Tube joint

Details Tube joint Tube joint

1998-11-10

2001-07-24

Luu, Teri Pham (Department: 3627)

Pipe joints or couplings

Packed

Wedge

C285S348000, C285S382700

Reexamination Certificate

active

06264250

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to plastic tube joints to transport warm water or tap water for air conditioning use, especially so-called simple-action tube joints,
BACKGROUND OF THE INVENTION
Principal embodiments of conventional tube joints are shown in
FIGS. 5
to
12
. They would be called simple-action tube joints for plastic tubes, and connection is complete only by inserting an insertion tube (
17
). In
FIG. 5
, numeral (
24
) represents a joint main unit, numeral (
25
) represents a sealing member e.g. an O-ring, and numeral (
26
) represents a protection ring.
Numeral (
29
) represents a flange which is disposed between the joint main unit (
24
) and the insertion tube (
17
), and a part of the flange (
29
) is split into plural arms (
27
) (eight arms in the figure) except for a portion adjacent to its brim, as shown in FIG.
6
.
In the case of this tube joint, the parts are made of metal or plastic. If the material is plastic, metal pieces (
28
) would be mounted at a tip of the arms as claws. Then in the event of inserting the insertion tube (
17
), the arms (
27
) are pressed and expanded, and subsequently the insertion tube (
17
) passes through the O-ring (
25
) to be inserted to a projecting portion (
32
). Thus, connecting operation is completed.
When pull-out force is supplied to the insertion tube (
17
), a diameter of the expanded arm group will be reduced by a tapered portion (
31
) of the joint main unit (
24
), a frictional force is generated between the claws and the insertion tube (
17
), so that it prevents separation of the insertion tube (
17
). In order to pull out the inserted tube (
17
), the flange (
29
) is pressed against the joint main unit (
24
). Then, the arm group (
27
) is released from the tapered portion (
31
) to enlarge the diameter of the arm group, and the claws loses their resistance force to easily pull out the insertion tube (
17
).
In
FIGS. 7 and 8
showing examples of conventional art, a clamping ring (
34
) made by punching out a metal plate is used as a clamping ring means to prevent separation of the insertion tube (
17
). In this system, when the insertion tube (
17
) is inserted, the clamping fin (
34
) is pressed and expanded, and separation of the insertion tube (
17
) is prevented only by the clamping ring (
34
).
In order to pull out the inserted tube (
17
), the flange (
29
) is pressed, and a tapered portion (
36
) at the tip integrated with the flange (
29
) enlarges the diameter of the clamping ring (
34
). Accordingly, it is not necessary to split the tip portion of the flange (
29
). This type of joint would be used especially for air piping of tubes having a small diameter (most of having an outer diameter of
12
mm or less). Numeral (
35
) represents a ring to hold the clamping ring (
34
) and a release ring.
FIGS. 9 and 10
show a conventional art of the simplest structure, and a plastic clamping ring (
38
) is used. This structure prevents separation of the insertion tube (
17
) by reducing the diameter of a C-shaped clamping ring (
38
) having a tapered portion.
In this case, a sealing material (
37
) has characteristic that it expands by contacting water. This type of joint is often used for flexible polyethylene tubes, but a clamping ring will not work for a rigid tube. Further, an additional tool is required in order to pull out the inserted tube (
17
).
In the case shown in
FIGS. 11 and 12
, a particular clamping ring (
39
) made of metal is used, in which a sleeve (
41
) is inserted into a tip portion of the insertion tube (
17
). Numeral (
40
) represents a cap to hold the clamping ring (
39
) and an O-ring (
25
). In this system, once the insertion tube (
17
) is inserted, the clamping ring (
39
) fixedly biting into the insertion tube (
17
) can not be detached while the joint main unit (
24
) and the cap (
40
) can be disassembled each other, and therefore such part of the insertion tube (
17
) is to be cut off and disposed. This type of joint is used only in the insertion direction.
However, the joint as shown in
FIGS. 5 and 6
requires high manufacturing costs due to its complicated structure. In the case of using a tube having a diameter of the maximum size in the permissible range, an insertion operation would be hard. If such tube is inserted forcibly, then the flange (
29
) will no be movable and the tube can not be pulled out any more.
The joint shown in
FIGS. 7 and 8
is mainly used in an air piping system. The clamping ring (
34
) has a mechanical upper limitation, i.e. a problem in its resistance force against an action of pulling out the inserted tube (
17
). The joint shown in
FIGS. 9 and 10
, as above-mentioned, is not used for rigid plastic tubes. Also, it is troublesome to use additional tools to pull out the inserted tube (
17
).
To pull out the inserted tube of the joint shown in
FIGS. 11 and 12
, it is necessary to remove a cap (
40
). In this case the clamping ring (
39
) which bites into the insertion tube (
17
) will be pulled out from the main unit (
24
) together with the O-ring (
25
). The clamping ring and the O-ring can not be easily removed from the insertion tube, and the insertion tube (
17
) has to be finally cut off to be used again.
Accordingly, if it is necessary to reinsert the insertion tube (
17
), the joint itself will be thrown away because the clamping ring (
39
) of the joint once inserted can not be reused. Moreover, in the case that insertion of the metal sleeve (
41
) is hard and impossible, the joint could be joined without using the sleeve (
41
). However, there is fear of water leakage even though the joint seems to have joined.
If the sleeve (
41
) can not be inserted, the outer diameter of the insertion tube (
17
) would be relatively small and an sealing operation of the O-ring (
25
) will not be complete. According to JIS (Japanese Industrial Standard), for example, an insertion tube made of polybutene having a diameter called “20A” (size) has a large permissible range that the inner diameter is 21.2 mm plus or minus 0.3 mm while the outer diameter of 27 mm plus or minus 0.15 mm. Therefore, it is obvious that problems will occur, namely an insertion tube having a relatively small diameter can not be inserted in a metal sleeve, or an insertion tube having a relatively large diameter would be loose for the sleeve and makes it ineffective.
The diameters of the O-rings and the clamping rings of all the above joints are formed to be smaller than the diameters of the insertion tubes (
17
) in order to complete the joints only by inserting the insertion tubes (
17
). Accordingly, the insertion operation is hard base a large-diameter insertion tube will be inserted into small-diameter rings.
In addition to the above-mentioned permissible range in the polybutene tube diameter, if the polybutene tube is provided in a rolled manner, such tube will be deformed as to have an oval cross section, and difference between a larger diameter and a smaller diameter of the tube will exceed 1 mm in the case of a tube of diameter called “13A” (normal outer diameter of 17 mm). A diameter of a joint should be selected to meet to the minimum limit of its permissible range of an outer diameter, and it is difficult to insert an insertion tube having a diameter selected based on the maximum limit of its permissible range. Therefore, it is recommended to apply lubricant onto an inner surface of a joint. However, the lubricant is only effective to an O-ring but not to a clamping ring.
All of such conventional joints are not applicable to absorb the lack of uniformity in the diameter size of plastic insertion tubes. The present invention is subject to solve the above problem and an object of the present invention is to provide a detachable tube joint which can be easily inserted or pulled out regardless the precision and/or deformation of the insertion tube, and which does not need an additional operation of inserting a sleeve into the insertion tube.
SUMMARY OF THE INVENTION
In order to solve the above problems, the tube joint of the invention comp

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