Scroll type fluid machine

A scroll type fluid machine comprising:

• a casing;
• a fixed scroll which is provided in said casing and is provided in a rising manner with a spiral wrap portion in a surface of a end plate;
• a orbiting scroll which is provided in a rising manner with a spiral wrap portion overwrapping the wrap portion of said fixed scroll in a surface of a end plate, and defines a plurality of fluid chambers compressing or expanding a fluid with respect to said fixed scroll on the basis of a orbiting motion;
• a drive shaft which has a main shaft portion rotatably provided in said casing via a main bearing and an eccentric shaft portion provided eccentrically in a leading end side of said main shaft portion and attached to said orbiting scroll via a orbiting bearing;
• a balance weight which is coupled to said drive shaft and cancels a centrifugal force of said orbiting scroll;
• a self-rotation preventing mechanism which prevents a self-rotation of said orbiting scroll;
• and
• said self-rotation preventing mechanism being constructed by a first auxiliary crank bearing which is provided in said casing side or the fixed scroll side, a second auxiliary crank bearing which is provided in said orbiting scroll side, and an auxiliary crank shaft in which one side shaft portion is rotatably supported by said first auxiliary crank bearing, and the other side shaft portion is rotatably supported by said second auxiliary crank bearing,
• wherein a diametrical gap (δb) of said main bearing is larger than a difference between a diametrical gap (δa) of said orbiting bearing and a twofold value of an eccentric amount difference (ε′−ε) between an eccentric amount (ε′) of said auxiliary crank shaft and an eccentric amount (ε) of said drive shaft.

A scroll type fluid machine comprising:

• a casing;
• a fixed scroll which is provided in said casing and is provided in a rising manner with a spiral wrap portion in a surface of a end plate;
• a orbiting scroll which is provided in a rising manner with a spiral wrap portion overwrapping the wrap portion of said fixed scroll in a surface of a end plate, and defines a plurality of fluid chambers compressing or expanding a fluid with respect to said fixed scroll on the basis of a orbiting motion;
• a drive shaft which has a main shaft portion rotatably provided in said casing via a main bearing and an eccentric shaft portion provided eccentrically in a leading end side of said main shaft portion and attached to said orbiting scroll via a orbiting bearing;
• a balance weight which is coupled to said drive shaft and cancels a centrifugal force of said orbiting scroll;
• a self-rotation preventing mechanism which prevents a self-rotation of said orbiting scroll;
• and
• said self-rotation preventing mechanism being constructed by a first auxiliary crank bearing which is provided in said casing side or the fixed scroll side, a second auxiliary crank bearing which is provided in said orbiting scroll side, and an auxiliary crank shaft in which one side shaft portion is rotatably supported by said first auxiliary crank bearing, and the other side shaft portion is rotatably supported by said second auxiliary crank bearing, wherein a diametrical gap (δb) of said main bearing is 15 μm or more larger than a difference between a diametrical gap (δa) of said orbiting bearing and a twofold value of an eccentric amount difference (ε′−ε) between an eccentric amount (ε′) of said auxiliary crank shaft and an eccentric amount (ε) of said drive shaft.