Hermetically sealed rotary compressor having an oil supply passage to the compression compartment

A hermetically sealed rotary compressor comprising:

• a generally cylindrical sealed vessel having an oil reservoir defined therein;
• a drive unit housed within said sealed vessel and including a drive motor and a crankshaft operably coupled with said drive motor;
• a compressor mechanism housed within said sealed vessel, said compressor mechanism comprising a cylinder having a compression compartment defined therein and also having upper and lower openings, an eccentric cam fixed for rotation with said crankshaft, and a ring-shaped piston encircling said eccentric cam and capable of undergoing a planetary motion in contact with said eccentric cam during rotation of said eccentric cam, said cylinder also having a refrigerant intake port defined therein in communication with said compression compartment;
• upper and lower bearing plates closing said upper and lower openings of said cylinder, respectively;
• a radial vane radially slidably accommodated in said cylinder, said radial vane having a radial inner end held in sliding contact with an outer peripheral surface of said ring-shaped piston;
• and
• an oil supply passage formed in said lower bearing plate and having first and second ends, a first portion of said oil supply passage adjacent said first end thereof extending in a radial direction, and said second end of said oil supply passage being connected to a portion of said compression compartment adjacent said refrigerant intake port.