Abstract: A workpiece for a fuel injection component is made of a steel having compositions, by mass %, of C: 0.08 to 0.16%, Si: 0.10 to 0.30%, Mn: 1.00 to 2.00%, S: 0.005 to 0.030%, Cu: 0.01 to 0.30%, Ni: 0.40 to 1.50%, Cr: 0.50 to 1.50%, Mo: 0.30 to 0.70%, V: 0.10 to 0.40%, s-Al: 0.001 to 0.100%, and Fe and unavoidable impurities as remaining components. After heating the workpiece to a temperature of 950° C. or more and 1350° C. or less, the workpiece is subjected to a hot forging, and thereafter cooled at an average cooling rate of 0.1° C./sec. or more in a temperature range from 800° C. to 500° C., and at the average cooling rate of 0.02° C./sec. or more and 10° C./sec. or less in the subsequent temperature range from 500° C. to 300° C. to set an area ratio of a bainite structure after hot forging to 85% or more.

Abstract: The present invention provides an age hardening type bainitic microalloyed steel having a composition which includes, in terms of mass %: 0.06-0.35% of C; 0.01-2.00% of Si; 0.10-3.00% of Mn; 0.001-0.200% of S; 0.001-2.00% of Cu; 0.40-3.00% of Ni; 0.10-3.00% of Cr; 0.10-1.00% of Mo; 0.10-1.00% of V; and 0.001-0.100% of s-Al, with the remainder being Fe and unavoidable impurities, and which satisfies a value of the following expression (1) to be 20 or larger and a value of the following expression (2) to be 0.82 or larger: 3×[C]+10×[Mn]+2×[Cu]+2×[Ni]+12×[Cr]+9×[Mo]+2×[V]??expression (1); 1.66×[C]+0.18×[Si]+0.27×[Mn]+0.09×[Ni]+0.32×[Cr]+0.34×[Mo]+0.44×[V]??expression (2), in which each [ ] in the expression (1) and the expression (2) indicates a content of the element shown therein in terms of mass %.

Abstract: A workpiece for a fuel injection component is made of a steel having compositions, by mass %, of C: 0.08 to 0.16%, Si: 0.10 to 0.30%, Mn: 1.00 to 2.00%, S: 0.005 to 0.030%, Cu: 0.01 to 0.30%, Ni: 0.40 to 1.50%, Cr: 0.50 to 1.50%, Mo: 0.30 to 0.70%, V: 0.10 to 0.40%, s-Al: 0.001 to 0.100%, and Fe and unavoidable impurities as remaining components. After heating the workpiece to a temperature of 950° C. or more and 1350° C. or less, the workpiece is subjected to a hot forging, and thereafter cooled at an average cooling rate of 0.1° C./sec. or more in a temperature range from 800° C. to 500° C., and at the average cooling rate of 0.02° C./sec. or more and 10° C./sec. or less in the subsequent temperature range from 500° C. to 300° C. to set an area ratio of a bainite structure after hot forging to 85% or more.

Abstract: An age-hardenable steel having a composition consisting of: C: 0.05 to 0.20%, Si: 0.01 to 0.50%, Mn: 1.5 to 2.5%, S: 0.005 to 0.08%, Cr: more than 0.50% and not more than 1.6%, Al: 0.005 to 0.05%, V: 0.25 to 0.50%, Mo: 0 to 1.0%, Cu: 0 to 0.3%, Ni: 0 to 0.3%, Ca: 0 to 0.005%, and Bi: 0 to 0.4%, the balance being Fe and impurities. Within the impurities, P?0.03%, Ti<0.005%, and N<0.0080%, and [C+0.3Mn+0.25Cr+0.6Mo?0.68], [C+0.1Si+0.2Mn+0.15Cr+0.35V+0.2Mo?1.05], and [?4.5C+Mn+Cr?3.5V?0.8Mo?0.12]. The steel has hardness before aging of not more than 310 HV. After aging, the fatigue strength is not less than 480 MPa and absorbed energy at 20° C. is not less than 12 J.

Abstract: Age hardenable steel is low in hardness after hot forging, providing a machine part with the desired fatigue strength and yield strength by aging treatment, and high in toughness after aging treatment, comprising C: 0.09 to 0.20%, Si: 0.01 to 0.40%, Mn: 1.5 to 2.5%, S: 0.001 to 0.045%, Cr: over 1.00% to 2.00%, Al: 0.001 to 0.060%, V: 0.22 to 0.55%, N: over 0.0080 to 0.0170%, and a balance of Fe and impurities, where an area rate of bainite structures is 80% or more, an effective V ratio (amount of dissolved V/total amount of V) is 0.9 or more, a P and Ti in the impurities is P: 0.03% or less and Ti: less than 0.005%, and the chemical composition is one where the following F1 is 1.00 or less and the F2 is 0.30 or more: F1=C+0.1×Si+0.2×Mn+0.15×Cr+0.35×V F2=?4.5×C+Mn+Cr?3.

Abstract: The present invention provides an age hardening type bainitic microalloyed steel having a composition which includes, in terms of mass %: 0.06-0.35% of C; 0.01-2.00% of Si; 0.10-3.00% of Mn; 0.001-0.200% of S; 0.001-2.00% of Cu; 0.40-3.00% of Ni; 0.10-3.00% of Cr; 0.10-1.00% of Mo; 0.10-1.00% of V; and 0.001-0.100% of s-Al, with the remainder being Fe and unavoidable impurities, and which satisfies a value of the following expression (1) to be 20 or larger and a value of the following expression (2) to be 0.82 or larger: 3×[C]+10×[Mn]+2×[Cu]+2×[Ni]+12×[Cr]+9×[Mo]+2×[V]??expression (1); 1.66×[C]+0.18×[Si]+0.27×[Mn]+0.09×[Ni]+0.32×[Cr]+0.34×[Mo]+0.44×[V]??expression (2), in which each [ ] in the expression (1) and the expression dicates a content of the element shown therein in terms of mass %.

Abstract: A bush incorporated in a common rail is formed with a smallest diameter orifice having a small inner diameter and an adjacent orifice having an inner diameter larger than that of the smallest diameter orifice on an inner peripheral face of the bush. A press-fitted portion, which is press-fitted into an inside-outside communication hole, and a non-press-fitted portion, which has a smaller outer diameter than the press-fitted portion, are formed on an outer peripheral face of the bush. The smallest diameter orifice and the press-fitted portion are deviated from each other in an axial direction of the bush to prevent an overlap in a radial direction of the bush. Thus, even if the bush is tightly press-fitted into the inside-outside communication hole, decrease of the inner diameter of the smallest diameter orifice can be averted.

Abstract: A bush incorporated in a common rail is formed with a smallest diameter orifice having a small inner diameter and an adjacent orifice having an inner diameter larger than that of the smallest diameter orifice on an inner peripheral face of the bush. A press-fitted portion, which is press-fitted into an inside-outside communication hole, and a non-press-fitted portion, which has a smaller outer diameter than the press-fitted portion, are formed on an outer peripheral face of the bush. The smallest diameter orifice and the press-fitted portion are deviated from each other in an axial direction of the bush to prevent an overlap in a radial direction of the bush. Thus, even if the bush is tightly press-fitted into the inside-outside communication hole, decrease of the inner diameter of the smallest diameter orifice can be averted.

Abstract: A flow damper is provided with a clearance to absorb a deformation occurring in proximate to a lower end of the valve body by the clearance on an entire outer circumference of a lower side of a large diameter portion of a piston. By the configuration in this manner, even if the slight deviation in the accuracy or the shape of the seat surface occurs a radially inward deformation of a lower portion of the valve body when the valve body is fastened to the common rail body at a large axial force, the clearance absorbs the deformation. Thus, the deformation of the valve body does not affect the piston sliding hole. Accordingly, a sliding clearance of the piston does not change, not to spoil a slide motion of the piston.

Abstract: In a pipe joint structure, a second screw thread formed on an outer circumference end of a joint member is screwed deep into a first screw thread formed on an inner circumference of a cylindrical joint fitting member whose axial end is bonded to a common rail body so that a second flat surface at an axial end of the joint member is pressed against a first flat surface on an outer circumference of the common rail body to form a fluid tight sealing surface therebetween in a state that a fluid passage opened to the second flat surface communicates with a through-hole opened to the first flat surface. Accordingly, even if a position of the joint fitting member to the common rail body is slightly shifted, fluid tight sealing between the first and second flat surfaces is assured.

Abstract: In a common rail for accumulating highly pressured fuel, a cylindrical body is provided with a chamber for accumulating highly pressured fuel and a delivery port which connects the chamber to the outer circumference thereof and communicates via a pipe-joining unit with a conduit in a distribution pipe. The longitudinal center axes of the chamber and the cylindrical body are disposed substantially coaxially with each other, and each of the longitudinal center axes of the delivery ports and the longitudinal center axis of the cylindrical body are skewed to each other. Accordingly, the durability of the cylindrical body is improved, and the thickness of the cylindrical body is uniform and the forging form of the cylindrical body becomes symmetric. The length of the delivery port is extended so that the durability of the cylindrical body is improved.

Abstract: A flow damper is provided with a clearance to absorb a deformation occurring in proximate to a lower end of the valve body by the clearance on an entire outer circumference of a lower side of a large diameter portion of a piston. By the configuration in this manner, even if the slight deviation in the accuracy or the shape of the seat surface occurs a radially inward deformation of a lower portion of the valve body when the valve body is fastened to the common rail body at a large axial force, the clearance absorbs the deformation. Thus, the deformation of the valve body does not affect the piston sliding hole. Accordingly, a sliding clearance of the piston does not change, not to spoil a slide motion of the piston.

Abstract: In a common rail for accumulating highly pressured fuel, a cylindrical body is provided with a chamber for accumulating highly pressured fuel and a delivery port which connects the chamber to the outer circumference thereof and communicates via a pipe-joining unit with a conduit in a distribution pipe. The longitudinal center axes of the chamber and the cylindrical body are disposed substantially coaxially with each other, and each of the longitudinal center axes of the delivery ports and the longitudinal center axis of the cylindrical body are skewed to each other. Accordingly, the durability of the cylindrical body is improved, and the thickness of the cylindrical body is uniform and the forging form of the cylindrical body becomes symmetric. The length of the delivery port is extended so that the durability of the cylindrical body is improved.

Abstract: In a pipe joint structure, a second screw thread formed on an outer circumference end of a joint member is screwed deep into a first screw thread formed on an inner circumference of a cylindrical joint fitting member whose axial end is bonded to a common rail body so that a second flat surface at an axial end of the joint member is pressed against a first flat surface on an outer circumference of the common rail body to form a fluid tight sealing surface therebetween in a state that a fluid passage opened to the second flat surface communicates with a through-hole opened to the first flat surface. Accordingly, even if a position of the joint fitting member to the common rail body is slightly shifted, fluid tight sealing between the first and second flat surfaces is assured.