Fluid coupling and method of designing the same
Each of ridges 7 on respective opposite side surfaces of a gasket 4 has a trapezoidal cross sectional shape defined by an outer tapered face 7 a providing an outer peripheral surface, an inner tapered face 7 b providing an inner peripheral surface and a flat face 7 c providing a top end surface. The hardness of the gasket 4 , the angle between the tapered faces 7 a, 7 b of the ridge 7 , the height of the ridge 7 and the area of the flat top end face 7 c of the ridge are so determined that the value of thrust for tightening up the coupling is between a predetermined minimum value and a predetermined maximum value.
1. A fluid coupling comprising a first and a second coupling member having respective fluid channels communicating with each other, and an annular gasket interposed between opposing end faces of the two coupling members and capable of being deformed to provide sealing properties, each of the first and second coupling members being provided in the end face thereof with an annular recessed portion having a flat bottom face, the gasket being annular and disposed within a space defined by the recessed portions of the two coupling members, the gasket having an annular ridge formed on one axial side surface and another annular ridge on the opposite axial side surface thereof,
wherein each ridge of the gasket has a trapezoidal cross sectional shape defined by a radially outer tapered face providing an outer peripheral surface, a radially inner tapered face providing an inner peripheral surface, a flat face adjoining both the inner tapered face and the outer tapered face to provide a top end surface of the trapezoidal cross sectional shape, and a base portion adjoining both the inner tapered face and the outer tapered face, the fluid coupling being characterized in that the gasket is metal and has an inner circumference surface which adjoins the base end of the inner tapered surface of the annular ridge and adjoins the base end of the inner tapered surface of the another annular ridge, and the flat face of each ridge of the gasket is orthogonal to the inner circumference surface, the radially outer periphery of the gasket comprises axially opposite beveled surfaces, a cavity having a circular-arc cross section in the axial midportion of outer periphery of the gasket, two connecting portions adjoining respective axially opposite beveled surfaces and the cavity, the two connecting portions being parallel to the inner circumference surface,
the axial side surfaces of the gasket further comprising a flat surface adjoining the respective base end of the inner tapered surface of the respective annular ridge and adjoining the respective axially opposite beveled surfaces of the radially outer periphery of the gasket, the flat surfaces being orthogonal to the inner circumference surface,
wherein the flat face of each ridge of the gasket contacts the flat bottom face of the respective annular recessed portion and the outer tapered face and the inner tapered face of each ridge of the gasket do not contact with the flat bottom face of the respective annular recessed portion when the two coupling members are fastened together.
2. A fluid coupling according to claim 1 wherein an angle α between the outer tapered face of the annular ridge of the gasket and the inner tapered face thereof is 50 to 130 deg.