CZ20001988A3 - Prefiltration element with filtering cloth - Google Patents

Abstract

Pre-filter element (2) for use in front of fine filter contains a filter fleece (7) which is sealed to an endless arrangement and is in the pre-filter element (2) k filtration is arranged continuously rotatably over the cross-section of the pre-filter element (2).

Description

Pre-filter element with filter fleece

Qblag £ _technics

The present invention relates to a pre-filter element for use upstream of a fine filter, wherein the pre-filter element comprises a filter fleece.

BACKGROUND OF THE INVENTION

It is known to use vortex separators, expanded metal filters or centrifuges as pre-filters. They are designed to filter out coarse dirt or other contaminants, for example from the ambient air. The subsequent fine filter is then loaded only by impurities of smaller diameters.

SUMMARY OF THE INVENTION

It is now an object of the present invention to provide a pre-filter element that has a long service life with low maintenance costs, but at the same time is able to filter out the oil and emulsion mist particles by means of a filter fleece.

This object is achieved by a pre-filter element having the features of claim 1. The invention further provides a filter web for use in a pre-filter element having the features of claim 13. Advantageous developments and embodiments are the subject of the respective dependent claims.

The pre-filter element, in particular for use in front of the fine filter, comprises a filter web which is closed in an infinite arrangement and is continuously rotatably arranged in the pre-filter element to be filtered over the cross-section.

-2 prefilter element. By closing the filter web in an endless configuration, it is possible for the surface of the filter web, always flowing through the stream of purified air, to be movable in the pre-filter element. Thus, the filter web is arranged over the cross-section of the pre-filter element such that it extends rotatably over it. As a result, the flow surface changes. Thus, a single solid surface of the filter web is not continuously flowed, but this surface varies.

A preferred embodiment assumes that the filter web forms an endless loop that is tensioned at least around the first and second return devices. The formation of an endless loop allows the filter web to be able to rotate continuously without defining a boundary start or start. boundary end for rotational movement. By means of tension between the first and second return devices, the rotation path over the cross-section of the pre-filter element is also determined. In particular, the tensioning is such that the filter web has, on the one hand, a certain adhesion to the return device, but at the same time a certain flexibility and elasticity is obtained due to the inherent tension in the filter web. First or. the second return device is formed, for example, in that case the nonwoven forms a pre-filtering and finishing unit around the return devices. While the purified air enters the first side of the filter web, then passes through the first thickness of the filter web, it then enters the interspace formed by the geometry of at least the first and second return devices. Subsequently, the cleaned, already pre-filtered air is returned to the filter web, this time onto the inner surface of the filter web facing the return device. From here the purified air flows back through the filter fleece and then exits to the return filter as tensioned filter • 9 4 4 ♦ ·

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an inner surface opposite the outer surface of the filter web.

A further embodiment of the pre-filter element assumes that the first return device is a drive for rotating the filter web across the cross-section of the pre-filter element. The drive is, for example, an electric motor that drives the return cylinder directly. The drive is controlled or regulated. This can be done by the electronics of the pre-filter element itself or the following main filter. In addition to the continuous drive of the filter web, which results in constant rotation over the cross-section of the pre-filter element, there is also the possibility of controlling or regulating the drive so that the movement of the filter web occurs only at intervals of time. This is dependent, for example, on the degree of contamination of the treated air at the speed of filtration

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pressure through the pre-filter element, which must be compensated by a fan connected to the pre-filter element.

Furthermore, it is advantageous if the first and second return devices are movable and lockable with respect to one another. This makes it easier to replace the filter fleece. If the filter web is to be removed, the distance between the two return devices is reduced. This releases the tension of the filter fleece. The filter fleece is then easily removable from the return devices. A new filter fleece can then be placed over the return devices without being immediately tensioned. When the return devices are subsequently shifted to increase their spacing, the stresses are applied to the filter web. Then

presses the filter web to the return devices so that the newly fitted filter web can follow the rotational movement of the drive without slipping. In a further embodiment, in addition to the first and second return devices, which determine the path of the filter web across the cross-section of the filter element, at least one third return device is provided. This is displaceably arranged to allow additional tension of the filter web. During operation, the material may be pulled out due to the formation of the filter fleece. The possibility of additional adjustment of the filter fleece tension by means of a third return device ensures that the drive remains effective.

In addition to the drive, the pre-filter element also comprises a device for compressing the filter fleece. This compression device cleans the filter fleece. When using a filter web as a pre-filter element, the filter web receives predominantly coarse dirt particles as well as oil and emulsion particles. This mist is sucked through the filter fleece and, as the accumulated liquid, is extruded by means of a compression device. Preferably, the device is arranged at least in proximity to the return point of the filter web, particularly with respect to the gravity of the lower return point. It uses the natural direction of the extruded droplets from the filter fleece down in the gravity direction. This can be supported by appropriately defined notches and effluents in the pre-filter element so that the filtered medium can be specifically collected and drained. This prevents the accumulation of coarse particles on the bottom of the cabinet.

A further embodiment envisages that the filter web compressing device exerts a variable pressure on the filter web. This is possible, for example, via ftft

The pressure roller, whose distance, for example against the return roller, is adjustable. As a result, the device can be specifically adjusted to different fleece materials, i.e. different filter fleeces. It is further preferred that the device comprises at least a first and / or a second return device and one pressure means, wherein the pressure means, in particular the pressure roller, is arranged against the first and / or the second return device to compress the filter web. In this way, it is not necessary to enlarge the necessary components of the pre-filter element. The interaction of the pressure means with the return device, which also forms the drive, allows the filter web to move in the pre-filter element without slipping. In this way, the otherwise necessary friction between the filter fleece drive, which would be caused by the actual tension of the filter fleece, can be reduced. This increases the life of the filter fleece. The pressing means, which is movable, in particular pivotable, in the pressing position, is preferably arranged adjacent the lower return point on the side on which the filter web moves again to the upper return point. On the one hand, the force of gravity can be used to remove the filtered medium. Further, the particles are immediately removed from the filter web shortly before being trapped on the filter web before they could penetrate too far inside the filter web.

A further embodiment assumes that the pre-filter element has at least a first pre-filter stage. In particular, it is designed that the coarse dirt particles and the large oil or emulsion particles are separated, for example, by means of a vortex separator. This filtering step prevents the subsequent filter fleece from being placed in a relatively short time

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4 4 4 · 4 · 4 · 4 · 4 · 4 · 4 · 4 · 4 · 4 · 4 · 4 · 4 · 4 · 4 · · · · · · · · · In a subsequent filtration step, for example a continuously circulating filter web, the remaining oil and emulsion particles are absorbed. The filter web forms an agglomerator. The smallest particles are collected in the web, forming larger droplets which are again released from the filter web by cleaning the filter using, for example, a filter web compressor, or separated from the air to be cleaned by a subsequent filter. According to a preferred embodiment, the pre-filter element with at least one downstream filter forms a filtration system. The downstream filter is, for example, a vortex separator in which agglomerates can be removed by either removing the fleece itself, the particles.

Further formation of the pre-filter element assumes that it is capable of modular expansion. On the one hand, other upstream or downstream valves can be used. downstream filters, for example in the form of plug-in filters. On the other hand, it is also possible to use a pre-filter element independently of the fine filter. For example, the pre-filter element can be integrated into the duct system, the cleaning performance being adjustable in accordance with the filter fleece used to meet the cleaning requirements.

The condition of the pre-filter element, in particular the filter web, can be controlled, for example, by means of a differential pressure device. By means of the differential pressure, it is possible to deduce the clogging of the filter web by impurities. Appropriate evaluation of the received signal can cause adequate fleece cleaning, for example by means of an additional

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44 · 4 4 4 4 integrated washing machine. A signal can also be sent when the maximum allowable differential pressure is exceeded. This signal indicates to the prefilter user that the filter fleece must be replaced. For better integration, the pre-filter element is arranged in the housing, while the upstream and downstream filters are mounted on the housing in the form of plug-in parts. In this way, the necessary maintenance costs can be reduced. It also allows the filter fleece to be replaced without a special tool. This does not require special training of the user of the pre-filter element.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantageous features are explained in more detail in the drawing. These features are combined with the prior art for other preferred embodiments. The drawing shows a pre-filter element with an upstream and downstream filter stage.

DETAILED DESCRIPTION OF THE INVENTION

In the prefilter housing 1 there is a prefilter element 2, a first plug-in filter 2 and a second plug-in filter 4. The first plug-in filter 2 and the second plug-in filter 4 are both vortex separators. The pre-filter element 2 has a return roller 2 that is idle. Opposite there is a drive roller 2, which at the same time forms a drive motor for the filter fleece arranged around the return roller 2 and the drive roller 2. In the vicinity of the drive roller 2, a pressure roller 2 is disposed. As a result, the spacing β is adaptable to various parameters, such as the wear state of the filter web 7, the velocity

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ΦΦ ΦΦ rotation of the drive roller,, particle content in the stream of purified air, etc. The filter fleece 1, which extends across the cross-section of the pre-filter element 2, is regenerated by a device consisting of the drive roller a and the pressure roller 8. £. The design of the pre-filter element 2, together with the first plug-in filter 4 and the second plug-in filter 4, prevents turbulent flow. On the one hand, in order to minimize the pressure loss through the pre-filter element 2, on the other hand, so that the incoming air does not bypass the filter fleece 2, the prefilter housing has corresponding baffle lines. For example, the cross-section of the prefilter housing 1 in the pre-filter element 2 can be narrowed so that only a minimal air flow does not pass through the filter web 7. For this purpose, for example, flexible, elastic closures can be pressed onto the filter web, e.g. According to another embodiment, they comprise co-rotating rollers or the like to minimize friction. Preferably, the filter web 7 is washable and thus reusable. This allows an extension of the shelf life of such a filter web 7. However, the service life of the pre-filter element 2 depends essentially on the rotation speed and the solids content.

The main field of application concerns air filtration with oil and emulsion mist particles. Due to the achievable high degree of separation, the downstream fine filter is less loaded. This greatly extends its service life. Due to the built-in filter fleece, the electrostatic separation principle can be dispensed with. Even highly conductive mixtures can be aspirated and filtered. Due to the absence of the electrostatic separation principle, it is possible to remove the electrostatic separation principle. n No ozone layer is formed. This also eliminates the corresponding ozone extraction device. As a result, the pre-filter element is variably usable, for example, for multiple suction points for which a single central pre-filtration can serve. Furthermore, the use of a filter fleece in the form of a closed endless hose is possible, in view of the efficient filtration due to the distribution of the filter fleece, in both the pre-filter and post-treatment filter unit.

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Claims (14)

PATENT CLAIMS Pre-filter element (2), in particular for use upstream of a fine filter, wherein the pre-filter element (2) comprises a filter fleece (7), characterized in that the filter fleece (7) is closed in an endless configuration and is in the pre-filter element (2) arranged for rotating through the cross-section of the pre-filter element (2). Pre-filter element (2) according to claim 1, characterized in that the filter web (7) forms an endless loop which is tensioned at least around the first (6) and second (5) return devices. Pre-filter element (2) according to claim 1 or 2, characterized in that the first return device (6) is a drive for rotating the filter web (7) over the cross-section of the pre-filter element (2). Pre-filter element (2) according to claim 1, 2 or 3, characterized in that the first (6) and second (7) return devices are movable relative to each other and lockable at a distance from one another. Pre-filter element (2) according to the preceding claims, characterized in that the pre-filter element (2) has a compression of the filter web (7). also with some by making the device for Pre-filter element (2) according to claim 5, characterized in that the device is arranged at least -11 • · • ft • ft • ft ft · ft ft • · • • · · « • · • ft · ft · • · • ftft • · ♦ ft ♦ ft near the return point of the filter web (7), particularly with respect to the gravity of the lower return point. Pre-filter element (2) according to claim 5 or 6, characterized in that the device comprises at least a first and / or a second return device (5, 6) and one pressure means (8), the pressure means (8), in particular The pressure roller is arranged against the first and / or second to compress the filter web (7). a return device (5, 6). Pre-filter element (2) according to claim 7, characterized in that the pressing means (8) is movable, in particular pivotable, in the pressing position. Pre-filter element (2) according to claim 7 or 8, characterized in that the pressing means (8) is arranged adjacent the lower return point on the side on which the filter web (7) moves again to the upper return point. Pre-filter element (2) according to one of the preceding claims, characterized in that the pre-filter element (2) has at least one first upstream filter stage (3). Pre-filter element (2) according to claim 10, characterized in that the first filtration stage (3) is a vortex separator. Pre-filter element (2) according to one of the preceding claims, characterized in that it has at least one subsequent filter (4). 13. Filter fleece (7) for use in pre-filtration ·· -12 » φ ♦ · · prvku prvku prvku prvku prvku prvku prvku prvku prvku prvku prvku »» prvku prvku prvku prvku »» »prvku prvku prvku prvku according to one of claims 1 to 12, wherein the filter web (7) is gas permeable and elastic, characterized in that the filter web (7) forms an endless closed loop. Filter web according to claim 13, characterized in that the filter web (7) is washable and reusable.