Scroll compressor

1. A scroll compressor comprising:

a fixed scroll including a fixed end plate, a fixed spiral wall protruding from the fixed end plate, and a discharge hole formed near the center of the fixed end plate, wherein the fixed spiral wall comprises an inner face, an outer face, and an inner end portion located at a center side of the fixed end plate, the inner end portion including a terminal end having an arc-shaped terminal face connecting the inner face and the outer face, the discharge hole located so that a given clearance is secured in between the discharge hole and the inner end portion of the fixed spiral wall;

a movable scroll mated with said fixed scroll, said movable scroll including a movable end plate disposed to face the fixed end plate and a movable spiral wall protruding from the movable end plate toward the fixed end plate and engaging with the fixed spiral wall to form a compression chamber in cooperation with the fixed spiral wall, wherein the movable spiral wall comprises an inner face, an outer face, and an inner end portion located at a center side of the movable end plate, the inner end portion having a terminal end with a terminal face, the terminal end of the inner end portion of the movable spiral wall being bigger than the terminal end of the inner end portion of the fixed spiral wall;

a drive unit for driving said movable scroll to revolve with respect to said fixed scroll, the revolving movement of said movable scroll causing a series of processes including suction of working fluid into the compression chamber, compression of the sucked working fluid, and discharge of the compressed working fluid from the compression chamber through the discharge hole; and

wherein a curvature radius of the terminal face of the fixed spiral wall is smaller than a curvature radius of the terminal face of the movable spiral wall, a curvature radius of the inner face of the fixed spiral wall is greater than a curvature radius of the inner face of the movable spiral wall, and curvature radiuses of the inner faces of the fixed and movable spiral walls are greater than curvature radiuses of the terminal faces of the fixed and movable spiral walls.

2. The scroll compressor according to claim 1 , wherein:

the terminal end of said inner end portion of the fixed spiral wall has a narrower width than the terminal end of the inner end portion of the movable spiral wall.

3. The scroll compressor according to claim 1 , wherein:

the outer and inner faces of the fixed and movable spiral walls, except for the inner end portions thereof, are defined by involute curved surfaces, and adapted to form seal-off points defining boundaries between the inner faces and the respective inner end portions; and

the inner end portions of the fixed and movable spiral walls are arc-shaped.

4. The scroll compressor according to claim 1 , wherein:

the inner end portions of the fixed and movable spiral walls each have a stepped shape so as to engage with each other.

5. The scroll compressor according to claim 4 , wherein:

each of the inner end portions of the fixed and movable spiral walls includes a base portion located on the end plate side of the corresponding spiral wall and having an arc-shaped terminal face and an arc-shaped inner face, and a top portion located on the end plate side of the counterpart spiral wall, having narrower width than the base portion, and having an arc-shaped terminal face and an arc-shaped inner face.

6. The scroll compressor according to claim 1 , wherein:

said fixed scroll further includes a spiral-shaped bottom sheet disposed on the end plate, avoiding said discharge hole, the bottom sheet extending along the fixed spiral wall; and

said movable scroll further includes a spiral tip seal attached onto an end face of the movable spiral wall, which is opposed to the bottom sheet, along the movable spiral wall, the tip seal sliding against the bottom sheet during the revolving movement of said movable scroll.