Gas spring apparatus

A gas spring apparatus comprising:

• a cylinder assembly including at least one cylinder housing and a rod, said rod being fitted in said cylinder housing and being movable in the axial direction of said cylinder housing, said cylinder assembly further including an oil chamber for containing oil and a gas chamber for containing gas;
• damping force generating means disposed inside said cylinder assembly, and being adapted to damp reciprocation of said rod by means of viscous resistance produced when the oil in said cylinder assembly is circulated;
• and
• a flexible bladder in the form of a bag, located between said oil chamber and said gas chamber and extending at least partly into said oil chamber, said gas chamber being defined inside the hollow of said bladder and said oil chamber being defined outside the hollow of said bladder, said bladder dividing said gas chamber from said oil chamber, and said oil in said oil chamber contacting an outer surface portion of said bladder;
• said bladder including a flexible elastomer body made of an oil impervious elastomer having a thickness of from about 0.1 mm to about 5 mm so as provide a gas-barrier characteristic to substantially prevent passage of said gas therethrough, and a gas-barrier film made of a non-elastomeric material impermeable to said gas forming an inner surface of said bladder that is directly exposed to said gas chamber, said non-elastomeric gas-barrier film having a gas-barrier characteristic which is better than that of said elastomeric body, said gas barrier characteristic of said gas-barrier film being not more than about 1.times.10.sup.-11 cc.multidot.cm/(cm.sup.2 .multidot.sec.multidot.cmHg), said elastomer body covering the outer surface of said gas-barrier film to protect said gas-barrier film, and said elastomer body being thicker than said gas-barrier film, said oil contacting said outer surface portion of said bladder contacting said elastomeric body to prevent said elastomer body from drying out and to provide lubrication if said elastomer body contacts a wall of said cylinder assembly.