Patent ID: 7434849

Claim:
A pipe joint for a refrigeration cycle, comprising: a male joint portion and a female joint portion, for connecting refrigerant passages of a refrigeration cycle, said male joint portion having a cylindrical fitting projection defining a shoulder and a terminal end, a backup ring directly engaging the female joint portion and the shoulder defined by the cylindrical fitting projection, the entire backup ring being disposed between the shoulder and the terminal end and functioning as a pressure receiving member, and an O-ring separate from the backup ring as a sealing member which directly engages the male and female joint portions, the O-ring being fitted on the fitting projection and the entire O-ring being located between the backup ring and the terminal end of the fitting projection, said female joint portion having a cylindrical fitting recess in which the fitting projection, the entire backup ring and the entire O-ring are fitted, so that when the fitting projection is fitted in the fitting recess, the refrigerant passages are joined, and leakage of a refrigerant to the outside is prevented, wherein an end portion of the fitting projection extending from the shoulder defined by the male joint portion to the terminal end of the fitting projection, has a diameter smaller than the inner diameter of the backup ring; the backup ring is an endless ring which continuously extends in a circumferential direction; the material of the backup ring has a lower refrigerant permeability than that of the material of the O-ring; a cap, which is located adjacent to the O-ring and closer to the terminal end of the fitting projection than the O-ring is provided on the terminal end of the fitting projection; and the female joint portion is provided with a cylindrical fitting recess in which the cylindrical fitting projection, the backup ring, the O-ring and the cap are fitted; the cap is detachably attached to the fitting projection; insertion preventing projections are provided on the portion of the cap, corresponding to the terminal end of the fitting projection; a cap holding groove is provided at the terminal end of the fitting projection; holding projections to be fitted in the cap holding groove are provided in the inner peripheral surface of the cap; the insertion preventing projections and the holding projections are spaced in a circumferential direction of the cap; and the material of the cap is softer than that of the male joint portion.