Pipe joint

Pipe joints or couplings – Ball and socket – Spring-biased ball

Reexamination Certificate

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Details

C285S047000, C285S334400, C285S271000

Reexamination Certificate

active

06279965

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pipe joint for hermetically connecting fluid pipelines, in such a manner that the relative angle therebetween can vary, by means of a ring-shaped sealing ring.
2. Description of the Related Art
Conventionally, exhaust systems for automotive vehicle have been devised in such a manner that the connection between the combining pipe of the exhaust manifold and an exhaust pipe, and connections between exhaust pipe and exhaust pipe, are capable of variation in the relative angle between pipes by means of a pipe joint having the composition described below, in order to suppress relative movement between the vehicle and engine, or the like, occurring due to vibration of the engine or vibrations from the road surface whilst the vehicle is moving.
For example, in a widely used composition such as the pipe joint
50
illustrated in
FIG. 6
, a tapered sealing seat
52
b
is formed on the inner circumference of an integrated flange
52
formed on the downstream end portion of the combining pipe
51
of an exhaust manifold provided in the engine of an automotive vehicle, and furthermore, a ring-shaped sealing ring
54
having a convex surface
54
a
corresponding to the aforementioned sealing seat
52
b
is installed on the outer circumference of the connecting end portion
56
of an exhaust pipe
53
connected to the aforementioned exhaust manifold
51
[sic], the aforementioned tapered sealing seat
52
b
and the aforementioned convex surface
54
a
being capable of hermetic sliding motion such that the relative angle therebetween can vary, under pressure applied by pressure connecting means
55
provided in the coupling region between the two pipelines.
Moreover, with regard to pipe joints for connecting together two exhaust pipes in an automotive vehicle, the spherical pipe joint disclosed in Japanese Patent Publication No.(Hei)2-33912 is known, for example. This joint is composed in such a manner that a ring-shaped sealing ring having a convex surface is installed on the outer circumference of the end portion of an upstream-side exhaust pipe, and a flange having a concave-shaped sealing seat corresponding to the aforementioned convex surface formed therein is fixed by welding to the connecting end portion of a downstream-side exhaust pipe, the convex surface of the aforementioned ring-shaped sealing ring and the concave surface of the aforementioned sealing seat being capable of hermetic sliding motion such that the relative angle therebetween can vary, under pressure applied by pressure connecting means provided in the coupling region between the two exhaust pipes.
The ring-shaped sealing rings used in conventional pipe joints of these kinds are generally obtained by overlaying a fire-resistant material in sheet form, such as expanded graphite or mica, for example, with fine metal wire made from stainless steel, or the like, winding and laminating same, and then applying strong pressure to the laminate surface from a perpendicular direction in a metal mould of a prescribed shape, thereby forming a truncated spherical shape having a cylindrical hole in the centre thereof. However, since the aforementioned fine metal wire has high elasticity, it has been difficult to ensure adequate precision in the moulding of the concave surface formed in the ring-shaped sealing rings.
Moreover, in order to ensure good sealing properties between the ring-shaped sealing ring and the outer circumference of the connecting end section, thereby preventing any leakage of exhaust, the ring-shaped sealing ring installed on the outer side of the aforementioned connecting end section is held under strong pressure by means of a fastening spring, and consequently the related installation task is complicated and leads to an increase in costs.
SUMMARY OF THE INVENTION
With the foregoing in view, it is an object of the present invention to provide a pipe joint whereby fluid pipelines, such as exhaust pipes, or the like, can be connected hermetically in such a manner that the relative angle therebetween can vary, whilst ensuring satisfactory manufacturing precision in the sealing surface of a ring-shaped sealing ring.
In order to achieve the aforementioned object, the present invention is a pipe joint for connecting a first fluid pipeline and a second fluid pipeline hermetically, in such a manner that the relative angle therebetween can vary; wherein a ring-shaped sealing ring comprising an inner circumference sealing surface having a tapered shape expanding in diameter towards an open end thereof is provided in the connecting section of the first fluid pipeline; an outer circumference sealing seat having a partially convex surface is provided in the connecting section of the second fluid pipeline, in a position confronting the ring-shaped sealing ring; and pressure connecting means for causing the inner circumference sealing surface of the ring-shaped sealing ring and the outer circumference sealing seat to contact under pressure, in a slidable fashion, is provided in a region extending across both the fluid pipelines.
In a pipe joint of this kind, the aforementioned tapered inner circumference sealing surface of the ring-shaped sealing ring provided in the connecting section of the first fluid pipeline and the partially convex outer circumference sealing seat provided in the connecting section of the second fluid pipeline are able to slide respectively, whilst in a state of pressure contact, and if a vibration acts on the fluid pipelines, due to engine vibration or another cause, this vibration is absorbed whilst maintaining a hermetically sealed state, by means of smooth variation in the relative angle between the two fluid pipelines. Moreover, a conical tapered inner circumference sealing surface, which is more easily formable than a convex surface, is provided in the ring-shaped sealing ring held in pressure contact with the partially convex outer circumference sealing seat, and hence the ease of manufacturing the ring-shaped sealing ring is improved dramatically and satisfactory manufacturing precision can be ensured.
Here, in a pipe joint, wherein the outer circumference surface of the ring-shaped sealing ring is formed with a tapered shape expanding in diameter towards the open end of the first fluid pipeline, the ring-shaped sealing ring being installed inside an inner circumference groove formed in the connecting section of the first fluid pipeline, the sealing ring can be installed readily by sliding into the tapered inner circumference groove, and moreover, the ranges of tolerance for the dimensions of both the ring-shaped sealing rings and the fluid pipes can be broadened compared to a conventional system where a ring-shaped sealing ring is held under pressure on the outer circumference of a pipe end section by means of a fastening spring, and satisfactory sealing properties can be ensured in the interlocking section between the ring-shaped sealing ring and the first fluid pipeline, when the sealing ring is installed.
In a pipe joint, wherein the outer circumference sealing seat having a partially convex surface is formed by causing the open end section of a second cylindrical fluid pipeline to expand by means of pressure deformation, the smooth surface properties of the fluid pipeline can be used directly for the surface of the outer circumference sealing seat, the sealing properties between the sealing seat and the aforementioned ring-shaped sealing ring can be stabilized readily to the required level, and sealing faults caused by tool marks on the component surfaces which arise inevitably during machine processing steps, such as cutting, grinding, and the like, can be prevented completely.
Preferably, the aforementioned first fluid pipeline or second fluid pipeline are, respectively, an exhaust manifold combining pipe or an exhaust pipe constituting the exhaust system of an internal combustion engine, a material having thermal resistance, wear resistance and corrosion resistance being used for the afor

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