g is restored to the original state by elastic shape restoring force each fastening surface s 1 to s 3 is restored in accordance with the distance corresponding to the fitting interference u03b5 because of the fastening interference u03b4 each fastening surface s 1 to s 3 is thus securely fastened to the outer circumferential surface 32 b of the stator core 32 in this manner without using the shrink fitting the stator core 32 is securely fastened to the motor housing 15 a forming angle defined by the fastening surface s 1 to s 3 of each fastening interference portion 15 e to 15 g with respect to the center of the motor housing 15 in the circumferential direction is set to for example 5 to 30 degrees if this forming angle is excessively small the fastening interference portions 15 e to 15 g may be deformed if the forming angle is excessively large the predetermined fastening interference u03b4 is hard to ensure it is thus preferred that the forming angle is set to 10 to 20 degrees referring to fig2 in the state that the motor housing 15 is assembled with the stator core 32 clearances g 1 g 2 g 3 are each defined between the inner circumferential surface of the corresponding one of the first to third expanded portions 15 b to 15 d and the outer circumferential surface 32 b of the stator core 32 each of the clearances g 1 to g 3 defines a passage for guiding the refrigerant gas drawn to the motor housing 15 through the inlet 16 a to the suction chamber 22 the.