Seal structure of fluid device

Abstract

A seal structure includes: first and second members defining a hollow internal area of a fluid device; and a seal member fixed to the first member for sealing a gap between the first and second members. The seal member includes a sliding contact member being in sliding contact with a surface of the second member and formed of a resin. The second member includes a resin layer and a resin layer holding structure. The resin layer is formed by sliding the second member on the sliding contact member to transfer the resin forming the sliding contact member onto a sliding contact portion of the surface of the second member at which the second member comes into contact with the sliding contact member. The resin layer holding structure is a porous film formed by electric discharge surface treatment and holds the resin layer in the sliding contact portion.

1 . A seal structure of a fluid device comprising:
 a first member defining a hollow internal area of the fluid device;   a second member defining the internal area together with the first member and being movable relative to the first member; and   a seal member fixed to the first member and configured to seal a gap between the first member and the second member, wherein   the seal member includes a sliding contact member being in sliding contact with a surface of the second member and formed of a resin,   the second member includes a resin layer and a resin layer holding structure in a sliding contact portion of the surface of the second member at which the second member comes into sliding contact with the sliding contact member, the resin layer being formed by sliding the second member on the sliding contact member to transfer the resin forming the sliding contact member, the resin layer holding structure being configured to hold the resin layer in the sliding contact portion, and   the resin layer holding structure comprises a porous film formed by causing electric discharge between a discharge electrode and the sliding contact portion of the surface of the second member and, by an energy of the electric discharge, depositing any one of a constituent material of the discharge electrode and a substance obtained by reaction of the constituent material onto the sliding contact portion.   
     
     
         2 . The seal structure of the fluid device according to  claim 1 , wherein
 the fluid device is a rotary machine,   the first member is a housing of the rotary machine,   the second member is a rotary shaft projecting from a through-hole provided in the housing,   the seal member is a packing configured to seal a gap between the housing and the rotary shaft,   the sliding contact member is an annular lip in sliding contact with an outer circumferential surface of the rotary shaft, and   the resin layer and the resin layer holding structure are formed in a sliding contact portion of the outer circumferential surface of the rotary shaft at which the rotary shaft comes into sliding contact with the lip.   
     
     
         3 . The seal structure of the fluid device according to  claim 1 , wherein
 the fluid device is a cylinder device,   the first member is a cylinder body of the cylinder device,   the second member is a piston rod projecting from a through-hole provided in the cylinder body,   the seal member is a packing configured to seal a gap between the cylinder body and the piston rod,   the sliding contact member is an annular lip in sliding contact with an outer circumferential surface of the piston rod, and   the resin layer and the resin layer holding structure are formed in a sliding contact portion of the outer circumferential surface of the piston rod at which the piston rod comes into sliding contact with the lip.   
     
     
         4 . The seal structure of the fluid device according to  claim 2 , wherein
 the packing includes an annular core formed of a metal, and   the lip is provided integrally with the core.   
     
     
         5 . The seal structure of the fluid device according to  claim 1 , wherein the resin is a self-lubricating resin. 
     
     
         6 . The seal structure of the fluid device according to  claim 1 , wherein the discharge electrode is molded out of any one of a metal powder, a metal compound powder, a ceramic powder, and a mixed powder thereof. 
     
     
         7 . The seal structure of the fluid device according to  claim 3 , wherein
 the packing includes an annular core formed of a metal, and   the lip is provided integrally with the core.