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High-pressure fuel supply pumpHigh-pressure fuel supply pump description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080056914, High-pressure fuel supply pump. Brief Patent Description - Full Patent Description - Patent Application Claims
CLAIM OF PRIORITY [0001]The present application claims priority from Japanese application serial no. 2006-235866, filed on Aug. 31, 2006, the content of which is hereby incorporated by reference into this application. BACKGROUND OF THE INVENTION [0002]1. Field of the Invention [0003]The present invention relates to a high-pressure fuel supply pump used to pressurize fuel supplied from a feed pump and then supply the pressurized fuel to a fuel injection valve and, more particularly, to a high-pressure fuel supply pump used in cylinder direct fuel injection type of internal combustion engine. [0004]More particularly, the present invention relates to a high-pressure fuel supply pump in which a relief valve mechanism is incorporated in a pump housing as a safety valve to eliminate an excessive pressure rise of the fuel in a fuel path on a high pressure side. [0005]2. Prior Art [0006]In conventional high-pressure fuel supply pumps of this type, a fuel relief path is provided in the pump housing in the high-pressure fuel supply pump, the fuel relief path connecting a high-pressure fuel path downstream of an discharge valve (outlet valve) to a low-pressure fuel path upstream of an inlet valve, and a check valve is provided in the fuel relief path as a relief valve that passes fuel only from the high-pressure fuel path to the low-pressure fuel path, as disclosed in Japanese Patent Application Laid-open Publication No. 2003-343395. [0007]If the pressure in the high-pressure fuel discharge path is excessively raised, the relief valve structured as the check valve opens and part of the high-pressure fuel is released to the low-pressure path, eliminating the excessively high pressure. [0008]Patent Document 1: Japanese Patent Application Laid-open Publication No. 2003-343395 SUMMARY OF THE INVENTION [0009]However, a high-pressure fuel supply pump structured as described above causes a state in which the pressure of the fuel to be discharged exceeds a pressure to open the relief valve in momentary in a transient state in which the discharge valve is opened and the fuel is being pressurized by the high-pressure fuel pump. [0010]This momentary high-pressure state is not abnormal as a system state, so the relief valve does not need to operate; if anything, it is not desired for the relief valve to operate. [0011]When the relief valve opens in this situation, the amount of fuel discharged by the high-pressure fuel supply pump is reduced and the energy efficiency is lowered. [0012]The present invention addresses this problem with the object of preventing the relief valve from opening even when the pressure of the fuel to be discharged is raised in momentary in the transient state in which the discharge valve is opened and the fuel is being pressurized by the high-pressure fuel pump. [0013]The above object is achieved by providing, in an discharge path disposed upstream of the relief valve in a relief path (that is, on the discharge valve side), a mechanism that prevents a momentary pressure rise caused in the discharge path from being transmitted to the relief valve. [0014]Specifically, the above object is achieved by providing, in the relief path, an energy attenuating mechanism that prevents energy acting on the relief valve on the basis of a pressure rise caused in a short period on the discharge path side while the high-pressure fuel supply pump is performing a valve open operation. [0015]Preferably, the energy attenuating mechanism can be structured with a plate that is disposed near the relief valve on the high-pressure path side (a discharge port side) and has at least one orifice. [0016]Preferably, the energy attenuating mechanism can be structured with a discharge valve in an open state that narrows or shuts down a fuel relief path near upstream of the relief valve. [0017]According to the present invention structured as described above, a high-pressure fuel supply pump can be provided which has a high compression ratio, that is, a high energy coefficient with the effect that when an excessive (abnormal) high-pressure is generated due to a fuel injection valve failure or the like, The fuel pressurized to the excessive (abnormal) high-pressure is released through the relief valve and high-pressure side piping and other high-pressure side devices are not damaged by the excessive (abnormal) high-pressure. [0018]The fuel released through the relief valve can be expelled not only to the low-pressure path but also to a pressurizing chamber. BRIEF DESCRIPTION OF THE DRAWINGS [0019]FIG. 1 is the vertical cross section drawing to show an entire high-pressure fuel supply pump in first and second embodiments of the present invention. [0020]FIG. 2 is the horizontal cross section drawing to show an entire high-pressure fuel supply pump in the first embodiment of the present invention. Continue reading about High-pressure fuel supply pump... Full patent description for High-pressure fuel supply pump Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this High-pressure fuel supply pump patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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