VALVE MECHANISM AND HIGH-PRESSURE FUEL SUPPLY PUMP PROVIDED WITH SAME

Provided is a solution to a problem on a discharge valve mechanism disposed at an exit of a pressurizing chamber of a high-pressure fuel supply pump, that is, an occurrence of a backward flow of the fuel concentrates on a limited fuel passage, leading to a higher fuel flow rate, and this easily induces the occurrence of cavitation, and collapse of the generated cavitation might damage a seat surface, making it difficult to maintain valve functions. The present invention provides a valve mechanism including a seat member having a seat section, a valve body configured to attach to or detached from the seat section, and a housing member arranged on an outer peripheral side of the seat member. A first fluid flow-path is formed to connect an inner peripheral side and an outer peripheral side of the seat section in a case where the valve is detached from the seat section. A second fluid flow-path is formed to be connected with the first fluid flow-path, between an outer peripheral surface of the seat member and an inner peripheral surface of the housing member, or between an outer peripheral surface of the valve body and the inner peripheral surface of the housing member. The cross-sectional area along the axial direction of the valve mechanism of the second fluid flow-path is 0.18 mm square or above.