GB1562255A - Filtration apparatus - Google Patents

Description

(54) FILTRATION APPARATUS (71) We, FILTERWERK MANN & HUMMEL GMBH, of Postbox No. 409, D 7140 Ludwigsburg, Germany (Fed. Rep.); a German body corporate, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to filtration apparatus for liquids including a filter insertable in a pressure pipe and having several filter inserts which are adapted to be discontinuously and successively flushed back by a pressure medium and wherein the filtering operation for the filter inserts not subjected to the flushing operation is maintained and including a cleaner or "after-cleaner" connected to said filter.

Whilst it is known for individual filter inserts to be cleansed or freed from dirt by back-flushing, there remains, however, a quantity of liquid containing with the flushed dirt and carried away through the sludge discharge conduit requiring further suspension in an after-cleaner. Usually, the dirty liquid is subsequently filtered through replaceable filter inserts having a high degree of dirt separation so that the filtrate of the after-cleaner can again be supplied to the general liquid circulation. After-cleaning is also necessary in water filters before a desired diversion into the drains or sewer.

Cleansing of the flushed, contaminated liquid in "after-cleaners" - fitted with interchangeable filter inserts whilst being satisfactory with regard to separation degree and value there does always exist the problem of ensuring the ready availability of replacement inserts in sufficient numbers.

With filters of the car industry, for example, which are produced in vast numbers and distributed substantially worldwide, this problem of availability is solved, by and large, by suitable organisation of obtaining spares. Flushing filters, however, do not constitute such mass produced devices to the same extent and throughout have considerably larger dimensions so that it is not possible for other industries to fall back on mass produced replacement inserts.

Filtration apparatus are also known which do not utilize such replacement filter inserts. One such apparatus includes the socalled "free jet centrifuge" in which the rotor is driven by the liquid which is emitted tangentially. These centrifuges produce good separation and have been used for continuous operation in the main flow or secondary flow. It has also become known in the filtering of lubricating oil of internal combustion engines to locate the free jet centrifuge behind the sludge outlet pipe of a hydro cyclone located in the main stream.

In flushing filters hitherto, the deployment of such centrifuges was not known because the flushing operation is relatively short and the liquid supply made available thereby proved too small to produce sufficient operating speed for the rotor of the centrifuge.

Proceeding from the initially mentioned liquid filter, it is an object of the invention to provide a flushable liquid filter independent of replacement or interchangeable cartridges whilst at the same time providing a sufficient degree of clarification in an after-cleaner.

According to the present invention there is provided filtration apparatus for liquids including a filter located in the flow path of a pressure pipe and having a plurality of filter inserts, and flushing means cooperable with the filter inserts to permit said inserts to be discontinuously and successively flushed by a pressure medium in a reverse direction of flow relative to the normal direction of filtration flow; and including an after-cleaner connectable to said filter via a sludge outlet pipe by which the reverse-flow flushing liquid is discharged from the filter, said filter being adapted such that the filtering operation for the filter inserts not subjected to the reverse-flow flushing operation is maintained during operation, characterised by the feature that the after-cleaner is formed by a free jet centrifuge having a rotor drivable by tangentially outflowing liquid, and that a change-over valve is provided for the alternative connection of the free jet centrifuge to a secondary flow pipe connected to the pressure pipe or to the sludge outlet pipe of the liquid filter.

It is thus now unnecessary to obtain and stock replacement cartridges because the impulse or free jet centrifuge collects the impurities in the rotor. The rotor may first be brought to speed by connecting of the free jet centrifuges via the secondary flow pipe to the pressure pipe and it is subsequently connected to the liquid filter via the flushing outlet in the flushing back operation. Continuous operation of the centrifuge is desirably avoided so that the rotor in fact separates and stores the impurities supplied mainly only via the sludge discharge pipe of the flushing filter and is thus not prematurely filled with impurities and dirt as would be the case if the centrifuge were connected, for example, to the pressure pipe for continuous operation.

To permit the dimensions of the centrifuge to be kept small whilst at the same time ensuring adequate flushing supply and speed, in a preferred embodiment of the invention, there is provided. in the sludge discharge pipe between the liquid filter and the change-over valve a stop valve and, downstream therefrom, an inter- mediate container which may be connected to the pressure medium. This permits the flushing liquid to first pass into the intermediate container and from there the contaminated liquid is slowly forced through a free jet centrifuge having suitably small dimensions.

In order to supply the centrifuge with as little dirt as possible during the starting operation, the secondary flow pipe is preferably connected to the section of the pressure pipe forming the filtrate pipe.

The invention will be described further, by way of example, with reference to the accompanying schematic drawing showing a filtering system for the lubricant of an internal combustion engine for a ship.

An oil filter unit 1 has several cage-like filter inserts 2 circularly and evenly arranged and which are located to be hermetically sealed in a partition wall 5 which divides filtrate chamber 3 from the chamber 4 for contaminated liquid. Each filter insert 2 has an impermeable cylindrical sleeve 6 associated therewith which is open at the bottom and projects into the contaminated liquid chamber 4. An angled pivot tube or arm 7 has an upper open end face which may be brought successively into alignment with the individual sleeve 6.

A pressure pump 10 displaces lubricant from storage container or reservoir 11 over a first section 12 of a pressure pipe 13 into chamber 4 of the liquid filter 1. The filtrate is conveyed, via a second section 14 of the pressure pipe 13, which section acts as a filtrate pipe to the compression combustion engine 15.

A sludge discharge pipe 20 is connected to pivot tube 7 and leads to an after-cleaner 21. The after-cleaner 21 is adapted as a free jet centrifuge 22 which includes a rotor 24 having tangentially located driving nozzles 25 and which is rotatably mounted on a supply tube 23. The "after-cleaned" liquid leaves the centrifuge 22 through the outlet sockets 26 and flows into the storage container 11 via filtered liquid pipe 27.

The sludge discharge pipe 20 includes a change-over valve 30 via which the centrifuge 22 may be alternately connected to a secondary flow pipe 40 connected to the outlet duct of the liquid filter 1 or to pipe 20. In the example shown, the secondary flow pipe 40 is connected to the section of the pressure pipe 13 forming the filtrate pipe 14.

A stop valve 31 and, downstream thereof, an intermediate container 32 are included in the sludge discharge pipe 20 between the liquid filter 1 and the change-over valve 30.

A pipe 34 with closure member 33 leads into the intermediate container 32 and is provided for supplying compressed air as pressure medium. Furthermore, the intermediate container 32 is provided with a bleed pipe 36 having a ventilating or bleed valve 35.

During normal filtering operation, the stop valve 31, the closure member 33 and the bleed valve 35 are closed. Changeover valve 30 is in a position in which it connects the intermediate container 32 with the centrifuge 22.

Lubricant containing impurities is conveyed by the pressure pump 10 from the storage container 11 via the first section 12 of the pressure pipe 13 into the chamber 4 for receiving contaminated or dirty liquid to be processed by the filter 1. The contaminated liquid traverses the filter inserts 2 which separate the greater proportion of the impurities from the lubricant. The filtered lubricant is then supplied via the section 14 of the pressure pipe 13 adapted as filtrate pipe to internal combustion engine 15, wherein it becomes permeated with further impurities and is then returned via the return pipe 38 to storage container 11.

The scavenging or flushing operation of a filter insert is initiated by twisting the change-over valve 30 into a position in which it connects the secondary flow pipe 40 to the centrifuge 22 and at the same time closes the sludge discharge pipe 20. Oil after being filtered by the liquid filter 1 now flows through the secondary flow pipe 40 via the changeover valve 30 through the supply pipe 23 and into the rotor 24 from which it leaves at high speed through the tangentially located driving nozzles 25.

The stop valve 31 is now opened and filtered oil flows as a pressure medium in reverse direction through one of the filter inserts 2 which is connected to the sludge discharge pipe 20 in order to dissolve and dislodge the previously separated impurities and to flush it away. Stop valve 31 remains open until an adequate supply for the flushing operation has accumulated in the intermediate container 32. The stop valve 31 is subsequently closed and closure member 33 opened. The change-over valve 30 is then turned into a position in which it connects the intermediate container 32 to the centrifuge 22 and at the same time closes the secondary flow pipe 40. The contaminated liquid which has accumulated in the intermediate container 32 is subjected to the effect of the compressed air supplied through the pipe 34 and is directed to the rotor 24 of the centrifuge 21 which has already been brought to operating speed prior thereto and which collects the impurities on the inside circumference of the rotor housing. The liquid thus "after-cleaned" passes to the storage container 11 via outlet pipe 26. When the intermediate container 32 is empty, the compressed air pipe 34 is closed by the closure member 33 and the ventilating valve 33 opened briefly. A new flushing operation may subsequently be commenced.

A secondary flow pipe 50 shown in chain-dotted lines may be provided in place of secondary flow pipe 40 and connects first section 12 of the pressure pipe 13 to the free jet centrifuge 22 via the change-over valve 30. It thus has to be appreciated that contaminated liquid is supplied for starting the centrifuge, which, of course, results in a more rapid filling of the centrifuge rotor 24 with impurities.

WHAT WE CLAIM IS: 1. Filtration apparatus for liquids including a filter located in the flow path of a pressure pipe and having a plurality of filter inserts, and flushing means cooperable with the filter inserts to permit said inserts to be discontinuously and successively flushed by a pressure medium in a reverse direction of flow relative to the normal direction of filtration flow; and including an after-cleaner connectable to said filter via a sludge outlet pipe by which the reverse-flow flushing liquid is discharged from the filter, said filter being adapted such that the filtering operation for the filter inserts not subjected to the reverse-flow flushing operation is maintained during operation, characterised by the feature that the after-cleaner is formed by a free jet centrifuge having a rotor drivable by tangentially outflowing liquid, and that a change-over valve is provided for the alternative connection of the free jet centrifuge to a secondary flow pipe connected to the pressure pipe or to the sludge outlet pipe of the liquid filter.

2. Filtration apparatus as claimed in claim 1, in which the sludge outlet pipe is provided with a stop valve and with an intermediate container downstream of said stop valve and connectable to a pressure medium; said stop valve and intermediate container being located between the liquid filter and the change-over valve.

3. Filtration apparatus as claimed in claim 1 or 2, in which the secondary flow pipe is connected to the section of the pressure pipe forming the filtrate outlet pipe of the filter.

4. Filtration apparatus constructed and arranged to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. through the secondary flow pipe 40 via the changeover valve 30 through the supply pipe 23 and into the rotor 24 from which it leaves at high speed through the tangentially located driving nozzles 25. The stop valve 31 is now opened and filtered oil flows as a pressure medium in reverse direction through one of the filter inserts 2 which is connected to the sludge discharge pipe 20 in order to dissolve and dislodge the previously separated impurities and to flush it away. Stop valve 31 remains open until an adequate supply for the flushing operation has accumulated in the intermediate container 32. The stop valve 31 is subsequently closed and closure member 33 opened. The change-over valve 30 is then turned into a position in which it connects the intermediate container 32 to the centrifuge 22 and at the same time closes the secondary flow pipe 40. The contaminated liquid which has accumulated in the intermediate container 32 is subjected to the effect of the compressed air supplied through the pipe 34 and is directed to the rotor 24 of the centrifuge 21 which has already been brought to operating speed prior thereto and which collects the impurities on the inside circumference of the rotor housing. The liquid thus "after-cleaned" passes to the storage container 11 via outlet pipe 26. When the intermediate container 32 is empty, the compressed air pipe 34 is closed by the closure member 33 and the ventilating valve 33 opened briefly. A new flushing operation may subsequently be commenced. A secondary flow pipe 50 shown in chain-dotted lines may be provided in place of secondary flow pipe 40 and connects first section 12 of the pressure pipe 13 to the free jet centrifuge 22 via the change-over valve 30. It thus has to be appreciated that contaminated liquid is supplied for starting the centrifuge, which, of course, results in a more rapid filling of the centrifuge rotor 24 with impurities. WHAT WE CLAIM IS:

1. Filtration apparatus for liquids including a filter located in the flow path of a pressure pipe and having a plurality of filter inserts, and flushing means cooperable with the filter inserts to permit said inserts to be discontinuously and successively flushed by a pressure medium in a reverse direction of flow relative to the normal direction of filtration flow; and including an after-cleaner connectable to said filter via a sludge outlet pipe by which the reverse-flow flushing liquid is discharged from the filter, said filter being adapted such that the filtering operation for the filter inserts not subjected to the reverse-flow flushing operation is maintained during operation, characterised by the feature that the after-cleaner is formed by a free jet centrifuge having a rotor drivable by tangentially outflowing liquid, and that a change-over valve is provided for the alternative connection of the free jet centrifuge to a secondary flow pipe connected to the pressure pipe or to the sludge outlet pipe of the liquid filter.

2. Filtration apparatus as claimed in claim 1, in which the sludge outlet pipe is provided with a stop valve and with an intermediate container downstream of said stop valve and connectable to a pressure medium; said stop valve and intermediate container being located between the liquid filter and the change-over valve.

3. Filtration apparatus as claimed in claim 1 or 2, in which the secondary flow pipe is connected to the section of the pressure pipe forming the filtrate outlet pipe of the filter.

4. Filtration apparatus constructed and arranged to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.