Pipe joints or couplings – Flexible joint – rigid members – Bellows
Reexamination Certificate
2001-03-08
2003-10-14
Browne, Lynne H. (Department: 3679)
Pipe joints or couplings
Flexible joint, rigid members
Bellows
C285S299000, C285S300000, C285S301000, C092S042000, C092S043000
Reexamination Certificate
active
06631928
ABSTRACT:
FIELD OF THE INVENTION
The preset invention relates to an expansion joint device connected to piping or equipment and the like that absorbs the expansion and contraction in the longitudinal axial direction and the displacement in the direction orthogonal to the axis thereby protecting the piping system, and especially to an expansion joint device constituting a part of a passage for transmitting fluid that disfavors contamination or quality deterioration, such as drugs, fluid-state food and drinks, and fluid for electronic components.
DESCRIPTION OF THE RELATED ART
Heretofore, expansion bend pipe (tako-bend), bellows (waveform) pipe, slip pipe and the like are known as examples of this type of expansion joint device. The latter two of the examples, the bellows pipe and the slip pipe, characterize in that the distance between the connecting surfaces at the ends of a connecting passage, such as a flange, can be very small.
The problem with the bellows pipe is that when fluid including slurry or fluid having high viscosity travels inside the bellows, impurities enter into the grooves of the bellows, making it impossible for the bellows to perform its primary role, which is to expand, and in cases even lead to breakage of the bellows pipe.
In the attempt to solve the above problems, Japanese Utility Model Laid-Open No. 2-6892 discloses a double (interior and exterior) bellows pipe, the interior bellows pipe being a molded bellows, or Japanese Utility Model Publication No. 49-9776 discloses a bellows pipe equipped with a cylindrical cloth mounted to the interior of the pipe.
According to the disclosure of the former document, though impurities do not easily get caught in the grooves on the inner peripheral surface of the molded bellows, the fluid traveling therein tends to reside in the pipe, causing multiplication of bacteria which is insanitary and could not be applied for drugs or food and drinks. Moreover, if impurity resides in the bellows, the fluid may be contaminated or deteriorated, and therefore it can only be used with limitation for fluid used for electronic components and the like.
According to the latter disclosure, the cylindrical cloth prevents impurities from contacting the inner surface of the bellows, but the fluid removed of the impurities will penetrate through the cylindrical cloth having fluid permeability and reaches the interior surface of the bellows, so the problems related to the bellows pipe mentioned above still exists.
On the other hand, in the case of the slip pipe, the eternal surface of the inner pipe may contact the atmosphere and bacteria may enter the inner pipe via the slide surface between the outer pipe, which generates an insanitary environment.
The present invention aims at solving the above-mentioned problems of the conventional expansion joint device having relatively small distance between connecting surfaces, and to provide an expansion joint device that is especially hygienic and enables to maintain the quality of the fluid traveling inside.
SUMMARY OF THE INVENTION
In order to achieve the above objects, the present invention provides an expansion joint device comprising:
a pair of connecting passage end regions equipped to both axial ends;
an expansion outer cylinder capable of axial expansion and contraction, with one axial end region thereof substantially connected in a leakproof manner to one of the connecting passage end regions and the other axial end region thereof substantially connected in a leakproof manner to the other of the connecting passage end regions; and
a cylindrical resin film having no permeability to fluid flowing therethrough, which is substantially cocentrically arranged within the interior of the expansion outer cylinder with one axial end thereof substantially connected in a leakproof manner to one of the connecting passage end regions and the other axial end thereof substantially connected in a leakproof manner to the other of the connecting passage end regions, the cylindrical intermediate region of the cylindrical resin film being arranged to cover the inner surface of the expansion outer cylinder in a leakproof manner.
According to the present invention, no matter whether the expansion outer cylinder is formed as a bellows pipe or a slip pipe, the cylindrical resin film prevents the fluid travelling therethrough from directly getting into contact with the inner surface of the expansion outer cylinder. Therefore, the present invention enables to provide an expansion joint device with an expansion outer cylinder shaped and structured to provide advantageous sanitariness and quality maintaining properties of the fluid flowing therethrough.
The cylindrical resin film is not made of material having fluid permeability such as cloth, but is made of material having no fluid permeability, and may if necessary have elasticity, and should preferably be heat resistant if the fluid traveling through the device must be sterilized using heat.
The actual examples of the cylindrical resin film include silicon, rubber and the like.
The elastic property of the cylindrical resin film is determined appropriately considering the expansion level of the expansion joint device, the tension-resistant power of the cylindrical resin film, the axial stress, and so on. There is also a need to appropriately select the elasticity level of the cylindrical resin film according to the structure of the expansion outer cylinder or the pressure of the flowing fluid. These elements of selection are appropriately determined according to the structure of the expansion joint device and the environment to which it is applied.
It is preferable that the cylindrical resin film is provided with axial pretension. This is to prevent generation of unevenness in the inner surface of the cylindrical resin film due to laxness of the film caused when the expansion joint device is contracted to its minimum length in the axial direction.
In the above invention, the state where the axial end regions of the cylindrical resin film is substantially connected to the connecting passage end regions refers not only to direct connection of the film ends to the connecting passage end regions by welding or bonding, but also to the film ends to be inserted and sandwiched between the connecting passage end region and another connecting member adjacent thereto.
The expansion outer cylinder can either be a prior-art metallic bellows-type outer cylinder, or may be formed of Teflon. In this case, the cylindrical resin film is mounted to the inner side of the bellows-type outer cylinder, and both axial ends thereof are connected to the connecting passage end regions respectively in a leakproof manner.
According to this aspect of the invention, the cylindrical resin film guides the flow of fluid smoothly, and no fluid flows into the grooves formed to the inner surface of the bellows, thereby preventing residence of fluid in the grooves and further preventing deposition of impurities.
Moreover, a plural number of low-hardness elastic resin filling rings may be filled to the spaces defined by grooves formed to the inner peripheral surface of the bellows-type outer cylinder, the inner peripheral surfaces of the rings being connected to form a substantially cylindrical surface. The elastic resin filling rings can be ring-shaped low-hardness elastic resin filling rings that are fit to the grooves formed to the inner surface of the bellows-type outer cylinder, or they can be nonrigid resin filled to the grooves and left for a predetermined time to set.
Accordingly, irrespective of the hardness or the elasticity of the cylindrical resin film, the inner surface of the bellows-type outer cylinder is formed smoothly in a substantial cylindrical shape, so even when the cylindrical resin film expands by fluid pressure, the film will be supported by this smooth cylindrical inner surface, and therefore, the cylindrical resin film will define a smooth inner surface without any residence space for the fluid. Therefore, the sanitariness and the quality of the fluid are maintained.
The plural ela
Asahi Beer Engineering Ltd.
Browne Lynne H.
Collins G M
Laubscher, Jr. Lawrence E.
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