Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
DIAPHRAGM PUMP
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a diaphragm pump, and
more particularly, relates to a diaphragm pump for effectively
preventing pulsation of liquid by providing a first pump
chamber for installing a diaphragm and a second pump chamber
for arranging a cylindrical partitioning plate having an
opening area at a lower portion.
Background of the Related Art
Generally, a typical diaphragm pump pumps liquid by
translating rotational movement of a motor into a
reciprocating, movement by a device such as a cam. Since the
amount of the discharged liquid from the diaphragm pump
fluctuates by small amounts of volume, the diaphragm pump is
generally used for precisely instilling liquid chemicals or
medicines.
Fig. lA to lE are cross sectional views illustrating one
embodiment of a conventional diaphragm pump. As shown in Fig.
lA, a diaphragm 110 is supported by a supporting ring 120 to
form a pump chamber 130 in an open end of a pump head 100. A
suction hole 105 and a discharge hole 106 are located at the
upper portion and the lower portion of a body 102, respectively.
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The suction hole 105 and the discharge hole 106 are
opened/closed by a check ball 140. Referring to Fig. 1C, an
opening-side valve seat 141 having a cross-shaped groove is
formed on a suction end of the suction hole 105 of the pump
head 100 and an end of a discharge-side connector 160. A
closing-side valve seat 142 having tapered shape is formed at
an end of a suction connector 150 and a discharge side of the
discharge hole 106 of the pump head 100.
The following describes the operation of the diaphragm
pump constructed in such a manner as mentioned above.
When a motor (not illustrated) is driven to operate the
pump, the rotational movement of the motor is translated into
the reciprocating movement of a diaphragm shaft 111 by a
device such as an eccentric cam, and thereby the diaphragm 110
is driven back and forth. Fig. lA illustrates a state of the
diaphragm being driven back, that is, a suction process, and
Fig. 1B illustrates a state of the diaphragm being driven
forward, that is, a discharge process.
During the suction process, due to internal pressure,
each check ball 140 of the suction side and the discharge side
moves toward the center of the pump head 100. Subsequently,
since the opening-side valve seat 141 is formed at the end of
the suction hole 105 of the pump head 100, liquid is drawn to
the pump chamber through the cross-shaped groove. Further, the
discharge hole 106 is closed by the check ball 140 during the
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suction process. On the other hand, during the discharge
process, each check ball 140 moves away from the pump head 100
to the outside such that the suction hole 105 is closed by the
check ball 140 and only the discharge hole 106 is opened.
Subsequently, the liquid in the pump chamber 130 is discharged
through the cross-shaped groove formed at the discharge-side
connector 160.
The advantage of such a conventional diaphragm pump in
the long term is that the average amount of the discharged
liquid is very constant. However, since the pumping operation
is separated into the suction process and the discharge
process, and it is intermittently performed, there results a
fundamental problem of a pulsation of the discharged liquid,
as shown in Fig. 1D.
Tn order to prevent such a pulsation of the discharged
liquid, two or more pumps are connected in parallel and
operated in different strokes, as shown in Fig. lE. Referring
to Fig. 2, another method is explained. By installing an air
chamber 200 at the center of a liquid pipe passage, during the
discharge process, the air in the air chamber 200 is
pressurized, and thereby the amount of the discharging liquid
from a discharge pipe 210 is reduced. During the suction
process, due to the expansion force of the pressurized air,
the liquid stored in the air chamber 200 during the discharge
process is discharged through the discharge pipe 210.
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In Figure 2, numeral 201 designated a pressure gauge.
Reference numeral 220 indicates a safety valve for receiving
high-pressured liquid through a return pipe 230. Safety valve
220 opens in the event that the pressure of the liquid
surpasses a predetermined pressure value.
However, the benefit of using two or more pumps
connected in parallel is significantly offset by the
substantial increase in installation cost. Moreover, it is
difficult to install the air chamber at the center of the
liquid pipe passage. Also, it is unsuitable to establish an
air chamber when the connector of the pump or the liquid pipe
passage is of the tube type. Furthermore, damage frequently
occurs to the connector caused by the vibration of the air
chamber when operating the pump. Furthermore, since such a
method cannot fundamentally remove the pulsation of the
discharged liquid, water hammering caused by the pulsation can
be generated and it may destroy pipes, especially at high
pressures.
SUI~lARY OF THE INVENTION
Therefore, the present invention attempts to overcome these
problems by providing a diaphragm pump having a simple
structure for efficiently preventing the pulsation of a
discharged liquid.
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Accordingly, the present invention provides a diaphragm pump
for pumping liquid, the pump comprising:
a body;
a dividing wall for internally dividing said body into a
first pump chamber and a second pump chamber;
a diaphragm installed in said first pump chamber;
a driving means for moving said diaphragm back and forth;
a cover plate sealing said second pump chamber;
a partitioning plate in the second pump chamber for
forming a constant pressure chamber having pressurized
air in an inside portion, wherein the partitioning plate
has an opening area on a lower portion;
an inlet in fluid communication with said first pump
chamber, said inlet having an inlet valve;
a discharge path for connecting said first pump chamber
and said second pump chamber;
a discharge valve for opening/closing said first
discharge path;
a discharge outlet formed on said second pump chamber.
In accordance with another aspect of the present invention,
the discharge path defines a discharge valve installation hole
for the discharge valve. Further, the discharge valve
includes a valve body having a hollow interior with an open
end and a closed end to house a check ball moveable within the
interior, the closed end having a plurality of perforations, a
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valve seat at the open end of the valve body, and a protrusion
extending from the closed end of the valve body engagable by a
cap installable into the discharge valve installation hole to
retain the valve body in the hole.
In accordance with yet another aspect of the present invention
the pump further includes a pressure control channel and a
high pressure liquid collecting channel, the pressure control
channel being in fluid communication with the constant
pressure chamber. There is additionally provided a valve
plate which covers both an end of the pressure control channel
and an end of the high pressure liquid collecting channel, and
a supporter for elastically supporting the valve plate against
the ends. If the pressure in the second pump chamber exceeds
a predetermined pressure, the supporter is biased to discharge
liquid under pressure in the pressure chamber through the
pressure control channel and the high pressure liquid
collecting channel.
BRIEF DESCRIPTION OF THE DRAWINGS
The advantages of the present invention will be more
clearly understood from the following detailed description
taken in conjunction with the accompanying drawings, in which:
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Fig. lA and 1B are cross sectional views showing the
structure and operation of a conventional diaphragm pump;
Fig. 1C is a plan view of an opening-side valve seat
having a cross-shaped groove;
Fig. 1D is a graph showing a pulsation of the amount of
discharged liquid of a conventional diaphragm pump of Fig. 1A;
Fig. lE is a graph showing a pulsation of the amount of
the discharged liquid in the case of reducing the pulsation
effect;
Fig. 2 a schematic view showing an air chamber and a
safety valve being installed on a conventional liquid pipe
passage;
Fig. 3 is a cross sectional view of a diaphragm pump
according to a preferred embodiment of the present invention;
Fig. 4 is a front elevational view of a constant pressure
chamber cut from the Line A to A' of Fig. 3;
Fig. 5 is an exploded perspective view of a diaphragm
pump according to a preferred embodiment of the present
invention;
Fig. 6 is a partially cutaway view showing a discharge-
side valve body; and
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Figs. 7 and 8 are cross sectional views illustrating
other embodiments according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The characteristics and advantages of the above-described
invention will be more clearly understood via the preferred
embodiments shown in the attached drawings.
Figs . 3 through 6 illustrate the structure and operation
of a diaphragm pump according to one embodiment of the present
invention. Fig. 3 is a cross sectional view, Fig. 4 is a front
elevational view of a constant pressure chamber taken by line
A to A' of Fig. 3, wherein the constant pressure chamber is
formed by a cylindrical partitioning plate having an opening,
Fig. 5 is an exploded perspective view of a diaphragm pump and
Fig. 6 is a partially cutaway view of a one-way discharge
valve body.
Referring to Figure 3, a cylindrical body 11 is divided
into right and left portions by a dividing wall 12 to form a
first pump chamber 13 and a second pump chamber 14.
A diaphragm 110 is compressively installed over an open
end of the first pump chamber 13 by a support ring 120. A
cover plate 15 is connected to an open end of the second pump
chamber 14 with a gasket 75 as an intermediary. A cylindrical
partitioning plate 21 having an opening 22 in the lower
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portion is installed in an inner portion of the second pump
chamber 14. In pumping operation, air in the second pump
chamber 14 is stored under pressure in the cylinder
partitioning plate 21, by the flow of liquid through an
outside portion of the cylindrical partitioning plate 21. The
cylinder partitioning plate 21 thereby defines a constant
pressure chamber 23.
An inlet 16 is farmed on a lower portion of the first
pump chamber 13. A one-way inlet valve 30, which includes a
suction-side valve body 32, a suction-side check ball 33 and a
suction-side valve seat 34, is installed on an inside portion
of a suction-side connector 31, wherein the suction-side
connector 31 is connected to the inlet 16. An outlet 18 is
formed on an upper portion of the second pump chamber 14 and
connected to a discharge-side connector 51.
A discharge path 17 is formed in the dividing wall 12 for
connecting the first pump chamber 13 and the second pump
chamber 14 and a discharge valve installation hole 45 is
formed intermediate the length of discharge path 17. A one-way
discharge valve 40, which includes a discharge-side valve body
42, a discharge-side check ball 43 and a discharge-side valve
seat 44, is installed on an inside portion of the discharge
valve installation hole 45. Referring to Figure 6, the
discharge-side valve body 42 defines a ball guide hole 42c and
a perforation 42b. The suction-side valve body 32 is formed
similarly with a ball guide hole and a perforating hole.
However, the discharge-side valve body 42 also forms a
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protrusion 42a on an upper portion. When a cap 41 is inserted
into the open end of the discharge valve installation hole 45,
the protrusion 42a is pressed by the end surface of the cap
41. Accordingly, the discharge-side valve body 42 is fixed in
place within the discharge valve installation hole 45, and the
space around the protrusion 42a forms a part of the discharge
path 17.
By structuring the one-way discharge valve according to
the present invention, the one-way discharge valve is more
exactly operated compared to a conventional valve means as
shown in Fig. 1C, can prevent the chattering, which occurs
with a conventional valve, and has increased durability of the
valve seat portion.
In Figures 3 to 5 and 7, 8, the description related to
reference numeral: 61 indicates a drain pipe; 62 indicates a
drain valve; 71 through 74 designate seals for preventing the
leakage of air and liquid; and 76 indicates a bolt for
connecting a cover plate, the cylindrical body and the support
ring.
The following describes the operation of the diaphragm
pump formed as the above-mentioned embodiment.
The state of the constant pressure chamber 23 in
operation is shown in Fig. 4. Specifically, the liquid to be
pumped is filled in the space between the cylindrical
partitioning plate 21 and the cylindrical body 11 and in the
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lower portion of the constant pressure chamber. The
pressurized air filled in the constant pressure chamber 23 is
isolated from the external environment by the gasket 75 and
the liquid filled in the lower portion, and the amount of the
air in the constant pressure chamber 23 is constant.
The state of the diaphragm 110 in forward movement, that
is in the discharge process, is shown in Fig. 3. In the
discharge process, the discharge-side check ball 43 moves up
to open the discharge path 17. Simultaneously, the liquid
previously collected in the first pump chamber 13 during a
previous suction process is discharged to the inside portion
of the second pump chamber 14 via the discharge path 17.
Simultaneously, as the liquid pressure increases on the inside
portion of the second pump chamber 14, the air in the constant
pressure chamber 23 experiences a greater pressure due to the
level of the liquid in the constant pressure chamber rising.
In other words, all of the pumped liquid flowing to the inside
portion of the second pump chamber 14 via the discharge path
17 is not discharged through the outlet 18. A certain portion
of the pumped liquid creates a rising level of the liquid in
the constant pressure chamber 23 and increasing the air
pressure, so that sudden change in the amount of liquid being
discharged through the outlet 18 is prevented.
On the other hand, during a suction process, the one-way
discharge valve 40 is closed to prevent reverse flowing of
liquid from the inside portion of the second pump chamber 14
to the first pump chamber 13, and liquid discharged from the
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first pump chamber 13 to the second pump chamber 14 is
stopped. However, due to air pressure in the constant pressure
chamber 23 which was pressurized during the previous discharge
process, the liquid in the inside portion of the second pump
chamber 14 is continuously discharged through the outlet 18
and the discharge-side connector 51, and the liquid level in
the constant pressure chamber 23 gradually decreases.
Accordingly, the amount of discharged liquid from the second
pump chamber 14 is not decreased rapidly, and it is almost
equal to the amount of the liquid discharged during the
discharge process of the first pump chamber 13.
Fig. 7 is a sectional view showing another embodiment of
the present invention. Referring to Fig. 7, a pressure control
channel 81 and a high pressure liquid collecting channel 82
are formed on a cover plate 15, to which the open end of the
second pump chamber 14 is connected. A valve plate 83 is
installed on an outside surface of the cover plate 15 to cover
both an end of the pressure control channel 81 and an end of
the high pressure liquid collecting channel 82, wherein the
valve plate 83 is elastically supported by a spring 85.
Preferably, the valve plate 83 is made of an elastic material.
The spring 85 is installed on an inside portion of a spring
casing 84, wherein the spring casing 84 is connected to one
side portion of the cover plate 15 by means of a screw. The
valve plate is smoothly operated by installing a push plate 86
between the spring 85 and the valve plate 83. A cap 88 is
connected to an end portion of the spring casing 84 for
controlling the elasticity of spring 85 by means of a screw. A
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spring seat 87 is formed between the cap 88 and the spring 85
for safely receiving the spring.
By structuring the pump in the above-mentioned manner,
when the pressure in the second pump chamber 14 exceeds a
predetermined pressure, the valve plate 83 is elastically
deformed and simultaneously, the spring 85 is compressed.
Accordingly, the liquid under pressure in the second pump
chamber 14 is discharged through the pressure control channel
81 and the high pressure liquid collecting channel 82.
Accordingly, as shown in Fig. 2, the pump apparatus of the
present invention can control the pressure in the pump and the
discharge path below a predetermined pressure without
installing an extra safety valve on the discharge path.
Accordingly, the installation of the pump apparatus becomes
much easier, thereby reducing installation costs.
Differing from the embodiment of the Fig. 3, Fig. 8 is
another embodiment of the present invention. The cylindrical
body 11 is divided into a first pump chamber body lla and a
second pump chamber body llb. The second pump chamber body
llb, the cover plate 15 and the cylindrical partitioning plate
21 are integrally formed in the embodiment of the Fig. 8, and
together define the constant pressure chamber. An annular
channel 24 provides a path for the flow of liquid between the
discharge path and the constant pressure chamber. Liquid may
pass into and out of the constant pressure chamber through the
opening 22.
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If the pump is not made of injection-molded resins but
metal such as a stainless steel, the embodiment of Fig. 8 is
less expensive than that of Fig. 3 from the point of view of
the production process and production costs. Further, the
S annular channel 24 can be relatively narrow, and does not have
to extend the full length of the constant pressure chamber
As described above, the diaphragm pump of the present
invention proficiently prevents the pulsation effect of the
l0 discharge liquid. Moreover, since there is no need for
installing extra parts, such as an air chamber and pipes, the
installation of the pump becomes much easier, thereby reducing
the installation costs.
15 Furthermore, even if an air chamber is installed to
reduce the pulsation of liquid according the conventional
method, the liquid is still discharged intermittently from a
diaphragm pump. As a result, the conventional diaphragm pump
is noisy, and the pipes are frequently damaged due to the
20 water hammer effect. However, since the diaphragm pump of the
present invention reduces the pulsation of the liquid with the
pump itself before discharging the liquid, the pipes are
guarded from such damage, and the level of noise can be
reduced.
Even though the present invention has been described in
application to a certain type of diaphragm pump for
convenience, it should be noted that the present invention can
be applied to any other type of diaphragm pump or any other
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type of pump in which the pulsation of the liquid is occurring
by the intermittent suction and discharge.
While the present invention has been described in
connection with preferred embodiments, various modification
and equivalent arrangements can be made without violating the
scope and spirit of the invention.
