Abstract:
An electronic metering pump system has a fluid flow detector for monitoring the output of the electronic metering pump to detect loss of prime. The fluid flow detector, upon detecting loss of fluid flow, initiates an electronic signal to a downstream solenoid valve which closes the output conduit of the electronic metering pump and facilitates the repriming of the pump and return of output fluid flow. The electronic signal may also be utilized to initiate an warning or alarm to an operator, either directly or by data network, that the system requires attention.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an electronic metering pump for creating fluid flow in a conduit system. More specifically, the device provides for the detection of fluid flow or loss of fluid flow and initiation of a priming operation of the metering pump for initiating of fluid flow after a stoppage without human or other intervention. 
       BACKGROUND OF THE INVENTION 
       [0002]    Metering pumps are typically used for transferring fluids including chemicals within a conduit system or from a reservoir or other location where they are manufactured under a given pressure to a location of higher pressure. Often the location of origin is at atmospheric pressure or lower, or in a reservoir located at a lower elevation than the destination location. The operation of the fluid pump is to pull the fluid into the pump and then to discharge the fluid at a higher pressure. This is accomplished by numerous means, most commonly by momentum or displacement. A common momentum system accelerates the fluid by means of centrifugal force using the mass of the fluid to maintain the flow into the pump. Displacement-type pumps typically have an inner chamber with a moveable element which displaces the fluid by changing the volume of the chamber. Common displacement pumps use reciprocating pistons, plungers, diaphragms, bellows, or other means to effect change to the volume. Check valves are used at suction and discharge ports of the inner chamber are typically used to determine flow direction. Pumps include many different types of internal designs, but all typically create a vacuum within a chamber such that fluid may be drawn from a reservoir or conduit and transported to another location through the creation of a pressurized line or conduit. A displacement device is typically utilized to draw ambient air or other fluid from within the pumping chamber in a controlled manner and through the use of appropriate check valves leading to and from said chamber, create a vacuum. In a diaphragm pump, a displaceable diaphragm member oscillates within the chamber to create the necessary pressure changes. The inlet and exits of the product chamber are provided with one way check valves. As the diaphragm is displaced in one direction, the exit check valve closes under reduced pressure to prevent backflow of downstream fluid and the inlet check valve opens in order to permit fluid to be drawn from the upstream fluid supply or reservoir into the chamber. Thereafter, as the diaphragm is displaced in a second direction, pressure increases on the fluid in the chamber, closing the inlet check valve and opening the outlet check valve. This causes the fluid in the chamber to be forced out of the exit valve. 
         [0003]    One of the most frequently reported problems with pumps of this type is “losing prime,” a term meaning that the level of the fluid being pumped has dropped below the pump head or chamber, an air pocket is trapped therein, or the suction side of the pump has lost its supply of liquid, and fluid is no longer being transferred. Prime may also be lost because of particulate or other contamination within the pumping path and the vacuum chamber. Prime is lost as the oscillating member works only against the compressible gas within the empty chamber. When this occurs the pump is working against compressible air or gas, into the higher pressure fluid destination location. Each time this happens, an individual must manually prime the pump. This may be accomplished by opening a valve to eliminate back pressure and/or reintroducing fluid into the chamber, or by removing the discharge side of the pump from the destination location, or pipe. This permits discharge of the compressible gases and allows a small vacuum from the pump to draw fluid into the suction side of the pump, and resumption of fluid transfer. Liquid fluid is reintroduced in certain situations to create hydraulic firmness in the pumping chamber and to displace any entrapped gas. This permits vacuum to be drawn from the supply line. In either case, the pump must then be run for several seconds until the liquid is seen to rise up to the pump head. In the event that the vacuum chamber is merely vented to reduce pressure in the chamber, the pump must be run at a high rate during priming in order to create enough vacuum in the chamber to draw liquid from the supply line. This is especially applicable to closed systems in which there is no addition or exchange of ambient air, gas or other fluid to the system from the environment. 
         [0004]    Operation of the pump during a lost prime condition results in excessive wear and damage to the pumping mechanism, as well as wasted energy and time. Several recent developments have been undertaken to add mechanisms to measure the actual liquid flow output from the pump output. Other efforts have been undertaken to prevent the loss of pump prime or to reinstitute pump prime after loss. 
         [0005]    Claude, et. al, United States Patent Application Publication No. 2004/0062662, filed Apr. 10, 2003, discloses a diaphragm pump having check valves disposed at the entry and exit ports. An alternative conduit into the pumping chamber is provided in association with an electronically controlled valve to permit fluid flow from the downstream portion of the pumping circuit to flow back into the pumping chamber in avoidance of the exit check valve. This recharges the chamber with liquid and creates more favorable pumping conditions. The operation of the bypass prime valve is controlled by a solenoid which is actuated by a timer at regular, preset intervals. There is no teaching of any detection of lost prime conditions or situational activation of the solenoid. 
         [0006]    Porter, U.S. Pat. No. 3,741,675, issued Jun. 26, 1973, discloses a pumping system which is intended to eliminate the then-common practice of constant venting of the pumping chamber in addition to the exit valve to permit gas escape. The Porter device detects fluid flow in the discharge line and closes the gas vent to prevent waste of pumping action. The Porter reference is silent with respect to how the pump is primed nor is there any teaching of the detection of loss of fluid flow initiating any priming activity. 
         [0007]    Beyer, et al., United States Patent Application Publication No. 2005/0271518, filed Jun. 4, 2004, discloses the use of a fluid flow sensor to activate, on an as-needed basis, a separate air pump device which draws vacuum into the pumping chamber upon detection of loss of prime. 
         [0008]    A number of other references utilize liquid reservoirs separate from the pumping path which are selectively vented into the pumping chamber, typically by gravity, upon detection of loss of prime. 
         [0009]    What is lacking in the art, therefore, is a simple and efficient pumping system which detects the loss of prime and initiates a priming operation on an as-needed basis and further without the need for reintroduction of fluid into the pumping chamber in a closed system. 
       SUMMARY OF THE INVENTION 
       [0010]    An electronic metering pump typically comprises a solenoid driven diaphragm which pushes the liquid to be pumped into and out of the head through a set of guided checkballs. A fluid transfer pump uses centrifugal force or displacement of a non-compressible liquid to effect pumping operations. It requires a constant supply of fluid so that it will not lose prime. The foot valve brings the liquid up through tubing out of a drum or other container and an injection valve delivers the liquid to the pressurized system. The pump works against this back pressure and gravity and must be primed so that the liquid is up beyond the lower set of checkballs to begin delivery. This may accomplished with a small manual valve at the rear of the pump head, with tubing returning to the drum. Once priming is accomplished this valve is shut off and the liquid is forced up into the system during pumping. 
         [0011]    A loss of prime condition typically requires trained personnel to make a trip to sometimes remote locations or hard to access equipment rooms. When a fluid reservoir or supply is being changed out or refilled as it empties, the operator needs to remember to check for loss of prime or wait until priming is accomplished. Similarly, in applications utilizing off gassing fluids, build up of effervescent or other generated gas products may result in vapor lock even after initial priming. In the prior art, an operator might leave the tank return valve partially open, similar to the situation described in the Porter reference, resulting in a reduction of output from the pump&#39;s maximum rating. Finally, the reliability and life of the pump can be improved by preventing ongoing operation should liquid not be flowing past the pump head. This situation wears on the pump without accomplishing any work, sometimes for days or weeks until someone notices the event and can respond. Depending on the pump design, it can actually damage the pump itself to run it while dry. Also, during this time, the liquid is not reaching the targeted system and depending on application this can create a whole other set of problems. 
         [0012]    In order to automate the priming process, three main components are assembled for cooperative operation. First is a detector for measuring actual fluid flow through the output end of the pump head. This signal indicates that the pump is primed and liquid is being delivered. Absence of a regular signal would indicate that no liquid is moving within the upper tubing line or other discharge line of the pump. Secondly, control logic with a relay or transistor output is located either within the pump itself or within a nearby controller which is already providing power and/or control functions to determine when the pump should be engaged. Third, a small solenoid driven or other electronic valve will be located within the return line, in place of or supplementing the hand priming valve. 
         [0013]    The control methodology includes provisions to open the priming valve for a period of time whenever the pump is powered up or a priming cycle is selected at either the pump or remote controller. A limit timer is further provided to indicate an alarm condition should the pump fail to prime, indicating that the fluid supply is exhausted or blocked, or that the pump or tubing has failed. During pump activation on an ongoing basis, a monitoring function will compare the signal from the flow measurement device and reinitiate a priming cycle automatically should flow loss be detected. 
         [0014]    The disclosed device and methodology is used as a stand alone pump or in conjunction with a separate logic controller. A flow meter is placed in the output line of the pump. This meter senses the amount of flow coming from the pump. If the pump is on and little or no flow is sensed, the smart pump opens a valve to allow the pump discharge to be vented back to the fluid container or rerouted to an atmospheric pressure location, such as the supply reservoir. It then turns the pump on at full speed to re-prime itself under the increased pressure in the supply conduit and decreased pressure in the output conduit. After this priming cycle, the flow meter again senses the proper flow or no flow condition. If the no flow condition is still present, the re-priming cycle is repeated. When the smart pump is used with a smart controller which is connected to a computer network or other communication device, the unit will send out an alarm after a preset number of unsuccessful tries at priming. This alarm will notify the remote operator that human intervention is needed at the location to repair or replace the pump, refill the supply of fluid or re-establish supply fluid flow. 
         [0015]    These and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the preferred embodiments and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a diagrammatic representation of the self priming pumping device. 
           [0017]      FIG. 2  is a diagrammatic representation, partially in section, of the self priming pumping device. 
           [0018]      FIG. 3  is a diagrammatic flow chart of the logic utilized to operate the primary device. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    Referring now to  FIG. 1 , self priming pump assembly  1  is comprised of a electronic metering pump  5  of a conventional type. Examples of typical pumps are (1) LMI Milton Roy model AA15392SI; (2) Pulsafeeder model LE13Sa-PHC1; and Prominent model g/4 . . . 0703. Pump  5  includes an electronic motor (not shown) which operates a displaceable element which creates a pressure differential within the pump. A flow sensor module  10  is affixed to pump  5  in fluid communication through a conduit. No specific geometry or arrangement of the fluid circuit is specified and the same is adapted to the particular physical and environmental needs of the application. A solenoid valve  15  is also engaged in fluid communication with pump  5  and/or flow sensor  10  to selectively provide an alternative fluid flow path upon the activation of solenoid valve  15  as part of the self priming functionality described more fully herein. Under normal operating conditions, pump inlet fluid flow  20  is drawn into pump  5  by the vacuum conditions created therein. Fluid flows from pump  5  through flow sensor module  10  under the pumping action of pump  5  and exits flow sensor module  10  as fluid flow output  25 . During conventional, manual priming of pump  5 , manual prime fluid flow  30  is temporarily present. In the event that solenoid  15  is activated to provide an alternative fluid flow path, self prime fluid flow output  35  is temporarily present. 
         [0020]    Referring now to  FIGS. 1 and 2 , pump  5  is provided with a power connector  40  for supplying electric energy to the pump motor within pump housing  50 . Pump housing  50  further comprises pump head  45 , which controls the fluid flow within the pumping circuit. Pump  5  in the preferred embodiment comprises a diaphragm pump in which the oscillations of the electronic motor displace a flexible pump diaphragm within pump vacuum chamber  60 . Pump activity draws vacuum within pump vacuum chamber  60 , causing pump inlet fluid flow  20  to pass through pump suction valve  65 , which is typically a ball check valve of conventional type. Under normal operating conditions, fluid flows through pump head  45  and pump connector  70  to flow sensor module  10 . Flow sensor module  10  is adapted to detect the presence and/or amount of fluid flowing through flow sensor chamber  90 . Examples of flow sensors of this type are Neptune Flow checker model FC-1 or Advantage Flow Tracker model FLT-R. Generically, fluid flow sensor module  10  incorporates a fluid flow detector  85  within an enclosed flow sensor chamber  90 . Engagement of the moving fluid through the chamber  90  causes fluid flow detector  85  to generate an electronic signal in the form of an electronic signal in the form of a pulse keeps the solenoid  15  closed, when no pulse is present and the pump  5  is pumping when the solenoid to drain conduit is opened and the pump  5  turned on full speed, as will be more fully described herein. Fluid flow sensor  10  also acts as a diverter, splitting the fluid path between fluid flow output  25  and the alternative fluid path including solenoid valve  15  which is utilized for the self priming function. 
         [0021]    Pump head  45  is also provided with manual prime valve  75  which provides an alternative fluid path back to the reservoir or other source of fluid for the fluid circuit. Manual prime fluid flow output  30  returns to the source as part of the manual priming function. Manual prime valve  75  is opened to relieve back pressure within pump vacuum chamber  60  and allow fluid flow to resume. The manual prime may also be utilized to add fluid to the chamber in the pump head. 
         [0022]    Referring now to  FIGS. 1 ,  2  and  3 , the self priming functionality is provided through the use of solenoid valve  15  as part of self priming assembly  17 . Self priming assembly  17  is connected within the fluid circuit as part of an alternative fluid path. Fluid is diverted by flow sensor module  10  through self prime conduit  105 , which terminates at solenoid chamber  115 . Under normal operating conditions, when fluid is flowing normally and a flow signal  200  is present, solenoid valve  15  is closed, utilizing solenoid armature  110  to block fluid flow beyond solenoid chamber  115 . During self priming operations, flow sensor module  10  senses a lack of flow signal  210 , and solenoid valve  15 , acting upon the presence of a lack of flow signal  210  along solenoid pump control line  120  from flow sensor module  15  ], retracts solenoid armature  110  at  220 , causing fluid communication between solenoid chamber  115  and the source and/or reservoir of fluid for the fluid circuit through solenoid discharge valve  130 . Self prime fluid flow output  35  is then discharged to the source or reservoir. In a situation where loss of prime is encountered, flow sensor module  15  would detect the absence of fluid flow within flow sensor chamber  90 . Solenoid valve  15  is then activated at  220 , opening fluid communication between pump vacuum chamber  60  and the source or reservoir of fluid. Simultaneously, pump  5  is activated to operate at maximum speed at  215 . This causes any entrapped gas within the fluid path to be returned to the solution tank at  225  and evacuated fluid flow to be increased from the reservoir as pump inlet fluid flow  20 , recharging pump vacuum chamber  60 . Once fluid flow is re-established and detected at  230  through flow sensor module  10 , solenoid valve  15  is signaled to close chamber  115  at  235  and terminate fluid flow through the alternative fluid path. All fluid flow is then concentrated in fluid flow output  25  for maximum efficiency. In the event that fluid flow is not detected at  240 , the cycle is repeated for a preselected period of time, for example  20  minutes as illustrated in  FIG. 3 , until flow is sensed. If flow is not sensed within the preselected period of time, the pump is shut off at  245 . 
         [0023]    Although particular embodiments of the present invention have been illustrated in the accompanying drawings and described in the foregoing detailed description, it is to be further understood that the present invention is not to be limited to just the embodiments disclosed, but that they are capable of numerous rearrangements, modifications and substitutions.