Diaphragm type air springs

Claim 1

A diaphragm type air spring, comprising: large and small piston members integrally connected to each other by a piston rod so as to bear a load of a vibration system at a side of said large piston member; large and small outer shells coaxially arranged with said piston members and integrally connected to each other with a common partition, each of said large and small outer shells having a diameter larger than that of each of said respective large and small piston members; first and second diaphragms airtightly connecting each of said large and small outer shells to each of said respective large and small piston members and secured at one end to an outward end portion of each of said large and small outer shells, between which said first and second diaphragms support a springing portion of said vibration system by at least one of said outer shells at its outer periphery; and an orifice formed in at least a portion of said partition excluding a regiin from a through-hole of said partition and said piston rod so as to establish fluid communication between a small air chamber defined by said small piston member, said small outer shell, said second diaphragm and said partition and, a large air chamber defined by said large piston member, said large outer shell, said first diaphragm and said partition, and said orifice having an opening area So and an axial length l satisfying: l/√So≦4.