lower balance weights placed at opposite ends of said rotor for balancing orbiting movement of said orbiting scroll; and   two couples formed between said crankshaft and the bushing of said main frame, each of said couples comprising a flat surface on one of said crankshaft and said bushing, and a surface curved in the direction of the axis of rotation of the crankshaft and engaged with said flat surface. .Iadd.   
     
     
       7.  A scroll type compressor comprising: a rotatable crankshaft having an eccentric shaft portion formed thereon, wherein said crankshaft further comprises a main shaft portion and a sub shaft portion;   a fixed scroll;   an orbiting scroll cooperable with said fixed scroll to compress gas;   bearing means rotatable connecting said orbiting scroll to said eccentric shaft portion so as to orbitally drive said orbiting scroll, wherein said bearing means comprises:   a) a bushing having an outer periphery fitted in said orbiting scroll, and   b) a non-rotatable connection between said bushing and said eccentric shaft portion, said non-rotatable connection including a portion curved in the direction of the axis of rotation of the crankshaft;   an upper balance weight and a lower balance weight placed on the opposite ends of a rotor to be balanced against a centrifugal force which is generated by an orbiting movement of the orbiting scroll; and   the rotor coupled to said crankshaft for driving said crankshaft;   bearing devices which are provided in a main frame and a sub frame to support the crankshaft at said main shaft portion and said sub shaft portion via further bushings;   wherein in order to prevent partial contact from occurring due to flexure-deformation of the crankshaft in the bearing devices, at least one of the main shaft portion and the sub shaft portion has a central portion provided with a barrel shaped band portion to present a convex surface in the entire peripheral direction, the band portion has a peripheral portion engaged with the further bushings through a minute gap. .Iaddend..Iadd.   
     
     
       8.  A scroll type compressor comprising: a rotatable crankshaft having an eccentric shaft portion formed thereon, wherein said crankshaft further comprises a main shaft portion and a sub shaft portion;   a fixed scroll;   an orbiting scroll cooperable with said fixed scroll to compress gas;   bearing means rotatably connecting said orbiting scroll to said eccentric shaft portion so as to orbitally drive said orbiting scroll, wherein said bearing means comprises:   a) a bushing having an outer periphery fitted in said orbiting scroll, and   b) a non-rotatable connection between said bushing and said eccentric shaft portion, said non-rotatable connection including a portion curved in the direction of the axis of rotation of the crankshaft;   an upper balance weight and a lower balance weight placed on the opposite ends of a rotor to be balanced against a centrifugal force which is generated by an orbiting movement of the orbiting scroll; and   bearing devices which are provided in a main frame and a sub frame to support the crankshaft at said main shaft portion via a bushing and at said sub shaft portion;   wherein in order to prevent partial contact from occurring due to flexure-deformation of the crankshaft at said main shaft portion, the main shaft portion has a central portion provided with a barrel shaped band portion to present a convex surface in the entire peripheral direction, the band portion has a peripheral portion engaged with the bushing at said main shaft portion and the bushing is coupled to the crankshaft by a pin in terms of a rotational direction; and   wherein the bearing device for supporting the sub shaft portion of the crankshaft is constructed by a ball bearing to prevent partial contact from occurring in the bearing device for supporting the sub shaft portion of the crankshaft due to flexure-deformation of the crankshaft. .Iaddend..Iadd.   
     
     
       9.  The scroll type compressor of claim 4 wherein said rolling bearing comprises a ball bearing. .Iaddend.