摘要 |
To reduce an excessively high vane back pressure to an appropriate pressure to thereby relieve operational load, and to improve the vane projectability at the start and during low speed operation to thereby prevent chattering; There are provided back pressure spaces including the bottom portion of vane grooves and attaining a middle pressure between suction pressure and discharge pressure during 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 establishing communication between the oil sump and the back pressure spaces, and an opening/closing valve for opening and closing the second high pressure oil passages.
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