Patent ID: 7004473

Claim:
A mechanical seal device for sealing between a housing containing a process fluid under pressure and a rotary shaft in said housing, the mechanical seal device comprising: a stationary seal ring and a rotary seal ring, said stationary seal ring being sealingly attached to said housing, the stationary seal ring being elastically biased in an axial direction of said rotary shaft, the stationary seal ring having a sealing face at one end and a pressure surface operated by said process fluid at a back face, said back face being disposed at the opposite side of said end, said rotary seal ring being fixed to a shaft sleeve, the rotary seal ring being disposed on the atmospheric region side relative to said stationary seal ring, the rotary seal ring having a oppositely disposed mating sealing face relative to said sealing face, an end face of said shaft sleeve engaging a shoulder of said rotary shaft, said shoulder being disposed on the process fluid region side relative to said stationary seal ring, a passage being defined around the stationary seal ring, wherein a pressure of the sealed process fluid acts on the end face of the shaft sleeve and the pressure surface of the back face of the stationary seal ring, and an inner diameter of said end face being larger than an inner diameter of the pressure surface of said back face, wherein a surface area of the end face of the shaft sleeve on which a pressure of the sealed process fluid acts is smaller than a surface area of the pressure surface of the back face of the stationary seal ring on which the pressure of the sealed process fluid acts, and wherein the sealed process fluid exerts a larger force on the back face of the stationary seal ring than on the end face of the shaft sleeve.