Hydraulic relief valve

The utility model discloses a hydraulic relief valve which comprises a valve seat with an end cover at the top, wherein the valve seat is internally provided with an oil inlet channel; the lower end of the oil inlet channel is provided with a high-pressure side oil inlet positioned at the lower end of the valve seat; the upper end port of the oil inlet channel is communicated with a control oil chamber, and the pore diameter of the control oil chamber is greater than that of the oil inlet channel; one side of the upper end of the oil inlet channel is provided with an oil outlet channel which is communicated with a low-pressure side oil outlet positioned at one side of the valve seat; the oil outlet channel is communicated with the control oil chamber through a communication channel; the valve seat is internally provided with a bulged-type valve core with a large diameter at the upper part and a small diameter at the lower part, and when the weight of the bulged-type valve core is greater than the pushing force applied by the hydraulic oil upward, the upper part with the large diameter of the valve core is positioned in the control oil chamber, and the lower part with the small diameter of the valve core is positioned on the upper part of the oil inlet channel and seals the oil outlet channel. The hydraulic relief valve has the advantages of accurate pressure variation, long service life, simple structure, safety and reliability, no requirement of adjustment and the like.