Pumps – Expansible chamber type – Having pulsation dampening fluid receiving space
Reexamination Certificate
2000-06-14
2001-11-27
Koczo, Michael (Department: 3746)
Pumps
Expansible chamber type
Having pulsation dampening fluid receiving space
C138S030000, C417S394000
Reexamination Certificate
active
06322338
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a pulsation damping device for a pump, which damps a pulsation caused by fluctuations of a flow rate and a pressure of a liquid to be transported such as processing chemical liquids used in a semiconductor production, via a piping system for supplying the transported liquid to each element by a reciprocal pump.
BACKGROUND ART
A pulsation damping device for a pump of this type, has been disclosed in, for example, Japanese Patent Publication Laying-open Nos. 6-17752 and 8-159016.
The pulsation damping device for a pump shown in Japanese Patent Publication Laying-open No. 6-17752 is illustrated in FIG.
4
. The proposed pulsation damping device has a hermetical device body casing
60
, a liquid chamber
61
a
disposed inside the device body casing
60
, for functioning as a storage of the liquid, which sucks and stores temporarily the transported liquid by the reciprocal pump, and discharges it, and a gas chamber
61
b
disposed inside the device body casing
60
, which is separated from the liquid chamber
61
a
via an extendable and contractible diaphragm
62
for suppressing pulsation, so as to seal a gas, whereby the pulsation suppression diaphragm is extendably and contractibly deformed by pulsation of the discharge pressure of the pump. The proposed device has the above configuration, thereby making it possible to damp the pulsation by change of the capacity of the liquid chamber
61
a.
When the discharge pressure of the reciprocal pump is fluctuated, it is necessary to keep the deformation amount of the pulsation suppression diaphragm
62
caused by extension and contraction, within a predetermined range, so that the liquid pressure inside the liquid chamber
61
a
and an atmospheric pressure inside the gas chamber
61
b
may balance each other. Therefore, the device as shown in
FIG. 4
adopts the following configuration. The device body casing
60
is provided with an automatic gas supply valve mechanism
63
and an automatic gas exhaust valve mechanism
64
. When the pulsation suppression diaphragm
62
is extendably deformed by the fluctuation of the liquid pressure inside the liquid chamber
61
a,
in the direction wherein the capacity of the liquid chamber is increased so as to be above a standard value S, thereby exceeding a predetermined range A, the diaphragm
62
for suppressing pulsation opens the gas supply port
66
via the valve press rod
65
of the automatic gas supply valve mechanism
63
, thereby adjusting the gas sealing pressure of the gas chamber
61
b
so as to be increased. Moreover, when the diaphragm
62
for suppressing pulsation is contractibly deformed in the direction wherein the capacity of the liquid chamber is decreased so as to be below the standard value S, thereby exceeding a predetermined range B, the automatic gas exhaust valve mechanism
64
opens the gas exhaust port
68
by means of a slider
67
abutting against an closed end portion
62
a
of the diaphragm
62
for suppressing pulsation. As a result, the gas inside the gas chamber
61
b
is exhausted and adjusted so as to decrease the gas sealing pressure.
On the other hand, a pulsation suppression device for a pump disclosed in Japanese Patent Publication Laying-open No. 8-159016 is shown in
FIG. 5A. A
switching valve mechanism for switching between gas supply and gas exhaust is shown in FIG.
5
B. The proposed device adopts a gas chamber internal pressure adjusting valve mechanism for restricting the change of the capacity of the liquid chamber
61
a
disposed in the same way as the liquid chamber
61
a
disclosed in Japanese Patent Publication Laying-open No. 6-17752 so as to be within the predetermined range of the displacement of the capacity. In the mechanism, the switching valve mechanism for switching between gas supply and gas exhaust having an operating rod
69
and a slide valve element
71
is protrusively fitted on an outer side of the device body casing
60
. The operating rod
69
is operated according to a displacement of the closed end side
62
a
of the diaphragm
62
for suppressing pulsation. The slide valve element
71
makes a gas supply and exhaust passage
70
for using both gas supply and gas exhaust, alternatively connect to the gas supply port
66
and the gas exhaust port
68
. The gas supply and exhaust passage
70
is operated by the operating rod
69
so as to communicate with the gas chamber
61
b.
The valve mechanism has the structure as below. The valve mechanism makes the gas supply port
66
connect to the gas supply and exhaust passage
70
when the capacity of the liquid chamber
61
a
is increased so as to be above the predetermined range. The valve mechanism makes the gas exhaust port
68
connect to the gas supply and exhaust passage
70
when the capacity of the liquid chamber
61
a
is decreased so as to be below the predetermined range. It has a cylindrical casing
72
provided with the gas supply and exhaust passage
70
which communicates with the gas supply port
66
, the gas exhaust part
68
, and the gas chamber
61
b,
and the slide valve element
71
which is coaxially coupled to the operating rod
69
so as to be slidably and displaceably engaged with the inside of the cylinder
73
housed inside the cylindrical casing
72
.
Among the two prior arts mentioned above, the device disclosed in the former one, i.e., Japanese Patent Publication Laying-open No. 6-17752, has a structure wherein the automatic gas supply valve mechanism
63
and the automatic gas exhaust valve mechanism
64
are integrally formed with the lower side member
60
a
as an element of the device body casing
60
. Therefore, when either of valve mechanisms
63
,
64
is damaged or destroyed, it is necessary to disassemble and repair the device body or replace a whole of the body. This requires much labor, thereby resulting in disadvantage in maintenance and cost. Moreover, the gas exhaust port
68
of the automatic gas exhaust valve mechanism
64
is structurally confined by a phenomenon wherein a gas exhaust valve element
75
drops owing to its weight. Therefore, the closing action is unstable, and the device must be installed so as to keep vertical arrangement relationship between the gas exhaust valve element
75
and the gas exhaust port
68
. For example, it cannot be allowed that the device is installed so that the gas exhaust valve element
75
may be horizontally arranged. As a result, kinds of the device are restricted.
The switching valve mechanism for switching between gas supply and gas exhaust disclosed in Japanese Patent Publication Laying-open No. 8-159016, i.e., the latter one, adopts a configuration wherein one valve is used for both the gas supply and the gas exhaust. Therefore, it is not necessary to disassemble the device body. It is efficient only to disassemble the switching valve mechanism and repair or replace it. In case of closing the gas supply port
66
and the gas exhaust port
68
, this does not structurally rely on the weight of the gas exhaust valve element
75
, which is different from the former one, thereby making it possible to overcome the problem in the former one. However, on the other hand, it has disadvantages as below. The structure of the switching valve is very complicated, the seal of the slide valve element
71
is so difficult, and it protrudes to the outside of the device body casing
60
, whereby a whole of the device is bulky and large-sized.
The present invention has been conducted in view of the above mentioned circumstances. Especially, an object of the present invention is to provide a pulsation damping device for a pump, which can be installed in either vertical or horizontal style by improving the gas exhaust valve mechanism. This can diversify kinds of the device.
Moreover, another object of the present invention is to provide the pulsation damping device for a pump whose structure is simple, which can be economically produced, and wherein it is easy to maintain the gas supply and exhaust valves.
DISCLOSURE OF THE INVENTION
A pulsation damping device fo
Jones Tullar & Cooper P.C.
Koczo Michael
Nippon Pillar Packing Co. Ltd.
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