Fluid handling – Systems – Flow path with serial valves and/or closures
Reexamination Certificate
2002-04-05
2004-01-27
Lee, Kevin (Department: 3753)
Fluid handling
Systems
Flow path with serial valves and/or closures
C251S149600
Reexamination Certificate
active
06681803
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tube joint for a fluid. In particular, the present invention relates to a tube joint having a detachable mechanism comprising a socket and a plug.
2. Description of the Related Art
A general tube joint for a liquid having a detachable mechanism comprises check valves for both of a socket and a plug. Therefore, no liquid leaks when the plug is disengaged from the socket. For example,
FIG. 14
shows a tube joint
500
comprising a socket
502
and a plug
552
.
In the following description, as for each of the socket and the plug, the side on which the connection is made is referred to as “frontward direction” or “front end”, and the opposite side on which the socket or the plug is connected to another tube passage (or a hose) is referred to as “rearward direction” or “rear end”.
The socket
502
comprises, for example, a cylindrical socket body
504
which has a rear end opening
514
and a front end opening
528
, a valve element
506
which has a tapered surface
506
b
, a pedestal
512
which has a plurality of through-holes, a cylindrical sleeve
520
which is disposed on the outer circumference of the socket body
504
on the front end side and which is fastened by a retaining ring
516
while being urged frontward by a coil spring
522
, a plurality of steel balls
526
which are inserted into a plurality of holes each having a gradually reducing diameter near the front end of the socket body
504
and which are pressed by the inner circumferential surface of the sleeve
520
, and an O-ring
524
which is disposed on the inner circumferential surface of the front end opening
528
.
An annular seal member
510
is disposed on the tapered surface
506
b
of the valve element
506
. One end of the coil spring
508
contacts the pedestal
512
. The valve element
506
is urged frontward by the coil spring
508
. The seal member
510
and the end surface of an annular projection
504
a
formed on the inner circumference of the socket body
504
contact each other to thereby function as a check valve which prevents the fluid from leaking frontward. Especially, even when the fluid pressure in the rear end opening
514
is high, the valve element
506
is pressed frontward by the fluid pressure. The liquid tightness (or air tightness) is kept because the tapered surface
506
b
is tightly inserted by force into the annular projection
504
a.
A forward end surface
506
a
, which is disposed at the front end of the tapered surface
506
b
, abuts against the plug
552
.
The plug
552
comprises a plug body
554
, a valve element
556
which has a tapered surface
556
b
, and a pedestal
562
which has a plurality of through-holes.
The plug body
554
includes a rear end opening
564
, an outer circumferential surface
554
b
which is disposed on the front end and which is inserted into the socket
502
, and an annular groove
554
a
which functions as a disengagement stopper when the plug body
554
is joined to the socket
502
.
An annular seal member
560
is disposed on the tapered surface
556
b
of the valve element
556
. The valve element
556
is urged frontward by a coil spring
558
which has one end fixed to the pedestal
562
. The seal member
560
contacts an annular projection
554
c
which protrudes in the inner circumferential direction at the forward end of the plug body
554
to thereby function as a check valve to prevent the fluid from leaking frontward. The liquid-tight function (or the air-tight function) is the same as the liquid-tight function (or the air-tight function) of the socket
502
.
A flat forward end surface
556
a
at the forward end of the tapered surface
556
b
abuts against the socket
502
.
When the socket
502
and the plug
552
are connected to one another, the force is applied to the rear of the sleeve
520
to move the sleeve
520
. The pressing force applied to the steel balls
526
is released. Therefore, the outer circumferential surface
554
b
at the front end of the plug body
554
can be inserted into the front end opening
528
of the socket
502
, while pushing the steel balls
526
out of the socket
502
.
The respective forward end surfaces
506
a
,
556
a
of the valve elements
506
,
556
of the socket
502
and the plug
552
abut each other. When the plug
552
is inserted deeply, the valve elements
506
,
556
are moved relatively rearward with respect to the socket body
504
and the plug body
554
while compressing the coil springs
508
,
558
. Then, the both seal members
510
,
560
are separated from the annular projections
504
a
,
554
c
to form a connecting flow passage
530
(see FIG.
15
). Therefore, the rear end opening
514
of the socket
502
and the rear end opening
564
of the plug
552
are communicated with each other via the through-holes of the pedestals
512
,
562
and the connecting flow passage
530
. The front end outer circumferential surface
554
b
of the plug body
554
and the O-ring
524
tightly contact each other to thereby serve as the sealing. Consequently, no fluid leaks externally.
When the plug
552
is sufficiently inserted into the socket
502
and the force applied to the sleeve
520
is released, the sleeve
520
is urged by the elastic restoration of the coil spring
522
and is restored to the original position.
The steel balls
526
are pressed again by the sleeve
520
toward the central axis of the socket body
504
. As a result, the steel balls
526
are engaged with the annular groove
554
a
of the plug body
554
.
Owing to the engagement with the steel balls
526
, the plug
552
is not disengaged from the socket
502
. The socket
502
and the plug
552
are tightly coupled to one another.
In the tube joint
500
, each of the socket
502
and the plug
552
uses the check valve mechanism using the tapered surface
506
b
,
556
b
of the valve element
506
,
556
. When the socket
502
is connected to the plug
552
, each of the valve elements
506
,
556
is moved toward the rear end opening
514
,
564
. Depending upon the amount of movement, the space of the connecting flow passage
530
is generated at the portion of the tapered surface
506
b
,
556
b.
During the connection and the disengagement, a gap
532
is generated between the front end surface
554
d
of the plug body
554
and the end surface
504
b
which abuts against the front end surface
554
d
. The gap
532
is generated due to the discrepancy between the timing at which the O-ring
524
and the outer circumferential surface
554
b
contact each other to form the seal structure and the timing at which the O-ring
524
slides on the outer circumferential surface
554
b
to allow the front end surface
554
d
and the end surface
504
b
to abut (or separate).
When the socket
502
is disengaged from the plug
552
with the connecting flow passage
530
being filled with the fluid, the fluid is extruded by the respective tapered surfaces
506
b
,
556
b
. Further, the fluid is drawn by the gap
532
and leaks externally.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a tube joint which prevents fluid from leaking in the tube joint when a socket and a plug are connected to and disengaged from each other.
Another object of the present invention is to provide a tube joint in which axial centers coincide with each other to effect correct connection when a socket and a plug are connected to one another.
According to the present invention, there is disposed a tube joint for a fluid, comprising a socket and a plug which is connected to and disengaged from the socket; wherein the socket or the plug comprises an outflow-preventive valve for closing a passage for the fluid with a cylindrical valve body which is coaxial with the socket or the plug and a valve element which is disposed in the valve body when the socket and the plug are disengaged from each other; and a first seal for sealing the socket and the plug before the valve body and the valve element are relatively moved when the socket
Naito Keiichirou
Taneya Yoshimoto
Guss Paul A.
Lee Kevin
SMC Kabushiki Kaisha
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