| 摘要 |
PROBLEM TO BE SOLVED: To provide a high pressure pump improving initial motion characteristics at opening of a relief valve by effectively using dynamic pressure of fuel flow. SOLUTION: A distal end surface 83a of a relief valve element 81 separates from a seat surface 78 and the relief valve 70 opens when fuel pressure of a fuel rail is prescribed relief pressure or higher. Fuel from a return channel 71 flows in along a relief surface 79 and impinges on a pressure receiving surface 83c. As lift rate X which is a movement length ratio to the maximum movement length from a valve close state to a full open sate increases, flow receiving area S(X) receiving impingement of fuel increases. Critical lift rateαwhich is a lift rate when the flow receiving area S(X) is consistent with pressure receiving surface all area S0 is set not less than 0.5 and not greater than 1. Consequently, dynamic pressure of fuel flow acts on a 100% pressure receiving surface 83c until at least a half open state, movement of the relief valve element 81 in a valve open direction is assisted, and initial motion characteristics at opening of the relief valve 70 is improved. COPYRIGHT: (C)2011,JPO&INPIT |
