The invention relates to a method and a device for cleaning a piston-based hydraulic accumulator.
Today, cleaning is carried out by washing/flushing piston accumulators by repeatedly pumping hydraulic fluid into and letting hydraulic fluid out of the accumulator, until the hydraulic fluid comes out clean.
From the patent literature are cited as the background art:
WO 2006/079931 A1 disclosing flushing of accumulated particles, typically sand, from the bottom of a process container without a piston, the particles being brought against the accumulator wall in a rotating, vortex-like flow pattern.
DE 4337380 A1 disclosing a cleaning device for cleaning drain pipes.
EP 0854296 B1 dealing with a particular accumulator, in which a sealing medium in the space between two piston parts of a double piston is compressed by a biasing spring. This medium functions together with the piston seals as a seal between the hydraulic side and the gas side.
GB 846307 A1 disclosing a special accumulator with an integrated filter device at the hydraulic oil side to avoid having a separate high-pressure filter housing, by using a lower end of the accumulator as a filter housing.
Running the piston cyclically in connection with cleaning of the piston-based hydraulic accumulator has several drawbacks:
1. It is a time-consuming operation, getting the particle contents of the accumulator down to a desired cleanness grade by running the piston.
2. There is a problem getting remains of dirt accumulating at the bottom of the accumulator out by known methods.
3. Long-duration running of the piston gives wear, and wear from the piston also causes particles to mix into the hydraulic fluid.
4. There is a risk of galling between the piston and cylinder wall, and it has happened that accumulators have become ruined during flushing, because of this operation.
Thus, there is a need for a more effective method of cleaning piston-based hydraulic accumulators, reducing the wear from the piston at the same time.
According to the invention, the method and the device provide for an improved cleaning of piston accumulators in connection with a flushing of hydraulic systems.
The present inventive method and device make use of novel flushing port(s) or duct(s) when cleaning a piston accumulator in which clean hydraulic oil is forced into the piston accumulator via axial bores of the flushing port(s) and further on in sloping bores, bringing said clean hydraulic oil into a volume of the piston accumulator in an upward, tangential direction below a piston of the piston accumulator, to bring a flushing hydraulic oil comprising the clean hydraulic oil and a polluted hydraulic oil into a flushing circulation, and returning the polluted hydraulic oil out via a main port and a return passage until a cleanness grade has been reached. By reducing a gas pressure on a gas side of the piston in relation to a flushing pressure input from a valve, the volume is created on an oil side between the piston and an end bottom. Further, the return passage is closed and the piston is brought into its upper position, so that an internal cylinder wall is cleaned, and that upon pressure build-up, the return passage is opened and the piston returns to its end position on the oil side while a supply of clean hydraulic oil is maintained. The operation is repeated until a desired grade of cleanness has been achieved.
The gas pressure on the gas side 4 of the piston 5 is reduced in relation to the flushing pressure input from the flushing pressure input valve 6 to the piston-based hydraulic accumulator 7. The gas is compressed somewhat, so that there will be the fluid volume 8 on the oil side, i.e. between the piston 5 and end bottom 3.
Clean hydraulic oil is forced into the piston-based hydraulic accumulator 7 via the flushing ports or ducts 1A and 1B, bringing the oil in the fluid volume 8 below the piston 5 into circulation at great velocity, and dirty oil is returned out via the main duct 2. When a desired cleanness grade has been achieved, the fluid return passage 9 is closed, so that the piston 5 compresses gas on the gas side 4 of the piston 5 and the piston 5 reaches its upper position. This cleans the internal cylinder wall 10 internally.
On pressure build-up, the fluid return passage 9 is opened and the piston 5 is allowed to return to its end position on the oil side while the supply of clean hydraulic oil is maintained, and the cleaning operation is repeated until the desired cleanness grade has been achieved.
Number | Date | Country | Kind |
---|---|---|---|
20083748 | Aug 2008 | NO | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/NO2009/000303 | 8/28/2009 | WO | 00 | 5/13/2011 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2010/024692 | 3/4/2010 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
2828760 | Desmond et al. | Apr 1958 | A |
3331117 | Jacobellis | Jul 1967 | A |
4186777 | Klope et al. | Feb 1980 | A |
4966200 | Bents | Oct 1990 | A |
5311910 | Hasegawa et al. | May 1994 | A |
5353840 | Paley et al. | Oct 1994 | A |
5505262 | Cobb | Apr 1996 | A |
6866066 | Weber | Mar 2005 | B2 |
20080314467 | Gray, Jr. | Dec 2008 | A1 |
Number | Date | Country |
---|---|---|
4337380 | May 1995 | DE |
0854296 | Jul 1998 | EP |
846307 | Aug 1960 | GB |
2006079931 | Aug 2006 | WO |
Entry |
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International Search Report for International Patent Application No. PCT/NO2009/000303 dated Oct. 28, 2009. |
Number | Date | Country | |
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20110214743 A1 | Sep 2011 | US |