US20140144131A1 - Energy Efficient Variable Displacement Dosing Pump - Google Patents

Abstract

An improved diaphragm type chemical dosing pumps can be designed as both a variable displacement accurate dosing pump and a fixed displacement accurate dosing pump. The improved dosing pump provides a required supply of pressurized fluid, to be called hereafter as process fluid, to an injection point against varying gas or liquid pressures. By eliminating the use of elastomeric sealing, the failing of the pump due to seal wear is eliminated. An internal pressure relief valve protects the pump mechanicals from premature failure. Use of a spring assisted suction assists positive suction for very accurate dosing. The working fluid is a driver fluid that is used to lubricate working components of the pump. The angled ports minimize friction losses to further improve pump efficiency and also eliminate building up of air pockets.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application asserts priority fromprovisional application 61/400,392, filed on Jul. 27, 2010 which is incorporated herein by reference.
FIELD OF THE INVENTION
• The present invention relates to dosing pumps. More specifically, the present invention relates to diaphragm actuated dosing pumps, and particularly variable displacement dosing pumps, which use less energy and/or are subject to reduced cavitation problems compared to many conventional designs. The pump employs a vertical design as opposed to conventional horizontal design which positively influences the refill and depressurization of the driver fluid and thus makes the pump more efficient wherein vertical movement of the piston creates uniform pathways for the lubricating driver fluid around the piston to thereby enhance pump life. Further, the piston never touches the bore so there will be no wear, and the diaphragm is pre-energized so it maintains constant NPSHR which is independent of the positive suction caused by the piston.
BACKGROUND OF THE INVENTION
• Dosing pumps are well known and are used in a wide variety of applications. Dosing pumps have commonly been employed in industrial applications where very accurate dosing is expected. Traditionally piston pumps were used in gas field applications which were powered by compressed air or pressurized sour gas. They are not very precise or energy efficient and moreover, the vented sour gas is an environmental hazard.
• However, while this type of dosing pump, and in particular diaphragm actuated pump, can provide several advantages over piston type pumps or other pumps, they do suffer from some disadvantages. In particular, diaphragm dosing pumps can break down if a suction or discharge port is blocked during operation and/or can suffer from cavitation effects which, over time can damage components of the pump and especially the diaphragm.
• This prompted an invention of a pump powered by renewable energy which can work efficiently for months without having to be repaired or requiring replacement of the seal. This also prevents over pumping of the process fluid and thus saves costly chemicals and also avoids polluting the land where it is pumped into.
• It is an object of the present invention to provide a novel dosing pump which obviates or mitigates at least one disadvantage of the prior art.
SUMMARY OF THE INVENTION
• According to a first aspect of the present invention, a dosing pump is provided for pressurizing a driver fluid, comprising: a pump housing with a pumping chamber and having an inlet port and an outlet port in fluid communication with a pump head on the pump process side; a piston reliably mounted within the pump chamber and having an eccentric cam rotating inside the pump chamber and being mounted concentrically with respect to the pump chamber such that the rotation of the cam pushes the piston in and out of the pumping chamber causing the diaphragm to successively move forward and reverse inside the pump to cause the process liquid to enter the inlet port of the process side head and be expelled through the outlet port as the motor rotates. The motor operates to rotate the cam and in turn reversibly pushes or drives the piston to pressurize the driver fluid which drives a balanced diaphragm to thereby pressurize the process fluid by means of the balanced diaphragm.
• The pump includes a refill port, relief port and a pumping chamber wherein the refill, relief and the pumping chamber are connected which eliminates the need for multiple areas for supply and storage of operating fluid.
• The present invention provides a novel and useful improvement to dosing pumps, both variable displacement dosing pumps and fixed displacement dosing pumps, by providing a means of pressure equalization and refill from the same port. Pressure relief is against the gravity and gravity assisted refill further increases the efficiency of the pump.
• Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• Preferred embodiments of the present invention will now be described, by way of example only, with reference to the attached figures, wherein:
• FIG. 1 is a side cross sectional view of a dosing pump of the invention.
• FIG. 2 is a perspective view thereof.
• FIG. 3 is an enlarged cross-sectional of the motor-cam unit.
• FIG. 4 is an enlarged cross-sectional view of the pump chamber.
• FIG. 5 is a partial perspective view thereof.
• FIG. 6 is an end view of a bearing-cam assembly.
• FIG. 7 is a side cross-sectional view as taken along section line8-A ofFIG. 6.
• FIG. 8 is a side view of a liner sleeve sub-assembly for the diaphragm pump.
• FIG. 9 is a cross-sectional view thereof as taken along line B-B ofFIG. 8.
• FIG. 10 is a connecting rod sub-assembly.
• FIG. 11 is an end view of the connecting rod sub-assembly.
• FIG. 12 is an end view of a front bearing holder sub-assembly.
• FIG. 13 is a side cross-sectional view as taken along line13-13 ofFIG. 12.
• FIG. 14 is an end view of a head sub-assembly.
• FIG. 15 is a side cross-sectional view of the head sub-assembly as taken along line15-15 ofFIG. 14.
• Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.
DETAILED DESCRIPTION OF THE INVENTION
• Before describing the present invention, prior art variable displacement dosing pumps generally have included a closed housing with a cam rotated by a drive shaft causing a reciprocating movement of the piston in the pumping chamber causing a driver fluid to be pressurized and depressurized and thus creating movement of a diaphragm. These known diagraph pumps work horizontally causing inefficient refill and piston lubrication.
• Generally, as to the present invention,FIG. 1 illustrates aninventive diaphragm pump10 which includes a motor “M”11 that rotatably drives a cam12 at a desired speed to move piston “PT”14 vertically downwardly and upwardly inside the piston bore “PB”16. A driver fluid “F”17 is provided in a driver fluid chamber orreservoir18 so as to communicate with a pump chamber “PC”19 of thepiston bore16, wherein thedriver fluid17 enters through arefill port20 that opens sidewardly or radially into thepiston bore16 to supplydriver fluid17 into thepump chamber19. With continuing descent of the piston “P”14 during motor operation, trappeddriver fluid17, which is located in thepump chamber19 in front of the piston “PT”14, is pressurized and thereby pressurizes an energized diaphragm “D”22 movably supported in apump head23. Pressurized diaphragm “D”22 moves forward into aprocess fluid chamber24 and pushes out theprocess fluid25 through a discharge port “DP”26.
• During the upward return stroke of the piston “PT”14, the pressurizeddriver fluid17 is depressurized when thepiston14 clears the refill port “R”20. The diaphragm “D”22 moves back to its original position by an attachedspring28 and a precise amount ofprocess fluid25 is filled inside the process chamber through the suction port “SP”30. Thedischarge port26 andsuction port30 are controlled by check valves so that process fluid flow is from thesuction port30 through to thedischarge port26.
• In case of accidental overpressure of thedriver fluid17 behind the energized diaphragm “D”22, a pressure relief port “P”34 is provided which is controlled by a spring-biasedpressure relief valve35 that opens when overpressure is encountered to allow theexcess driver fluid17 to flow there through causing excess pressure to be expelled out into thedriver fluid chamber18 which is in fluid communication with therelief port34.
• In more detail as toFIG. 1, thepump10 comprises a generally U-shapedbase plate36 that is mountable to any suitable support surface by mountingflanges37. Thebase plate36 also includes a plate-like pump support38 defining an upward-facingsupport surface39. Thepump10 further comprises ahousing unit40 which comprises amain housing41 that is directly mounted to thepump support38. The top of themain housing40 supports anintermediate housing body42 which in turn supports anupper housing body43. One side of themain housing40 also supports thepump head23 as will be described further.
• First as to themain housing40, as seen inFIGS. 1,2 and4, the main housing has a bottom end formed with a first chamber orpocket45, and a second chamber orpocket46. Thefirst chamber45 provides an air space between thebase36 and the portion of themain housing40 that is disposed next to thepiston bore16 andpump chamber19 which helps insulate these cavities from the surrounding environment. Similarly, thesecond chamber46 is located next to thepump head23 and provides additional thermal separation between thepump head23 and the remaining portions of themain housing40.
• Themain housing40 includes anouter housing wall48 and aninner chamber wall49 which is radially spaced inwardly from theouter wall48 to define thedriver fluid reservoir18 radially therebetween. Thefluid reservoir18 thereby has an annular shape surrounding theinner chamber wall49. Theouter wall48 also includes abore51 which normally is closed by a set screw52 (FIG. 1) but is removable to help indicate the level of thedriver fluid17 within thereservoir18.
• Theinner wall49 further defines an open-ended central bore53 (FIG. 4) which opens vertically upwardly into theintermediate housing body42 and opens downwardly into atransverse fluid passage54 that allows thedriver fluid18 to flow transversely from thepump chamber19 to thediaphragm22 for operation thereof by reciprocation of thepiston14.
• Thetransverse fluid passage54 therefore has aninner end55 receivingdriver fluid17 from thepump chamber19, and anouter end56 that widens into asecondary passage55 so as to open into and fluidly communicate with thepump head23 as will be described further hereinafter. Since thefluid passage54 receives pressurizeddriver fluid17, thisfluid17 is then able to communicate with thediaphragm22 through communication with thesecondary fluid passage55.
• If the fluid is over-pressurized, theaforementioned relief port34 is provided that opens radially through theouter housing wall48. In particular, theouter housing wall48 includes anenlarged valve section56 that is provided with a verticallyelongate passageway57 comprising avalve seat58 that receives the tapered or pointedvalve body35A (FIGS. 4 and 5) of therelief valve35 therein. Thispassageway57 has a taperedinner end59 that cooperates with the tapered end of therelief valve35 so as to selectively block fluid flow therethrough. Thepassageway57 at this location further communicates with arelief passage60 that opens radially downwardly into thesecondary fluid passage55 described above. During over-pressurization, thedriver fluid17 is able to enter therelief passage60 to unseat or move therelief valve body35A upwardly away from the taperedpassage end59 and allow thedriver fluid18 to flow into thepassageway57, into therelief port34 and then into thedriver fluid reservoir18 described above. Normally, thevalve body35A is maintained in a closed position by aspring61 which allows therelief valve35 to selectively open and close while automatically returning thevalve35 to the normally closed position. The spring force also sets the maximum pressure of thedriver fluid17 before pressure is released.
• Thepassageway57 is enclosed by a valve cap orclosure62 which prevents leakage of thedriver fluid17 from thepassageway57. As such, therelief valve35 allowsexcess driver fluid17 to be automatically returned to thereservoir18 without affecting the desired operating pressure of thedriver fluid17 when operating thediaphragm22. Once the operating pressure is returned to the desired operating level, thevalve35 would automatically close in response to thespring61 or other biasing or closing means.
• For the pumping operation, theinner chamber wall49 is provided with a plurality of therefill ports20 which are circumferentially spaced apart and open radially through the entire thickness of theinner wall48.
• To define thepump chamber19 and piston bore16, theinventive pump10 includes a liner sleeve sub-assembly65 (FIGS. 4,8 and9) which slidably fits downwardly into thecentral bore53. Theliner sleeve assembly65 comprises acylindrical holder66 having an upper mountingflange67, which includes a fastener bore68 that allows for secure engagement to theinner chamber wall49. The outer surface of theholder66 includescircumferential grooves69 that receive seals like O-rings therein to seal theholder66 relative to the inside surface of thecentral bore53. Theholder66 includes a long cylindrical liner orsleeve71 which is preferably formed of steel and defines thepump chamber19 at the bottom end72 thereof and the piston bore16 at theupper end73 thereof. To allow for entry of thedriver fluid18 through therefill ports20 into thepump chamber19,respective liner ports75 andholder ports76 are provided on diametrically opposite sides of theliner71 andholder66 so as to thereby align with therefill ports20 and essentially define radial extensions of therefill ports20. Hence, reference to therefill ports20 herein comprises theactual ports20 formed in theinner chamber wall49 as well as the port extensions defined by theliner ports75 andholder ports76 which together define continuous radial passages between thereservoir18 and thepump chamber19.
• As seen inFIG. 4,piston14 at the top end of stroke clears therefill ports20 at least partially so as to allow a balanced level of thedriver fluid17 which can flow into thepump chamber19 if necessary through therefill ports20. During downward travel during the pump stroke, the bottom end of thepiston14 extends into thepump chamber19 as diagrammatically represented byreference line78 which thereby causes thepiston14 to close therefill ports20 and drive the fluid17 out of thepump chamber19 and into thetransverse fluid passage54 for driving operation of thediaphragm22. As thepiston14 travels upwardly through its return stroke, the bottom end of thepiston14 eventually clears therefill ports20 at least partially to then release any fluid pressure in the pumped or driven fluid and allow thedriver fluid18 to refill thepump chamber19 for subsequent pumping. Reciprocating operation of thepiston14 thereby causes thedriver fluid18 to reciprocatingly drive thediaphragm22 as will be described further herein. All of therefill ports20,pump chamber19 andpressure relief port34 are in common communication with thereservoir18 so that separate systems are not required to accommodate the separate functions of refilling thepump chamber19, driving thedriver fluid17 with thepiston14, and releasing over-pressurization through therelief valve35. Further, it is not necessary to seal thedriver fluid17 within this fluid system so that wear-susceptible seals between thepiston14 and theliner71 are avoided, which avoids any wear problems or leakage of fluid which might occur if a piston were to require elastomeric seals or other types of seals to prevent leakage of a driven fluid.
• To effect driving of thepiston14, the motor11 is provided with a cam assembly79 (FIG. 3) which connects arotatable drive shaft80 of the motor11 with thepiston14. More particularly as toFIGS. 10 and 11, thepiston14 is formed as part of apiston sub-assembly81 which comprises apiston rod82 that mounts within asupport bracket83. Thesupport bracket83 includes aconnector pin84 that pivotally joins thesupport bracket83 to adrive collar85 having a central cam-receivingbore86 extending there through.
• Referring toFIGS. 3 and 4, themotor drive shaft80 is supported by afirst bearing88 that provides support to theshaft80 on the upper end of theupper housing body43. Thebearing88 is supported within amotor flange89 that in turns mounts with the motor11 to thehousing body43 by mountingplate assembly90. The inboard free end of themotor shaft80 supports a cam sub-assembly (FIGS. 3,6 and7) for driving operation of thepiston assembly81. In particular, thecam assembly79 has acam body91 through which passes acentral axis92 that defines arotation axis93 for thecam assembly79 during shaft rotation. The motor-driven end of theaxle92 includes a shaft-receivingbore94 that receives themotor shaft80 therein (FIG. 3) which is then secured therein by aset screw95. This end of theaxle92 has the bearing98 mounted thereon to support such end, while theaxle92 has afree end97 opposite the drivenend96 which is configured to receive anadditional bearing98 thereon.
• To drive thepiston assembly81, thecam body91 is formed with an outer, radially-projectinghub99 that has a circular outer surface which extends about a center hub axis that is positioned eccentric to therotation axis93. As such, thehub99 is formed eccentrically relative to theshaft axis93 so that thehub99 effectively works as a cam. Thecircular hub99 is rotatably fitted within the circular bore86 of thedrive collar85 so that rotation of thecam body91 causes reciprocating vertical motion of thepiston assembly81 during rotation of themotor shaft80.
• Referring toFIGS. 3,12 and13, theaxle end97 is supported by a bearing sub-assembly101 which comprises a mountingcover102 formed with ashallow bearing seat103 for receiving theaforementioned bearing98 therein. Thebearing seat103 includes aspring104 to ensure proper axial positioning of thebearing98. Thecover102 has an outer mountingflange105 formed with holes for receiving fasteners there through that secure to theupper housing body43.
• Next as toFIG. 3, theupper housing body43 also includes a removabletop cap106 that allows for thedriver fluid17 to be poured into the open vertical column or passageway defined internally by theintermediate housing body42 andupper housing body43. Preferably, thedriver fluid17 is any suitable type of oil or other working fluid which can be poured through thetop cap106 to appropriately fill thereservoir18 to the appropriate level indicated by theset screw52. Other types of fluids are suitable. Since this fluid is able to flow freely into and around the various components including thepiston14 itself, thedriver fluid17 not only serves as a pump driver for thediaphragm22, but also serves as a lubricant that lubricates the movable components including thepiston14 as it moves relative to the opposing interior surface of thesteel liner71 and the interior liner surface which forms the piston bore16 and pumpchamber19.
• Next as to thepump head23, saidpump head23 is best illustrated inFIGS. 5,14 and15. Thepump head23 comprises aninner head body110 and anouter head body111 which define opposing interior faces112 and113 defining an interface therebetween. Thesurfaces112 and113 have central cavities which face in opposing relation and define a circular, thin cavity that defines theprocess fluid chamber24. Thefluid chamber24 on the outboard side communicates with thedischarge port26 andsuction port30 byangled ports114 and115, wherein the angled ports minimize friction loss so as to further improve pump efficiency and also eliminate build-up of air pockets. The inner andouter head bodies110 and111 are joined together byfasteners117 extending through fastener bores118. Theouter head body111 also includes anindicator119 showing the flow direction which would be dictated by the check valves in thedischarge port26 andsuction port30.
• Thediaphragm22 preferably comprises a flexible,circular disk121 which is formed from elastomeric Teflon and has anouter rib122 that seats within opposing grooves formed in the head body faces112 and113. Therib122 is sandwiched or compressed between the interface of the inner andouter head bodies110 and110 and defines a fluid-tight seal therebetween. Thedisk121 thereby sealingly separates theprocess fluid chamber24, which is on the outboard side of thediaphragm22, from an innerdriver fluid chamber123, which is on the inboard side of thediaphragm22, such that axial flexing of thediaphragm disk121 effects variations, i.e. increases and decreases in the volume of thepump chamber24 and thereby effects pumping operation of theprocess fluid25 that passes through theangled ports114 and115 into and out of theprocess fluid chamber24.
• Thediaphragm122 includes a stainlesssteel drive head125 on the driven fluid side which drivehead125 has aconnector collar126 that is threadedly engaged with theshaft126 of abolt127. Thehead128 of thebolt127 has aspring129 disposed in compression between thebolt head128 and a divider wall130 to normally bias thediaphragm122 axially rightwardly inFIG. 15. This divider wall130 includes passages131 (FIG. 5) which allows for driver fluid to flow into thedriver fluid chamber123 adjacent the inboard side of thediaphragm22.
• To mount thepump head23 to themain housing body41, theinner head body110 has aninboard flange135 which fits in sealed engagement into a corresponding cavity in the main housing body41 (FIG. 2). Theflange135 defines afluid passage136 which aligns with and opens into the correspondingfluid passage55 ofFIG. 4. As such, thedriver fluid17 during pump operation is driven through thepassages54,55,136 and131, and into thepump chamber123 so as to pressurize the inboard side of thediaphragm22 and effect axial displacement or deformation of the central portion of thediaphragm122 leftwardly inFIG. 15 during the pumping stroke of thepiston14. During the return stroke of thepiston14, thedriver fluid17 can then flow out of these passages so that the spring-energizeddiaphragm22 is then driven rightwardly by theaforementioned spring129. Thediaphragm22 therefore is energized to provide for spring-assisted suction of the process fluid into theprocess fluid chamber24 during the return stroke which provides for positive suction and very accurate dosing of the process fluid.
• Hence, reciprocating upward and downward movement of thepiston14 causes a corresponding reciprocating horizontal movement of thediaphragm22 to effect pumping of the process fluid. Theimproved dosing pump10 provides a required supply ofpressurized process fluid25 to an injection point even against varying gas or liquid pressures. Thispump10 eliminates the use of elastomeric sealing within the piston configuration, and eliminates failing of the pump due to seal wear. Further the internalpressure release valve35 protects the pump structures from premature failure, and providing thedriver fluids17 as a lubricant thereby lubricates the working components of the pump.
• The above-described embodiments of the invention are intended to be examples of the present invention and alterations and modifications may be effected thereto, by those of skill in the art, without departing from the scope of the invention which is defined solely by the claims appended hereto.

Claims (13)

What is claimed is:

1. A diaphragm dosing pump comprising a pump housing having a process side head including an inlet port in fluid communication with a liquid supply reservoir through a suction valve, and an outlet port in fluid communication with a supply line through a discharge valve configured to be driven in a pumping direction, wherein said pump housing includes a pre-energized diaphragm having a driven side and a driver side, a pump chamber defining a pump piston bore, and a piston in said pump piston bore on the driver side which advances inside the pump piston bore during a discharge stroke, said piston being driven by an eccentric cam housed in the pump housing concentrically with respect to the pump chamber such that as the cam is driven in a pumping direction, a measured volume of driver fluid is pushed by the piston behind the pre-energized diaphragm on the driver side and the pressure is transmitted by the pre-energized diaphragm to a process fluid on the driven side of the pump which is in communication with the inlet and discharge port, and expels a measured amount of process fluid through the discharge port, wherein when the cycle of the piston reverses, the piston moves up in the pump chamber and the pressurized driver side liquid depressurizes as the piston clears the pressure chamber to receive the driver fluid from a reservoir through a refill port.

2. The dosing pump ofclaim 1 wherein the pump chamber positively refills automatically by gravity.

3. The dosing pump ofclaim 2 wherein a process fluid passageway which is provided between the pre-energized gasket and each of the inlet port and outlet port, and is angled relative to each other in the process side head to eliminate air entrapment and minimize frictional losses.

4. The dosing pump ofclaim 3 wherein each said passageway is properly sized to supply a desired volume of process fluid without restriction, to a displacement chamber adjacent the pre-energized diaphragm for being efficiently drawn and expelled through the suction and discharge ports.

5. The dosing pump ofclaim 4 wherein the dosing pump further comprises a motor drive which rotates the eccentric cam at desired rotation per minute to attain the desired displacement rate.

6. The dosing pump ofclaim 1 further comprising a pressure control valve strategically placed at a location within the pump housing, to protect the pump from over pressurization by eliminating excess driver fluid through an energized relief valve to protect the pump mechanical components from damage.

7. The dosing pump ofclaim 6 further wherein said pressure control valve is in fluid communication with a fluid passage on the driven side of said pre-energized diaphragm and said reservoir to protect the pump from over pressurization by permitting the excess driver fluid to flow through the energized relief valve to the reservoir to protect from damage.

8. A diaphragm dosing pump comprising:

a pump housing having a process side head including an inlet port receiving process fluid, and an outlet port receiving said process fluid from said inlet port and a pre-energized diaphragm which has a driver side and a driven side and operates to pump said process fluid located on said driven side from said inlet port to said outlet port;

said pump housing including a fluid passage on said driver side of said pre-energized diaphragm, a pump chamber defining a pump piston bore which communicates with said fluid passage, and a piston in said pump piston bore on the driver side which advances inside the pump piston bore during a discharge stroke to pump driver fluid into said fluid passage to actuate said pre-energized diaphragm, said piston being driven by an eccentric cam housed in the pump housing such that as the cam is driven in a pumping direction, a measured volume of the driver fluid is pushed by the piston toward the pre-energized diaphragm on the driver side and the pressure is transmitted by the pre-energized diaphragm to the process fluid on the driven side for pumping said process fluid between said inlet port and said outlet port, to thereby expel a measured amount of process fluid through the outlet port, said pump housing including a refill reservoir disposed exteriorly of said pump piston bore and a refill port allowing the driver fluid to flow into said pump piston bore by gravity wherein when the cycle of the piston reverses, the piston moves up in the pump chamber and the pressurized driver side liquid depressurizes as the piston clears the refill port wherein said refill port is unblocked and receives the driver fluid from the reservoir through the refill port by gravity.

9. The dosing pump ofclaim 8 wherein the dosing pump further comprises a motor drive which rotates the eccentric cam at desired rotation per minute to attain the desired displacement rate.

10. The dosing pump ofclaim 8 further comprising a pressure control valve strategically placed at a location within the pump housing, to protect the pump from over pressurization by eliminating excess driver fluid through an energized relief valve to protect the pump mechanical components from damage.

11. The dosing pump ofclaim 10 further wherein said pressure control valve is in fluid communication with a fluid passage on the driven side of said pre-energized diaphragm and said reservoir to protect the pump from over pressurization by permitting the excess driver fluid to flow through the energized relief valve to the reservoir to protect from damage.

12. The dosing pump according toclaim 8, wherein said piston moves vertically and said refill port opens sidewardly into said pump piston bore to allow free flow of said driver flow from said reservoir into said pump piston bore.

13. The dosing pump according toclaim 12, wherein said pre-energized diaphragm moves horizontally.

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