Pumps – One fluid pumped by contact or entrainment with another – Liquid pumped by supplying or exhausting gaseous motive...
Reexamination Certificate
1997-08-08
2001-06-12
Freay, Charles G. (Department: 3746)
Pumps
One fluid pumped by contact or entrainment with another
Liquid pumped by supplying or exhausting gaseous motive...
C417S133000, C417S135000, C137S418000, C137S196000
Reexamination Certificate
active
06244828
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pump and trap for feeding a liquid such as water, fuel, etc. The pump and trap of the present invention is suitable particularly for use in collecting a condensate generated in a steam piping system and feeding this condensate to a boiler or a waste heat recovery system.
2. Description of the Related Art
Condensate generated in a steam piping system in most cases still has a considerable quantity of heat. It therefore has been a widespread practice to provide a condensate recovery system, including a pump for recovering the condensate and feeding it into a boiler or a waste heat recovery system for the purpose of effective utilization of waste heat from the condensate, thus making effective use of this energy.
The pump used in prior art condensate recovery system collects the condensate in a vessel, and then introduces a high-pressure working fluid—such as steam—into the vessel by operating a change-over valve. The pressure of the high-pressure working fluid discharges the condensate from the inside of the vessel. To insure high-efficiency operation of the pump, it is necessary to collect as much condensate as possible within the vessel and to properly switch the change-over valve.
The pump of the prior art, therefore, generally adopts a snap mechanism, provided with a coil spring. in order to insure reliable switching of the change-over valve. A pump which is equipped with a built-in snap mechanism provided with a coil spring is disclosed in U.S. Pat. No. 5,141,405, to Francart.
FIG. 13
is a front view of a snap mechanism used in the prior art pump described in the Francart patent. In the pump disclosed in the Francart patent, the snap mechanism
100
comprises a main arm
101
, a first arm
102
, and a coil compression spring
103
. The main arm
101
is pivotally supported, by a first shaft
106
, on a supporting member or frame
105
. On the forward end of the main arm
101
is connected a float
108
, through a screw member
104
which is fastened to the float
108
.
The first arm
102
is connected at one end to the supporting member
105
by the first shaft
106
, and therefore to the main arm
101
, and at the other end to one end of the coil spring
103
by a third shaft
110
, through a spring bracket member
116
. The other end of the coil spring
103
is connected to the main arm
101
by a second shaft
112
through a spring bracket member
115
. A valve spindle operating rod
111
is connected by a shaft
107
to the center part of the first arm
102
. The valve spindle (not shown) and the snapping mechanism
100
are linked to the change-over valve through the valve spindle operating rod
111
.
In the prior art pump, accumulation of condensate in the vessel (not shown) causes the float
108
to rise. As the float
108
rises, the spring bracket member
115
side of the coil spring
103
moves upward, thus compressing the coil spring
103
. With further rise of the float
108
, the coil spring
103
is in line with the first arm
102
. The float
108
rises further until an angle between the coil spring
103
and the first arm
102
exceeds 180 degrees. As a result, the coil spring
103
suddenly recovers from compression, and the connecting section (the third shaft
110
) between the coil spring
103
and the first arm
102
snaps downward. This movement results in downward movement of the valve spindle operating rod
111
connected to the first arm to thereby suddenly switch the change-over valve (not shown).
The prior art pump has a problem—notwithstanding its simple design and its ability to relatively efficiently pump liquid—that a great deal of buoyancy, or a large float, is needed to obtain a large force for proper switching of the change-over valve. This is because, in a triangle formed by the first shaft
106
, the second shaft
112
, and the third shaft
110
, the distance between the first shaft
106
and the second shaft
112
is longer than that between the first shaft
106
and the third shaft
110
. The distance between the first shaft
106
and the second shaft
112
is long, and accordingly the magnification of buoyancy produced by the main arm
101
and transmitted to the first arm
102
is small. Furthermore, since the distance between the first shaft
106
and the third shaft
110
is short, the magnification of buoyancy by the first arm
102
which is transmitted to the valve spindle operating rod
111
is also small.
SUMMARY OF THE INVENTION
In the view of the above-described disadvantages inherent to the prior art apparatus, it is an object of the present invention to provide a pump which is capable of actuating the change-over valve with a large force, even with a float with little buoyancy, while still performing reliably.
The present invention features a pump in which a float, a change-over valve, and a snap mechanism are built in a vessel having a working fluid inlet port, a working fluid discharge port, a liquid inlet port, and a liquid discharge port. The snap mechanism includes a first shaft pivotally supported within the vessel, a main arm rotating around the first shaft, a first toggle link rotating around the first shaft, a second shaft pivotally supported functionally on the main arm at a point spaced a small distance from the first shaft and parallel with the first shaft, a third shaft pivotally supported functionally to the first toggle link at a point spaced a large distance from the first shaft and parallel with the first shaft, and a second toggle link mounted between the second shaft and the third shaft and pivotable at both mounting positions. A connecting mechanism functionally connects the float to the main arm at a point spaced from the first shaft, and another connecting mechanism functionally connects the change-over valve to the first toggle link. A compressible-expandable mechanism, which compresses to keep the first toggle link at rest until the second shaft is aligned with the first shaft and the third shaft, extends when the second shaft has gone beyond the position of alignment with the first shaft and the third shaft, thus snapping to move the first toggle link.
In the pump of the present invention, accumulation of condensate in the vessel causes the float to rise to rotate the main arm around the first shaft, and the second shaft moves between the first shaft and the third shaft until aligning with the first shaft and the third shaft, thus compressing to deform the compressible-expandable mechanism. As the float goes further upward, the second shaft exceeds the position of alignment with the first shaft and the third shaft and the compressible-expandable mechanism suddenly extends to recover from deformation, thus snapping to move the third shaft. As a result, the change-over valve is suddenly switched, allowing liquid accumulated within the vessel to be pumped.
In the snap mechanism used in the pump of the present invention, the distance between the first shaft and the third shaft is longer than that between the first shaft and the second shaft. In a triangle formed by the first shaft, the second shaft and the third shaft, the distance between the first shaft and the second shaft is short while the distance between the first shaft and third shaft is long; the magnification of buoyancy by the main arm which is transmitted to the first toggle link is therefore large and the magnification of buoyancy by the first toggle link which is transmitted to the change-over valve is also large. Consequently, the change-over valve can operate properly with great force even when little buoyancy, i.e., a small float, is used.
The present invention also includes a valve at the liquid discharge port which acts as a trap for the vessel. The valve is connected to the float mechanism, so that the valve opens when the float rises in response to accumulation of liquid in the vessel. The valve ensures that a liquid seal is maintained at the liquid discharge port. The valve includes a double seal, to equalize fluid pressure on the valve and the
Freay Charles G.
Kenyon & Kenyon
TLV Co. Ltd.
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