| 摘要 |
<p>A suction pump (22) suitable for use in a fuel dispensing system (20) or other fluid delivery system for volatile liquids. The suction pump includes a pump casing that defines a pump chamber (52) with inlet and outlet ports. A rotor (54) with vanes (58) is seated in the pump chamber. The vanes define fluid cavities (96a, 96b, 96c, ... 96f) that rotate between the inlet and outlet ports. During each turn of the rotor, each fluid cavity passes through a section of the pump chamber in which it is isolated from both the inlet port and outlet port. A bleed duct (102) extends from the outlet port. A bleed port (104) extends from the bleed duct to the section of the pump chamber that defines the isolated position of the fluid cavities. During operation of the pump, pressurized fluid discharged from the outlet port flows through the bleed duct and bleed port into the isolated fluid cavity. This pressurized fluid compresses vapor bubbles in the fluid cavity to prevent their rapid decompression when the cavity is later subjected to additional decompression. This initial decompression of the vapor bubbles reduces the noise generated when the fluid cavity is subjected to rapid compression when it is positioned adjacent the outlet port.</p> |
