Internal-combustion engines – Valve – Valve seat relation
Reexamination Certificate
2000-07-31
2001-11-27
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Valve
Valve seat relation
C123S188110
Reexamination Certificate
active
06321710
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a diffusion joining in which a mounted member is pressed against a mounting member while the mounted member and the mounting member are being heated.
2. Description of the Related Art
Diffusion joining structures as described above have already been known in JP-A-7-103070, JP-A-7-189628 and JP-A-9-122924, and the official gazettes of those unexamined patent publications disclose diffusion joining structures in which a valve seat as a mounted member is diffusion joined to a cylinder head as a mounting member, which valve seat is formed of a material different from that of the cylinder head.
In the conventional diffusion joining structures as described above, however, since the external face of a portion of the mounted member which is to be joined to the mounting member has a transverse cross-sectional configuration comprising a combination of straight lines in a state prior to joining, sufficient plastic flows are not generated at the straight line portions, and therefore a sufficient joining strength cannot be obtained. This seems to be because the plastic flow is generated sufficiently at the distal portion of the mounted member which is adapted to first be brought into contact with the mounting member when the mounted member is pressed to the mounting member since the distal portion is formed acutely to thereby generate a sufficient diffusion joining layer thereat, whereas no sufficient diffusion joining layer is formed at the portion having the straight transverse cross-sectional configuration and linking up with the distal end portion since the sliding speed and volume of the plastic flow substance are clearly reduced thereat when compared with the distal end portion.
SUMMARY OF THE INVENTION
The present invention was made in view of the above situations and an object thereof is to provide a diffusion joining structure for increasing the sliding speed and volume of a plastic flow substance generated between a mounted member and a mounting member when a diffusion joining takes place so as to obtain a sufficient joining strength.
With a view to attaining the aforesaid object, according to a first aspect of the invention, there is provided a diffusion joining structure in which a mounted member is pressed against a mounting member in a state that the mounted member and the mounting member are heated, wherein an external surface configuration prior to joining of a portion of the mounted member which is to be joined to the mounting member, comprises: a first curved surface bulged toward the mounting member with a first radius of curvature, the first curved surface being disposed at a distal end position which first comes into contact with the mounting member when the mounted member is pressed against the mounting member; and a second curved surface having a second radius of curvature larger than the first radius of curvature and linking up with the first curved surface.
According to the construction described above, the sliding speed and volume of a plastic flow substance generated between the mounted member and the mounting member can be increased to thereby obtain a sufficient joining strength by virtue of good diffusion joining. In other words, the sliding speed of the plastic flow substance relative to a stroke can be increased further by the portion of the mounted member which is joined to the mounting member when the external surface configuration thereof prior to joining is formed into a curved surface than when formed into a flat surface. In addition, since the curved surface of the portion of the mounted member which first comes into contact with the mounting member is formed such that the radius of curvature thereof becomes relatively small, the volume of the plastic flow substance can be increased which is generated when the curved surface at the distal end sinks into the mounting member, and additionally since the portions linking up with the curved surface at the distal end are also formed into the curved surfaces, the sliding speed of the plastic flow substance can be increased to thereby aggressively discharge the plastic flow substance. Therefore, the mounted member can be diffusion joined to the mounting member well to thereby obtain a sufficient joining strength.
Further, according to the second aspect of the invention, there is provided a diffusion joining structure, comprising: a mounting member having a mounting face having an inner diameter which reduces toward one end of an axial direction thereof; a mounted member diffusion joined with the mounting member by pressing the mounted member toward the mounting member in a state that the mounted member and the mounting member are heated, the mounted member prior to joining having: a confronting end face located at one end in the axial direction and confronting the mounting face in at least an outer circumferential portion thereof; an external side face having a circular cross-section; and a linking portion disposed between the confronting face and the external side face, the linking portion being first brought into contact with the mounting face, wherein the linking portion is formed into a curved face bulged toward the mounting member side, the portions of the confronting end face and the external side face which are to be joined to the mounting member are formed into curved faces each having a radius of curvature larger than that of the linking portion, and an annular recessed portion is formed radially inwardly of the portion of the confronting end face which is to be joined to the mounting member, for receiving a plastic flow substance discharged from a joining interface between the mounting face and the confronting end face.
According to the construction described in the second aspect of the invention, the sliding speed and volume of the plastic flow substance generated between the mounted member and the mounting member are increased so as to obtain the sufficient joining strength through the good diffusion joining. Namely, since the sliding speed of the plastic flow substance relative to a stroke can be increased further by the portion of the mounted member which is joined to the mounting member when it has a curved external face in a state prior to joining than when having a flat one and since the linking portion adapted to first be brought into contact with the mounting face of the mounting member when the mounted member is pressed to the mounting member is formed into a curved face having a relatively small radius of curvature, the volume of the plastic flow substance generated when the linking portion sinks into the mounting member can be increased. In addition, since the portions of the confronting end face and the external side face that are to be joined to the mounting member are formed into curved faces each having a radius of curvature larger than that of the linking portion, the sliding speed of the plastic flow substance can be increased so that the plastic flow substance is aggressively discharged. Moreover, since the annular recessed portion is formed radially inwardly of the portion of the confronting end face which is to be joined to the mounting member, the plastic flow substance discharged from between the confronting end face and the mounting face is allowed to escape into the annular recessed portion so formed to thereby suppress as low as possible the scattering of the pressed resistance value generated when the discharged plastic flow substance sinks into between the mounting face and the confronting end face, whereby the joining depth can be controlled with higher accuracy.
In addition, prior to mounting the mounted member to the mounting member, a recessed joining portion may be provided on the mounting face of the mounting member which is constituted by an annular bottom face confronting the outer circumferential portion of the confronting end face and an internal side face rising from an outer circumferential edge of the annular bottom face toward the mounted member so as to confront the exter
Hashimoto Tomoyuki
Mizoue Kiyonobu
Sato Makoto
Satoh Masakatsu
Ueda Kouji
Honda Giken Kogyo Kabushiki Kaisha
Huynh Hai
Sughrue Mion Zinn Macpeak & Seas, PLLC
Wolfe Willis R.
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