EP0451942A1 - Double-acting positive displacement pump - Google Patents

Double-acting positive displacement pump Download PDF

Info

Publication number
EP0451942A1
EP0451942A1 EP91301762A EP91301762A EP0451942A1 EP 0451942 A1 EP0451942 A1 EP 0451942A1 EP 91301762 A EP91301762 A EP 91301762A EP 91301762 A EP91301762 A EP 91301762A EP 0451942 A1 EP0451942 A1 EP 0451942A1
Authority
EP
European Patent Office
Prior art keywords
piston
cylinder
pump
upstroke
downstroke
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP91301762A
Other languages
German (de)
English (en)
French (fr)
Inventor
Frank E. Ives
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
PMC Inc
Original Assignee
PMC Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by PMC Inc filed Critical PMC Inc
Publication of EP0451942A1 publication Critical patent/EP0451942A1/en
Ceased legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B9/00—Piston machines or pumps characterised by the driving or driven means to or from their working members
    • F04B9/08—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid
    • F04B9/12—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid the fluid being elastic, e.g. steam or air
    • F04B9/129—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid the fluid being elastic, e.g. steam or air having plural pumping chambers
    • F04B9/1295—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being fluid the fluid being elastic, e.g. steam or air having plural pumping chambers having two or more pumping chambers in series
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B11/00—Equalisation of pulses, e.g. by use of air vessels; Counteracting cavitation
    • F04B11/005—Equalisation of pulses, e.g. by use of air vessels; Counteracting cavitation using two or more pumping pistons
    • F04B11/0075—Equalisation of pulses, e.g. by use of air vessels; Counteracting cavitation using two or more pumping pistons connected in series
    • F04B11/0083—Equalisation of pulses, e.g. by use of air vessels; Counteracting cavitation using two or more pumping pistons connected in series the pistons having different cross-sections
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B5/00—Machines or pumps with differential-surface pistons
    • F04B5/02—Machines or pumps with differential-surface pistons with double-acting pistons

Definitions

  • the present invention relates to positive displacement pumps and, more particularly to double-acting positive displacement pumps used to pump relatively viscous liquids at a substantially constant pressure.
  • Double-acting positive displacement pumps have been utilized for years to pump polyester resin or other viscous resin materials to an applicator gun.
  • a second double-acting positive displacement catalyst pump is normally slaved to the piston rod of the resin pump, which is driven by a single air motor.
  • all resin and catalyst pumps are produced from standard stock tubing, rods, packing and seals.
  • the resin and catalyst are pumped to the applicator gun and are normally mixed within the gun. It is extremely important that the delivery pressure to the applicator gun for both the resin and the catalyst be substantially constant so as to obtain a proper admixture of the two components prior to spraying onto a substrate.
  • accumulators have been inserted in both the resin output and catalyst output lines downstream from the pump. In the better pumps of the prior art, the accumulators have been precharged to provide sufficient back pressure during operation to assist in smoothing out pressure fluctuations occurring on opposing strokes of the piston pump.
  • the present invention comprises an improvement in double-acting positive displacement pumps.
  • These pumps include a cylinder having a first end and a second end, a fluid intake and check valve at the first end and a fluid outlet at the second end.
  • a piston is mounted for reciprocating movement between the first and second ends of the cylinder.
  • a piston rod is operably coupled to the piston and extends through an opening in one end of the cylinder. Seals are mounted on the piston between the piston and the wall of the cylinder to prevent fluid flow past the cylinder as the cylinder reciprocates. Seals are also provided between the piston rod and the end of the cylinder to prevent fluid from escaping from the cylinder other than through the fluid outlet.
  • the improvement evolved from the recognition that the dimensions of the stock components and their arrangement are for the large part responsible for the pressure differentials on the downstroke and upstroke of prior pumps. Accordingly, the improvement comprises sizing the piston rod to a predetermined diameter relative to the diameter of the cylinder so that the differential pressures created on an upstroke and downstroke of the cylinder counteract and balance the differential frictional forces generated by the seals.
  • the diameter of the piston rod is predetermined to also substantially compensate for the string weight of the pump components on the upstroke to substantially equalize the output pressure on both the upstroke and the downstroke.
  • the piston rod is driven by a double-acting air motor.
  • the piston rod diameter within the cylinder is further sized to a predetermined diameter to compensate for the differential forces generated by the air motor on the upstroke and the downstroke to thereby again substantially equalize the output pressure of the pump on the upstroke and the downstroke.
  • a resin pump generally designated 10 and a catalyst pump generally designated 12 is mounted on a bracket 14 extending transversely from the housing of the pump 10.
  • the resin pump 10 includes a cylinder 16 having a lower inlet end 18 and an upper outlet end 20.
  • a piston 22 is mounted for up-and-down reciprocating movement in the cylinder 16.
  • the piston 22 houses a check valve 24 that allows resin to flow from the lower portion of the cylinder through the piston to the upper portion of the cylinder on the downstroke of the piston.
  • the lower end of the cylinder also carries a check valve 26 that allows resin to flow into the cylinder 16 on the upstroke of the piston 22 and prevents resin from flowing back towards the resin supply on the piston downstroke.
  • An accumulator 36 is coupled between the filter housing and the conduit 32. As the system pressure builds up, resin flows into an accumulator reservoir 38 and creates a fluid back pressure in the upper portion of the reservoir 38. As the piston reverses, and consequently as check valves 24 and 26 momentarily float, the back pressure in the accumulator will maintain a substantially constant line pressure in resin conduit 32 during reversal.
  • the piston 22 carries seals 40 that wipe the interior cylinder walls to prevent resin from flowing past the piston as it reciprocates in an upward and downward direction.
  • the piston 22 is driven by a piston rod 42 affixed to the upper end of the piston and extending through the upper end 20 of the cylinder 16. Seals 44 mounted in the upper end of the cylinder wipe the surface of the rod 42 to prevent resin from flowing past the rod to the exterior of the cylinder.
  • An air motor 50 is positioned at the upper end of the pump 10.
  • the upper end of the piston rod 42 is coupled to the cylinder 52 of the air motor.
  • the air motor is of standard construction. Pressurized air is supplied to the air motor to drive the piston first in a downward direction and then in an upward direction.
  • a conventional shuttle valve 54 is employed to reverse the airflow.
  • the catalyst pump 12 is a similar double-acting positive-displacement pump. Housed in a cylinder 60, the catalyst pump has substantially the same components as the resin pump and operates in a manner very similar to that of the resin pump. Catalyst is pumped from a supply through the cylinder 60 by the piston 62, through an accumulator 64, and into a catalyst conduit 66. Catalyst conduit 66 is also coupled to the spray gun 34.
  • the piston rod 68 of the catalyst pump 12 is driven by a slave arm 70 that is coupled between the piston rod 42 of the resin pump and the bracket for the catalyst pump. As the resin piston rod 42 reciprocates upwardly and downwardly, the slave arm similarly moves upwardly and downwardly to reciprocate the piston rod 68 of the catalyst pump.
  • air at a constant pressure is supplied to the motor.
  • the air acts on the entire surface of the cylinder.
  • the air acts on the area of the cylinder less the rod area.
  • a slightly lesser force is created on the upstroke than on the downstroke.
  • substantially equal pressure is generated on both sides of the seals, creating little frictional resistance to movement of the piston.
  • pressure on the upper side of the seal is system pressure, sometimes on the order of 1000 psi, while the pressure below the seal is substantially zero.
  • This differential pressure drives the seals against the cylinder wall, generating substantial frictional forces and thus causing resistance to upward movement of the piston.
  • the seals 44 generate more frictional resistance to upward motion of the piston rod than downward motion.
  • a positive displacement pump modified in accordance with the present invention has many advantages.
  • the principal advantage is constant resin and catalyst supply pressure to the resin gun 34 which results in a constant homogeneous mixture being sprayed upon a substrate. More importantly, because the improved pump substantially equalizes the output pressure, it is no longer necessary to precharge the accumulators. Thus, only an atmospheric charge is needed to compensate for the check valve slippage occurring on piston reversal. This is a significant operating advantage because it is no longer necessary to precharge the accumulators prior to initiating operation of the pump.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
EP91301762A 1990-04-11 1991-03-04 Double-acting positive displacement pump Ceased EP0451942A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US508368 1983-06-27
US50836890A 1990-04-11 1990-04-11

Publications (1)

Publication Number Publication Date
EP0451942A1 true EP0451942A1 (en) 1991-10-16

Family

ID=24022476

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91301762A Ceased EP0451942A1 (en) 1990-04-11 1991-03-04 Double-acting positive displacement pump

Country Status (3)

Country Link
EP (1) EP0451942A1 (ja)
JP (1) JPH04228881A (ja)
CA (1) CA2037591A1 (ja)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993010352A1 (en) * 1990-10-19 1993-05-27 Tauno Pirhonen Mixing pump
US9421563B2 (en) 2013-12-17 2016-08-23 Kärcher North America, Inc. Self-contained spray apparatus for disinfectants
EP3021979A4 (en) * 2013-07-19 2017-06-21 Graco Minnesota Inc. Multi-point seal lubrication system
WO2020126504A1 (de) * 2018-12-20 2020-06-25 Henkel Ag & Co. Kgaa Vorrichtung und verfahren zum gleichmässigeren fördern einer flüssigkeit
US10933392B2 (en) 2016-10-31 2021-03-02 Bridgestone Corporation Catalyst delivery system for polymerization vessel
USD919208S1 (en) 2019-07-26 2021-05-11 Kärcher North America, Inc. Portable cleaning device
CN117450040A (zh) * 2023-12-12 2024-01-26 北京杰利阳能源设备制造有限公司 一种用于柱塞泵的动态平衡系统

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3160105A (en) * 1963-02-18 1964-12-08 Johnstone Pump Co Inc Pump for high viscosity fluids
FR2161476A5 (ja) * 1971-11-26 1973-07-06 Graham George
FR2228389A5 (en) * 1973-05-02 1974-11-29 Hale Jean Claude Spray pump for low viscosity lubricant - piston has low pressure and differential high pressure portions
US4509903A (en) * 1983-10-18 1985-04-09 Fram Jerry R Catalyst slave pump

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3160105A (en) * 1963-02-18 1964-12-08 Johnstone Pump Co Inc Pump for high viscosity fluids
FR2161476A5 (ja) * 1971-11-26 1973-07-06 Graham George
FR2228389A5 (en) * 1973-05-02 1974-11-29 Hale Jean Claude Spray pump for low viscosity lubricant - piston has low pressure and differential high pressure portions
US4509903A (en) * 1983-10-18 1985-04-09 Fram Jerry R Catalyst slave pump

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993010352A1 (en) * 1990-10-19 1993-05-27 Tauno Pirhonen Mixing pump
EP3021979A4 (en) * 2013-07-19 2017-06-21 Graco Minnesota Inc. Multi-point seal lubrication system
US10173232B2 (en) 2013-07-19 2019-01-08 Graco Minnesota Inc. Multi-point seal lubrication system
US9421563B2 (en) 2013-12-17 2016-08-23 Kärcher North America, Inc. Self-contained spray apparatus for disinfectants
US10933392B2 (en) 2016-10-31 2021-03-02 Bridgestone Corporation Catalyst delivery system for polymerization vessel
WO2020126504A1 (de) * 2018-12-20 2020-06-25 Henkel Ag & Co. Kgaa Vorrichtung und verfahren zum gleichmässigeren fördern einer flüssigkeit
USD919208S1 (en) 2019-07-26 2021-05-11 Kärcher North America, Inc. Portable cleaning device
CN117450040A (zh) * 2023-12-12 2024-01-26 北京杰利阳能源设备制造有限公司 一种用于柱塞泵的动态平衡系统

Also Published As

Publication number Publication date
JPH04228881A (ja) 1992-08-18
CA2037591A1 (en) 1991-10-12

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