Pipe joints or couplings – Safety release – With frangible or deformable element
Reexamination Certificate
1999-04-23
2001-07-10
Nicholson, Eric K. (Department: 3629)
Pipe joints or couplings
Safety release
With frangible or deformable element
C285S004000, C285S145300, C411S005000
Reexamination Certificate
active
06257625
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flexible joint and a long nut for flexible joint, and more particularly, to a telescopic flexible tube joint which is used for connecting a water pipe and is capable of absorbing external force even if excessive external force is applied and thus, is capable of preventing the tube from being destroyed, and is easily handled, and to a long nut used for such a telescopic flexible tube joint.
2. Description of the Related Art
Tubes such as long water pipes laid on or under the ground are subjected, in some cases, to various external force such as compression force and tensile force in a direction of the core of the tube shaft due to ground subsidence or earthquake, and shearing force and bending moment. If such external force is too great, stress is concentrated on a tube joint which connects the tubes, and the tube joint is destroyed. Thereupon, it is necessary to absorb the external force applied to the water pipe portion to prevent the tube joint from being damaged.
Conventionally, in order to absorb the external force to prevent the destruction, there has been developed a tube joint which is telescopic by its own. However, since this tube only telescopically moves, the movable region is two dimensional, and this tube can not sufficiently cope with the external force due to ground subsidence or earthquake.
To solve such a problem there has been developed a tube joint having three dimensional flexibility by employing the structure for bringing spherical surfaces into contact with each other for sliding movement. However, since the tube joint itself has the telescopic flexibility, when the water pressure test is carried out prior to use or when the tube joint is being transported and moved, various members constituting the joint are moved by vibration. For this reason, it is troublesome to handle the tube joint before the tube joint is connected to the tube, and it is not convenient for actual use.
Thereupon, there has been developed a joint provided with preventing means for preventing the relative movement of cylinders relatively movably connected to each other (e.g., Japanese Patent Application Laid-open No. H8-121665). This joint has structure that a pair of casing tubes constituting the joint are provided at their outer peripheral surfaces with bosses, a rod is provided between the pair of casing tubes, and a long nut having a through hole in its center is fitted into a substantially center portion of the rod in its longitudinal direction. This long nut is formed with a notched portion, and when great external force applied to the joint, this notched portion is broken so that the flexible telescopic characteristics can be exhibited.
However, in this structure, since the long nut used here is provided with the through hole and the rod is threaded into the through hole, there is a possibility that the long nut is not necessarily be constantly located over the longitudinal direction of the joint. That is, two to four rods are disposed around the tube joint and position of each rod is not necessarily constant, and even if the rods are initially located at constant positions, there is a probability that the long nut may move during transportation. Further, locating the rod at constant position itself is troublesome. As a result, when great external force is applied to a tube joint which is buried in the ground, there is a possibility that the long nut is not reliably broken from its notched portion, the timing for exhibit the inherent telescopic flexibility is delayed, and the tube joint itself or the tube is damaged.
Thereupon, it is an object of the present invention to provide a joint which has a great telescopic flexibility so that the drawbacks of the conventional joints can be overcome and the joint can sufficiently cope with the excessive external force applied due to the ground subsidence or earthquake, and which has substantially constant breaking position of the rod so as to reliably maintain the inherent telescopic flexibility, and position of a long nut is not deviated easily during transportation, and which is convenient for handling.
SUMMARY OF THE INVENTION
The above object is achieved by the invention described in claims.
That is, a flexible joint of the present invention comprises: first cylindrical bodies comprising a pair of spherical ring members each formed with a partially spherical outer peripheral surface; a second cylindrical body comprising a sleeve relatively movably inserted in the first cylindrical bodies from an axial direction X of the second cylindrical body; third cylindrical bodies comprising a pair of casing tubes which are fitted around outer peripheral surfaces of the first cylindrical bodies and are provided with mutually slidable spherical inner peripheral surfaces, the casings being formed at their opposite ends with connecting portions, and being provided at their outer peripheral surfaces of large diameter portions with projections having through holes; and rods capable of being inserted into the through holes formed in the outer peripheral surfaces of the large diameter portions, each of the rods being provided and fixed between the projections of the pair of third cylindrical bodies for restricting the telescopic movement of the tube joint, wherein the rods comprise a pair of rods connected to each other in the vicinity of a substantially central portion between the opposed projections, the pair of rods being threadedly connected to at least one of bottomed holes opened and formed on opposite ends of a long nut which is provided at its substantially central portion with a notched portion so that when excessive external force is applied, the notched portion is preferentially broken to restore telescopic flexible effect of the tube joint.
If the flexible joint is structured as described above, the joint can sufficiently cope with excessive external force due to ground subsidence or earthquake, and can move three dimensionally. Further, when the tube joint of the present invention is connected to a pipe such as a water pipe or water pressure test is carried out, or when the telescopic flexible tube joint is transported and moved, various members constituting the joint are not moved by vibration. Therefore, handling before the tube joint is connected to a pipe is facilitated. Further, there is no possibility that the long nut is easily moved during transportation, and it is possible to conveniently determine the position of the long nut by the initial setting. Therefore, when great external force is applied to a tube joint buried under the ground, the long nut is reliably cut from the notched portion, the timing for exhibiting the inherent telescopic flexibility should not be delayed, and the tube joint should not be damaged.
Therefore, according to the tube joint of the present invention, it is possible to realize a joint structure having great telescopic movement range and high flexibility, and the telescopic flexibility range can be increased and the inherent telescopic flexibility can be maintained so that the joint can sufficiently cope with excessive force due to ground subsidence or earthquake, and even when the tube joint is being transported, the assembling structure of the tube joint is not easily varied, and it is possible to provide a tube joint which is convenient for handling.
It is preferable that each of the bottomed holes opened and formed on the opposite ends of the long nut is threaded. With such a structure, the rod and the long nut are connected with each other more strongly and the cutting or breaking position is determined, and the handling is facilitated which is convenient.
It is preferable that a protecting sleeve is fitted over the outside of the long nut. With such a structure, when the telescopic flexible tube joint is transported, it is convenient because the long nut is unintentionally cut from the notched portion.
Further, a flexible joint of the present invention may be structured in the following manner. That is, the
Fujita Yasushi
Kitamura Masaru
Kitani Kenji
Knobbe Martens Olson & Bear LLP
Nicholson Eric K.
Taisei Kiko Co., Ltd.
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