Design of pressure compensating type for O-ring bore

　Generally speaking, O-ring seal only for fixed sealing and low-pressure (2.5MPa below) motion sealing; and for high pressure motion sealing is used with compensation type Y, U, V type with lip sealing ring.　　

For the use of hydraulic equipment units, often because of the shortage of various with compensation seal ring and affect the production of O-ring shaft pressure compensation type structure widely used in the cylinder piston seal; and the cylinder mouth and piston rod seal the same Y type, U type, V type with compensation type seal, and can still use the ordinary O-ring to solve the cylinder mouth and piston rod seal it? I have done the following design tests: a typical cylinder port and piston rod seal, is to use the common Y, U type seal. Firstly, a simple analysis of the nature of this seal: the lip in contact with the cylinder block (outer lip) is actually a fixed seal; the lip in contact with the piston rod (inner lip) is a motion seal.　The principle of using a common O-ring to solve the seal between the piston rod and the cylinder port is designed. It uses two ordinary O-ring, one is fixed seal; the other contact with the piston rod in the tapered O-ring is the movement of the seal; it increases with the pressure, the stronger the compression force plays a role in the compensation seal. This structure is in the original placement of the Y seal space installed a seal seat ring sleeve, outside the round car a sink cut groove, to place the O seal for fixed sealing, its requirements according to the fixed seal requirements design; outer circle size and cylinder mouth with the requirements of the dynamic fit; inner hole d size and the piston rod is also a dynamic fit; thickness H is equal to the original installation of the Y seal thickness of the actual space size negative 0.1 ~ 0.2mm ; bore turned into a 60 ° taper, its finish requirements are slightly higher (Ra3.2 above can be); its tapered large end d1 size for the piston rod diameter plus twice the diameter of the seal used section; the rest of the roughness Ra6.3 can be; in addition placed on the piston rod and tapered surface for the movement of the seal with O-ring inner diameter should be selected smaller than the diameter of the piston rod 1 ~ 5 mm, section diameter as large as possible.　　Through the hydraulic excavator (pressure about 20MPa), broaching (pressure in about 10MPa), bending machine (pressure in about 15MPa), combined machine tools (about 2MPa) and other hydraulic systems nearly half a year of use, performance is very good, no oil leakage at all.