Patent ID: 6478557
Filing Date: 2002-11-12
Classification: F04C

Abstract:
A scroll compressor for use in a helium refrigerating apparatus, comprising:a fixed scroll and an orbiting scroll engaged with each other, wherein an operating pressure range in which an operating pressure ratio which is a ratio of a discharge pressure to a suction pressure is around 1.5 to around 5 and an upper limit value of the suction pressure is set on a lower limit value of the operating pressure ratio, and wherein said fixed scroll is fixed to a frame provided on a back side of said orbiting scroll to form a back pressure chamber by said frame and a back surface of an end plate of said orbiting scroll; and an oil filler port, through which oil for cooling said helium gas is injected into compression chambers formed by said fixed scroll and said orbiting scroll is provided on end plate of said fixed scroll; a thin hole, through which a part of the helium gas halfway in compression stroke in the compression chambers is introduced into said back pressure chamber is formed on said end plate of said orbiting scroll; and a ratio Pb/Ps of pressure Pb in said back pressure chamber to suction pressure Ps is set to around 1.5.