| 摘要 |
PROBLEM TO BE SOLVED: To reduce troubles such as occurrence of abnormal noise caused by occurrence of cavitation, without complicating structure. SOLUTION: A discharge port 9 is formed at a position biased from a minimum capacity position side in a reduction area where capacity of a pump chamber 7 is reduced, and a seal land part 12 is formed in a section between an intake port 9 and a discharge port 11. A communicating groove 13 making a plurality of pump chambers 7 mutually communicate is formed in the seal land part 12, and a narrowed shape part 7a functioning as a throttle is formed at end parts of the pump chambers 7. A bypass passage 14 connecting the communicating groove 13 with the discharge port 9 is disposed, and a relief valve 15 is disposed in the passage 14. When cavitation occurs, the capacities of the pump chambers 7 are reduced in the seal land part 12 to slowly break air bubbles. When air bubbles in a part of the pump chambers 7 are broken and pressure in the pump chambers is increased, the pressure acts to break air bubbles in other chambers 7 through the communicating groove 13. COPYRIGHT: (C)2004,JPO&NCIPI
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