Pipes and tubular conduits – With pressure compensators – Variable capacity chambers
Reexamination Certificate
2002-09-30
2004-01-06
Brinson, Patrick (Department: 3753)
Pipes and tubular conduits
With pressure compensators
Variable capacity chambers
C138S026000, C137S207000, C220S721000
Reexamination Certificate
active
06672337
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an in-line-connector type of fluid hammer prevention device connected in series incorporated in a fluid channel such as a cold/hot water supply system or a fluid apparatus. More particularly, the present invention relates to an in-line fluid hammer prevention device capable of maintaining the pressure energy conversion efficiency for a long period of time by increasing the fluid sealing tightness of an elastic cushion by means of an elastic cylindrical diaphragm.
BACKGROUND ART
There have been several types of fluid hammer prevention device (arrestor) in conventional and popular style, for example known as “water hammer arrestor,” which effectively reduce the phenomenon of fluid hammer occurring in a fluid channel such as a cold-hot water supply system or inside a fluid apparatus. The conventional fluid hammer prevention device may be roughly classified into two types, that is, an branch-off type connected at any intermediate position of the fluid channel to introduce the fluid branched from the main channel, and an in-line type in a shape of connector connected in series in a fluid channel such as a water pipe.
In particular, as referred to the Official Gazette of Japanese Patent No. 2908998, there are several products currently available in the market as “water hammer arrestor” having excellent pressure energy fluctuation absorption performance. According to the water hammer prevention device (arrestor) of Japanese Patent No. 2908998, an orifice is placed at the position opposite to a diaphragm and cushion material, “syntactic foam” (or may be called as “synthetic foam”) made from the mixture of elastic micro balloon fillers and silicone resin is used as the cushion material, and a two-stage orifice is provided. The conventional branch-off type of fluid hammer prevention device, however, is protruding in the perpendicular direction from the pipe, thus having the problem of poor appearance and design, and of requirement of wider installation space and additional branch-off parts. Consequently, the current branch-off type water hammer arrestors have the problem of being difficult to cope with the demand of down-sizing and cost-reduction of cold/hot water supply system and fluid apparatus.
As the rising of concern about water hammer, the branch-off type of products discussed above have become widely used, and currently the in-line type connected in series in a piping system is drawing attention of many users as the fluid hammer prevention device which may be attached to the pipe by using the minimum space. There have already been disclosed several examples of this in-line type of fluid hammer prevention device as illustrated FIGS.
17
(A)-(D), i.e. Japanese Unexamined Patent Publication No. Hei 3-186691, Japanese Unexamined Patent Publication No. Hei 2-253099, Japanese Unexamined Patent Publication No. Hei 6-147391 and Japanese Unexamined Utility Model Publication No. Hei 7-28296.
With reference to the Official Gazette of Japanese Unexamined Patent Publication No. Hei 3-186691, the fluid hammer prevention device as disclosed in FIG.
17
(A) shows an embodiment, wherein, a cushion material
7
is fixed on and covers the inner peripheral wall of a connector
8
connected to the pipe at an intermediate point of a standpipe
3
(preferably in the vicinity of a valve
2
). The diameter of the inner peripheral wall of the connector
8
, in the area between connecting portions
9
,
10
at the both ends, are larger by a predetermined value than the diameter of the inner peripheral wall of the standpipe
3
, where the cushion material is fixed on and covers the inner wall of the connector
8
, so that the whole inner surface in this larger-diameter space may serve as the pressure receiving surface. Further, with reference to the Official Gazette of Japanese Unexamined Patent Publication No. Hei 2-253099, the fluid hammer prevention device as disclosed in FIG.
17
(B) shows an embodiment comprising a pressure absorbing body
2
, a casing
3
and connectors
4
,
5
. The pressure absorbing body
2
comprises a cylindrical part
6
and an absorbing chamber
7
formed around the cylindrical part
6
. The cylindrical part
6
is made of elastic rubber material, wherein a pressure wave absorbing channel is provided.
Each of the fluid hammer prevention devices discussed above is provided with the portion of larger inner diameter serving as the cushion chamber at an intermediate position of pipe, so that the cylindrical shape of cushion part may be fixed on the cushion chamber. However, since the subject fluid directly passes the pressure transmission passage penetrating through the center of the cushion part, the pressure fluctuation is directly supplied to the cushion part without passing any orifice, the corresponding larger volume of the cushion part according to such pressure fluctuation is required. Thus, the ordinary volume of the cushion part would be insufficient for showing the pressure fluctuation absorption effect.
On the other hand, with reference to the Official Gazette of Japanese Unexamined Patent Publication No. Hei 6-147391, the fluid hammer prevention device as disclosed in FIG.
17
(C) shows an embodiment, wherein, a tube
30
made of elastic material such as rubber and serving as a second cylinder inside a cylindrical shape of case
3
, is inserted and fitted in a space surrounded by an inner peripheral wall of the case
3
in the shape of cylindrical connector connected to an intermediate position of a pipe “a”, and a sponge
31
occupies the space between the outer peripheral surface of the tube
30
and the inner peripheral surface of the case
3
. When the pressure fluctuation is generated inside the pipe “a”, the pressure fluctuation (pressure wave) may be absorbed while the tube
30
is expanded and presses the sponge
31
due to the generated pressure. According to this structure, although the good durability of cushion part may be expected because the sponge
31
made of elastic material is protected by the tube
30
, the pressure fluctuation absorption effect would not be shown thoroughly, since the pressure fluctuation directly affects the cushion part via the tube
30
without passing any small holes, the corresponding larger volume of the cushion part according to such pressure fluctuation is required. Thus, the ordinary volume of the cushion part would provide the limited pressure fluctuation absorption effect, and the problem remains.
FIG.
17
(D) of the present invention corresponds to FIG. 4(C) of the Official Gazette of Japanese Unexamined Utility Model Publication No. Hei 7-28296. This prior art is provided with numerous holes 53 on a pipe wall 52
a
, whereby the sufficient pressure fluctuation absorption effect may be obtained since the pressure fluctuation affects the cushion part filled with a compressive gas by passing through the orifice part. There are several problems, however, in regard to the durability such as that the compressive gas filled in the cushion part chronically goes out through the cushion wall.
The preferable in-line type fluid hammer prevention device would comprise, small holes leading to the fluid channel, a cylindrical diaphragm facing to the small holes with having a space between the diaphragm and the holes, and a cushion material provided around the outer periphery of the cylindrical diaphragm. When this type of fluid hammer prevention device is to be adopted, it is most important how this structure can be accomplished by simple assembly with least cost, at the same time, maintaining the pressure energy conversion efficiency of the cushion part for a long period of time.
DISCLOSURE OF THE INVENTION
The inventors focused on the problems arisen from the conventional type of fluid hammer prevention device as discussed above, and it is an object of the present invention to provide a compact in-line type fluid hammer prevention device, which maintains the superior pressure energy conversion efficiency for a long period of time by securing the fluid sealing tightness by means of the
Kobayashi Tatsuya
Suzuki Eiji
Brinson Patrick
McGinn & Gibb PLLC
Suzuki Sogyo Co., Ltd.
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