US20190093651A1 - Drive system for a positive displacement pump - Google Patents

Abstract

A drive system for a pump includes a housing, first and second fluid displacement members, a solenoid disposed within the housing, and a reciprocating member configured to be driven by the solenoid. The reciprocating member is connected to the first and second fluid displacement members and is configured to mechanically displace the first and second fluid displacement members.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)
• This application is a continuation based off of U.S. Utility application Ser. No. 14/579,551 filed Dec. 22, 2014, and entitled “Mechanical Drive System for a Pulseless Positive Displacement Pump, which claims benefit to U.S. Provisional Application No. 62/022,263 filed on Jul. 9, 2014, and entitled “Mechanically-Driven Diaphragm Pump with Diaphragm Pressure Chamber,” and to U.S. Provisional Application No. 61/937,266 filed on Feb. 7, 2014, and entitled “Mechanically-Driven Diaphragm Pump with Diaphragm Pressure Chamber,” the disclosures of which are incorporated by reference in their entirety.
BACKGROUND
• This disclosure relates to positive displacement pumps and more particularly to an internal drive system for positive displacement pumps.
• Positive displacement pumps discharge a process fluid at a selected flow rate. In a typical positive displacement pump, a fluid displacement member, usually a piston or diaphragm, drives the process fluid through the pump. When the fluid displacement member is drawn in, a suction condition is created in the fluid flow path, which draws process fluid into a fluid cavity from the inlet manifold. The fluid displacement member then reverses direction and forces the process fluid out of the fluid cavity through the outlet manifold.
• Air operated double displacement pumps typically employ diaphragms as the fluid displacement members. In an air operated double displacement pump, the two diaphragms are joined by a shaft, and compressed air is the working fluid in the pump. Compressed air is applied to one of two diaphragm chambers, associated with the respective diaphragms. When compressed air is applied to the first diaphragm chamber, the first diaphragm is deflected into the first fluid cavity, which discharges the process fluid from that fluid cavity. Simultaneously, the first diaphragm pulls the shaft, which is connected to the second diaphragm, drawing the second diaphragm in and pulling process fluid into the second fluid cavity. Delivery of compressed air is controlled by an air valve, and the air valve is usually actuated mechanically by the diaphragms. Thus, one diaphragm is pulled in until it causes the actuator to toggle the air valve. Toggling the air valve exhausts the compressed air from the first diaphragm chamber to the atmosphere and introduces fresh compressed air to the second diaphragm chamber, thus causing a reciprocating movement of the respective diaphragms. Alternatively, the first and second fluid displacement members could be pistons instead of diaphragms, and the pump would operate in the same manner.
• Hydraulically driven double displacement pumps utilize hydraulic fluid as the working fluid, which allows the pump to operate at much higher pressures than an air driven pump. In a hydraulically driven double displacement pump, hydraulic fluid drives one fluid displacement member into a pumping stroke, while that fluid displacement member is mechanically attached to the second fluid displacement member and thereby pulls the second fluid displacement member into a suction stroke. The use of hydraulic fluid and pistons enables the pump to operate at higher pressures than an air driven diaphragm pump could achieve.
• Alternatively, double displacement pumps may be mechanically operated, without the use of air or hydraulic fluid. In these cases, the operation of the pump is essentially similar to an air operated double displacement pump, except compressed air is not used to drive the system. Instead, a reciprocating drive is mechanically connected to both the first fluid displacement member and the second fluid displacement member, and the reciprocating drive drives the two fluid displacement members into suction and pumping strokes.
SUMMARY
• According to one embodiment of the present invention, a drive system for a pumping apparatus includes a housing, an internal pressure chamber filled with a working fluid and defined by the housing, and a fluid displacement member sealingly enclosing a first end of the internal pressure chamber. A reciprocating member is disposed within the internal pressure chamber, and the reciprocating member has a pull chamber. A pull is secured within the pull chamber and a fluid displacement member is coupled to the pull.
• According to another embodiment, a drive system for a pumping apparatus includes a housing, an internal pressure chamber filled with a working fluid and defined by the housing, a reciprocating member disposed within the internal pressure chamber, and a plurality of fluid displacement members. The reciprocating member has a first pull chamber and a second pull chamber. A first pull is secured within the first pull chamber and a first one of the plurality of fluid displacement members is coupled to the first pull. A second pull is secured within the second pull chamber and a second one of the plurality of fluid displacement members is coupled to the second pull.
• According to yet another embodiment, a drive system for a pumping apparatus comprises a housing, an internal pressure chamber filled with a working fluid and defined by the housing, and a fluid displacement member sealingly enclosing a first end of the internal pressure chamber. A drive extends into the internal pressure chamber, and a hub is disposed on the drive with an attachment member on the hub. A flexible belt is connected to the fluid displacement member and to the attachment portion.
• Yet another embodiment of the present invention includes a drive system for a pumping apparatus that has a housing, an internal pressure chamber filled with a working fluid and defined by the housing, and a plurality of fluid displacement members. A drive extends into the internal pressure chamber, and a hub is disposed on the drive. The hub has a first attachment portion and a second attachment portion, and a first flexible belt is connected to a first one of the plurality of fluid displacement members and a second flexible belt is connected to a second one of the plurality of fluid displacement members.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a rear perspective view of a pump, drive system, and motor.
• FIG. 2 is an exploded perspective view of a pump, drive system, and drive.
• FIG. 3A is a cross-sectional view, along section3-3 inFIG. 1, showing the connection of pump, drive system, and drive.
• FIG. 3B is a cross-sectional view, along section3-3 inFIG. 1, showing the connection ofFIG. 3A during an over-pressurization event.
• FIG. 4 is a top, cross-sectional view, along section4-4 inFIG. 1, showing the connection of pump, drive system, and drive.
• FIG. 5 is a cross-sectional view, along section5-5 inFIG. 1, showing the connection of a pump, a drive system, and a drive.
• FIG. 6 is a cross-sectional view, along section6-6 inFIG. 1, showing the connection of a pump, a drive system, and a drive.
• FIG. 7 is a cross-sectional view, along section7-7 inFIG. 1, showing the connection of a pump, a drive system, and a drive.
DETAILED DESCRIPTION
• FIG. 1 shows a perspective view ofpump10,electric drive12, anddrive system14.Pump10 includesinlet manifold16,outlet manifold18, fluid covers20aand20b,inlet check valves22aand22b, andoutlet check valves24aand24b.Drive system14 includeshousing26 andpiston guide28. Housing includes workingfluid inlet30 and drive chamber32 (best seen inFIG. 2).Electric drive12 includesmotor34,gear reduction drive36, and drive38.
• Fluid covers20aand20bare attached toinlet manifold16 byfasteners40.Inlet check valves22aand22b(shown inFIG. 2) are disposed betweeninlet manifold16 and fluid covers20aand20brespectively. Fluid covers20aand20bare similarly attached tooutlet manifold18 byfasteners40.Outlet check valves24aand24b(shown inFIG. 2) are disposed betweenoutlet manifold18 and fluid covers20aand20b, respectively.Housing26 is secured between fluid covers20aand20bbyfasteners42.Fluid cavity44a(best seen inFIG. 3) is formed betweenhousing26 andfluid cover20a.Fluid cavity44b(best seen inFIG. 3) is formed betweenhousing26 andfluid cover20b.
• Motor34 is attached to and drivesgear reduction drive36.Gear reduction drive36drives drive38 to actuatepump10.Drive38 is secured withindrive chamber32 byfasteners46.
• Housing26 is filled with a working fluid, either a gas, such as compressed air, or a non-compressible hydraulic fluid, through workingfluid inlet30. When the working fluid is a non-compressible hydraulic fluid,housing26 further includes an accumulator for storing a portion of the non-compressible hydraulic fluid during an overpressurization event. As explained in more detail below, drive38 causes drivesystem14 to draw process fluid frominlet manifold16 into eitherfluid cavity44aorfluid cavity44b. The working fluid then discharges the process fluid from eitherfluid cavity44aorfluid cavity44bintooutlet manifold18.Inlet check valves22aand22bprevent the process fluid from backflowing intoinlet manifold16 while the process fluid is being discharged tooutlet manifold18. Similarly,outlet check valves24aand24bprevent the process fluid from backflowing into eitherfluid cavity44aor44bfromoutlet manifold18.
• FIG. 2 is an exploded, perspective view ofpump10,drive system14, and drive38.Pump10 includesinlet manifold16,outlet manifold18, fluid covers20aand20b,inlet check valves22aand22b, andoutlet check valves24aand24b.Inlet check valve22aincludesseat48aandcheck ball50a, andinlet check valve22bincludesseat48band checkball50b. Similarly,outlet check valve24aincludeseat49aandcheck ball51a, andoutlet check valve24bincludesseat49band checkball51b. Althoughinlet check valves22a/22bandoutlet check valves24a/24bare shown as ball check valves,inlet check valves22a/22bandoutlet check valves24a/24bcan be any suitable valve for preventing the backflow of process fluid.
• Pump further includesfluid displacement members52aand52b. In the present embodiment,fluid displacement members52aand52bare shown as diaphragms, butfluid displacement members52aand52bcould be diaphragms, pistons, or any other suitable device for displacing process fluid. Additionally, whilepump10 is described as a double displacement pump, utilizing dual diaphragms, it is understood thatdrive system14 could similarly drive a single displacement pump without any material change. It is also understood thatdrive system14 could drive a pump with more than two fluid displacement members.
• Drive system14 includeshousing26,piston guide28,piston54, pulls56aand56b, andface plates58aand58b.Housing26 includes workingfluid inlet30, guide opening60,annular structure62, andbushings64aand64b.Housing26 definesinternal pressure chamber66, which contains the working fluid during operation. In the present embodiment, the reciprocating member ofdrive system14 is shown as a piston, but it is understood that the reciprocating member ofdrive system14 could be any suitable device for creating a reciprocating motion, such as a scotch yoke or any other drive suitable for reciprocating withinhousing26.
• Piston guide28 includesbarrel nut68 andguide pin70.Piston54 includespull chamber72adisposed within a first end ofpiston54 and pullchamber72b(shown inFIG. 3A) disposed within a second end ofpiston54.Piston54 further includescentral slot74,axial slot76, andopenings78aand78b(not shown) for receivingface plate fasteners80. Pull56ais identical to pull56bwith like numbers indicating like parts. Pull56aincludes attachment end82a,free end84a, and pullshaft86aextending between attachment end82aandfree end84a.Free end84aofpull56aincludesflange85a.Face plate58ais identical to faceplate58bwith like numbers indicating like parts.Face plate58aincludes fastener holes88aand pull opening90a. In the present embodiment,fluid displacement member52aincludesattachment screw92aanddiaphragm94a.Drive38 includeshousing96, crankshaft98,cam follower100, bearing102, andbearing104.Annular structure62 includesopenings106 therethrough.
• Inlet manifold16 is attached tofluid cover20abyfasteners40.Inlet check valve22ais disposed betweeninlet manifold16 and fluid cover20a.Seat48aofinlet check valve22asits uponinlet manifold16, and checkball50aofinlet check valve22ais disposed betweenseat48aand fluid cover20a. Similarly,inlet manifold16 is attached tofluid cover20bbyfasteners40, andinlet check valve22bis disposed betweeninlet manifold16 and fluid cover20b.Outlet manifold18 is attached tofluid cover20abyfasteners40.Outlet check valve24ais disposed betweenoutlet manifold18 and fluid cover20a.Seat49aofoutlet check valve24asits uponfluid cover20aandcheck ball51aofoutlet check valve24ais disposed betweenseat49aandoutlet manifold18. Similarly,outlet manifold18 is attached tofluid cover20bbyfasteners40, andoutlet check valve24bis disposed betweenoutlet manifold18 and fluid cover20b.
• Fluid cover20ais fixedly attached tohousing26 byfasteners42.Fluid displacement member52ais secured betweenhousing26 and fluid cover20ato definefluid cavity44aand sealingly encloses one end ofinternal pressure chamber66.Fluid cover20bis fixedly attached tohousing26 byfasteners42, andfluid displacement member52bis secured betweenhousing26 and fluid cover20b. Similar tofluid cavity44a,fluid cavity44bis formed byfluid cover20bandfluid displacement member52b, andfluid displacement member52bsealingly encloses a second end ofinternal pressure chamber66.
• Bushings64aand64bare disposed uponannular structure62, andpiston54 is disposed withinhousing26 and rides uponbushings64aand64b.Barrel nut68 extends through and is secured withinguide opening60.Guide pin70 is fixedly secured tobarrel nut68 and rides withinaxial slot76 to preventpiston54 from rotating about axis A-A.Free end84aofpull56ais slidably disposed withinpull chamber72aofpiston54. Pullshaft86aextends through pull opening90aofface plate58a.Face plate58ais secured topiston54 byface plate fasteners80 that extend throughopenings88aand into fastener holes78aofpiston54. Pull opening90ais sized such that pullshaft86acan slide through pull opening90abutfree end84ais retained withinpull chamber72abyflange85aengagingface plate58a. Attachment end82ais secured to attachment screw92ato joinfluid displacement member52ato pull56a.
• Crankshaft98 is rotatably mounted withinhousing96 by bearing102 andbearing104.Cam follower100 is affixed to crankshaft98 such thatcam follower100 extends intohousing26 and engagescentral slot74 ofpiston54 whendrive38 is mounted tohousing26. drive38 is mounted withindrive chamber32 ofhousing26 byfasteners46 extending throughhousing96 and into fastener holes108.
• Internal pressure chamber66 is filled with a working fluid, either compressed gas or non-compressible hydraulic fluid, through workingfluid inlet30.Openings106 allow the working fluid to flow throughoutinternal pressure chamber66 and exert force on bothfluid displacement member52aandfluid displacement member52b.
• Cam follower100 reciprocatingly drivespiston54 along axis A-A. Whenpiston54 is displaced towardsfluid displacement member52a, pull56bis pulled in the same direction due toflange85bonfree end84bofpull56bengagingface plate58b. Pull56bthereby pullsfluid displacement member52binto a suction stroke. Pullingfluid displacement member52bcauses the volume offluid cavity44bto increase, which draws process fluid intofluid cavity44bfrominlet manifold16.Outlet check valve24bprevents process fluid from being drawn intofluid cavity44bfromoutlet manifold18 during the suction stroke. At the same time that process fluid is being drawn intofluid cavity44b, the charge pressure of the working fluid ininternal pressure chamber66 pushesfluid displacement member52aintofluid cavity44a, causingfluid displacement member52ato begin a pumping stroke. Pushingfluid displacement member52aintofluid cavity44areduces the volume offluid cavity44aand causes process fluid to be expelled fromfluid cavity44aintooutlet manifold18.Inlet check valve22aprevents process fluid from being expelled intoinlet manifold16 during a pumping stoke. Whencam follower100 causespiston54 to reverse direction,fluid displacement member52ais pulled into a suction stroke bypull56a, andfluid displacement member52bis pushed into a pumping stroke by the charge pressure of the working fluid ininternal pressure chamber66, thereby completing a pumping cycle.
• Pullchambers72aand72bpreventpiston54 from exerting a pushing force on eitherfluid displacement member52aor52b. If the pressure in the process fluid exceeds the pressure in the working fluid, the working fluid will not be able to push eitherfluid displacement member52aor52binto a pumping stroke. In that overpressure situation, such as whenoutlet manifold18 is blocked, drive38 will continue to drivepiston54, but pulls56aand56bwill remain in a suction stroke because the pressure of the working fluid is insufficient to cause eitherfluid displacement member52aor52bto enter a pumping stroke. Whenpiston54 is displaced towardsfluid displacement member52a, pullchamber72aprevents pull56afrom exerting any pushing force onfluid displacement member52aby housing pull56awithinpull chamber72a. Allowingpiston54 to continue to oscillate without pushing eitherfluid displacement member52aor52binto a pumping stroke allowspump10 to continue to run whenoutlet manifold18 is blocked without causing any harm to the motor or pump.
• FIG. 3A is a cross-sectional view ofpump10,drive system14, andcam follower100 during normal operation.FIG. 3B is a cross-sectional view ofpump10,drive system14, andcam follower100 afteroutlet manifold18 has been blocked, i.e. thepump10 has been deadheaded.FIG. 3A andFIG. 3B will be discussed together.Pump10 includesinlet manifold16,outlet manifold18, fluid covers20aand20b,inlet check valves22aand22b,outlet check valves24aand24b, andfluid displacement members52aand52b.Inlet check valve22aincludesseat48aandcheck ball50a, whileinlet check valve22bsimilarly includesseat48band checkball50b.Outlet check valve24aincludesseat49aandcheck ball51a, andoutlet check valve24bincludesseat49band checkball51b. In the present embodiment,fluid displacement member52aincludesdiaphragm94a,first diaphragm plate110a,second diaphragm plate112a, and attachment screw92a. Similarly,fluid displacement member52bincludesdiaphragm94b,first diaphragm plate110b,second diaphragm plate112b, and attachment screw92b.
• Drive system14 includeshousing26,piston guide28,piston54, pulls56aand56b,face plates58aand58b,annular structure62, andbushings64aand64b.Housing26 includes guide opening60 for receivingpiston guide28 therethrough, andhousing26 definesinternal pressure chamber66.Piston guide28 includesbarrel nut68 andguide pin70.Piston54 includes pullchambers72aand72b,central slot74 andaxial slot76. Pull56aincludes attachment end82a,free end84aand pullshaft86aextending betweenfree end84aand attachment end82a.Free end84aincludesflange85a. Similarly, pull56bincludesattachment end82b,free end84b, and pullshaft86b, andfree end84bincludesflange85b.Face plate58aincludes pull opening90aandface plate58bincludes opening90b.
• Fluid cover20ais affixed tohousing26, andfluid displacement member52ais secured between fluid cover20aandhousing26. Fluid cover20aandfluid displacement member52adefinefluid cavity44a.Fluid displacement member52aalso sealingly separatesfluid cavity44afrominternal pressure chamber66.Fluid cover20bis affixed tohousing26 opposite fluid cover20a.Fluid displacement member52bis secured betweenfluid cover20bandhousing26.Fluid cover20bandfluid displacement member52bdefinefluid cavity44b, andfluid displacement member52bsealingly separatesfluid cavity44bfrominternal pressure chamber66.
• Piston54 rides onbushings64aand64b.Free end84aofpull56ais slidably secured withinpull chamber72aofpiston54 byflange85aandface plate58a.Flange85aengagesface plate58aand preventsfree end84afrom exitingpull chamber72a. Pullshaft86aextends through opening90a, and attachment end82aengagesattachment screw92a. In this way, attachesfluid displacement member52atopiston54. Similarly,free end84bofpull56bis slidably secured withinpull chamber72bofpiston54 byflange85bandface plate58b. Pullshaft86bextends through pull opening90b, and attachment end82bengagesattachment screw92b.
• Cam follower100 engagescentral slot74 ofpiston54.Barrel nut68 extends through guide opening60 intointernal pressure chamber66.Guide pin70 is attached to the end ofbarrel nut68 that projects intointernal pressure chamber66, and guidepin70 slidably engagesaxial slot76.
• Inlet manifold16 is attached to both fluid cover20aand fluid cover20b.Inlet check valve22ais disposed betweeninlet manifold16 and fluid cover20a, andinlet check valve22bis disposed betweeninlet manifold16 and fluid cover20b.Seat48arests oninlet manifold16 and checkball50ais disposed betweenseat48aand fluid cover20a. Similarly,seat48brests oninlet manifold16 and checkball50bis disposed betweenseat48band fluid cover20b. In this way,inlet check valves22aand22bare configured to allow process fluid to flow frominlet manifold16 into eitherfluid cavity44aand44b, while preventing process fluid from backflowing intoinlet manifold16 from eitherfluid cavity44aor44b.
• Outlet manifold18 is also attached to both fluid cover20aand fluid cover20b.Outlet check valve24ais disposed betweenoutlet manifold18, and fluid cover20a, andoutlet check valve24bis disposed betweenoutlet manifold18 and fluid cover20b.Seat49arests uponfluid cover20aandcheck ball51ais disposed betweenseat49aandoutlet manifold18. Similarly,seat49brests uponfluid cover20band checkball51bis disposed betweenseat49bandoutlet manifold18.Outlet check valves24aand24bare configured to allow process fluid to flow fromfluid cavity44aor44bintooutlet manifold18, while preventing process fluid from backflowing into eitherfluid cavity44aor44bfromoutlet manifold18.
• Cam follower100 reciprocatespiston54 along axis A-A.Piston guide28 preventspiston54 from rotating about axis A-A by havingguide pin70 slidably engaged withaxial slot76. Whenpiston54 is drawn towardsfluid cavity44b, pull56ais also pulled towardsfluid cavity44bdue toflange85aengagingface plate58a. Pull56athereby causesfluid displacement member52ato enter a suction stroke due to the attachment of attachment end82aand attachment screw92a. Pullingfluid displacement member52acauses the volume offluid cavity44ato increase, which draws process fluid throughcheck valve22aand intofluid cavity44afrominlet manifold16.Outlet check valve24aprevents process fluid from being drawn intofluid cavity44afromoutlet manifold18 during the suction stroke.
• At the same time that process fluid is being drawn intofluid cavity44a, the working fluid causesfluid displacement member52bto enter a pumping stroke. The working fluid is charged to a higher pressure than that of the process fluid, which allows the working fluid to displace thefluid displacement member52aor52bthat is not being drawn into a suction stroke bypiston54. Pushingfluid displacement member52bintofluid cavity44breduces the volume offluid cavity44band causes process fluid to be expelled fromfluid cavity44bthroughoutlet check valve24band intooutlet manifold18.Inlet check valve22bprevents process fluid from being expelled intoinlet manifold16 during a pumping stoke.
• Whencam follower100 causespiston54 to reverse direction and travel towardsfluid cavity44a,face plate58bcatchesflange85bonfree end84bofpull56b. Pull56bthen pullsfluid displacement member52binto a suction stroke causing process fluid to enterfluid cavity44bthroughcheck valve22bfrominlet manifold16. At the same time, the working fluid now causesfluid displacement member52ato enter a pumping stroke, thereby discharging process fluid fromfluid cavity44athroughcheck valve24aand intooutlet manifold18.
• A constant downstream pressure is produced to eliminate pulsation by sequencing the speed ofpiston54 with the pumping stroke caused by the working fluid. To eliminate pulsation,piston54 is sequenced such that when it begins to pull one offluid displacement member52aor52binto a suction stroke, the otherfluid displacement member52aor52bhas already completed its change-over and started a pumping stroke. Sequencing the suction and pumping strokes in this way prevents thedrive system14 from entering a state of rest.
• Referring specifically toFIG. 3B, pullchamber72aand pullchamber72bofpiston54 allowpump10 to be deadheaded without causing any damage to thepump10 ormotor12. Whenpump10 is deadheaded, the process fluid pressure exceeds the working fluid pressure, which prevents the working fluid from pushing eitherfluid displacement member52aor52binto a pumping stroke.
• During over-pressurizationfluid displacement member52aandfluid displacement member52bare retracted into a suction stroke bypiston54; however, because the working fluid pressure is insufficient to push thefluid displacement member52aor52binto a pumping stroke, thefluid displacement members52aand52bremain in the suction stroke position.Piston54 is prevented from mechanically pushing eitherfluid displacement member52aor52binto a pumping stroke bypull chamber72a, which houses pull56awhen the process fluid pressure exceeds the working fluid pressure andpiston54 is driven towardsfluid displacement member52a, and pullchamber72b, which houses pull56bwhen the process fluid pressure exceeds the working fluid pressure andpiston54 is driven towardsfluid displacement member52b. Housing pull56awithinpull chamber72aand pull56bwithinpull chamber72bpreventspiston54 from exerting any pushing force onfluid displacement members52aor52b, which allowsoutlet manifold18 to be blocked without damagingpump10.
• FIG. 4 is a top cross-sectional view, along line4-4 ofFIG. 1, showing the connection ofdrive system14 and drive38.FIG. 4 also depicts fluid covers20aand20b, andfluid displacement members52aand52b.Drive system14 includeshousing26,piston54, pulls56aand56b,face plates58aand58b, andbushings64aand64b.Housing26 andfluid displacement members52aand52bdefineinternal pressure chamber66.Housing26 includesdrive chamber32 andannular structure62.Piston54 includes pullchambers72aand72bandcentral slot74. Pull56aincludes attachment end82a,free end84a,flange85a, and pullshaft86a, while pull56bsimilarly includesattachment end82b,free end84b,flange85b, andshaft86b.Face plate58aincludes pull opening90aandopenings88a. Similarly, faceplate58bincludes pull opening90band openings88b. In the present embodiment, drive38 includeshousing96, crankshaft98,cam follower100, bearing102, andbearing104. Crankshaft98 includesdrive shaft chamber114 andcam follower chamber116.
• Fluid cover20ais attached tohousing26 byfasteners42.Fluid displacement member52ais secured between fluid cover20aandhousing26. Fluid cover20aandfluid displacement member52adefinefluid cavity44a. Similarly,fluid cover20bis attached tohousing26 byfasteners42, andfluid displacement member52bis secured betweenfluid cover20bandhousing26.Fluid cover20bandfluid displacement member52bdefinefluid cavity44b.Housing26 andfluid displacement members52aand52bdefineinternal pressure chamber66.
• In the present embodiment,fluid displacement member52ais shown as a diaphragm and includesdiaphragm94a,first diaphragm plate110a,second diaphragm plate112a, and attachment screw92a. Similarly,fluid displacement member52bis shown as a diaphragm and includesdiaphragm94b,first diaphragm plate110b,second diaphragm plate112b, and attachment screw92b. Whilefluid displacement members52aand52bare shown as diaphragms, it is understood thatfluid displacement members52aand52bcould also be pistons.
• Piston54 is mounted onbushings64aand64bwithininternal pressure chamber66.Free end84aofpull56ais slidably secured withinpull chamber72abyface plate58aandflange85a.Shaft86aextends through opening90a, and attachment end82aengagesattachment screw92a.Face plate58ais secured topiston54 byface plate fasteners80aextending throughopenings88aand intopiston54. Similarly,free end84bofpull56bis slidably secured withinpull chamber72bbyface plate58bandflange85b. Pullshaft86bextends through pull opening90b, and attachment end82bengagesattachment screw92b.Face plate58bis attached topiston54 byface plate fasteners80bextending through openings88band intopiston54.
• Drive38 is mounted withindrive chamber32 ofhousing26. Crankshaft98 is rotatably mounted withinhousing96 by bearing102 andbearing104. Crankshaft98 is driven by a drive shaft (not shown) that connects to crankshaft98 atdrive shaft chamber114.Cam follower100 is mounted to crankshaft98 opposite the drive shaft, andcam follower100 is mounted atcam follower chamber116.Cam follower100 extends intointernal pressure chamber66 and engagescentral slot74 ofpiston54.
• Drive38 is driven by electric motor12 (shown inFIG. 1), which rotates crankshaft98 onbearings102 and104. Crankshaft98 thereby rotatescam follower100 about axis B-B, andcam follower100 thus causespiston54 to reciprocate along axis A-A. Becausepiston54 has a predetermined lateral displacement, determined by the rotation ofcam follower100, the speed of thepiston54 can be sequenced with the pressure of the working fluid to eliminate downstream pulsation.
• Whencam follower100drives piston54 towardsfluid displacement member52b,piston54 pullsfluid displacement member52ainto a suction stroke viapull56a.Flange85aofpull56aengagesface plate58asuch thatpiston54 causes pull56ato also move towardsfluid displacement member52b, which causes pull56ato pullfluid displacement member52ainto a suction stroke. Pull56apullsfluid displacement member52ainto a suction stroke through attachment end82abeing engaged withattachment screw92a. At the same time, the pressurized working fluid withininternal pressure chamber66 pushesfluid displacement member52binto a pumping stroke.
• FIG. 5 is a cross-sectional view, along section5-5 ofFIG. 1, showing the connection ofpump10,drive system214, andcam follower100.Pump10 includesinlet manifold16,outlet manifold18, fluid covers20aand20b,inlet check valves22aand22b,outlet check valves24aand24b, andfluid displacement members52aand52b.Inlet check valve22aincludesseat48aandcheck ball50a, whileinlet check valve22bincludesseat48band checkball50b.Outlet check valve24aincludesseat49aandcheck ball51a, whileoutlet check valve24bincludesseat49band checkball51b. In the present embodiment,fluid displacement member52aincludesdiaphragm94a,first diaphragm plate110a,second diaphragm plate112a, andattachment member216a. Similarly,fluid displacement member52bincludesdiaphragm94b,first diaphragm plate110b,second diaphragm plate112b, andattachment member216b.Drive system214 includeshousing26,hub218,flexible belts220aand220b, and pins222aand222b.Housing26 definesinternal pressure chamber66.
• Fluid cover20ais affixed tohousing26, andfluid displacement member52ais secured between fluid cover20aandhousing26. Fluid cover20aandfluid displacement member52adefinefluid cavity44a, andfluid displacement member52asealingly separatesfluid cavity44aandinternal pressure chamber66.Fluid cover20bis affixed tohousing26, andfluid displacement member52bis secured betweenfluid cover20bandhousing26.Fluid cover20bandfluid displacement member52bdefinefluid cavity44b, andfluid displacement member52bsealingly separatesfluid cavity44bandinternal pressure chamber66.Housing26 includesopenings106 to allow working fluid to flow withininternal pressure chamber66.
• Hub218 is press-fit tocam follower100.Pin222aprojects from a periphery ofhub218 along axis B-B. Similarly, pin222bprojects from a periphery ofhub218 along axis B-B andopposite pin222a. Flexible belt220ais attached to pin222aand toattachment member216a.Flexible belt220bis attached to pin222band toattachment member216b.
• Cam follower100drives hub218 along axis A-A. Whenhub218 is drawn towardsfluid cavity44b, flexible belt220ais also pulled towardsfluid cavity44bcausingfluid displacement member52ato enter a suction stroke due to the attachment of flexible belt220atoattachment member216aand pin222a. Pullingfluid displacement member52acauses the volume offluid cavity44ato increase, which draws process fluid throughcheck valve22aand intofluid cavity44afrominlet manifold16.Outlet check valve24aprevents process fluid from being drawn intofluid cavity44afromoutlet manifold18 during the suction stroke.
• At the same time that process fluid is being drawn intofluid cavity44a, the working fluid causesfluid displacement member52bto enter a pumping stroke. The working fluid is charged to a higher pressure than that of the process fluid, which allows the working fluid to displace thefluid displacement member52aor52bthat is not being drawn into a suction stroke byhub218. Pushingfluid displacement member52bintofluid cavity44breduces the volume offluid cavity44band causes process fluid to be expelled fromfluid cavity44bthroughoutlet check valve24band intooutlet manifold18.Inlet check valve22bprevents process fluid from being expelled intoinlet manifold16 during a pumping stoke.
• Whencam follower100 causeshub218 to reverse direction and travel towardsfluid cavity44apin222bengagesflexible belt220b, andflexible belt220bthen pullsfluid displacement member52binto a suction stroke causing process fluid to enterfluid cavity44bfrominlet manifold16. At the same time, the working fluid now causesfluid displacement member52ato enter a pumping stroke, thereby discharging process fluid fromfluid cavity44athroughcheck valve24aand intooutlet manifold18.
• Flexible belts220aand220ballowoutlet manifold18 ofpump10 to be blocked during the operation ofpump10 without risking damage to pump10,drive system214, or electric motor12 (shown inFIG. 1). Whenoutlet manifold18 is blocked, the pressure influid cavity44aandfluid cavity44bequals the pressure of the working fluid ininternal pressure chamber66. When such an over-pressure situation occurs,hub218 will draw bothfluid displacement member52aandfluid displacement member52binto a suction stroke. However,drive system214 cannot push eitherfluid displacement member52aor52binto a pumping stroke becauseflexible belts220aand220bare not sufficiently rigid to impart a pushing force on eitherfluid displacement member52aor52b.
• FIG. 6 is a cross-sectional view, along section6-6 ofFIG. 1, showing the connection ofpump10 anddrive system314.Pump10 includesinlet manifold16,outlet manifold18, fluid covers20aand20b,inlet check valves22aand22b,outlet check valves24aand24b, andfluid displacement members52aand52b.Inlet check valve22aincludesseat48aandcheck ball50a, whileinlet check valve22bincludesseat48band checkball50b.Outlet check valve24aincludesseat49aandcheck ball51a, whileoutlet check valve24bincludesseat49band checkball51b. In the present embodiment,fluid displacement member52aincludesdiaphragm94a,first diaphragm plate110a, andsecond diaphragm plate112a, and attachment screw92a. Similarly,fluid displacement member52bincludesdiaphragm94b,first diaphragm plate110b, andsecond diaphragm plate112b, and attachment screw92b.
• Drive system314 includeshousing26,second housing316,piston318, and pulls320aand320b.Piston318 includes reciprocatingmember322 and pullhousings324aand324b. Pull housing324adefinespull chamber326aand includes pull opening328a. Pullhousing324bdefinespull chamber326band includes pull opening328b. Pull320aincludes attachment end330a,free end332aand pull shaft334aextending betweenfree end332aand attachment end330a.Free end332aincludes flange336a. Similarly, pull320bincludesattachment end330b,free end332b, and pullshaft334bextending betweenfree end332band attachment end330b, andfree end332bincludesflange336b.Second housing316 includespressure chamber338aandpressure chamber338b,aperture340a,aperture340b, first o-ring342, second o-ring344, and third o-ring346.
• Fluid cover20ais affixed tohousing26, andfluid displacement member52ais secured between fluid cover20aandhousing26. Fluid cover20aandfluid displacement member52adefinefluid cavity44a, andfluid displacement member52asealingly separatesfluid cavity44aandinternal pressure chamber66.Fluid cover20bis affixed tohousing26, andfluid displacement member52bis secured betweenfluid cover20bandhousing26.Fluid cover20bandfluid displacement member52bdefinefluid cavity44b, andfluid displacement member52bsealingly separatesfluid cavity44bandinternal pressure chamber66.
• Second housing316 is disposed withinhousing26.Piston318 is disposed withinsecond housing316. First o-ring342 is disposed around reciprocatingmember322, and first o-ring342 and reciprocatingmember322 sealinglyseparate pressure chamber338aandpressure chamber338b. Pull housing324aextends from reciprocatingmember322 throughaperture340aand intointernal pressure chamber66. Pullhousing324bextends from reciprocatingmember322 throughaperture340band intointernal pressure chamber66. Second o-ring344 is disposed around pull housing324aataperture340a. Second o-ring344 sealingly separatespressure chamber338afrominternal pressure chamber66. Third o-ring346 is disposed around pullhousing324bataperture340b. Third o-ring346 sealingly separatespressure chamber338bfrominternal pressure chamber66.
• Free end332aofpull320ais slidably secured withinpull chamber326aby flange336a. Pull shaft334aextends through pull opening328a, and attachment end330aengagesattachment screw92a. Similarly,free end332bofpull320bis slidably secured withinpull chamber326bbyflange336b. Pullshaft334bextends through pull opening328b, and attachment end330bengagesattachment screw92b.
• Piston318 is reciprocatingly driven withinsecond housing316 by alternatingly providing pressurized fluid to pressurechamber338aandpressure chamber338b. The pressurized fluid can be compressed air, non-compressible hydraulic fluid, or any other fluid suitable for drivingpiston318. First o-ring342 sealingly separatespressure chamber338aandpressure chamber338b, which allows the pressurized fluid toreciprocatingly drive piston318. When pressurized fluid is provided to pressurechamber338a, second o-ring344 sealingly separates the pressurized fluid from the working fluid disposed withininternal pressure chamber66. Similarly, when pressurized fluid is provided to pressurechamber338b, third o-ring346 sealingly separates the pressurized fluid from the working fluid disposed withininternal pressure chamber66.
• Whenpressure chamber338ais pressurized,piston318 is driven towardsfluid displacement member52b. Pull320ais thereby also drawn towardsfluid displacement member52bdue to flange336aengaging pull housing324a. Pull320acausesfluid displacement member52ato enter into a suction stroke due to the connection between attachment end330aand attachment screw92a. At the same time, the working fluid ininternal pressure chamber66 pushesfluid displacement member52binto a pumping stroke. During this stroke, pullchamber326bpreventspiston318 from pushingfluid displacement member52binto a pumping stroke.
• The stroke is reversed whenpressure chamber338bis pressurized, thereby drivingpiston318 towardsfluid displacement member52a. In this stroke, pull320bis drawn towardsfluid displacement member52adue toflange336bengagingpull housing324b. Pull320bcausesfluid displacement member52bto enter into a suction stroke due to the connection betweenattachment end330band attachment screw92b. Whilefluid displacement member52bis drawn into a suction stroke, the working fluid ininternal pressure chamber66 pushesfluid displacement member52ainto a pumping stroke. Similar to pullchamber326b, pullchamber326apreventspiston318 from pushingfluid displacement member52ainto a pumping stroke.
• FIG. 7 is a cross-sectional view, along section7-7 ofFIG. 1, showing the connection ofpump10 anddrive system414.Pump10 includesinlet manifold16,outlet manifold18, fluid covers20aand20b,inlet check valves22aand22b,outlet check valves24aand24b, andfluid displacement members52aand52b.Inlet check valve22aincludesseat48aandcheck ball50a, whileinlet check valve22bincludesseat48band checkball50b.Outlet check valve24aincludesseat49aandcheck ball51a, whileoutlet check valve24bincludesseat49band checkball51b. In the present embodiment,fluid displacement member52aincludesdiaphragm94a,first diaphragm plate110a, andsecond diaphragm plate112a, and attachment screw92a. Similarly,fluid displacement member52bincludesdiaphragm94b,first diaphragm plate110b, andsecond diaphragm plate112b, and attachment screw92b.
• Drive system414 includeshousing26,second housing416, reciprocatingmember418,solenoid420, and pulls422aand422b. Reciprocatingmember418 includesarmature424 and pullhousings426aand426b. Pull housing426adefines pull chamber428aand includes pull opening430a. Pullhousing426bdefinespull chamber428band includes pull opening430b. Pull422aincludes attachment end434a,free end436a, and pullshaft438aextending between attachment end434aandfree end436a.Free end436aincludesflange440a. Similarly, pull422bincludesattachment end434b, free end436b, and pull shaft438bextending betweenattachment end434band free end436b. Free end436bincludes flange440b.
• Fluid cover20ais affixed tohousing26, andfluid displacement member52ais secured between fluid cover20aandhousing26. Fluid cover20aandfluid displacement member52adefinefluid cavity44a, andfluid displacement member52asealingly separatesfluid cavity44aandinternal pressure chamber66.Fluid cover20bis affixed tohousing26, andfluid displacement member52bis secured betweenfluid cover20bandhousing26.Fluid cover20bandfluid displacement member52bdefinefluid cavity44b, andfluid displacement member52bsealingly separatesfluid cavity44bandinternal pressure chamber66.
• Reciprocatingmember418 is disposed withinsolenoid420. Pull housing426ais integrally attached to afirst end armature424, and pullhousing426bis integrally attached to a second end ofarmature424opposite pull housing426a.Free end436aofpull422ais slidably secured within pull chamber428abyflange440a. Pullshaft438aextends through pull opening430a, and attachment end434aengagesattachment screw92a. Similarly, free end436bofpull422bis slidably secured withinpull chamber428bby flange440b. Pull shaft438bextends through pull opening430b, and attachment end434bengagesattachment screw92b.
• Solenoid420 reciprocatingly drives armature424, which thereby reciprocatingly drives pullhousing426aand pullhousing426b.
• The strokes are reversed bysolenoid420driving armature424 in an opposite direction from the initial stroke. In this stroke, pullhousing426bengages flange440bofpull422b, and pull422bthereby drawsfluid displacement member52binto a suction stroke. At the same time, the working fluid ininternal pressure chamber66 pushesfluid displacement member52ainto a pumping stroke. During the pumping stroke offluid displacement member52a, pull chamber428aprevents pull422afrom exerting any pushing force onfluid displacement member52a.
• Thepump10 anddrive system14 described herein provide several advantages.Drive system14 eliminates the need for downstream dampeners or surge suppressors because thedrive system14 provides a pulseless flow of process fluid whenpiston54 is sequenced. Downstream pulsation is eliminated because when onefluid displacement member52aor52bis changing over from one stroke, the otherfluid displacement member52aor52bis already displacing process fluid. This eliminates any rest within thepump10, which eliminates pulsation because fluid is being constantly discharged, at a constant rate. So long as the working fluid pressure remains slightly greater than the process fluid pressure, thedrive system14 is self-regulating and provides a constant downstream flow rate.
• The working fluid pressure determines the maximum process fluid pressures that occur when the downstream flow is blocked or deadheaded. Ifoutlet manifold18 is blocked,motor12 can continue to run without damagingmotor12,drive system14, or pump10. Pullchambers72aand72bensure that thedrive system14 will not cause over pressurization, by preventingpiston54 from exerting any pushing force on eitherfluid displacement member52aor52b. This also eliminates the need for downstream pressure relief valves, because thepump10 is self-regulating and will not cause an over-pressurization event to occur. This pressure control feature serves as a safety feature and eliminates the possibility of over-pressurization of process fluids, potential pump damage, and excessive motor loads.
• Whendrive system14 is used with diaphragm pumps, thedrive system14 provides for equalized balanced forces on the diaphragms, from both the working fluid and the process fluid, which allows for longer diaphragm life and use with higher pressure applications over mechanically-driven diaphragm pumps.Pump10 also provides better metering and dosing capabilities due to the constant pressure on and shape offluid displacement members52aand52b.
• When compressed air is used as the working fluid,drive system14 eliminates the possibility of exhaust icing, as can be found in air-driven pumps, because the compressed air indrive system14 is not exhausted after each stroke. Other exhaust problems are also eliminated, such as safety hazards that arise from exhaust becoming contaminated with process fluids. Additionally, higher energy efficiency can be achieved withdrive system14 because theinternal pressure chamber66 eliminates the need to provide a fresh dose of compressed air during each stroke, as is found in typical air operated pumps. When a non-compressible hydraulic fluid is used as the workingfluid drive system14 eliminates the need for complex hydraulic circuits with multiple compartments, as can be found in typical hydraulically driven pumps. Additionally,drive system14 eliminates the contamination risk between the process fluid and the working fluid due to the balanced forces on either side offluid displacement members52aand52b.
• While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (20)

1. A drive system for a displacement pump, the drive system comprising:

a first housing;

a first fluid displacement member disposed at a first end of the first housing;

a second fluid displacement member disposed at a second end of the first housing;

a solenoid disposed within the first housing; and

a reciprocating member disposed within the solenoid and configured to be driven by the solenoid;

wherein the reciprocating member is connected to the first fluid displacement member and the second fluid displacement member to mechanically displace the first fluid displacement member and the second fluid displacement member.

2. The drive system ofclaim 1, wherein the first fluid displacement member comprises a first diaphragm and the second fluid displacement member comprises a second diaphragm, wherein the first diaphragm, the second diaphragm, the reciprocating member, and the solenoid are disposed coaxially on a pump axis, and wherein the reciprocating member is configured to reciprocate on the pump axis.

3. The drive system ofclaim 2, further comprising:

a first fluid cover abutting the first end of the first housing, wherein a circumferential edge of the first diaphragm is retained between the first fluid cover and the first housing.

4. The drive system ofclaim 2, wherein:

the first diaphragm includes a first attachment screw;

the reciprocating member is connected to the first attachment screw.

5. The drive system ofclaim 1, wherein the reciprocating member is connected to the first fluid displacement member by a first intermediate member and connected to the second fluid displacement member by a second intermediate member.

6. The drive system ofclaim 1, wherein the solenoid and the reciprocating member are disposed between the first fluid displacement member and the second fluid displacement member.

7. The drive system ofclaim 1, wherein the reciprocating member is configured to oscillate along a pump axis to drive the first fluid displacement member and the second fluid displacement member through respective suction strokes.

8. The drive system ofclaim 7, wherein the reciprocating member comprises:

an armature configured to be driven along a pump axis by an electrical field generated by the solenoid.

9. The drive system ofclaim 8, wherein the reciprocating member further comprises:

a first end member extending from the armature, wherein the first end member is connected to the first fluid displacement member; and

a second end member extending from the armature, wherein the second end member is connected to the second fluid displacement member.

10. The drive system ofclaim 7, further comprising:

a second housing disposed within the first housing;

wherein the solenoid is disposed within the second housing; and

wherein the first housing and the second housing are disposed coaxially on the pump axis.

11. The drive system ofclaim 10, wherein the first housing defines an internal chamber within which the second hosing is disposed.

12. The drive system ofclaim 11, further comprising:

a first fluid cover abutting the first end of the first housing, wherein a circumferential edge of the first fluid displacement member is retained between the first fluid cover and the first housing;

a second fluid cover abutting the second end of the first housing, wherein a circumferential edge of the second fluid displacement member is retained between the second fluid cover and the first housing;

wherein the first fluid displacement member and the first fluid cover define a first fluid cavity therebetween;

wherein the second fluid displacement member and the second fluid cover define a second fluid cavity therebetween; and

wherein the first fluid displacement member sealingly separates the first fluid cavity from the internal chamber and the second fluid displacement member sealingly separates the second fluid cavity from the internal chamber.

13. The drive system ofclaim 7, wherein the solenoid is configured to drive the reciprocating member in a first direction towards the first fluid displacement member and in a second direction towards the second fluid displacement member.

14. The drive system ofclaim 13, wherein the first direction is away from the second fluid displacement member.

15. A displacement pump comprising:

a first cover having a first fluid inlet and a first fluid outlet;

a second cover having a second fluid inlet and a second fluid outlet;

a drive system comprising:

a first housing disposed between the first cover and the second cover;

a solenoid disposed within the first housing; and

a reciprocating member disposed within the solenoid and configured to be driven by the solenoid along a pump axis;

a first diaphragm disposed between the first cover and the first housing, wherein the first diaphragm is configured to pump fluid through a first cavity defined between the first diaphragm and the first cover; and

a second diaphragm disposed between the second cover and the first housing, wherein the second diaphragm is configured to pump fluid through a second cavity defined between the second diaphragm and the second cover;

wherein the reciprocating member is configured to mechanically displace the first diaphragm and the second diaphragm.

16. The displacement pump ofclaim 15, wherein the reciprocating member comprises:

an armature disposed within the solenoid and configured to be driven along the pump axis by an electrical field generated by the solenoid;

a first connector extending from a first end of the armature and attached to the first diaphragm; and

a second connector extending from a second end of the armature and attached to the second diaphragm.

17. The displacement pump ofclaim 16, further comprising:

a first attachment screw extending from the first diaphragm, wherein the first attachment screw is attached to the first connector; and

a second attachment screw extending from the second diaphragm, wherein the second attachment screw is attached to the second connector.

18. The displacement pump ofclaim 15, wherein the solenoid, the reciprocating member, the first diaphragm, and the second diaphragm are disposed coaxially on the pump axis.

19. The displacement pump ofclaim 15, wherein:

the solenoid and the reciprocating member are disposed between the first diaphragm and the second diaphragm;

the solenoid is configured to drive the reciprocating member in a first direction towards the first diaphragm and in a second direction towards the second diaphragm;

the reciprocating member is configured to pull the first diaphragm in the second direction to cause the first diaphragm to enter a suction stoke; and

the reciprocating member is configured to pull the second diaphragm in the first direction to cause the second diaphragm to enter a suction stroke.

20. A method comprising:

driving, with a solenoid, an armature along a pump axis in a first direction;

pulling, with the armature, a first fluid displacement member in the first direction such that first fluid displacement member enters a suction stroke, wherein the first fluid displacement member pulls fluid into a first fluid chamber defined between the first fluid displacement member and a first fluid cover during the suction stroke;

driving, with the solenoid, the armature along the pump axis in a second direction opposite the first direction;

pulling, with the armature, a second fluid displacement member in the second direction such that second fluid displacement member enters a suction stroke, wherein the second fluid displacement member pulls fluid into a second fluid chamber defined between the second fluid displacement member and a second fluid cover during the suction stroke;

wherein the first fluid displacement member is sealingly disposed between a first housing and the first fluid cover;

wherein the second fluid displacement member is sealingly disposed between the first housing and the second fluid cover.

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