| 摘要 |
PROBLEM TO BE SOLVED: To reduce an excessively high vane-back-pressure to an appropriate pressure to thereby relieve an operational load, and to improve the vane projectability at the start and during low speed operation to thereby prevent chattering. SOLUTION: This gas compressor is provided with back-pressure spaces 14 including the bottom portions of vane grooves 12 and attaining a medium pressure between a suction pressure and a discharge pressure during a normal operation of the compressor main body, a first high pressure oil passage establishing communication between an oil sump and the vane groove bottom portions when the vanes are in their discharge stroke positions, second high-pressure oil passages 32, 33 establishing communication between the oil sump and the back-pressure spaces, and opening/closing valves 34, 35, 35a, 37 for opening and closing the second high-pressure oil passages. The opening/closing valves are opened only at the start and during low-speed operation and high-pressure oil is supplied to a back-pressure chamber at the stroke of supplying medium pressure oil to the back pressure chamber, so that the vane projectability is improved and the extrusion force of the vane is strengthened. During the normal operation, the supply of the high pressure oil is stopped by operation of the opening/closing valves. As a result, it is possible to obtain such an effect that the operational load is relieved at the stroke of supplying only the medium pressure oil to the back-pressure chamber. COPYRIGHT: (C)2004,JPO
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