Oil pump for a refrigeration compressor

A refrigeration compressor comprising a shell interiorly defining an oil reservoir and carrying:

• a cylinder block in which is journalled a crankshaft having a lower portion;
• an electric motor rotor affixed around the lower portion of the crankshaft;
• an oil pump having a tubular pump body, mounted to said crankshaft and rotor, so as to operationally rotate therewith and having a lower end immersed in the oil reservoir, wherein the tubular pump body having an interior and comprising at least one collecting wall portion, a portion of the at least one collecting wall being immersed in oil, the at least one collecting wall portion formed by an indent, the indent having a concave surface extending inwardly along the axis of rotation of the crankshaft so as to be eccentric in relation to the axis of rotation of the crankshaft and defining an opening adjacent a distal end of the tubular pump body, the opening for admitting the oil to the interior of the pump body, wherein the collecting wall portion includes at least one open step, disposed in a plane secant to a cross section of the tubular pump body, in the region of said collecting wall portion, and a respective inner impeller wall portion defining a deflector disposed transversally to the direction of admission of the oil through the open step and which, with the operational rotation of the tubular pump body, acts on said oil, impelling the oil axially and ascendingly, the distal end of the tubular pump body is closed by a revolution surface with a generatrix selected between a straight line segment and a convex arc, the at least one collecting wall portion being defined within said lower end of the tubular pump body.