| 摘要 |
<p>PURPOSE:To prevent the generation of surge pressures and reduce noises by providing nonreturn valves and passages in areas of switching points from the discharge area to the suction area and of opposite direction in a ring for opening nonreturn valves when pressures in airtight chambers are excessively reduced or increased over a discharge pressure. CONSTITUTION:After discharging, a plunger 5a is moved as an arrow illustrated shows as keeping a plunger chamber airtight, and simultaneously, the pressure in the chamber is rapidly reduced as low as a suction pressure. When the pressure in the airtight chamber is excessively reduced, a nonreturn valve 13 burried in a ring 7 positioned in an area where the plunger 5a is moved to the suction area from the discharge area is opened, and the oil from a suction port 9 is introduced into the chamber of the plunger 5a via the nonreturn valve 13 for preventing the generation of a surge pressure. Meanwhile, a nonreturn valve 16 is provided in the ring 7 in a switching area from the suction area to the discharge area, and connected to passages 17 and 18. Consequently, when the pressure in the airtight chamber is increased over a discharge pressure, the nonreturn valve 16 is opened, and high pressure oil is discharged to a discharge port 10 via the plunger 5a chamber. This construction permits to prevent the generation of the surge pressure.</p> |
