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WO2002101246A1 - A method and device for fine filtering - Google Patents

A method and device for fine filtering Download PDF

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Publication number
WO2002101246A1
WO2002101246A1 PCT/NO2002/000190 NO0200190W WO02101246A1 WO 2002101246 A1 WO2002101246 A1 WO 2002101246A1 NO 0200190 W NO0200190 W NO 0200190W WO 02101246 A1 WO02101246 A1 WO 02101246A1
Authority
WO
WIPO (PCT)
Prior art keywords
pump
fine filter
working fluid
filter
fine
Prior art date
Application number
PCT/NO2002/000190
Other languages
French (fr)
Inventor
Jørgen GRØNFUR
Original Assignee
Groenfur Joergen
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 Groenfur Joergen filed Critical Groenfur Joergen
Priority to EP02778857A priority Critical patent/EP1392982A1/en
Priority to US10/480,017 priority patent/US20040141854A1/en
Publication of WO2002101246A1 publication Critical patent/WO2002101246A1/en

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/04—Special measures taken in connection with the properties of the fluid
    • F15B21/041—Removal or measurement of solid or liquid contamination, e.g. filtering
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/61—Secondary circuits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/615—Filtering means

Definitions

  • This invention regards a method of ensuring stable fine filtering of liquids in e.g. oil-hydraulic installations.
  • the invention also regards a device for carrying out the method.
  • Such installations therefore normally comprise at least one filter designed to filter out contaminants.
  • a simple and inexpensive solution is to provide the suction side of the pump with a relatively coarse suction strainer and the return line to the reservoir of the installation with a return filter.
  • contaminants that are generated in the hydraulic pumps will not be captured before they flow into valves and actuators.
  • a high pressure full flow filter is normally placed between the valves and pump(s) of the installation.
  • An ordinary full flow filter is not capable of filtering out the smallest of the contaminants in question. It has therefore been necessary in order to overcome this situation, to carry out relatively frequent oil changes or perform fine filtration, also termed deep filtration, of the working fluid.
  • Fine filters of the type mentioned here are, if used correctly, capable of filtering out sufficiently fine contaminants to allow the working fluid to be considered of satisfactory value in terms of contaminants, after treatment.
  • Fine filters may be equipped with a water separator.
  • the fluid fed to the fine filter must lie within a relatively narrow pressure range, so as to keep the pressure drop across the filter constant.
  • the fine filter works best without overpressure on the outlet side of the filter.
  • the flow rate through the filter must be constant and preferably in a laminar form.
  • a first method working fluid is pumped via a separate pump from the main reservoir of the installation to a fine filter.
  • the excess and filtered fluid is returned to the reservoir in a depressurized state.
  • a second method a certain volume of working fluid is drained to the fine filter from the pressure loop of the installation by means of e.g. a constant flow valve.
  • the working fluid may flow back to the reservoir in a depressurized state; however it is more common to use a separate reservoir for fine filtered fluid, from where the fluid is later returned by means of a separate pump to the main reservoir.
  • the pumps used with a separate reservoir may be level controlled in order to allow automatic control of the treatment plant.
  • the object of the invention is to remedy the disadvantages of prior art.
  • the object is achieved in accordance with the invention by the characteristics stated in the description below and in the appended claims.
  • a double pump, a tandem pump, a pump with a feed part and a main part, alternatively another pump equipped with two separate pump parts, are driven by one drive motor.
  • the suction side of the first pump, the feed pump is connected to the main reservoir of the installation, and in operation pumps working fluid from the reservoir to a fine filter. Any excess volume from the delivery side of the first pump flows through a pressure control valve to the suction side of the second pump, where the fine filtered working fluid from the outlet of the fine filter also flows in.
  • Excess volume means the difference between the volume delivered by the first pump, and the volume that may pass though the fine filter without causing the pressure drop across the filter to become higher than specified.
  • the pressure control valve maintains a constant pressure drop across the filter. As the fine filter gets clogged, the flow of working fluid through the pressure control valve will increase.
  • working fluid flows back to the main reservoir from the delivery side of the second pump at a high velocity, so as to prevent any deposits and water accumulation from occurring.
  • working fluid from the delivery side of the second pump is passed to a downstream hydraulic installation that may also include other pumps, filters, valves and actuators. It may be advantageous always to feed a limited amount of working fluid from the delivery side of the first pump to the suction side of the second pump in order to prevent the second pump from running dry and/or cavitating.
  • Figure 1 shows a schematic circuit diagram for a fine filter treatment plant in which cleaned working fluid is led back to the reservoir
  • Figure 2 shows a schematic circuit diagram of the installation in Figure 1, but here, the outlet/delivery side of the second pump is connected to a downstream hydraulic installation.
  • reference number 1 denotes a fine filter treatment plant for working fluid.
  • Working fluid flows from a main reservoir 2 via a pipe 4 to the inlet/suction side of a first pump 6.
  • the pump 6 and a second pump 8 are driven by a motor 10.
  • Working fluid flows from the delivery side of the first pump 6 via pipe connections 12, 14 and 16 to a pressure reducing valve 18 and to the inlet side of a fine filter 20 via a check valve 22. From the outlet of the fine filter 20 and the outlet of the pressure reducing valve 18, working fluid flows through pipes 24 and 26 to the suction side of the second pump 8.
  • a limited amount of working fluid flows through the connection 28 from the delivery side of the first pump 6 to the suction side of the second pump 8 for reasons of lubrication and cooling.
  • the fine filter 20 may be equipped with a differential pressure indicator 34 and a flow meter 34a. All the components of the installation are of a type that is known per se.
  • the pressure reducing valve 18 will maintain an accurate inlet pressure to the fine filter 20 through opening the pipes 14 and 26 to flow. This means that the fine filter 20 can be utilised in the best possible manner with regard to both treatment capability and service life.
  • Working fluid flows to the suction side of the second pump 8 from the fine filter 20 through the pipe 24 in a manner such that the outlet side of the fine filter is not subjected to overpressure, and from the pressure relief valve 18 through the pipe 26.
  • the pressure is increased in order to enable the fluid to be used in a subsequent operation, whereby the velocity of the working fluid may be increased when flowing back to the reservoir 2 via the pipe 30, by means of e.g. a restriction (not shown) in the pipe.
  • the pipe 30 is connected to a downstream hydraulic installation 40 that may include one or more of the following components: a pump 42 with a motor 44, a main filter 46, a check valve 48, a pressure relief valve 50 and valves and actuators 52. All these of a type that is known per ⁇ re.
  • the fine filter treatment plant 1 can take care of the entire supply of working fluid to the hydraulic installation 40.
  • the pump 42 may through use of the motor 44 also pump working fluid to the hydraulic installation 40.
  • the main filter 46 is a full flow pressure filter protected by the bypass coupled check valve 48.
  • the pressure relief valve 50 prevents overloading of valves and actuators 52.
  • one drive unit will be sufficient for the pumps of the installation, both in the case of pressurized installations and unpressurized installations. Returning the working fluid to the reservoir 2 at a substantial velocity results in good circulation in the reservoir, whereby deposits are prevented.
  • fine filtering according to the proposed method is relatively insensitive to sudden movement and thus well suited for mobile equipment.
  • a further advantage is the freedom of placement of the fine filter in relation to the remaining components of the hydraulic installation, and the fact that there is no requirement for a separate filter reservoir.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Details Of Reciprocating Pumps (AREA)
  • Cyclones (AREA)
  • Filtration Of Liquid (AREA)

Abstract

A method for use of an oil-hydraulica fine filter (20) of the type where the outlet side of the fine filter (20) is designed to operate without overpressure, where the working fluid that flows from the fine filter (20) in depressurized state is pumped on by a second pump (8), and where the second pump (8) is driven by the same driving device (1) as the feed pump (6) of the fine filter (20).

Description

A METHOD AND DEVICE FOR FINE FILTERING
This invention regards a method of ensuring stable fine filtering of liquids in e.g. oil-hydraulic installations. The invention also regards a device for carrying out the method.
It is well known that the presence of contaminants in the form of e.g. metal and mineral particles in the working fluid in oil-hydraulic installations may reduce the service life of the components of the installation significantly. Such installations therefore normally comprise at least one filter designed to filter out contaminants. A simple and inexpensive solution is to provide the suction side of the pump with a relatively coarse suction strainer and the return line to the reservoir of the installation with a return filter. However, with this filter positioning, contaminants that are generated in the hydraulic pumps will not be captured before they flow into valves and actuators. In particular when using more "complex equipment such as servo valves, a high pressure full flow filter is normally placed between the valves and pump(s) of the installation. An ordinary full flow filter is not capable of filtering out the smallest of the contaminants in question. It has therefore been necessary in order to overcome this situation, to carry out relatively frequent oil changes or perform fine filtration, also termed deep filtration, of the working fluid.
Fine filters of the type mentioned here are, if used correctly, capable of filtering out sufficiently fine contaminants to allow the working fluid to be considered of satisfactory value in terms of contaminants, after treatment. Fine filters may be equipped with a water separator.
In order to obtain a satisfactory result from fine filtering through filters of the type in question, the fluid fed to the fine filter must lie within a relatively narrow pressure range, so as to keep the pressure drop across the filter constant. The fine filter works best without overpressure on the outlet side of the filter. Thus the filtered working fluid flows away from the filter by means of gravity. The flow rate through the filter must be constant and preferably in a laminar form.
According to prior art, two principal methods are employed in connection with the use of fine filters. By a first method, working fluid is pumped via a separate pump from the main reservoir of the installation to a fine filter. The excess and filtered fluid is returned to the reservoir in a depressurized state. By a second method, a certain volume of working fluid is drained to the fine filter from the pressure loop of the installation by means of e.g. a constant flow valve. The working fluid may flow back to the reservoir in a depressurized state; however it is more common to use a separate reservoir for fine filtered fluid, from where the fluid is later returned by means of a separate pump to the main reservoir. The pumps used with a separate reservoir may be level controlled in order to allow automatic control of the treatment plant.
It is also known to use a reversible pump that will feed working fluid to the fine filter when rotating in one direction, and transfer the working fluid between the reservoirs when rotating in the opposite direction. Inevitably of necessity, this latter method will prolong the filtration period.
The possible positioning of the fine filter in relation to the remaining components of the hydraulic installation is limited to a considerable degree by the fact that the return side of the fine filter is unpressurized. Installations according to prior art are not suited for use in mobile installations such as diggers and equipment on wheels.
In fine filter installations where the filtered working fluid is returned to a separate reservoir in a depressurized state, experience has shown that deposits of contaminants and accumulation of water may occur after a period of use. The cleaning required results in periodic shutdowns of the installation.
The object of the invention is to remedy the disadvantages of prior art. The object is achieved in accordance with the invention by the characteristics stated in the description below and in the appended claims.
A double pump, a tandem pump, a pump with a feed part and a main part, alternatively another pump equipped with two separate pump parts, are driven by one drive motor. The suction side of the first pump, the feed pump, is connected to the main reservoir of the installation, and in operation pumps working fluid from the reservoir to a fine filter. Any excess volume from the delivery side of the first pump flows through a pressure control valve to the suction side of the second pump, where the fine filtered working fluid from the outlet of the fine filter also flows in.
Excess volume here means the difference between the volume delivered by the first pump, and the volume that may pass though the fine filter without causing the pressure drop across the filter to become higher than specified.
Thus the pressure control valve maintains a constant pressure drop across the filter. As the fine filter gets clogged, the flow of working fluid through the pressure control valve will increase.
In one embodiment, working fluid flows back to the main reservoir from the delivery side of the second pump at a high velocity, so as to prevent any deposits and water accumulation from occurring. In an alternative embodiment, working fluid from the delivery side of the second pump is passed to a downstream hydraulic installation that may also include other pumps, filters, valves and actuators. It may be advantageous always to feed a limited amount of working fluid from the delivery side of the first pump to the suction side of the second pump in order to prevent the second pump from running dry and/or cavitating.
The following describes a non-limiting example of a preferred method illustrated in the accompanying drawings, in which:
Figure 1 shows a schematic circuit diagram for a fine filter treatment plant in which cleaned working fluid is led back to the reservoir; and
Figure 2 shows a schematic circuit diagram of the installation in Figure 1, but here, the outlet/delivery side of the second pump is connected to a downstream hydraulic installation.
In the drawings, reference number 1 denotes a fine filter treatment plant for working fluid.
Working fluid flows from a main reservoir 2 via a pipe 4 to the inlet/suction side of a first pump 6. The pump 6 and a second pump 8 are driven by a motor 10. Working fluid flows from the delivery side of the first pump 6 via pipe connections 12, 14 and 16 to a pressure reducing valve 18 and to the inlet side of a fine filter 20 via a check valve 22. From the outlet of the fine filter 20 and the outlet of the pressure reducing valve 18, working fluid flows through pipes 24 and 26 to the suction side of the second pump 8.
A limited amount of working fluid flows through the connection 28 from the delivery side of the first pump 6 to the suction side of the second pump 8 for reasons of lubrication and cooling.
From the delivery side of the second pump 8, working fluid flows back to the reservoir 2 via a pipe 30, possibly through a check valve 32.
The fine filter 20 may be equipped with a differential pressure indicator 34 and a flow meter 34a. All the components of the installation are of a type that is known per se.
When the pump 6 feeds a greater volume of working fluid to the fine filter 20 through the pipes 4, 12 and 16 than that for which the fine filter 20 is dimensioned, the pressure reducing valve 18 will maintain an accurate inlet pressure to the fine filter 20 through opening the pipes 14 and 26 to flow. This means that the fine filter 20 can be utilised in the best possible manner with regard to both treatment capability and service life.
Working fluid flows to the suction side of the second pump 8 from the fine filter 20 through the pipe 24 in a manner such that the outlet side of the fine filter is not subjected to overpressure, and from the pressure relief valve 18 through the pipe 26. In the second pump 8, the pressure is increased in order to enable the fluid to be used in a subsequent operation, whereby the velocity of the working fluid may be increased when flowing back to the reservoir 2 via the pipe 30, by means of e.g. a restriction (not shown) in the pipe. In an alternative embodiment, see Fig. 2, the pipe 30 is connected to a downstream hydraulic installation 40 that may include one or more of the following components: a pump 42 with a motor 44, a main filter 46, a check valve 48, a pressure relief valve 50 and valves and actuators 52. All these of a type that is known per ≤re.
Thus the fine filter treatment plant 1 can take care of the entire supply of working fluid to the hydraulic installation 40. Alternatively, the pump 42 may through use of the motor 44 also pump working fluid to the hydraulic installation 40. The main filter 46 is a full flow pressure filter protected by the bypass coupled check valve 48. The pressure relief valve 50 prevents overloading of valves and actuators 52.
By using the method according to the invention, one drive unit will be sufficient for the pumps of the installation, both in the case of pressurized installations and unpressurized installations. Returning the working fluid to the reservoir 2 at a substantial velocity results in good circulation in the reservoir, whereby deposits are prevented.
Furthermore, it is an advantage that fine filtering according to the proposed method is relatively insensitive to sudden movement and thus well suited for mobile equipment.
A further advantage is the freedom of placement of the fine filter in relation to the remaining components of the hydraulic installation, and the fact that there is no requirement for a separate filter reservoir.

Claims

C l a i m s
A method for use of an oil-hydraulic fine filter (20) of the type where the outlet side of the fine filter (20) is designed to operate without overpressure, c h a r a c t e r i s e d i n that working fluid that flows from the fine filter (20) in a depressurized state is pumped on by a second pump (8), where the second pump ( 8 ) is driven by the same driving device ( 1 ) as the first pump/feed pump (6) of the fine filter (20).
A method in accordance with Claim 1, c h a r a c t e r i s e d i n that working fluid from the second pump (8) flows to the reservoir (2).
A method in accordance with Claim 1, c h a r a c t e r i s e d i n that working fluid from the second pump (8) flows to a hydraulic installation (40).
A method in accordance with one or more of the preceding claims, c h a r a c t e r i s e d i n that working fluid flows from the delivery side of the feed pump (6) via a pressure relief valve (18) to the suction side of the second pump ( 8 ) .
A method in accordance with one or more of the preceding claims, c h a r a c t e r i s e d i n that a limited amount of working fluid flows from the delivery side of the feed pump (6) to the suction side of the second pump A device by an oil-hydraulic fine filter (20) of the type where the outlet side of the fine filter (20) is designed to operate without overpressure, c h a r a c t e r i s e d i n that the outlet side of the fine filter. (20) is connected to the suction side of the second pump (8), and where the second pump (8) is operated together with the feed pump (6) of the fine filter (20), by the same driving device (1).
PCT/NO2002/000190 2001-06-08 2002-05-30 A method and device for fine filtering WO2002101246A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP02778857A EP1392982A1 (en) 2001-06-08 2002-05-30 A method and device for fine filtering
US10/480,017 US20040141854A1 (en) 2001-06-08 2002-05-30 Method and device for fine filtering

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO20012862A NO314341B1 (en) 2001-06-08 2001-06-08 Process and apparatus for fine filtration
NO20012862 2001-06-08

Publications (1)

Publication Number Publication Date
WO2002101246A1 true WO2002101246A1 (en) 2002-12-19

Family

ID=19912544

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO2002/000190 WO2002101246A1 (en) 2001-06-08 2002-05-30 A method and device for fine filtering

Country Status (4)

Country Link
US (1) US20040141854A1 (en)
EP (1) EP1392982A1 (en)
NO (1) NO314341B1 (en)
WO (1) WO2002101246A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101655116B (en) * 2009-09-17 2011-12-14 成都成设航空科技有限公司 Hydraulic power source system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102650306A (en) * 2011-02-25 2012-08-29 上海液力液压机电制造有限公司 Vacuum oil pumping circulation filter system
CN108397432B (en) * 2018-02-27 2019-11-19 首钢京唐钢铁联合有限责任公司 A kind of blast furnace air machine hydraulic system

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3777888A (en) * 1970-05-21 1973-12-11 Bosch Gmbh Robert Arrangement for pumping a filtered fluid
US5395519A (en) * 1993-08-03 1995-03-07 Caterpillar Inc. Filter device for a hydraulic system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5251442A (en) * 1991-10-24 1993-10-12 Roche Engineering Corporation Fluid power regenerator
US5549832A (en) * 1994-12-22 1996-08-27 Century Manufacturing Company Vehicle coolant recycling

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3777888A (en) * 1970-05-21 1973-12-11 Bosch Gmbh Robert Arrangement for pumping a filtered fluid
US5395519A (en) * 1993-08-03 1995-03-07 Caterpillar Inc. Filter device for a hydraulic system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101655116B (en) * 2009-09-17 2011-12-14 成都成设航空科技有限公司 Hydraulic power source system

Also Published As

Publication number Publication date
EP1392982A1 (en) 2004-03-03
US20040141854A1 (en) 2004-07-22
NO20012862D0 (en) 2001-06-08
NO314341B1 (en) 2003-03-10
NO20012862L (en) 2002-12-09

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