Fitting nut, fitting, fluid pressure device, and fluid control system

A fitting comprising:

• a fitting nut made of a resin material and having a female thread formed thereon;
• and
• a joint body made of a resin material and having, on an outer peripheral wall thereof, a male thread that is engaged with the female thread,
• wherein the fitting nut includes
• a large-diameter tube portion that is hollow and includes the female thread formed on an inner peripheral wall thereof, and
• a small-diameter tube portion that has a hollow cylindrical shape with a smaller diameter than the large-diameter tube portion and includes, in an end surface thereof, an insertion hole in which a pipe member may be inserted, and
• the small-diameter tube portion includes, in an outer peripheral wall thereof:
• a plurality of ridges protruding outward in a diameter direction of the small-diameter tube portion, extending in a longitudinal direction that is orthogonal to the diameter direction, and terminating at a diametrical transition portion provided between the large-diameter tube portion and the small-diameter tube portion based on a difference in diameter between the large-diameter tube portion and the small-diameter tube portion;
• and
• a plurality of engagement grooves formed between the ridges adjacent to each other, the plurality of engagement grooves being depressed inwardly in the diameter direction of the small-diameter tube portion and extending straight along the longitudinal direction, and terminating at the diametrical transition portion,
• wherein an outer diameter of the ridges of the small-diameter tube portion is smaller than a smallest outer diameter of the large-diameter tube portion, wherein said smallest outer diameter is constant along at least a portion of an axial length of the large-diameter tube portion, and
• wherein an outer diameter of said ridges is smaller than an outer diameter of the diametrical transition portion, and the small-diameter tube portion includes a portion in which the outer diameter of the ridges is constant along the axial direction of the small-diameter tube portion.

A fluid pressure device in which a fluid supply pipe configured to supply a fluid, a fluid discharge pipe configured to discharge the fluid, and a pilot fluid passage pipe configured to allow a pilot fluid to flow therethrough, are connected respectively through fittings,

• wherein at least one of the fittings includes a fitting nut made of a resin material and having a female thread formed thereon, and a joint body made of a resin material and having, on an outer peripheral wall thereof, a male thread that is engaged with the female thread,
• the fitting nut includes
• a large-diameter tube portion that is hollow and includes the female thread formed on an inner peripheral wall thereof, and
• a small-diameter tube portion that has a hollow cylindrical shape with a smaller diameter than the large-diameter tube portion and includes, in an end surface thereof, an insertion hole in which the fluid supply pipe, the fluid discharge pipe, or the pilot fluid passage pipe may be inserted, and
• the small-diameter tube portion includes, in an outer peripheral wall thereof:
• a plurality of ridges protruding outward in a diameter direction of the small-diameter tube portion, extending in a longitudinal direction that is orthogonal to the diameter direction, and terminating at a diametrical transition portion provided between the large-diameter tube portion and the small-diameter tube portion based on a difference in diameter between the large-diameter tube portion and the small-diameter tube portion;
• and
• a plurality of engagement grooves formed between the ridges adjacent to each other, the plurality of engagement grooves being depressed inwardly in the diameter direction of the small-diameter tube portion and extending straight along the longitudinal direction, and terminating at the diametrical transition portion,
• wherein an outer diameter of the ridges of the small-diameter tube portion is smaller than a smallest outer diameter of the large-diameter tube portion, wherein said smallest outer diameter is constant along at least a portion of an axial length of the large-diameter tube portion, and
• wherein an outer diameter of said ridges is smaller than an outer diameter of the diametrical transition portion, and the small-diameter tube portion includes a portion in which the outer diameter of the ridges is constant along the axial direction of the small-diameter tube portion.

A fluid control system comprising at least two fluid pressure devices that are arranged adjacent to each other in a row,

• wherein, in each of the fluid pressure devices, a fluid supply pipe configured to supply a fluid, a fluid discharge pipe configured to discharge the fluid, and a pilot fluid passage pipe configured to allow a pilot fluid to flow therethrough, are connected respectively through fittings,
• at least one of the fittings includes a fitting nut made of a resin material and having a female thread formed thereon, and a joint body made of a resin material and having, on an outer peripheral wall thereof, a male thread that is engaged with the female thread,
• the fitting nut includes
• a large-diameter tube portion that is hollow and includes the female thread formed on an inner peripheral wall thereof, and
• a small-diameter tube portion that has a hollow cylindrical shape with a smaller diameter than the large-diameter tube portion and includes, in an end surface thereof, an insertion hole in which the fluid supply pipe, the fluid discharge pipe, or the pilot fluid passage pipe may be inserted, and
• the small-diameter tube portion includes, in an outer peripheral wall thereof:
• a plurality of ridges protruding outward in a diameter direction of the small-diameter tube portion, extending in a longitudinal direction that is orthogonal to the diameter direction, and terminating at a diametrical transition portion provided between the large-diameter tube portion and the small-diameter tube portion based on a difference in diameter between the large-diameter tube portion and the small-diameter tube portion;
• and
• a plurality of engagement grooves formed between the ridges adjacent to each other, the plurality of engagement grooves being depressed inwardly in the diameter direction of the small-diameter tube portion and extending straight along the longitudinal direction, and terminating at the diametrical transition portion,
• wherein an outer diameter of the ridges of the small-diameter tube portion is smaller than a smallest outer diameter of the large-diameter tube portion, wherein said smallest outer diameter is constant along at least a portion of an axial length of the large-diameter tube portion, and
• wherein the outer diameter of said ridges is smaller than an outer diameter of the diametrical transition portion, and the small-diameter tube portion includes a portion in which the outer diameter of the ridges is constant along the axial direction of the small-diameter tube portion.