Reciprocating hermetic motor compressor with a thermetically insulatable non-rotatable muffler

A reciprocating hermetically sealed motor compressor unit having a suction portion and a delivery portion comprising a driving electric motor, a frame, a cylinder positioned within said frame, a piston reciprocatable in said cylinder, a valve plate placed at one end of said cylinder and defining a circular suction hole, a head which fixes said valve plate to said frame and a muffler on the suction portion of said unit, said head defining a delivery chamber and said muffler having a portion seated within said circular suction hole, said refrigerant gas, from said muffler directly entering said cylinder without having a thermic exchange with said chamber, said head and muffler defining complementary walls to prevent said muffler from rotating about the axis of said hole and to fix said muffler to said hole, said complementary walls being defined by two inclined walls forming the lower end of said muffler and converging toward said suction hole and a perimetrical side wall formed in said head complementary to said walls of said muffler.