DE3332324A1 - Separating filter element, process for the production of such a filter element and filter device using such a filter element - Google Patents

Abstract

Filter element, in particular for separating liquid aerosols for compressed air, having a tubular retention body the surface of which is directly covered with a layer of microfilaments without any resin impregnation, the layer thickness being chosen so that a filter effect can occur. To produce such a filter element, a resin-free slurry of microfilaments is passed from one surface to the other of a retention body held in a perforated tubular mould, so that the microfilaments are directly deposited on the retention body. <IMAGE>

Description

Separation filter element, method of manufacturing a

such a filter element and filter device using a such filter element The invention relates to a filter element, in particular for Separation of liquid aerosols from compressed air.

Separation filter for separating liquid aerosols from one compressed gas are in common use. The most common area of application is that Separation of oil / water aerosols from compressed air supplied by compressors. For this purpose, a large number of filter types have become known, the most common are cylindrical filter elements, through which the compressed air either from the inside to the outside or from outside of the inside. In the first case it will be too filtering compressed air is introduced axially into the filter from one end and flows through it the filter and is expelled into the atmosphere through the radially outer surface; in the second case, the compressed air to be filtered is released from the outer surface passed through the filter and expelled axially from one end of the filter interior.

A non-woven mass is generally used as the filter medium Borosilicate microfibers are used for the purpose of increasing the strength of the filter mass impregnated with resin. At least the downstream side of the tubular filter material is of supported by a porous sleeve. It is also possible to use the upstream in a similar way to prevent tearing of the filter layer to prevent if back pressure occurs within the system concerned.

Many proposals are known for supporting the filter layer, for example, it is supported by perforated metal sleeves, but there are also sleeves made of woven synthetic materials, for example nylon or polyester, known. However, these sleeves can also be made of a filter material of larger size Strength than that of the borosilicate fiber sleeves.

Also different compositions and exchanges of elements have been proposed in a variety of forms.

When separating liquid aerosols from gas streams it is necessary to ensure that the separated liquid is separated from the filter and is diverted away and does not flow back into the filtered gas stream. thats why it is common practice to combine the filter sheet and support members downstream of the Assign a re-entry barrier to the filter element.

Re-entry barriers or barriers are generally relatively thick Sleeves of high porosity, through the channels formed in this way, the deposited Liquid diverted by gravity and from the lower part of the re-entry barrier flow away. The filtered gas can very easily pass through the pores of the re-entry barrier pass through and is the re-entry of liquid into the filtered gas essentially prevented.

Usually the re-entry barrier is made with a microfiber filter material and the support element or the unit comprising the support elements connected after this unit has been assembled.

The object of the invention is the known filter elements of this Kind of further training in such a way that they are extraordinary while avoiding their disadvantages simply and cheaply, so that the filter arrangements are also simpler and cheaper than before, as well as a method for producing such filter elements create.

This object is achieved according to the invention by a tubular Retaining body with a microfiber layer free of any resin impregnation covered surface with a layer thickness sufficient for a filter effect.

The filter element according to the invention is therefore characterized by large Simplicity, because in its simplest form it consists of just two elements, namely a restraint body or a barrier, on one surface of which a Layer of non-impregnated microfiber is deposited. Will this filter element Used in conjunction with a filter device that determines the direction of flow is directed from the inside out with respect to the filter element, is located according to the invention the microfiber layer on the inner surface of the retaining body. In this case, the retaining body has sufficient strength to withstand the radial outward pressure to withstand the gas flow so that no further Support means are to be provided radially outside the microfiber layer.

For safety reasons, however, it is known in filter technology that Take action against the effects of back pressure forces in the system; for such cases, according to the invention, a perforated, essentially rigid shell is provided disposed adjacent the radial inner surface of the microfiber layer. For further Use cases it may be advisable to use a similar sleeve on the outer surface as well to assign the restraint body adjacent.

In the case of a filter device, cie for a flow direction of the to cleaning gas is suitable from the outside in with respect to the filter element, are inventively the microfibers on the outer surface applied to the restraint body. As it is unlikely in this embodiment is that the rear body has sufficient hoop stress against the pressure, to resist collapse, and with it the filter element, is for such applications according to the invention a perforated, essentially rigid Sleeve brought into contact with the inner radial surface of the retainer body. According to a further feature of the invention, a similar sleeve should also be used for the outer one Surround the surface of the microfiber layer to prevent the fiber layer from tearing, if pressure surges or back pressure effects occur in the system.

A method for producing such a filter element is according to the invention characterized by the following process steps: - In a perforated, tubular shape Form is a likewise tubular retaining body with a first circumferential surface, located adjacent to a face of the mold, - a resin-free slurry Microfiber is used to flow through the retention body in weight of the second circumferential surface brought to the first circumferential surface, such that a layer of microfibers are located directly on the second circumferential surface of the retaining body ii a starch allowing a filter effect settles, and drying the settled Filter layer.

The invention is applicable to any form of restraint body and therefore also for every form of microfiber layer. Preferably there is the retention body made of a felt-like material with fibers in the diameter range from 5 to 50'ihm, the thickness of the restraint body being in the range from 1.5 to 8 mm.

The fibers used to manufacture the filter element are preferred Borosilicate microfibers with a range of diameters of 0.05 to 10 µm. The thickness of the microfiber layer is in the range from 2 to 15 mm.

A separation filter according to the invention contains one according to the invention Filter element in one of the shapes described above, the axial ends of which are in contact with corresponding end caps, of which at least one is the gas passage Has in the filter interior enabling opening. It is necessary that the filter is formed gas-tight in the axial end areas, therefore, are at these points suitable seals are provided. Compound seals, immersion seals are suitable for this (for example with methane), knife edge seals, pinch seals using the filter element material or labyrinth seals, etc.

Further features of the invention emerge from the subclaims.

The invention is illustrated below with reference to several in the drawing Embodiments described. They show: FIG. 1 a perspective illustration of a filter element according to the invention, Figure 2 shows a cross section through a shape for the production of a filter element according to FIG. 1, FIG. 3 is a schematic Jarrepresentation of a molding device for the production of filter elements according to FIG 1, FIG. 4 shows a first exemplary embodiment of a form of application of the filter element according to the invention in a filter device, FIGS. 5 to 7 further exemplary embodiments of filter devices with the filter element according to the invention.

A filter element shown in Figure 1 is used for filtering of oil / water aerosols from compressed air, which pass through the filter element from the inside to the outside flows. This filter element comprises a filter fiber preventing entrainment Barrier 1 made of a felt-like material made of polyester or nylon or a Mixtures of these, or of polypropylene fibers, the fibers having a diameter in Range from 5 to 50 µm. This barrier can be seamless or flat Plate which is joined together to form a tube by known means exist. The inner surface of the barrier is immediately covered with a layer 2 of non-impregnated Borosilicate microfiber covered; the microfibers have a diameter in the range from 0.05 to 10 ~ him.

The thickness of the barrier is about 1.5 to 8 mm and the thickness of the Layer 2 made of microfibers about 2 mm to 15 mm. Although the microfiber layer in itself is soft, the barrier has enough tension in the circumferential as well as in the longitudinal direction, to keep the filter element in its position in the applications to be described no = h.

FIGS. 2 and 3 show processes for the production of the in FIG 1 shown filter element. For this purpose, there is a slurry in a mixing tank 1a Provided by borosilicate microfibers suspended in water that have a pH of about 3, by which the dispersion of the microfibers is aided. These Slurry is resin free. The tank is powered by a motor Stirrer 2a provided, through which the slurry is constantly stirred to the Maintain fiber dispersion at a uniform fiber concentration.

A pump 3 is connected to an outlet of the tank and delivers in measurable quantities the slurry in an intermediate tank 4 as soon as a delivery valve 5 is open. After closing the feed valve 5 is under pressure Air passed from a compressed air source 6 to the intermediate or holding tank 4 to by there to press the slurry into the interior of a mold 8 via a valve 7.

*consists The form 8 consists of an upper half 8a and a lower half 8b, both halves being axially aligned with one another are. The lower half 8b can be moved towards and away from the upper half be, with the mediation of a pneumatic piston 10. As soon as the lower Half of its upper position is - as shown in Figure 2 - are the wall sections 8c and 8d of the two halves in mutual contact at 8e. As from Figure 2 further can be seen, the walls of the halves are each perforated.

If this form is opened by moving the lower half 8b down, the prefabricated barrier 1 can be used in one of the halves that are after the closing of the mold comes to lie radially inside the wall sections 8c and 8d.

As soon as the slurry through an opening 11 under pressure into the When the mold is injected, the microfiber-retaining barrier is pressed against it 1 in close contact with the wall sections 8c and 8d. The liquid to the slurry passes through the material of the barrier hindurci and then through the openings in the wall sections 8c and 8d. The microfibers of the slurry, on the other hand, can do not pass the barrier 1 and are therefore caught by its inner surface, so that they build up a layer of microfiber that is in direct contact with the interior The area of the retaining barrier is in place.

The liquid passing through the wall portions Ec and 8d is collected in a cleaning tank 13 and transferred to a storage tank by means of a pump 14 15 pumped. The storage tank 15 is used to hold another batch of the slurry to mix.

The mixing takes place by means of a motor-driven propeller 16.

The tank 1 a is charged from the Vorritstank 15 by means of a pump 17.

As soon as the predetermined amount of the slurry is introduced into the mold 11 and the liquid has passed through the wall portions 8c and 8d the layer having the desired weight and strength of the microfibers on the inner surface of the barrier down. Then a certain amount Compressed air is blown through the mold without the slurry, thereby creating the Molding is partially dried. After this partial drying, the shape opened and the structure produced is covered with a layer of microfibers Barrier removed from the mold and dried in an oven to the filter element to finish.

In Figure 4, a first embodiment is generally one with the reference number 20 designated filter device using the described Filter element according to Figure 1 indicates.

For this purpose, a filter element is provided which consists of a retaining fiber Barrier 21 and a layer 22 of borosilicate microfibers applied to its inner surface consists. This structure is pushed over a perforated cylinder 24, the one has integrally molded cap 23 and consists of substantially rigid material. A top cap 25 is connected to the cylinder 24 by a screw connection 26. The top cap has a threaded pin 27 by means of which the filter is inserted into a filter housing 28 can be screwed in, with an interposed seal 29 being provided is. Furthermore, between the axial ends of the filter element and the surfaces seals are provided on the upper and lower cap against which the filter element abuts, for example in region 32 at the bottom of the filter in the form of a suitable composite gasket 33.

In use, the gas to be filtered becomes an inlet 30 in the filter housing and passed from there into the interior of the filter 20. The gas happens the openings 31 in the cylinder 24 and the liquid aerosol in the gas is through the Microfiber layer 22 deposited. The separated liquid flows through the Gravity down. along the fiber retention barrier 21, and is collected at the base of the filter housing, from where it depends on the requirements is further derived.

FIG. 5 shows a further form of use of the one shown in FIG Filter element. Similar to the exemplary embodiment according to FIG. 4, a filter element surrounds it 40 a perforated cylinder 41 having an integral bottom cap 42. One top cap 43 is screwed onto the top end of cylinder 41.

Composite seals are provided at 44 and 45 where the end caps bump against the filter element.

The top cap 43 has an externally threaded one Pin 46.

One such type of filter is preferably an air silencer / oil separator Applicable in pneumatic systems, where made up of valves, pistons and other components escaping air is contaminated with oil. The pin 46 is therefore a pipe connection formed directly into the opening of a pneumatic valve or another Device fits. In this way, the oily air coming out of the device is blown off, fed into the filter and only occurs after flowing through the filter the end.

The oil is separated and gets through the layer of microfibers along the barrier downwards, the filter at the same time having the effect of soundproofing which has leakage noises. The filtered air goes directly into the atmosphere.

The filter element shown in Figure 5 has a bowl-shaped Cap 47 which is detachably attached to the bottom cap. This cap 47 has an outflow opening through which the air and other liquid contaminants that have accumulated there can drain.

In Figure 6, a filter 50 is shown similar to that in Figure 5, the is suitable with a pneumatic device by means of a threaded pin 51 to be connected, with the axis of the filter oriented more horizontally than vertically is. In this case a length of the lower part of the filter is extending Drip tray 52 from the front and rear (top and bottom) caps carried at 53 and 54 to contain liquids separated by the filter will. The collected liquids are drained off through an outflow opening 55.

In Figure 7 is a further embodiment of a filter arrangement with a filter element not shown in FIG. A filter element 60 is provided there, dts has a microfiber layer 61 on the inner surface, which is covered by a perforated Cylinder or a coil spring 62 is supported. This arrangement is through a upper and rear cap 63 and 64 encapsulated with the mediation of a suitable one Composite seal. The cylinder or coil spring 62 prevents it from collapsing of the filter element if the flow direction of the medium to be filtered changes conversely, in the arrangements according to Figures 4 to 6 through from the inside to the outside the filter element is directed.

In each of the described Fi teranorders it can be seen that when arranging a perforated cylinder or other porous reinforcing sleeve this radially surrounds the filter layer outside the barrier. It is also possible in these constructions a thin layer of a fine-pored lining layer (scrim) to be placed between the microfiber layer and the inner radial cylinder, Jer protects the filter layer from the effects of reverse flow. Such Lining layer prevents microfibers from migrating through the filter layer the inner support cylinder when reversing the direction of flow of the filter to be filtered Medium takes place. if the Perforation on the inner support cylinder is small enough, there is of course no need to arrange a special lining layer.

The invention described can also be used to produce a filter element to create that for an outward-inward flow direction of the the medium to be filtered is suitable. In this case it is the microfiber layer to be placed on an outer surface of the fiber-retaining barrier. Accordingly is to modify the manufacturing method according to Figure 3 accordingly.

Filter assemblies with such filter elements are known, so that their description is superfluous. It is also readily apparent that also methods other than the one described for producing the described inventive method Filter element are possible and that such filter elements in other than that described filter arrangements can be used.

Claims (13)

PATENT \ NSPRÜCHE 1. Filter element, especially for separating liquid aerosols from compressed air, g e k e n n z e i c h -n e t by a tubular retaining body (1) with one of each resin impregnation free microfiber layer (2) covered surface with a filter effect sufficient thickness of the shoe. 2. Filter element according to claim 1, characterized in that g e k e n n -z e i c h n e t that the inner surface of the backing body (1) from the microfiber layer (2) is covered. 3. Filter element according to claim 1 or claim 2, characterized in that g e -k e It is noted that the retaining body (1) is made of a felt-like material consists of fibers in the range of 5 to 50 µm in diameter. 4. Filter element according to one of the preceding claims, characterized it is noted that the material thickness of the retaining body is 1.5 to 8 mm. 5. Filter element according to one of the preceding claims, characterized it is not noted that the microfibers of the layer (2) are made of borosilicate with a diameter of 0.05 to 10 pm exist. 6. Filter element according to one of the preceding claims, characterized it is not noted that the thickness of the microfiber layer (2) is 2 to 15 mm. 7. Separation filter device using a filter element according to one of the preceding claims 1 to 6, characterized in that e t that end caps (23, 25) are provided which correspond to the ends of the filter body (1, 2, 24) are in contact, at least one of which has a gas inlet opening (30), which leads into the interior of the filter element (1, 2), and through gas-tight seals between the end caps and the filter element (1, 2). 8. separator filter device according to claim 7, characterized in that g e -k e n It is not noted that a perforated, essentially rigid sleeve (24) ds-r inner radial surface of the filter element (1, 2) is adjacent. 9. separating filter device according to claim 8, characterized in that g e -k e n n z e i c h n e t that the radially inner part of the filter element d: e microfiber layer (2) and that between the microfiber layer (2) and the substantially rigid Sleeve (62) z a layer of fine-pored material is arranged. 10. Separation filter device according to one of claims 7 to 9, characterized it is not noted that a perforated, substantially rigid sleeve (62) arranged adjacent to the radially outer surface of the filter element (1, 2) is. 11. A method for producing a filter element according to the claims 1 to 6, g e k z n n z e i c h n e t through the following process steps: - A retaining body, which is also tubular, is made into a perforated, tubular shape with a first circumferential surface located adjacent to a surface of the FDrm, inserted, A resin-free slurry of microfibers is made to flow through the containment body brought in the direction from the second circumferential surface to the first circumferential surface, such that that a layer of v # n microfibers is immediately on the second circumferential surface the restraint body settles in a strength that enables a filter effect, and drying the deposited filter layer. 12. The method according to claim 11, characterized in that g e k e n n z e i c h -n e t that the retaining body is inserted radially inside the mold and that the Direction of flow of the slurry from the inner to the outer peripheral surface of the retention body is directed for the purpose of depositing the microfiber layer on the inner peripheral surface of the restraint body. 13. The method according to claim 11 or 12, characterized in that g e k e n n -z e i c h n e t that the mold split in half successively in axial Direction apart, that the retaining body is moved into one of the mold halves is used that the mold halves are moved together in the axial direction, to fully encompass the retention body that the slurry through the mold is passed, and that after the deposition of the microfiber layer, the mold is opened and removing the filter element from the mold.