Duplex Metering Pump Having a Single Liquid End

Abstract

An improved motor driven duplex metering pump comprising two diaphragms in a single duplex liquid end pump housing assembly. The single duplex liquid end is rigidly attached to a main pump housing at a single mounting position and includes integrated check valves to allow for a single discharge process connection and a single suction process connection. The pump utilizes an improved cam mechanism that creates continuous positive uniform reciprocating motion. That continuous positive uniform reciprocating motion is imparted from its cam mechanism and its follower assembly to drive shafts that are connected to a cross arm and in collectively they impart the same motion to its two diaphragms that reciprocate 180° out of phase from each other. The result is substantially continuous liquid flow rate delivery by the invention.

Description

FIELD OF THE INVENTION

This application relates to motor driven metering pumps, and specifically to an improved motor driven duplex liquid end metering pump.

BACKGROUND OF THE INVENTION

Motor driven chemical metering pumps or proportional pumps are commonly utilized to pump various liquids. They have the ability to vary their volumetric liquid displacement during their normal operation. This is typically achieved with their ability to change their discharge stroke length and or motor speed to vary the strokes per minute during their operation. This changes their liquid volumetric displacement. There are commercially available pumps that change their flow delivery by changing their motor speed or stroke length only.

These motors typically have one or more displacers commonly of a plunger, diaphragm or tube design. Two displacer pumps are commonly termed as duplex metering pumps. Duplex metering pumps would typically have each of the two separate displacers held in its separate liquid end pump housings. A side view of a duplex metering pump would show the pump housings parallel aligned side to side, either horizontally or vertically. Each pump housing has its own pump gear box or transmissions housing or main pump housing that are rigidly connected side to side. Both would typically have four liquid process connections. That is one discharge and one suction on each separate liquid end pump housing.

Conventional duplex pump metering pumps typically have four check valve assemblies. These valves are external, but rigidly connected to each liquid end. This prior art design has the pumped liquid flowing through all four valves. This requires more complex piping to integrate the two suction and two discharge check valves.

It therefore, would be desirable to construct a duplex motor driven duplex metering pump having a compact design of a simplex pump configuration having one liquid end with one diaphragm that is mounted at one position to the main pump housing. It would be advantageous to integrate the check valves into a single duplex liquid end as opposed to being external to the liquid ends. This would allow for a duplex metering pump to be connected to a process with a single pipe connection at the suction and the discharge sides of the pump. These process connections would be incorporated into the body of the single duplex liquid end.

This allows the liquid pumped through the pump to flow through housing and not through the check valves. This is advantageous, because the valves can be smaller in size for a given flow capacity of the duplex metering pump. This is due to the check valve body does not have to be large enough to have liquid flow around the valve's internal geometry.

Typically these duplex motor driven metering pumps will have a transmission housing or a pump housing. Within the housing there will be some form of one or two eccentric members, such as a cam or other form of mechanics. These mechanics convert rotary motion to rectilinear reciprocating motion. Typically there is a gear set within the pump's transmission for motor speed reduction and torque multiplication. Gears require some form of lubrication and the state of art metering pumps use gear oil or grease, depending on its design. The pumps will have various shafts that are reciprocating and rotating and where they protrude through the transmission housing, wiping seals are used to contain the lubricant. It would desirable to have a metering pump that does not utilize gearing. Gears within the pump housing add expenses to the pump's manufacturing costs. During the normal operation of the prior art motor driven pumps with gearing, the required gear lubricant will be need to be changed. In addition to contain the lubricant in the pump housing for the current state of art metering pumps over time the seals around the pump's shafts need to be replaced.

It would be desirable to design a metering pump that does not require a lubricant or wiping seals. It would be desirable to have all reciprocating and rotating shafts within a pump design that are supported and aligned with self-lubricated bearings that do require external lubrication.

This class of pumps utilize current state of art motors including digital type of motors. They typically are so designed to utilize motor control technology that allows for the drive motor to vary its speed to change the pump's momentary liquid flow creation. There are manufactures with a commercially available pumps that utilizes a digitally driven synchronous motors. For example, U.S. Pat. No. 6,948,914 and U.S. Pat. No. 7,118,347 disclose a digital impulse control logic. This digital impulse controls the velocity of the pump's single diaphragm to create a desired liquid delivery velocity. Its digital control electronics utilizes an impulse modulation that turns its motor on and off for prescribed time intervals. It would be desirable to have a metering pump that utilizes a digital motor, but only requires standard available state of art speed control to operate for speed modulation.

There are various patents that utilize a stepper motor or motors. For example, U.S. Pat. No. 6,293,756 is a pump system with four plungers that is designed for the needs of High Performance Liquid Chromatography (HPLC) applications. The concept is to control a desired flow rate based on an input of a pressure variable to the pump's controller. The basic design concept is four independent plunger pumps driven by four independent stepper motors. In the patent description it describes each motor driving a wheel cam via a 4:1 gear reducer set. The liquid flow of each independent pump is combined to create a single liquid continuous flow rate. The controller independently controls each motor speed to get the desired combined liquid flow rate relative to pressure.

It would be advantageous to divide the work of the pump's momentary liquid displacement and replenish over multiple synchronized stepper motors or other types of synchronous motors. These motors are either connected to the pump's eccentric member via gearing or directly coupled without gearing depending on the design. The momentary liquid displacement is equally divided to two motors driving one displacer that is pumping the liquid at any given moment in the pump's operation. This is opposed to U.S. Pat. No. 6,293,756 that has a stepper motor connected to each of its single displacer, described as plungers.

Metering pumps of this class typically have defined batch flow rate delivery. Each displacer displaces a given batch volume of liquid for each of its displacement cycles. The current state of art metering pumps typically have the liquid being pumped going from zero velocity at the beginning of a batch to peak velocity and back to zero at the end of the batch. This causes negative pulsating pressures being acted upon by the pump's liquid flow rates. These pressure variations are transferred to the liquid up-stream and down-stream of the liquid end of the pump. These sudden changes in liquid velocity creates mass acceleration problems being transferred to the pumped liquid. This causes undesirable pressure variations that in turn creates what is commonly called water hammer or cavitation. This is due to the sudden stopping of the liquid on the suction and discharge side of the pump at an end of a batch cycle. This causes wide pressure variations to be established, including negative pressures at the suction and discharge sides of the pump.

These pumps requires check valves to operate. These check valves require sufficient substantially continuous differential pressure across them to operate properly. Widely varying differential pressure at the check valves cause its ball or other geometry in the check valves to not properly seat. That is that the sealing geometry can float or bounce if the proper differential pressure is not maintained across the pump's check valves. It would be advantageous to design a duplex metering pump that better sustains a more constant differential pressure across its check valves for better pump performance.

These wide pressure variations, as described above are typically mitigated by the installation of a back pressure valve on the discharge side of the pump. It helps assure that there is sufficient back pressure for the check valve on the pump to properly seat. It further mitigates the magnitude of the pressure variations on the discharge side of the pump. It does not always solve the problem. It would be desirable to have a duplex metering pump that mitigates this pulsating flow rate and wide pressure variations being imposed on the pumped liquid. That is the batch flow delivery remains, but the time between batches is sufficiently small to mitigate the wider pressure variations being created by a duplex metering pump.

In addition, when the liquid displacement velocity of one batch ends, the liquid velocity of the next beginning is substantially the same. The velocity of the liquid being pumped virtually never goes to zero across the liquid end of the pump. It would be advantageous to have a virtually continuous liquid flow across a duplex metering pump's liquid end. The liquid that is pumped across the pump's liquid end does not go to zero velocity which minimizes the wider pressure variations at the suction and discharge sides of the duplex metering pump. Each liquid batch stream is commingled one after the other with virtually equal velocities and no dwell. It would be desirable to not require a back pressure valve to be installed on the liquid discharge side of a duplex metering pump on many process applications.

These negative wide pressure variations and pulsating flow, as described above are typically also mitigated by the installation of a pulsation dampener. The dampener is installed in the discharge piping of the pump. The dampener allows the discharge piping to be quickly expanded volumetrically during a liquid discharge event by the pump. The pulsation dampener then reduces its volume to force the pumped liquid to the discharge side of the pump when the pump is between a liquid discharge events. The pulsation dampener reduces the magnitude of the pulsating flow rate delivery. It would be advantageous to design a duplex metering pump that does not typically require a pulsation dampener to create substantially low pulsating liquid flow delivery.

As described above conventional pumps require proper sustained differential pressure across them to allow their check valves to properly operate. A properly operating check valve requires a limited time period to adjust from opened to closed. During short time period, the suction side and the discharge liquids are comingled within the liquid in the cavity or cavities of the pump. Yet that time interval is sufficiently short for pump to operate properly. When this time period is sufficiently short, the pump will create repeatable accurate liquid flow rate creation. These check valves can have poor seating performance when this time interval becomes too long. This can happen when the pump is operating at very low operational speeds.

The typical state of art metering pumps at low liquid displacement velocities can have operating issues due to their check valves not seating properly. This is due to the time period being too long for the pump's displacers to change from at state of open to closed or closed to open. The check valve's sealing elements will have too long of a time period with the elements floating. This allows the differential pressure across the liquid end of the pump to be equalized over the time period. This effects the accuracy and the ability of the pump to operate. This in practical terms reduces the achievable low end liquid displacement by many state of art metering pumps.

It would be advantageous for the pump to have speed modulation at the low end of its pump capacities. This would quickly increase the liquid displacement velocity just before and after the cross over position for a change is the reciprocating direction of the displacers. Then return to a low displacer velocity as chosen for the application between the cross over reciprocating change in direction positions.

Metering pumps are positive displacement pumps and therefore it is of common industry practice to utilize a safety relief valve (“SRV”) to protect the pumping system from unsafe over pressurization. This SRV is typically installed inline in the discharge piping of the pumping system. The valve is typically so installed to allow for the liquid to be piped back to the suction side of the pump or back to the source of the liquid being pumped. That is this valve will open to allow the over pressurized pumped liquid to safely be relieved. This protects the pumping system from self-destruction. Typically this over pressure condition happens when you have a blocked or partially blocked discharge condition in the discharge piping. The state of art SRV is sized for the maximum liquid flow capacity for any given state of art metering pump. Typically the SRV's valve body size and capacity is determined by the manufactures recommended discharge pipe size specifications. These pipe sizes are sufficiently large to minimize the liquid velocities to in turn minimize liquid mass accelerations of the pumped liquid. A drawback of sizing the SRV based on discharge pipe size is that the SRV can get quite large and this adds costs to the overall pumping system.

As described metering pumps of this type cause liquid displacement by reciprocating a displacer and creating and collapsing a cavity or cavities. By creating a cavity, the liquid to be pumped is displaced into the created cavity and by collapsing the cavity the liquid is displaced out of the pump. The process is repeated and each occurrence is termed a stroke. A duplex pump would have two discharge and two suction events per stroke. It is measured in strokes per minute (“SPM”). It would be advantageous to have an integral safety equalization valve (SEV) or SRV that is integrated into the single duplex liquid end.

A drawback of locating the SRV in the discharge piping is that it is sized based on the pump's total capacity that is made up of the maximum sum of SPM. It would be advantageous for the SRV design capacity and physical size being based on the liquid volume of one stroke. It would therefore be advantageous to directly attach the SRV or SEV on the single liquid end. This would allow a much smaller SRV to accomplish the same over pressurization protection allow for a more advantageous discharge piping from a duplex metering pump. This is because the pumped liquid is not piped back to the suction side of the pump or to the source of the liquid, such as a tank.

SUMMARY OF THE INVENTION

The embodiments of the present invention address and overcome drawbacks of duplex metering pumps by providing a single duplex metering pump having a single liquid end with two oppositely phased diaphragms.

Embodiments of the present invention is a two motor driven duplex metering pump. That these two motors are synchronized concurrently to drive one displacer shown as a diaphragm displacing liquid at a given operational moment and one diaphragm in liquid replenish. This is achieved with drive gears or direct connect type without drive gears.

Embodiments of the invention is to incorporate the eccentric cam system from the invention U.S. Pat. No. 8,752,451 fixed cam assembly design with multiple congruent non-cardioid shaped cam profiles that are so designed to create continuous positive motion with constant or uniform velocity for its imparted reciprocating motion. This is virtually sustained over the complete 360° of cam angle. That is the drive motor operating at any given constant speed results in an advantageous virtual continuous uniform liquid displacement by the invention. The liquid velocity entering the liquid end is virtually equal to the liquid discharged from the invention. Other eccentric members of common art to create reciprocating motion can be utilized, but not shown or described.

Embodiments of the present invention is a design that it utilizes a stepper or other type of motor or motors with direct drive. That is there is no gear reduction utilized by the pump.

Embodiments of the invention is to have motor speed modulation control for diaphragm velocity management when the invention is at low liquid rate delivery. This assure that the momentary liquid velocity is sufficient to quickly activate the check valve's change in state to maintain proper differential pressure across the liquid end pump housing.

Embodiments of the invention is to have its four check valve assemblies integral within its single duplex liquid end or within a pump housing assembly closely rigidly connected to the duplex liquid end. This facilitates the integration of two fluid streams pumped by each independent diaphragm or displacer to be comingled within the single duplex liquid end. That is the liquid on the suction side of the pump is comingled independent of the discharge side of the invention and the same is true for the discharge side of the pump. To the discharge side of the invention within the single duplex liquid end, the two liquid streams for the two displacers are combined. During normal operation a virtual sustained back pressure is applied to the pumped liquid on the discharge of the invention. This is within the internal liquid discharge channels. That sustained back pressure would be applied to the check valve geometries within the check valve assemblies for efficient seating.

Embodiments of the present invention is for an integral is for over pressurization protection with an incorporated integral or close mounted safety relief pressure equalization valve SEV or SRPEV to protect the invention and the pumping system.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.

Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings illustrate by way of example and are included to provide further understanding of the invention for the purpose of illustrative discussion of the embodiments of the invention. No attempt is made to show structural details of the embodiments in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Identical reference numerals do not necessarily indicate an identical structure. Rather, the same reference numeral may be used to indicate a similar feature of a feature with similar functionality. In the drawings:

FIG. 1 depicts a representative composite side view of a conventional simplex motor driven metering pump with one liquid end rigidly attached at one mounting position;

FIG. 2 depicts a representative composite side view of a conventional duplex motor driven metering pump with two opposing liquid ends across the pump, each with their separate mounting positions;

FIG. 3 depicts a representative side view of a conventional motor driven duplex metering pump with two pumps aligned side to side to each other with their independent liquid ends;

FIG. 3a is an end view of the liquid end for the duplex pump depicted on FIG. 3;

FIG. 4 depicts a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention;

FIG. 4a is an end view of a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention, illustrating four integrated check valve assemblies;

FIG. 5 depicts an exploded view of a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention;

FIG. 6 is a exploded top view of a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention, illustrating drive gears between a motor shaft and a cam shaft;

FIG. 7 is a side view of a duplex metering pump having a single liquid end constructed in accordance with an alternative embodiment of the present invention, illustrating a single duplex liquid wet end pump housing assembly that could be substituted on the invention rather than the single duplex liquid end assembly;

FIG. 8 is a perspective side view of a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention;

FIG. 8a is an elevation side view of the duplex metering pump having a single liquid end illustrated in FIG. 8;

FIG. 8b is a cross-sectional view of the duplex metering pump having a single liquid end taken along line D-D of FIG. 8a;

FIG. 8c is a cross-sectional view of the duplex metering pump having a single liquid end taken along line B-B of FIG. 8a;

FIG. 9 is an exploded view of a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention, illustrating a two motor construction of the duplex metering pump with the mated motors and cam assemblies rotated 90 degrees for a better viewing of this embodiment;

FIG. 10 is an end view of a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention;

FIG. 10a is a side elevation view of a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention;

FIG. 10b is a cross-sectional view of the duplex metering pump having a single liquid end taken along line F-F in FIG. 10;

FIG. 11 is a perspective view of a check valve cartridge that is constructed in accordance with an embodiment of the present invention;

FIG. 11a is a front elevation view of the check valve cartridge assembly of FIG. 11;

FIG. 11b is a side elevation view of the check valve cartridge assembly of FIG. 11, illustrating a ball element inside the check valve cartridge assembly;

FIG. 12 is an end view of a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention, illustrating an integral safety equalization valve;

FIG. 12a is a side elevation view of a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention, illustrated without the integrated safety equalization valve;

FIG. 12b is an enlarged view of the integrated safety equalization valve of FIG. 12;

FIG. 13 shows an end view of a duplex metering pump having a single liquid end constructed in accordance with an embodiment of the present invention;

FIG. 13a is an end view of the duplex metering pump having a single liquid end of FIG. 13;

FIG. 13b is a cross-sectional view of the duplex metering pump having a single liquid end taken along line A-A in FIG. 13;

FIG. 14 is a graphical example to depict a given liquid volumetric displacement for a first diaphragm within the invention;

FIG. 14a a graphical example to depict a given liquid volumetric displacement for a second diaphragm within the invention;

FIG. 14b is a graphical example for the combined liquid volumetric displacement for a first and second displacer diaphragms;

FIG. 15 is a diagrammatic example of fluid flow characteristics for an embodiment of the invention, illustrating velocity modulation for improved check valve seating; and

FIG. 15a is a diagrammatic example depicting velocity of an alternative modulation for check valve seating resulting in a continuous displacement velocity over time and a resultant constant volumetric displacement over time.

DETAILED DESCRIPTION OF THE INVENTION

As a preliminary matter, it should be noted that in this document (including the claims) directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the various embodiments of the invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., without departing from the principles of the invention.

Prior art examples of a conventional simplex and duplex metering pump designs are shown in FIGS. 1, 2 and 3. FIG. 1 illustrates a simplex metering pump 28 shown in the prior art. These pumps 44 and 68 as shown in FIGS. 2 and 3 are diaphragm pumps, the diaphragms are not shown. The current art for duplex metering pumps typically have each of the two independent liquid ends 36 or 56 with two separate rigidly mated mechanical flanged support positions 12 or 36 as shown on FIGS. 2 and 3 respectively. The mounting supports flange positions 38 or 60 are incorporated into the transmission housing, also known as the main pump housing 40 or 66 for rigid support as shown on FIGS. 2 and 3 respectively. Pump 44 depicts a conventional design that has its mounting flanges 38 opposing to either side of transmission 40, each supporting a liquid end 36 at a separate mounting flange positions 38. The prior art version as shown on FIG. 3 pump 68 has two support flanges 60 each mated to a liquid pump end 56.

FIG. 1 is a representative side view of a conventional motor driven simplex metering pump 8. Metering pump 28 has a single liquid end pump housing 10 that is rigidly held to the transmission gear box housing 14 at liquid end mounting flange 12 by bolts 18. This mounting flange position 12 is typically rigidly incorporated into the transmission gear box housing 14. They typically will have two external single check valve housings 20. The motor mount flange 16 is incorporated into the gear box housing 14 with an attached motor 26. It would typically have a set of drive gears, an eccentric member and other components not shown, to reciprocate its displacer within its liquid end 10. It can have a stroke length adjustment knob 22 that changes the stroke length and its liquid flow rate change or a motor driven stroke adjustor, not shown. There are commercially available simplex metering pumps that do not have stroke adjustment and will not have a knob 22 and utilize speed modulation only by its drive motor to vary the volumetric liquid displacement of the pump.

FIG. 2 is representative side view for a conventional motor driven duplex metering pump 44 with two opposing liquid ends 36 across the gear box or pump housing 40. The pump 44 has two liquid end pump housings 36 rigidly held to their mating pump mounting flanges 38 by bolts 34 to the pump housing 40. Each of the liquid end pump housings 36 has its pair of external check valve assemblies 32, one suction and one discharge. This conventional duplex metering pump has four process connections at each of the four check valves 32, including two suction and two discharge connections. The motor mount flange 46 and motor 48 are rigidly connected to gear box 40. The motor 48 would typically drive the internal eccentric or eccentrics within the pump housing 40 that in turn cause the reciprocating motion of the pump's two displacer diaphragms, not shown. Each liquid end pump head 36 would have a single diaphragm, not shown.

FIGS. 3 and 3 a are a representative views for another design of a conventional duplex metering pump 68. This duplex metering pump 68 is a representative inline side-to-side pump design having at least two liquid ends 56. It would typically have one gear housing 66 per liquid end 56. As is consistent with other duplex metering pump designs, pump 68 has a liquid end pump housing 56 connected at pump mounting flanges 60 with attachment bolts 62. The pump 68 has its common motor 52, mounted to flange 54 and a single stroke adjustor knob 70 for each displacer. This pump design typically allows for additional pumps 68 to be added beyond two. There is a variety of ancillary components of common art not shown on these drawings to comprise a functional metering pump. Pumps 44 and 68 depict common designs for commercially available duplex metering pumps, but there is a wide variation of these two designs with similar layouts not shown.

FIG. 4 illustrates a duplex metering pump 76 having a single liquid end housing 92 that is constructed in accordance with an embodiment of the invention 76. FIG. 4a is an end view of the same embodiment of the invention with a single duplex liquid end housing 92. FIGS. 4 and 4a depict a composite configuration for one embodiment of the invention as a motor driven duplex metering pump 76 with similar viewable profile of a simplex pump illustrated in FIG. 1. Pump 76 includes a motor 72. In the depicted embodiment motor 72 is described to be a stepper motor, but other variable speed motors can be utilized. Pump 76 further includes a main pump housing 78 that has a rigid liquid end mounting position 80. The single duplex liquid end housing 92 is rigidly secured at position 80 with bolts 86.

This is the opposite to conventional duplex metering pumps which include two liquid ends 36 or 56 and two flange mounting positions 38 or 60 as shown in FIGS. 2 and 3 respectively. Thus, FIGS. 1 and 4 share a similar side profile of having only one liquid end pump housing mounted rigidly to one mounting position 80 shown in FIG. 4 and mounting position 12 as shown in FIG. 1. The pump 76 shown in FIG. 4 includes a cover cap 90 that covers the pump head bolts 86 and other ancillary components not shown.

Pump 76 utilizes four integral check valve assemblies 152, not shown in FIG. 4, but depicted in FIGS. 11, 11a and 11b. These valve assemblies 152 are designed to be located within the duplex liquid end housing 92, as shown in FIG. 10, and allow for a single suction process connection 82 and a single discharge connection 94. The liquid end housing 92 includes plugs 84 to seal ports along the side of liquid end housing 92. The ports are to aid in manufacturing pump 76 and provide alternate process connection positions 82 and 94. The pump 76 will have an electronic controller 74 with typical state of art speed modulation to control electronic components, not illustrated in the figures. The controller will allow the pump 76 to vary its liquid flow rate creation by varying speed of motor 72. FIGS. 14, 14, 14b, 15 and 15a diagrammatically illustrate the unique motor speed modulation characteristics.

FIGS. 13, 13 a, and 13b illustrate a liquid end 208 that pump 76 can use in place of liquid end housing 92. Pump 76 could also utilize a split liquid end pump housings 142a and 142b of assembly 142 as depicted in FIG. 7 rather than liquid end housing 92 and its components. Referring to FIGS. 10, 10a, and 10b, liquid end housing 92 would have a pair of diaphragms 114a and 114b not shown. The liquid flow rate creation of pump 76 is depicted and graphically illustrated in FIGS. 14, 14a and 14b.

Referring to FIG. 5, pump 76 is shown with motor 72 alternatively extending from the side of pump 76. Pump 76 includes a base frame 98 and mounting holes 96. As depicted in FIG. 5, pump 76 is also shown in a partial exploded view to illustrate the relationship between the single duplex liquid end pump housing 92, the transmission housing 78, and the end cap 90 to many of its components. The liquid end housing 92 is rigidly connected at mounting position 80 with bolts 86. It should be understood that liquid end pump housing 92 can be replaced with liquid end 208 or liquid end housing assembly 108. There is also other wet end designs not shown that would have similar design elements. For example they could be composed of multiple components to form a complete liquid end pump housing.

As depicted, pump 76 further includes a direct coupled stepper motor 72 or other variable speed motor to drive the pump 76. This embodiment of the invention does not have a gear set within it, such as shown on FIG. 6 with gear set 134. The shaft of motor 72 is directly connected to a cam shaft 124 with a motor coupling 122, as best seen in FIG. 5. The motor 72 and the cam assembly 100 could be in this orientation shown or in the vertical orientation as shown in FIGS. 4 and 4a.

The liquid end housing 92 with plugs 84 is further detailed in FIGS. 10, 10a and 10b. In the embodiment depicted in FIGS. 10, 10a, and 10b, pump 76 has valve assemblies 152 integrated into liquid end housing 92.

Referring to FIG. 5, in the depicted embodiment of the invention, the cam assembly 100 includes three congruent cams 126 on a common cam shaft 124 attached to a cam follower assembly 130 that has an integrated cam follower drive cross arm 106, follower bearings 128, follower frame 132 and other components not detailed. This depicted cam assembly 100 is so designed to cause substantially continuous uniform positive reciprocating motion. The cam system 100 has its cam follower assembly 130 that has its follower bearings 128 in virtual constant contact with the cams 126 during operation. The follower frame 132 is not fully detailed, but depicted as a rigid assembly. An example of a suitable cam is described in U.S. Pat. No. 8,752,451 incorporated herein by reference.

An alternative design is to split the follower frame 132 into two halves that are held together with compression or tension springs depending on design, however, this embodiment is not illustrated in the figures. The springs would be utilized to hold the split cam follower frame 132 together as a complete assembly. Each of the cams 126 are congruent to each other with non-cardioid cam profiles. The cams 126 are rigidly connected to cam shaft 124 and properly phased to cause in unison virtual continuous positive uniform reciprocating motion. There are at least two cams 126 on a common cam shaft 124 or on multiple shafts, not shown, depending on design requirements.

The follower assembly 130 has an integral drive cross arm 106 as part of the cam follower frame 132 that in turn is mechanically connected to the two drive connecting shafts 108a and 108b. The drive connecting shafts 108a and 108b project through cross arms 106 and 118 and are partially supported and aligned by guide linear bearings 112 that are in liquid end housing holes 174 as best seen in FIGS. 10, 12, and 13. The rods 108a and 108b are threaded at each end and have mating nuts 104 to rigidly connect the shafts 108a and 108b to cross arms 106 and cross arm 118. The cross arm 118 is rigidly connected to a diaphragm connector shaft 110a that is connected to a first diaphragm 114a. The cam follower drive cross arm 106 is connected to a second diaphragm 114b at its connector shaft 110b. The first and second diaphragms 114a and 114b are each secured against the liquid end housing 92 by the two separate diaphragm retainer rings 116. The end cap 90 covers the outer diaphragm 114a and the other components. The liquid end housing 92 is secured to the pump transmission housing 78 at flange mounting point 80 by bolts 86. A controller 74 is not shown on FIG. 5, but would be required as shown on FIGS. 4 and 4a.

The stepper motor 72 is controlled for speed variation by controller 743. The pump 76 further includes an encoder 120 for electronic feedback to the controller 74 for the motor 72 speed control verification. In operation, when the motor 72 is rotating the direct connected cam shaft 124 rotates. This results in a 1:1 speed relationship between the motor 72 and cam shaft 124 and its integrated cams 126. The follower bearings 128 are in constant contact with cams 126. This causes a substantially constant, positive velocity ratio of 1:1 and rectilinear reciprocating motion being imparted to the cam follower 130, its integrated drive arm 106, shafts 108a and 108b and drive arm 118. This reciprocating motion would have a substantially uniform velocity of motion for any given motor rotational speed. The drive arm 106 is directly driving diaphragm 114a and 114b via its connecting shafts 110a and 110b.

Drive arm 106 drives the shafts 108a and 108b that are driving the arm 118 and its reciprocating motion is transferred to the first diaphragm shaft 110a and in turn to the first mated diaphragm 114a. All of these named components will operate in unison with a resultant common uniform displacement and replenish velocity for both diaphragms 114a and 114b. The 1:1 speed relationship of motor 72 through to both diaphragms 114a and 114b reciprocating is preserved during normal operation of the invention. Normal operation has each diaphragm sustained 180° out of phase. There are two cross over moments 214 as shown on FIGS. 14, 14a, 14b, 15 and 15a, where there is directional change of the reciprocating motion being applied to the diaphragms 114a and 114b. The displacers, shown as diaphragms 114a and 114b have equal velocities during normal operation. These velocities can be constant or varied to achieve desirable hydraulic flow rate characteristics, as further described herein.

The resultant liquid flow rate creation by this embodiment of the invention is as shown and described by FIGS. 14, 14a and 14b. That flow rate creation can be further modified as described and shown by FIGS. 15 and 15a. This is one design configuration of an embodiment of the invention, but there can be many variations of design to achieve the same.

FIG. 6 is a top cut away view of an embodiment of the pump 76 with a partial cut away of the liquid end 92 and its common related components as shown in FIG. 5. The orientation of the motor 72 is different than shown in FIG. 4, 4a, or 5 but the functionality is not changed. The pump 76 as depicted in FIG. 6 has a gear reduction assembly 134 for the drive coupling of the motor 72 shaft to the cam shaft 124. All other components remain the same as shown on FIG. 5 and so numerically identified, but not all are shown. The normal operation of pump 76 would be the same as shown in FIG. 5, with the exception of the gear reduction 124 between the cam system 100 and motor 72. The resultant liquid flow rate creation by this embodiment of the invention is as shown and described by FIGS. 14, 14a and 14b. That flow rate creation can be further modified as described and shown by FIGS. 15 and 15a. The substantially continuous uniform low pulsating liquid flow creation as described in FIG. 5 of the pump 76 remains the same.

FIG. 7 is an embodiment for an alternate liquid end housing assembly 64 of the invention that can be substituted for the liquid end housing 92 or liquid end 208. The design of the liquid end housing assembly 64 is consistent with liquid end housing 92 or liquid end 208 being rigidly attached at a single mounting position 80. It and other components form the assembly 64 that can be utilized by the pump 76 depicted in FIGS. 4, 4a, 5, 6, 8 or pump 156 depicted in FIG. 9. The assembly is rigidly mounted at position 80 of transmission housing 78, not shown.

To form a liquid end assembly 64 with two liquid ends split components 142a and 142b that are combined to create one single duplex liquid end housing assembly 142 as a component within the complete pump liquid housing assembly 64. Each liquid end 142a and 142b could be made up of multiple components, not shown. Other components, such as diaphragms 114a and 114b and their shafts 110a and 110b not detailed, to drive shafts 108a and 108b are combined with a single drive arm 144 with various other ancillary components, not detailed, to form the liquid end assembly 64. This complete liquid end assembly 64 with its liquid end components 142a and 142b and its mated components are an alternate design to the liquid end housing 92 or liquid end 208 and their mated components. This design concept is to show that the opposing diaphragms 114a and 114b can be mounted in a different opposing back to back orientation. Each of the two diaphragms 114a and 114b and their drive shafts 110a and 110b are rigidly connected to a common drive arm 144. The liquid end housings 142a and 142b are held together by bolts 86 and additional bolts not shown to create a complete liquid end pump housing assembly 64. Diaphragm 114a is attached to liquid end pump housing 142a and diaphragm 114b is attached to liquid end pump housing 142b. Each diaphragm 114a and 114b are held to their respective liquid end pump housing 142a and 142b by a diaphragm mounting ring, not shown. This design would also have its complete liquid end pump housing assembly 64 rigidly mounted to the pump transmission 78 with bolts 86 to its integrated mounting flange 2 position.

Drive arm 144 is rigidly attached to the two drive shafts 108a and 108b. The drive shafts 108a and 108b connected to diaphragms 114a and 114b by their shafts 108a and 108b. The mechanics and all the components required to accomplish these rigid connections between the diaphragm's shafts 108a and 108b and the drive arm 144 and drive shafts 108a and 108b are not shown. The drive shafts 108a and 108b and nuts 104 will be rigidly connected to the cam follower's drive arm 106 as shown on FIGS. 5, 6, 8 and 9.

FIG. 7 as shown would utilize four external check valve assemblies. The four check valves are rigidly connected to the liquid end pump housing assembly 142. It could utilize the duplex check valve assemblies 152 as shown in FIGS. 11, 11a, 11b that would be incorporated into the liquid end housings 142a and 142b. The valves 152 would have a similar installation an alternate designs as detailed in FIGS. 10, 11, 11a and 11b. The liquid end 64 would have one suction process connection 82 and one discharge process connection 94, not shown. Operationally the drive arm 144 are driven by shafts 108a and 108b. The operation of the cam system 100 and follower arm 106 to shafts 108a and 108b to arm 144 to diaphragm shafts 110a and 110b to diaphragms 114a and 114b would be the same as described in FIGS. 5 and 6, not shown. Operationally the diaphragms 114a and 114b would reciprocate the same as described for pump 76 in relation to FIG. 5, FIGS. 14, 14a and 14b and as modified as described by FIGS. 15 and 15a.

FIG. 8 is a side perspective view of the pump 76 illustrated in FIG. 6 with the liquid end 92. It shows most of the same components as shown on FIG. 6. That is head bolts 86, duplex liquid end 92, plugs 84, liquid discharge process connection 94, but suction process connection 82 is not shown, cam follower bearings 128, cam follower frame assembly 130, transmission gear box base frame 146 with mounting holes 96, drive cross arm 106, back of a diaphragm 114b, diaphragm retainer ring 116, one of the diaphragm drive connecting shafts 108a and 108b, cam follower driver cross arm 106, cam follower assembly 130, stepper motor 72 and encoder 120. Operationally it is the same as detailed for pump 76 in FIG. 5, except for the gears 124 as shown in FIG. 6.

FIG. 8c with liquid end 92 or 208 is shown with a sectional view of the cam assembly 100 on cam shaft 124 and gear set 134. The cross arm 106 is connected to the shafts 108a and 108b that is connected to arm 118. The second diaphragm 114b and its shaft 110b are connected to arm 106 and the other diaphragm 114a and its shaft 110a is connected to arm 118. The porting channels 168 and other internal details of the single duplex liquid end are not shown.

FIG. 9 is a partially exploded top view of an embodiment of the duplex metering pump having a single liquid end 156 that incorporates two motors 72. Each motor 72 has a point of connection 158 that connects motor coupling 122 to its independent cam shaft 124. The point of connection 39 could be a direct coupled drive as shown in FIG. 5 at coupling 122 or have gear set 134 at position 158 as shown at FIGS. 6, 8 and 8c. Pump 156 has two independent cam shaft assemblies 100, each with its independent cam shaft 124 at its independent point of connection 158 with its independent mated motor 72. It also has three congruent cams 102 on cam shaft 124 as shown for each independent cam assembly 100 that are combined to compose a double cam system combined as 154a and 154b. It is understood that each cam shaft includes at least two cams, however this number could be larger depending on the application. The cams 126 of pump 156 operate in the same manner as cams 126 of pump 76. A description of which does not bear repeating.

Each independent cam follower assembly 130a and 130b has its cam follower bearings 128, follower frame 132a and 132b and an integrated common follower frame drive cross arm 106. Operationally the embodiment of pump 156 with two motors 72 is basically the same as pump 76 with a single motor as shown in FIGS. 4, 4a, 5, 6 and 8. This is true with or without gears at the two positions 158. For the pump 156 as compared to pump 76 with a single cam assembly 100 as shown on FIG. 5, the work of liquid displacement being applied by the cross arms 106 is divide virtually equally to each cam assembly 100 of cam system 154a and 144b. Each encoder 120 gives an electrical signal feedback as to each drive motor's momentary rotational speed and digital count position. As discussed in relation to pump 14, controller 74 will use the electrical feedbacks from each encoder 120 to automatically vary the speed of each drive motor 72. This is to equalize the velocity of its mated cam's reciprocating velocity throughout the stroke motion of pump 156. The pump 156 would compare the two motors' 72 momentary speed to determine their momentary velocity being imparted equal to the common connected drive arm 106. That is that each connection position of the cross arm 106 within cam follower assembly 130a and 139b will have virtually equal rectilinear reciprocating velocity applied by each cam assembly 100. This causes a virtual equalized reciprocating motion to be applied to the drive arm 106, by each cam assembly 100. There would be certain mechanical tolerances to allow for slight miss-alignment of forces being applied by the two independent cam follower assemblies 130 to the cross arm 106.

It is understood that there are many ways to achieve the same equalized and divided work of liquid displacement of pump 156 by the two cam assemblies 100. Also, it is understood that the use of other forms of mechanical, electro mechanical, or electrical feedback components may be used to keep the two drive shafts 108a and 108b synchronized.

All other components depicted are the same as shown on FIGS. 5, 6, and 8, except where noted. In the depicted embodiment, the torque from the motors 72 is combined to increase the pump's 156 volumetric displacement. Operationally as each motor 72 rotates it in turn rotates the attached cams 126 of its cam system 100 that are mechanically summed to cam system 130a and 130b that imparts the reciprocating motion to the shared cross arms 106 and then to shafts 108a and 108b and then to arm 106. These rigidly integrated arms 106 and 118 will drive the first and second diaphragm shafts 110a and 100b and the attached diaphragms 114a and 114b, respectively. An alternate design is of two independent separated cam systems 100 without a common drive arm 106 could be utilized, not shown. That is each cam system 100 is independently driving a shaft 108a and 108b. The encoder's electronic feedback will allow for precise volumetric liquid displacement by controller 74 of the pump 156. With the exception of the two motors 72 and its specific design mechanics and electronics herein described, the operation of the pumps 156 is similar to pump 76 as described in FIGS. 5 and 6.

Operationally the resultant liquid flow rate creation by pump 43 is as shown and described by FIGS. 14, 14a and 14b. The flow rate creation can be further modified as described and shown by FIGS. 15 and 15a. The substantially continuous low pulsating liquid flow displacement of the invention remains the same.

FIGS. 10, 10 a and 10b illustrate a liquid end housing 92 as a single component, it is understood that liquid end housing 92 could be composed of more than one component to form an assembly to achieve the same. FIG. 10 is an end view of the single duplex liquid end pump housing 92. In the depicted embodiment, liquid end pump housing includes four integrated check valve assemblies or cartridges 152 that seat in area 170. It has internal liquid passage ways 168 within the housing 92 that allow the liquid to be channeled in or out of the housing 92. The passage ways or channels 168 on the discharge of the pump during normal operation has a virtual sustained positive back pressure when the invention is operating. That is the pressure wave of one displacer beginning to displace liquid is sufficiently close with respect to time over cam angle change to the other displacers ending its liquid displacement that a virtual continuous process back pressure is sustained within the discharge channel 168 or general area 168 during the invention's normal operation. This back pressure will be reflective of the back pressure from the process pressure that the invention is pumping against. The pump during normal operation will mitigate the creation of sudden low pressure issues as described above. When the propelling displacer ends it liquid discharge displacement, the liquid tends to sustain the motion of the displacer.

To ensure there is adequate back pressure, it is common to install a back pressure valve into a pump. This mitigates cam system 20 having virtually zero dwell at the two moments of change in the direction of reciprocating motion being applied to the diaphragms 114a and 114b. This sustained back pressure within zone in the discharge channel area 168 assures that there is sufficient back pressure across the check valves 152 to assure proper seating on the valves when the pump is operating under normal conditions. The cartridge check valve assembly 152 would be rigidly seated in a portion of the channels 168 at areas 170. The cartridge check valves 152 could be of a different design, such as being shaped like a ball and be disposed along a seating area built into the liquid end housing 92, not shown. For example, a portion of the channel 168 within the liquid end 92 could be so designed to comprise a check valve body rather than utilizing the valve body 182 as shown on FIGS. 11 and 11a. The invention could have other combinations of components to form an integral functioning check valve assemblies not shown.

As shown in FIG. 10, pump housing has a threaded section 82 for inlet to suction side liquid channels 168 and the same for the discharge channels 168 has a thread section discharge connection 94. Operationally the liquid flows through the inlet area 82 and into suction side area channel 168, through the check valve 152, by entering the bottom of the check valve 152 and out the side and into area 170 through inlet 172, when the suction check valve 152 is open and then into the cavity areas 162. When the discharge check valve 152 is open and inlet valve closes the liquid exits the cavity 162 through outlet opening 170 through area 170 through the discharge check valve 152 into the discharge channels 168. The liquid would then flow out of the discharge area 94. This hydraulic flow is caused by the motion of the diaphragms 114a and 114b that collapse and expands the volumetric area of the cavities 162. Whereas the area 162 is expanded to cause a low pressure in area 162 that atmospheric pressure will force liquid into this cavity area 162, due to the differential pressure acting on the liquid. Whereas the diaphragms 114a and 114b collapse the cavity area to force the liquid to exit the pump. This process is repeated and alternated between the cavities 162 of the liquid end 92. The appropriate check valves 152 opening and closing at 180° out of phase to each other at positions 214 as shown in the FIGS. 14, 14a, 14b, 15 and 15a. The pump housing's two cavity areas 162 and their mated diaphragms 114a and 114b comprise the defined two cavities of the single duplex pump housing 92.

In addition the bolt holes 166 are to allow bolts 86 to pass through to be connect to mounting position 80 and holes 174 are for the linear bearings 112 to seat and support the drive shafts 108a and 108b. Area 172 is the opening that connects the cavity areas 162 to channels 168. The holes 176 are the threaded holes that allow the diaphragm mounting ring 116, not shown, to be rigidly attached to the liquid end housing 92 to secure the diaphragms 114a and 114b. The areas 160 are passage ways for alternate suction or discharge ports and would be sealed with plugs 84, not shown, if not utilized for fluid porting. They also allow for the creation of the passage way 168.

FIG. 11 illustrates a cartridge ball check valve assembly 152 that are to be integrated into the duplex liquid end housing 92, as shown in FIG. 10, or into liquid end assembly 64 housings 142a and 142b, as described in relation to FIG. 7. The check valve assembly 152 is depicted as a ball type check valve, but the ball could be a disc, cone or other objects. There are four check valve assemblies 152, two on the suction side and two on the discharge side of the pump. The four check assemblies 152 would be integrated into the liquid passage ways 168 at area 170 as shown on FIG. 10. The check valve assembly 152 includes the body 182, a fluid passage way 178, with a ball mating seating area 184.

FIG. 12 is an embodiment of the invention shown as a side view of liquid end housing 92 with the addition of an integral safety pressure flow equalization valve assembly “SPFEV” 74, such as safety relief valve (“SRV”). As shown, the SRV is connected along the side of the single duplex liquid end housing 92 and has channel 200 that is hydraulically interconnected when the diaphragm 192 is not in a fully seated position. The channel 200 is not hydraulic connected when the diaphragm 192 is fully seated as shown. The SRV 202 includes a bonnet 188, a spring 190, the diaphragm 192 and two spring discs 206, located at either end of the spring 190, an adjustment bolt, and locking nut 194 having a cover cap 204. It is understood that valve 202 may be located at different positions on the single duplex liquid end. The SRV 202 is used to protect the pump and pumping system from over pressurization.

Operationally the SRV 202 changes the pressure setting by turning the adjustment bolt 194 to load the diaphragm 192 with sufficient spring force to stay on its seat during normal pump operation. If there is an unsafe pressure reached the diaphragm 192 overcome the spring 190 resistance. This will allow the diaphragm 192 to lift off its seating area allowing pressure to equalize in the channel 200. This will cause liquid flow equalization and comingling between the two diaphragms 14a and 114b and protect an over pressurization condition within the invention and the piping system. When the pump continues to operate, the liquid is shuttled between the two cavities 162 within the liquid end 92, 64 or 208. When the valve 202 is open, liquid is unable to be displaced from the pump. When the over pressure condition is equalized, the diaphragm 192 will re-seat and the liquid within the liquid end will be pumped. FIG. 12a is a top view of the liquid end 92 without the SRV. The SRV can be attached and integrated into all of the liquid ends including 92, 64 and 208 of liquid end assemblies in FIG. 5, FIG. 7, and FIGS. 13, 13a and 13b.

Referring now to FIGS. 13, 13a and 13b, the single duplex liquid end pump housing 208 is depicted without an internal check valve assembly 152. It has four external check valves assemblies typical of FIG. 2 check valve 32 not shown. The check valve assembly 32 would be attached at each of the four process connections located along the exterior of the housing 208, not shown, and include two independent suction process connections and two independent discharge process connections. All other features of liquid end 208 are the same as liquid end 92 as shown and described with regard to FIGS. 10, 10a and 10b, except channel 168 is not interconnected for each diaphragm 114a and 114b. Operationally the liquid end 208 would operate similar as to how liquid end 92 is described in FIG. 10, except the liquid would not be comingled within channels 168.

FIGS. 14, 14 a and 14b depict a diagrammatic example of the pump's liquid volumetric flow rate displacement. That is the preferred embodiment that utilizes multiple cams 126 that are congruent geometries as described and detailed in U.S. Pat. No. 8,752,451, the entirety of which is incorporated herein by reference. These cam profiles create uniform continuous positive reciprocating motion with non-cardioid cam profiles that impart continuous uniform positive reciprocating motion to be transferred to both diaphragms 114a and 114b over virtually 360° of cam angle. This creates substantially continuous liquid displacement by the pump over a significant range of motor speeds. That is the suction liquid and discharge liquid velocities are substantially equal across the duplex liquid end 92, 64 and 208 of the invention. Therefore the diaphragms 114a and 114b motion is sustained to a given direction until the crossover moment at position 214 and motion is reversed, which occurs every 180 degrees. There is virtually no or very minimal dwell time created by the profiles of cams 126. This is accomplished without spring return being applied to the cam follower. FIG. 14 depicts a ratio of volumetric liquid displacement to the discharge side of the pump for one diaphragm 114a over 180° of cam angle. V1 and V0 of FIG. 14 show the volumetric replenishment over 180° of rotation of the cam. Specifically, V1 is the volumetric liquid to be displaced to the discharge side of the invention by a diaphragm 114a and V0 represents the volumetric liquid to be replenished on the suction side of the invention by the diaphragm 114a.

The line 210 represents the sustained volumetric displacement as a uniform velocity virtually without acceleration and 212 represents acceleration of the volumetric displacement with virtually no velocity for the liquid to be displaced by the invention. In practical terms this velocity to acceleration relationship is not absolute due to characteristics of the pump's practical application of mechanics and the pumping system. FIG. 14a represent the same as FIG. 14 for the second diaphragm 114b and its V2 volumetric displacement and V0 it's replenish by the diaphragm 11b. Whereas V1 and V2 are 180° out of phase. The summed continuous liquid flow rate displacement by the pump is shown in FIG. 14b. Each displacer's volumetric displacement as depicted as V1 and V2 is shown in FIG. 14b and over 360° of cam angle change. The 360° of cam angle is virtually equally divided at 180° at positions 214. That is that the acceleration of each volumetric displacement as shown by line 212 for V1 and V2 is substantially achieved over a very small cam angle. This allows a virtually sustained high pressure within the pump's liquid end housing 92 liquid discharge channels 168 as shown and described by FIGS. 10, 10a and 10b. The same for liquid end 64FIG. 7. Liquid end 208 on FIGS. 13, 13a and 13b that would have the same substantially sustained back pressure where the two liquid flow streams combine on the discharge side of the process back to the liquid end. Within the invention there is substantially sustained back pressure within the discharge cavity 168 for single duplex liquid end housings 92 and 64, where the liquid is comingle from the two liquid streams from each displacer 114a and 114b.

FIGS. 15 and 15 a are graphical depictions of the pump operating with low diaphragm velocity and resultant low liquid volumetric displacement. FIGS. 15 and 15a depict the addition of an acceleration and velocity change being applied to the diaphragms 114a and 114b before and after the reciprocating directional cross over positions 214 every 180°. Whereas position 214 is the moment when diaphragms 114a and 114b change their direction of reciprocating motion. This controlled change in acceleration and velocity increases volumetric displacement across the positions 214 to assist check valve seating performance. Whereas the motor 72 or motors 72 are at very low rotational speed and the diaphragms 114a and 114b are at very low uniform reciprocating velocity and results in lower volumetric displacement 216 as compared to full rotational speed at having a full volumetric displacement 226.

The running cam angle change over time and resultant liquid displacement 216 is insufficient to properly operate the pump's check valve assemblies 152 or other external check valves. That is the free moving ball or other geometry in the pump's check valve assemblies is in a float position and will not sufficiently seat. That is there is too much time where the check valve will not seat properly.

To mitigate this inefficient check valve seating, the controller 74 would be monitoring this low velocity condition of the pump 76 or 156 or other embodiments of the invention. The controller 74 would change the motor 72 or motors 72 speed for a sudden rise in acceleration and velocity of the diaphragms 114a and 114b between points 224. The curves 220 illustrating the diaphragms 114a and 114b velocity change, as shown in FIGS. 15 and 15a, for volumetric velocity and acceleration displacement have a varied time duration and peak velocities 218. This is dependent on the controller's 74 commands to the motor 72 or motors 72. This is to cause a quick velocity change to shorten the time differential between positions 224. This is to assist in the proper seating of the balls 180 in the check valve assemblies across position 214. This is to properly assure that the differential pressure across the pump is not equalized due to the extended time period when the suction and discharge check valves 152 or external check valves would virtually not be open simultaneously.

The liquid of the suction and discharge of the pump would be connected and be of one liquid stream across the liquid end of the pump when the ball or other element is floating. The sudden change in diaphragms 114a and 114b velocity, as shown, would increase the volumetric displacement by the invention over a shorter time period of cam angle change. Whereas, FIG. 15a adds a velocity modulation to the displacement deceleration compensation 228, compared to displacement leading velocity of curve 220 shown in FIG. 15. To accomplish this, the controller 23 will reduce the diaphragms' 114a and 114b velocities for the portion of the curve 228 that goes below the mean average velocity curve 216 to offset the velocity curve 220 that is above the mean velocity curve 216. With the volumetric curve 228, the pump's net flow rate creation over the running average displacement curve would be closer to the running mean average liquid volumetric displacement curve of 216. That is to have the summation of the total liquid displacement of the invention over time be approximately constant for the running liquid flow creation over time for the displacement curve 220 at a given motor 72 speed.

A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. A liquid end of a duplex pump, the liquid end comprising: a body having opposite first and second sides, a first pump cavity formed through said first side, a second pump cavity formed through said second side, a first suction passage formed through said body and in fluidic communication with said first pump cavity, a first discharge passage formed through said body and in fluidic communication with said first pump cavity, a second suction passage formed through said body and in fluidic communication with said second pump cavity, a second discharge passage formed through said body and in fluidic communication with said second pump cavity, a suction port formed through said body and in fluidic communication with said first and second suction passages, and a discharge port formed through said body and in fluidic communication with said first and second discharge passages.

2. The liquid end of claim 1, further comprising: a first check valve disposed across said first suction passage;a second check valve disposed across said first discharge passage;a third check valve disposed across said second suction passage;a fourth check valve disposed across said second discharge passage;wherein said first and second check valves operate cooperatively to alternate a fluid flow in a first direction from said suction port through said first suction passage and a second direction from said suction port through said second suction passage; andwherein said second and forth check valves operate cooperatively to alternate a fluid flow in a third direction from said first discharge passage through said discharge port and a fourth direction from said second discharge passage through said discharge port.

3. The liquid end of claim 2, wherein each of said first, second, third, and fourth check valves are disposed within said body.

4. The liquid end of claim 1, further comprising: a first diaphragm disposed across said first pump cavity;a first cap attached to said first side and closing said first pump cavity;a second diaphragm disposed across said second pump cavity; anda second cap attached to said second side and closing said second pump cavity.

5. The liquid end of claim 4, further comprising: first and second connecting shaft passages formed through said body between said first and second sides;a first connecting shaft disposed within said first connecting shaft passage for reciprocating motion therein;a second connecting shaft disposed within said second connecting shaft passage for reciprocating motion therein;a first cross arm attached to and extending between first ends of said first and second connecting shafts;a second cross arm attached to and extending between second ends of said first and second connecting shafts;a first diaphragm shaft connected at one end to said first cross arm for conjoined movement therewith and connected at a second end to said first diaphragm; anda second diaphragm shaft connected at one end to said second cross arm for conjoined movement therewith and connected at a second end to said second diaphragm.

6. The liquid end of claim 5, wherein: said first diaphragm shaft extends through said first cap and is fluidically sealed therewith; andsaid second diaphragm shaft extends through said second cap and is fluidically sealed therewith.

7. The liquid end of claim 1, further comprising: a first check valve disposed across said first suction passage;a second check valve disposed across said first discharge passage;a third check valve disposed across said second suction passage;a fourth check valve disposed across said second discharge passage;wherein said first and second check valves operate cooperatively to alternate a fluid flow in a first direction from said suction port through said first suction passage and a second direction from said suction port through said second suction passage;wherein said second and forth check valves operate cooperatively to alternate a fluid flow in a third direction from said first discharge passage through said discharge port and a fourth direction from said second discharge passage through said discharge port;a first diaphragm disposed across said first pump cavity;a first cap attached to said first side and closing said first pump cavity;a second diaphragm disposed across said second pump cavity;a second cap attached to said second side and closing said second pump cavity;first and second connecting shaft passages formed through said body between said first and second sides;a first connecting shaft disposed within said first connecting shaft passage for reciprocating motion therein;a second connecting shaft disposed within said second connecting shaft passage for reciprocating motion therein;a first cross arm attached to and extending between first ends of said first and second connecting shafts;a second cross arm attached to and extending between second ends of said first and second connecting shafts;a first diaphragm shaft connected at one end to said first cross arm for conjoined movement therewith and connected at a second end to said first diaphragm; anda second diaphragm shaft connected at one end to said second cross arm for conjoined movement therewith and connected at a second end to said second diaphragm.

8. The liquid end of claim 7, wherein each of said first, second, third, and fourth check valves are disposed within said body.

9. The liquid end of claim 7, wherein: said first diaphragm shaft extends through said first cap and is fluidically sealed therewith; andsaid second diaphragm shaft extends through said second cap and is fluidically sealed therewith.

10. A duplex pump comprising: a liquid end having a body, a suction port and a discharge port through said body, a first diaphragm disposed within a first pump cavity formed into said body, a second diaphragm disposed within a second pump cavity formed into said body, said first and second pump cavities being fluidically connected to said suction port and said discharge port;a transmission operatively connected to said first and second diaphragms to reciprocate said first and second diaphragms; anda motor operatively connected to said transmission and operating to drive said transmission.

11. The duplex pump of claim 10, wherein said liquid end further comprises: first and second connecting shaft passages formed through said body between said first and second sides;a first connecting shaft disposed within said first connecting shaft passage for reciprocating motion therein;a second connecting shaft disposed within said second connecting shaft passage for reciprocating motion therein;a first cross arm attached to and extending between first ends of said first and second connecting shafts;a second cross arm attached to and extending between second ends of said first and second connecting shafts;a first diaphragm shaft connected at one end to said first cross arm for conjoined movement therewith and connected at a second end to said first diaphragm;a second diaphragm shaft connected at one end to said second cross arm for conjoined movement therewith and connected at a second end to said second diaphragm; andwherein said transmission is operatively connected to said first and second diaphragms by said first and second connecting shafts.

12. The duplex pump of claim 10, wherein said liquid end further comprises: a first suction passage formed through said body and in fluidic communication with said first pump cavity, a first discharge passage formed through said body and in fluidic communication with said first pump cavity, a second suction passage formed through said body and in fluidic communication with said second pump cavity, a second discharge passage formed through said body and in fluidic communication with said second pump cavity;wherein said suction port is in fluidic communication with said first and second suction passages; andwherein said discharge port is in fluidic communication with said first and second discharge passages.

13. The duplex pump of claim 12, wherein said liquid end further comprises: a first check valve disposed across said first suction passage;a second check valve disposed across said first discharge passage;a third check valve disposed across said second suction passage;a fourth check valve disposed across said second discharge passage;wherein said first and second check valves operate cooperatively to alternate a fluid flow in a first direction from said suction port through said first suction passage and a second direction from said suction port through said second suction passage; andwherein said second and forth check valves operate cooperatively to alternate a fluid flow in a third direction from said first discharge passage through said discharge port and a fourth direction from said second discharge passage through said discharge port.

14. The duplex pump of claim 10, wherein said motor is a stepper motor.

15. A duplex pump comprising: a liquid end having a body, a suction port and a discharge port through said body, a first diaphragm disposed within a first pump cavity formed into said body, a second diaphragm disposed within a second pump cavity formed into said body, said first and second pump cavities being fluidically connected to said suction port and said discharge port;a first transmission operatively connected to said first and second diaphragms to reciprocate said first and second diaphragms; anda first motor operatively connected to said first transmission and operating to drive said first transmission;a second transmission operatively connected to said first and second diaphragms to reciprocate said first and second diaphragms; anda second motor operatively connected to second transmission and operating to drive said second transmission.

16. The duplex pump of claim 15, wherein each of said first and second motors are stepper motors.

17. The duplex pump of claim 15, wherein said liquid end further comprises: first and second connecting shaft passages formed through said body between said first and second sides;a first connecting shaft disposed within said first connecting shaft passage for reciprocating motion therein;a second connecting shaft disposed within said second connecting shaft passage for reciprocating motion therein;a first cross arm attached to and extending between first ends of said first and second connecting shafts;a second cross arm attached to and extending between second ends of said first and second connecting shafts;a first diaphragm shaft connected at one end to said first cross arm for conjoined movement therewith and connected at a second end to said first diaphragm;a second diaphragm shaft connected at one end to said second cross arm for conjoined movement therewith and connected at a second end to said second diaphragm;wherein said first transmission is operatively connected to said first and second diaphragms by said first and second connecting shafts; andwherein said second transmission is operatively connected to said first and second diaphragms by said first and second connecting shafts.

18. The duplex pump of claim 15, wherein said liquid end further comprises: a first suction passage formed through said body and in fluidic communication with said first pump cavity, a first discharge passage formed through said body and in fluidic communication with said first pump cavity, a second suction passage formed through said body and in fluidic communication with said second pump cavity, a second discharge passage formed through said body and in fluidic communication with said second pump cavity;wherein said suction port is in fluidic communication with said first and second suction passages; andwherein said discharge port is in fluidic communication with said first and second discharge passages.

19. The duplex pump of claim 18, wherein said liquid end further comprises: a first check valve disposed across said first suction passage;a second check valve disposed across said first discharge passage;a third check valve disposed across said second suction passage;a fourth check valve disposed across said second discharge passage;wherein said first and second check valves operate cooperatively to alternate a fluid flow in a first direction from said suction port through said first suction passage and a second direction from said suction port through said second suction passage; andwherein said second and forth check valves operate cooperatively to alternate a fluid flow in a third direction from said first discharge passage through said discharge port and a fourth direction from said second discharge passage through said discharge port.

20. The duplex pump of claim 19, wherein each of said first, second, third, and fourth check valves are disposed within said body.