Patent ID: 7159610

Claim:
A relief valve comprising: a sleeve ( 10 ) provided with a high-pressure inlet ( 11 ) for hydraulic fluid to be supplied from a pump, and a tank fluid channel ( 12 ) for the hydraulic fluid of the high-pressure inlet to be returned to a tank; a main poppet ( 20 ) in the sleeve, provided with a back pressure chamber ( 23 ) in a rear thereof and resiliently supported by a main poppet spring ( 24 ) to open/close the high-pressure inlet to the tank fluid channel; a passage seat ( 21 ) coupled to a front end of the main poppet to provide an inflow fluid passage ( 22 ) communicating with the high-pressure inlet and an annular fluid passage ( 30 ) defined by an inner wall of the main poppet and an outer wall of the passage seat between the inflow fluid passage and the back pressure chamber; a seat ( 40 ) to the rear of the main poppet to support a rear end of the main poppet spring and provided a seat fluid channel ( 43 ) communicating with the back pressure chamber; and a pilot poppet ( 50 ) resiliently supported by a pilot poppet spring ( 51 ) to open/close the seat fluid channel.