US20050287009A1

US20050287009A1 - Metered quantity transfer device

Info

Publication number: US20050287009A1
Application number: US10/536,372
Authority: US
Inventors: Tadashi Kukitome
Original assignee: Tacmina Corp
Current assignee: Tacmina Corp
Priority date: 2002-11-28
Filing date: 2003-11-21
Publication date: 2005-12-29
Also published as: EP1574713A1; WO2004048780A1; EP1574713A4; AU2003284657A1; EP1574713B1

Abstract

It is an object of the present invention to provide a metering delivery device that is capable of keeping the fluid discharge rate at a predetermined level for a long time by using a metering pump without the necessity of adjustment or the like. In order to achieve this object, there is provided a metering delivery device 10 with a metering pump 11 disposed in a delivery passage 31 for fluid delivery, which is characterized in that it includes a discharge rate checker 12 disposed in the delivery passage 31 downstream of the metering pump 11, and a constant pressure valve 13 disposed in the delivery passage 31 downstream of the discharge rate checker 12, in which the driving condition of the metering pump 11 is controlled based on a detection signal of the discharge rate checker 12.

Description

FIELD OF THE INVENTION

The present invention relates to a metering delivery device that has a metering pump disposed in a delivery fluid passage through which fluid is delivered.

BACKGROUND OF THE INVENTION

In such as chemical or medical fields, in which various chemical products are manufactured such as by delivering chemical agents, medicinal agents and the like, it is highly necessary to deliver strongly acid or strongly alkali fluid in a measured or regulated amount. For achieving such metering delivery, various types of metering pumps are conventionally used.
As such a metering pump, a diaphragm reciprocating pump (hereinafter referred simply to a reciprocating pump) that delivers fluid by driving (reciprocating) a diaphragm or the like is known.
The reciprocating pump thus arranged by the use of a diaphragm converts rotational motion obtained by a driving means such as a motor to linear reciprocating motion via a cam and drives the diaphragm through this linear reciprocating motion.
The above reciprocating pump, which delivers fluid based on the reciprocating motion of the diaphragm, pressurizes fluid within a pump head by a forward stroke of the diaphragm, thereby pushing out fluid (a forward stroke process), and decreases pressure within the pump head by a backward stroke of the diaphragm, thereby pulling in fluid (a backward stroke process).
A conventional reciprocating pump enables metering delivery as a whole by repeating a given number of relatively short forward and backward strokes for a given time. Specifically, the reciprocating pump is disposed in a fluid delivery passage, and a metering delivery device is basically made up by the use of only this reciprocating pump so as to achieve fluid metering delivery.
The above conventional metering delivery device has a problem mentioned below.
The above conventional metering delivery sets the fluid discharge rate and the like based on a driving signal (pulse number or the like) supplied from an electric power unit or the like. That is, a given relationship is established between the driving signal (pulse number or the like) and the fluid discharge rate under a certain condition, and therefore the fluid discharge rate (pulse number or the like) is determined in light of this condition.
However, in a case where the metering pump is actually driven, the above “certain condition”, which was originally expected, may not be kept in an upstream or downstream side (particularly in the downstream side), which poses a problem of making it hard to keep the fluid discharge rate at a predetermined level for a long time.
The present invention has been conceived in order to solve the problem associated with the above conventional technique. It is an object of the present invention to provide a metering delivery device that is capable of keeping the fluid discharge rate at a predetermined level for a long time by using a metering pump without the necessity of adjustment or the like.

SUMMARY OF THE INVENTION

According to the present invention conceived to solve the above problem, there is provided a metering delivery device with a metering pump disposed in a delivery passage for fluid delivery, which is characterized in that it includes a discharge rate checker disposed in the delivery passage downstream of the metering pump, and a constant pressure valve disposed in the delivery passage downstream of the discharge rate checker, in which the driving condition of the metering pump is controlled based on a detection signal of the discharge rate checker.
With the above arrangement, the metering pump is driven based on a predetermined setting, the fluid discharge rate during the driving is detected by the discharge rate checker, and the driving condition of the metering pump is controlled based on this detection signal. That is, the metering pump is properly controlled by using the discharge rate checker, not relying on only the preset condition of the metering pump, so that the metering pump can keep the discharge rate at a preset level for a long time.
Further, with the above arrangement having the constant pressure valve disposed downstream of both the metering pump and the discharge rate checker, even if the driving condition has been changed or the discharge rate has been fluctuated (which change lies within the set level of the constant pressure valve) on the downstream side of the constant pressure valve (a fluid using side), it is possible to limit the fluctuation of the fluid pressure in the delivery passage on the upstream side of the constant pressure valve. Therefore, the metering pump and the discharge rate checker properly function and hence the fluid discharge rate (discharge pressure) can be kept at a predetermined level with higher accuracy.
According to the present invention, there is also provided a metering delivery device with a metering pump disposed in a delivery passage for fluid delivery, which is characterized in that it includes a discharge rate checker disposed downstream of the metering pump, and a constant pressure valve disposed downstream of the discharge rate checker, in which the driving condition of the metering pump is controlled based on a detection signal of the discharge rate checker. That is, according to the present invention, the metering delivery device is formed with an integral arrangement of these elements.
With the above arrangement, the respective elements are integrally arranged without interposing of any delivery passages, and therefore it is possible to for example measure the discharge rate by the discharge rate checker with high accuracy without influences of such as pipe breakage. Therefore, it is possible to control the actual discharge rate of the metering pump with higher accuracy.
In the metering delivery device of the present invention, the metering pump is preferably a reciprocating pump with a moving part having a stroke length set constant, and the number of strokes of the moving part is controlled based on the detection signal.
According to the above preferred arrangement having the stroke length of the moving part set constant (e.g., 100%), it is possible to stabilize the discharge condition of the metering pump and increase the measuring accuracy of the discharge rate checker disposed downstream of the metering pump. That is, the increase of the measuring accuracy of the discharge rate checker makes it possible to adjust the discharge rate of fluid to be delivered by using the metering delivery device with higher accuracy.
In the metering delivery device of the present invention, the metering pump is preferably a reciprocating pump having a moving part that comprises at least one of a diaphragm, a plunger and a bellows.
In the metering delivery device of the present invention, the constant pressure valve preferably includes a diaphragm disposed in contact with fluid to be delivered, and an urging means provided to urge the diaphragm towards the fluid.
With the above preferred arrangement, the constant pressure valve has damper function, and therefore it is possible to reduce pulsation during the discharging operation of the metering pump, and hence improve controllability for control of the fluid discharge rate thanks to the reduction of pulsation.
The metering delivery device of the present invention preferably further includes a display means that displays an actual discharge rate of the metering pump based on a discharge rate signal of the metering pump.
The metering delivery device of the present invention preferably further includes a deviation alarm means that alerts based on an actual deviation obtained from an actual discharge rate and a target discharge rate, of the metering pump, and a preset given deviation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a metering delivery device according to an embodiment of the present invention.
FIG. 2 is a schematic view of a metering delivery device according to another embodiment of the present invention.
FIG. 3 is a schematic view of a metering delivery device having an integral structure according to still another embodiment of the present invention.
FIG. 4 is an enlarged cross sectional view of a constant pressure valve of the metering delivery device of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The description will be made for the embodiments of the present invention with reference to the accompanied drawings.
FIG. 1 is a schematic view of a metering delivery device according to an embodiment of the present invention. A metering delivery device 10 of this embodiment includes a metering pump 11, a discharge rate checker 12 and a constant pressure valve 13.
More specifically, the metering delivery device 10 is disposed in a delivery passage 31 extending between a reservoir tank 21 as a fluid supply source and a conduit 22 for communication with a site at which fluid is used. The discharge rate checker 12 is provided in the delivery passage 31 downstream of the metering pump 11, and the constant pressure valve 13 is disposed in the delivery passage 31 downstream of the discharge rate checker 12.
The metering pump 11 of the metering delivery device 10 is designed to discharge fluid at a constant rate by the reciprocating motion of a diaphragm or the like in order to achieve a preset value. That is, the metering pump 11 of this embodiment determines the driving conditions (the number of strokes according to the discharge rate, the stroke length and the like) based on the ongoing calculation so as to achieve a preset fluid discharge rate. Therefore, in a normal driving condition, it is possible to discharge fluid in a given amount by using only the metering pump 11.
However, even with the thus arranged metering pump, the fluid discharge rate may be fluctuated depending on the change in operational condition or the like. As possible factors for such fluctuation, variation of the operational conditions due to pressure fluctuation in the conduit 22 (or a fluid-using site located downstream of the conduit 22), the temperature difference and the like are conceivable. The fluid discharge rate may be also fluctuated by the fluctuation of the voltage of the metering pump.
Thus, the metering delivery device 10 of this embodiment is arranged with the discharge rate checker 12 and the constant pressure valve 13 disposed downstream of the metering pump 11 in order to prevent the fluctuation of the fluid discharge rate of the metering pump 11 due to the influence of such as the above pressure fluctuation.
As illustrated in FIG. 1, in this metering delivery device 10, the metering pump 11 is electrically connected to the discharge rate checker 12 disposed downstream thereof via control wiring 41.
The discharge rate checker 12 is designed to measure the actual discharge rate of fluid delivered by the metering pump 11, perform comparison and calculation of a target discharge rate (a set value) and a measured discharge rate, and adjust such as the number of strokes of the metering pump 11 based on the calculated result.
More specifically, in this embodiment, the stroke length of the operational condition of the metering pump 11 is set constant (e.g., 100%), and the discharge rate checker 12 is disposed so as to detect (monitor) the discharge rate of fluid delivered under this operational condition. At this moment, the set value relative to the metering pump 11 is also recognized at the discharge rate checker 12. This discharge rate checker 12 is so arranged as to perform comparison and calculation of a measured value of delivered fluid (detection signal) and the set value, and automatically correct the number of strokes based on the calculated result.
In the metering delivery device 10 of this embodiment, the constant pressure valve 13 is disposed further downstream of the discharge rate checker 12. That is, the constant pressure valve 13 is disposed downstream of the discharge rate checker 12, which detects the actual discharge rate of the metering pump 11, so that influences of such as pressure fluctuation in the conduit 22 and the like can be limited.
The constant pressure valve 13 used in this embodiment is made up of for example a diaphragm disposed so as to contact delivery fluid, an urging means (a compression coil spring, a blade spring, etc.) for applying a given pressure to the diaphragm, and the like so that this urging means is adjusted (e.g., the length (compression length) of the compression coil spring is adjusted) to determine the regulation pressure of the constant pressure valve.
According to this embodiment, as described above, the constant pressure valve is made up of such as the diaphragm and the urging means so as to have damper function based on this structure. Therefore, it is possible to reduce pulsation during the discharging operation of the metering pump 11, and hence improve controllability for control of the fluid discharge rate thanks to the reduction of pulsation.
As described above, in this embodiment, the discharge rate checker 12 is disposed downstream of the metering pump 11 and the constant pressure valve 13 is disposed downstream of the discharge rate checker 12, so that the driving condition of the metering pump 11 is controlled based on the detection signal of the discharge rate checker 12. That is, in the metering delivery device 10 of this embodiment, the number of strokes of the metering pump 11 is controlled by using the discharge rate checker 12 in order to achieve a preset discharge rate by the metering pump 11. Also, the arrangement with the constant pressure valve 13 disposed downstream of the discharge rate checker 12 limits the influence of varied condition such as in the conduit 22 and the downstream side thereof, and hence stabilizes the discharge condition of the metering pump 11.
Therefore, according to the metering delivery device 10 of this embodiment, the metering pump 11 is properly controlled by using the discharge rate checker 12, not relying on only the set condition of the metering pump 11, and hence it is possible to keep the fluid discharge rate at a predetermined level for a long time. The arrangement with the constant pressure valve 13 disposed downstream of the discharge rate checker 12 can limit the pressure fluctuation on the upstream side of the constant pressure valve 13, allow the metering pump 11 and the discharge rate checker 12 to properly function, and keep the discharge rate (discharge pressure) at a given level with higher accuracy.
It is not necessary to limit the present invention to the above embodiment, and it is possible to make various modifications in addition to those mentioned above without departing from the scope of the present invention.
For example, the above embodiment was described by taking for example the case where the discharge rate checker 12 performs calculation and substantially controls the metering pump 11. The present invention is not necessarily limited to this arrangement and therefore a given control device may be provided according to needs and circumstances so as to control the metering pump 11. Specifically, a control device may be disposed in the control wiring 41 between the discharge rate checker and the metering pump 11, allowing the discharge rate checker to have a simple structure that only measures the discharge rate. With this arrangement, it is possible to easily achieve the metering delivery device of the present invention by using a conventional discharge rate checker.
Although no specific description was made for the structure of the metering pump 11 in the above embodiment, the metering pump 11 of the present invention is not necessarily limited to a specific structure, as long as it has a moving part that is reciprocated to deliver fluid (or it is a reciprocating pump). Therefore, for example, as long as the metering pump is a reciprocating pump that has a moving part like a diaphragm, plunger or bellows, it is possible to achieve the metering delivery device of the present invention by any structure.
The above embodiment was described by taking for example the case where the metering delivery device 10 is made up of the metering pump 11, the discharge rate checker 12 and the constant pressure valve 13. The present invention is not necessarily limited to this arrangement. As long as the metering delivery device has at least these elements, any other elements may be added to make up the metering delivery device.
Therefore, for example, as illustrated in FIG. 2, a metering delivery device 10′ may be achieved by adding an outside output device 14. Herein, the outside output device 14 is designed to have such as a display part (not shown) for display of the actual discharge rate of delivered fluid having been discharged by the metering pump 11, and a deviation alarm part (not shown) for alerting in a case where a “deviation” between the actual discharge rate and the target discharge rate has exceeded a given level.
In the arrangement as illustrated in FIG. 2, the metering pump 11 is driven based on a control signal obtained from the discharge rate checker 12 via the control wiring 41, and the actual discharge rate (discharge rate signal) measured and calculated by the metering pump 11 is transmitted to the outside output device 14 via output signal wiring 42. A display part (“display means” of the present invention) of the outside output device 14 displays the actual discharge rate of the metering pump 11 based on the discharge rate signal. That is, the user can easily follow the actual discharge rate of the metering pump 11 by the observation of the display part of the outside output device 14.
In this embodiment, an output signal (analogue signal) of 0-20 mA or 4-20 mA is transmitted via the output signal wiring 42, and the actual discharge rate is displayed on the display part based on this output signal. This embodiment is however not necessarily limited to this arrangement. The actual discharge rate may be displayed based on a digital signal obtained from the metering pump 11 according to needs and circumstances.
Further, in the embodiment of FIG. 2, in a case where a “deviation between the actual discharge rate and the target discharge rate has exceeded a preset level, alarm is provided, taking advantage of the characteristics resulting from the actual measurement of the discharge rate of the metering pump 11. For example, a target discharge rate and a given deviation (e.g., 1-20%) are set to (stored in) the metering pump 11, the actual deviation is calculated based on the actual discharge rate and the target discharge rate so that where the actual deviation exceeds the given deviation, a deviation alarm signal is transmitted to the outside output device 14 from the metering pump 11 via output signal wiring 43. In this embodiment, the deviation alarm part (corresponding to a “deviation alarm means” of the present invention) of the outside output device 14 alerts based on this deviation alarm signal. The deviation alarm part may be made up by using a light emitting means such as a lamp, a sound means such as a speaker or the like, or the combination of the light emitting means and the sound means.
With reference to FIG. 2, the description was made for the case where the discharge rate signal and the deviation alarm signal are transmitted to the outside output device 14 via the different output signal wirings. The present invention is not necessarily limited to this arrangement. It is also possible to employ an arrangement where only the discharge rate signal is transmitted to the outside output device 14. In this arrangement, a target discharge rate, a given deviation and the like are stored in the outside output device 14 so that the calculation of the actual deviation and the like, and the comparison and calculation of the given deviation and the actual deviation are made based on the discharge rate signal, and the deviation alarm part alerts based on this calculation result.
With reference to FIG. 2, the description was made for the case where the display part and the deviation alarm are disposed in the outside output device 14. The present invention is not necessarily limited to this arrangement. They may be arranged independently of each other (i.e., as a display device and a deviation alarm device).
Further, in the metering delivery device of the above embodiment, the description was made by taking for example the case where the metering pump 11, the discharge rate checker 12 and the constant pressure valve 13 are disposed independently of each other in the delivery passage 31. The present invention is not necessarily limited to this arrangement. Two or more than two of these elements may be integrally arranged according to needs and circumstances.
Accordingly, for example, as illustrated in FIG. 3, all the elements are integrally arranged so as to make up a metering delivery device 10″. According to the metering delivery device 10″ of FIG. 3, the discharge rate checker 12 is connected to a delivery fluid discharge port of the metering pump 11; the constant pressure valve 13 is connected to a portion downstream of the discharge rate checker 12; and a relieve valve 15 is disposed opposite to the constant pressure valve 13. That is, in this embodiment, the thus integrally arranged metering delivery device 10″ is disposed in the delivery passage 31.
According to the metering delivery device 10″ as illustrated in FIG. 3, the respective elements are integrally arranged without interposing of any delivery passages, so that, for example, it is possible to measure the discharge rate with high accuracy by the discharge rate checker 12 without any influences of such as pipe breakage. As a result, it is possible to control the actual discharge rate of the metering pump 11 with higher accuracy.
FIG. 4 is an enlarged cross sectional view of the constant pressure valve 13 of the metering delivery device 10″ as illustrated in FIG. 3.
In FIG. 4, the constant pressure valve 13 of this embodiment is made up by using such as a diaphragm 131 being in contact with fluid passages 32, 33 that are held in communication with the delivery passage 31, a compression coil spring 132 for applying an urging force to the diaphragm 131, a spring guide 133 disposed between the diaphragm 131 and the compression coil spring 132, and a spring retainer 134 for pressing the compression coil spring 132 towards the spring guide 133.
According to the constant pressure valve 13 of this embodiment, a given pressure is set to the constant pressure valve 13 through the adjustment of the compressed length of the compression coil spring 132 or the like by the spring retainer 134. Flow-in of delivery fluid with a pressure not smaller than a given pressure causes the diaphragm 131 to be bent in a direction of arrow X and hence achieves proper fluid delivery.
Herein, the detailed description for the structure of the relief valve 15 was omitted. As the relief valve 1 ₅, for example, a similar structure to the constant pressure valve 13 may be used. In this case, it is possible to properly deliver fluid by setting a set pressure of the relief valve 15 at a pressure level greater than the set pressure of the constant pressure valve 13 by an adjustment bolt, as long as the fluid has a pressure that is not smaller than the set pressure of the constant pressure valve 13 but is smaller than the set pressure of the relief valve 15. Also, it is possible to properly discharge fluid to the outside of the delivery passage 31 via a relief conduit (not shown) provided in the relief valve 15, as long as the fluid has a pressure that is not smaller than the set pressure of the relief valve 15. It is possible to properly protect a conduit and the like by providing the thus arranged relief valve 15, even in a case where fluid having a pressure not smaller than the set level has been delivered.
As described above, according to the present invention, a metering delivery device has a metering pump that is disposed in a fluid delivery passage for delivering fluid, in which a discharge rate checker is provided in the fluid delivery passage downstream of the metering pump; a constant pressure valve is disposed in the fluid delivery passage downstream of the discharge rate checker; and the driving condition of the metering pump is controlled based on a detection signal of the discharge rate checker.
As a result, according to the present invention, since the metering pump can be properly controlled by the discharge rate checker while limiting influences on the downstream side of the constant pressure valve, it is possible to have the metering delivery device that is capable of automatically keeping the discharge rate at a preset level for a long time without any adjustment.

Claims

1. A metering delivery device with a metering pump disposed in a delivery passage for fluid delivery comprising:

a discharge rate checker disposed in the delivery passage downstream of the metering pump, and a constant pressure valve disposed in the delivery passage downstream of the discharge rate checker; wherein

the driving condition of the metering pump is controlled based on a detection signal of the discharge rate checker.

2. A metering delivery device with a metering pump disposed in a delivery passage for fluid delivery comprising:

a discharge rate checker disposed downstream of the metering pump, and a constant pressure valve disposed downstream of the discharge rate checker; wherein

3. A metering delivery device according to any one of claims 1 and 2, wherein the metering pump is a reciprocating pump with a moving part having a stroke length set constant, and the number of strokes of the moving part is controlled based on the detection signal.

4. A metering delivery device according to any one of claims 1-3, wherein the metering pump is a reciprocating pump having a moving part that comprises at least one of a diaphragm, a plunger and a bellows.

5. A metering delivery device according to any one of claims 1-4, wherein the constant pressure valve comprises a diaphragm disposed in contact with fluid to be delivered, and an urging means provided to urge the diaphragm towards the fluid.

6. A metering delivery device according to any one of claims 1-5, further comprising a display means that displays an actual discharge rate of the metering pump based on a discharge rate signal of the metering pump.

7. A metering delivery device according to any one of claims 1-6, further comprising a deviation alarm means that alerts based on an actual deviation obtained from an actual discharge rate and a target discharge rate, of the metering pump, and a preset given deviation.