WO2010149228A1

WO2010149228A1 - Filter unit

Info

Publication number: WO2010149228A1
Application number: PCT/EP2009/058069
Authority: WO
Inventors: Erik Lans
Original assignee: Camfil AB
Current assignee: Camfil AB
Priority date: 2009-06-26
Filing date: 2009-06-26
Publication date: 2010-12-29
Anticipated expiration: 2011-12-26

Abstract

It is disclosed a filter unit having a filter element comprising filter media connected to a mounting frame that is receivable in a holding frame. The filter unit may be arranged such as to among other things enable effectuation of a releasable coupling between the mounting frame and the holding frame by means of a snapping action.

Description

FILTER UNIT

Technical field

The present invention generally relates to separation of contaminants from a gaseous flow. In particular, the present invention relates to a filter unit comprising a filter element and a holding frame for receiving the filter element.

Background Inlet filter systems, typically for filtering air taken from the atmosphere, are generally utilized in power generating systems such as gas turbine systems. Inlet filter systems are also known to be utilized in other applications, such as air pollution control, manufacturing process dust collection, air ventilation in buildings, etc. In order to maintain the performance of power generating systems or machines used in other applications utilizing filter inlet system and/or keep the need for maintenance of the power generating system or machines used in other applications utilizing filter inlet system, the inlet filter system should be kept in such condition so as to be capable of providing efficient separation of pollutants or contaminants from the inlet flow. As filters used in inlet filter systems generally have a limited holding capacity of pollutants or contaminants, filters in inlet filter systems generally need to be replaced at regular intervals.

Filters in inlet filter systems are generally provided in so called filter banks comprising a plurality of filter units. Filter units comprising a holding frame and a filter element comprising a mounting frame and a filter, which mounting frame may be received and held within the holding frame, are known. However, known solutions for connecting, fixing, and/or replacing the filter elements in the filter units are in general time-consuming and/or complicated to perform. Additionally, such known solutions are in general associated with a significant risk of damage to the filter media in the filter that may occur for example during the process of connecting the mounting frame within the holding frame and/or releasing the mounting frame from the holding frame. Summary

It is with respect to the above considerations and others that the present invention has been made. In particular, the inventor has realized that it would be desirable to achieve a filter unit having a filter element comprising filter media connected to a mounting frame that is receivable in a holding frame, which filter unit is arranged such as to among other things enable effectuating a releasable coupling between the mounting frame and the holding frame by means of a snapping action. In this manner, the filter may easily and quickly be replaced by means of a few manipulations without the need for specialized tools and/or fixing devices.

To better address one or more of these concerns, a filter unit having the features defined in the independent claim is provided. Further advantageous embodiments of the present invention are defined in the dependent claims.

According to a first aspect of the present invention, there is provided a filter unit for separation of contaminants from a gaseous flow. The filter unit comprises a filter element, comprising a mounting frame and filter media connected to the mounting frame, and a holding frame for receiving the mounting frame. The filter unit further comprises a coupling mechanism for releasably coupling the mounting frame and the holding frame to each other. The coupling mechanism comprises at least one coupling element, comprising a resilient member arranged on one of the holding frame and the mounting frame. The resilient member comprises an engaging end for engaging at least one corresponding first receiving surface portion on the other frame (i.e. the frame on which the resilient member is not arranged). The engaging end engaged with the first receiving surface portion by a snapping action such that a releasable coupling between the mounting frame and the holding frame is obtained, such that movement of the mounting frame in at least one longitudinal direction is impeded.

By such a filter unit, the filter element of the filter unit may be installed or replaced into a position received by the holding frame for performing the operation of separation of contaminants, e.g. comprising solid material, from a gaseous flow. By the resiliency of the resilient member(s), the installation, removing or replacing action may be performed in a quick and easy manner by means of a few manipulations that may be performed by hand without the need for specialized tools and/or fixing devices. In this manner, maintenance of filter systems comprising such filter units may be facilitated. Consequently, costs for maintenance may be reduced.

Furthermore, such a configuration may reduce or eliminate the risk of damaging the filter element, e.g. the filter media, on installation of a filter element or on replacement of filter elements, compared to known solutions for coupling the mounting frame and the holding frame to each other and/or releasing the mounting frame and the holding frame from each other.

The filter media comprised in the filter element may be of various types, such as microfiber glass media, blends of cotton and polyester, synthetic fibres, etc. The selection of type of filter media may be made on the basis of user needs and/or capacity requirements.

The resilient member may be arranged on the holding frame and the at least one first receiving surface portion may be provided on the mounting frame, or vice versa.

The resilient member of the coupling element may for example be integral with the coupling element. One or more resilient members may alternatively or optionally be fixedly arranged on respective coupling elements. The mounting frame may be received within the holding frame, or be received such that, once received, the inner sides of the mounting frame faces the outer side(s) of the holding frame.

The mounting frame, once received by the holding frame, may be closely coupled to (e.g., abutting against), e.g., side surfaces of the holding frame. Alternatively or optionally, at least portions of the mounting frame, once received by the holding frame, may be loosely coupled to, e.g., side surfaces of the holding frame (e.g. allowing for a predetermined amount of play between the at least portions of the mounting frame and the holding frame). This may enable other components to be positioned in between the mounting frame and the holding frame, such as a gasket.

One or more resilient members may for example be wholly or partly constituted by a plate spring member or the like and/or an appropriately bent piece of metal plate, as described further in the following.

The first receiving surface portion may be located directly or indirectly on a surface of the frame that the first receiving surface is provided on. By indirectly located it means that one or more intermediate components may be arranged between the first receiving surface portion and the frame that the first receiving surface is provided on (thus the first receiving surface portion may not necessarily be integral with the frame that the first receiving surface is provided on). The first receiving surface portion may constitute a portion the frame surface. The cross section of the mounting frame may for example be at least partially square-shaped or rectangularly shaped. Alternatively or optionally, at least portions of the mounting frame may comprise cross sections having arbitrary shapes or shapes chosen on the basis of user needs and/or capacity requirements (e.g. on the basis of the desired or required mechanical strength and/or stability of the mounting frame).

Similarly, the cross section of the holding frame may for example be at least partially square-shaped or rectangularly shaped. Alternatively or optionally, at least portions of the holding frame may comprise cross sections having arbitrary shapes or shapes chosen on the basis of user needs and/or capacity requirements (e.g. on the basis of the desired or required mechanical strength and/or stability of the holding frame).

The coupling mechanism may comprise any number of coupling elements, for example arranged on one of the mounting frame and the holding frame at predetermined coupling positions. The choice of the coupling positions may be made on the basis of, e.g., application requirements.

The coupling elements may extend a short or a long distance along a frame, have an extension substantially along a whole side of a frame, half the length of a frame side, or any other suitable fraction of a frame side length. In the context of at least some embodiments of the present invention, by "snapping action" it is referred to a sudden motion of, e.g., a resilient element caused by build-up of a force applied to the resilient element over a period of time to a predetermined level (e.g., a "critical" level), which sudden motion causes the resilient element to engage with a receiving member. An examples of a coupling mechanism involving snapping action is a ratchet and pawl combination.

The coupling mechanism may also comprise other elements in addition to the described coupling element. For example, the coupling mechanism can comprise fhctionally engaging elements or stop elements. These elements may for example be arranged at one side and the snapping coupling elements at an opposite side of the frames. Then, when the holding frame is to be coupled to the mounting frame, the holding frame can be brought into engagement with the additional coupling elements at one side and thereafter tilted into snapping engagement with the coupling element.

According to a second aspect of the present invention, there is provided a filter bank comprising a plurality of filter units according to the first aspect of the present invention or any embodiment thereof, the plurality of filters being arranged in an array configuration.

According to a third aspect of the present invention, there is provided a coupling element, comprising a resilient member having an engaging end, for use in a filter unit according to the first aspect of the present invention or any embodiment thereof.

According to a fourth aspect of the present invention, there is provided an actuator for use in a filter unit according to an embodiment of the present invention.

According to an exemplifying embodiment of the present invention, the mounting frame and the holding frame may be releasably coupled to each other by pushing the mounting frame longitudinally towards the holding frame, wherein the first receiving surface portion travels (or slides) past the resilient member until the engaging end is brought into engagement with the at least one first receiving surface portion by the snapping action. In this manner, a user (e.g. maintenance and/or installation personnel, filter unit manufacturer personnel) may in a relatively easy and intuitive manner install or replace the filter unit, e.g. in a filter bank.

For example, the resilient member (or a surface portion thereof) may be slidingly engageable with the frame on which the first receiving surface portion is provided.

The engagement between the engaging end and the first receiving surface portion may be such that there is a predetermined amount of play between the engaging end and the first receiving surface portion, or such that the engaging end substantially abuts against the first receiving surface portion.

The resilient member may be arranged such that the engaging end is biased towards the at least one first receiving surface portion. In this manner, the coupling between the holding frame and the mounting frame may be effectuated in an increasingly sealingly manner. This may further improve the capacity of the filter unit, in particular the coupling between the mounting frame and the holding frame, to handle (i.e. to cope with without suffering from mechanical damage) relatively large forces acting on the filter unit. Such forces may for example be caused by a strong flow of gaseous medium, e.g. air or any other gas, that is flowing through the filter medium.

The amount of the bias may be selected according to user needs and/or capacity or application requirements. In other words, the resilient member may be arranged such that the engaging end is biased towards the at least one first receiving surface portion with a bias sufficient for user, capacity and/or application requirements.

According to an exemplifying embodiment of the present invention, the resilient member may further comprise an abutment surface portion for abutting against at least one corresponding second receiving surface portion on the other frame for further impeding movement of the mounting frame in at least one lateral direction. According to at least one example embodiment of the invention, coupling elements are arranged in positions around the frame in question such that lateral movements are impeded in all lateral directions. In other words, the mounting frame may in general be locked against motion in both lateral and longitudinal directions. For example, by such a configuration a more sealingly coupling between the mounting frame and the holding frame may be achieved.

In this manner, the coupling mechanism between the holding frame and the mounting frame may be arranged such that the mounting frame is substantially immovable once it has been received by the holding frame (i.e. when it is in the mounted position). In this manner, (relatively large) lateral movements of the mounting frame may be mitigated or avoided, whereby the risk for damage to the filter media, in case a portion of the mounting frame laterally slips past the second surface portion, at which the second surface portion may be caused to be brought into engagement with the filter media, may be reduced or eliminated.

In view of the above, by a configuration in accordance with the embodiment described immediately above, there may be no preferred orientation of the filter unit in a filter bank, or the filter element in the filter unit, with regards to which side of the filter unit or the filter element, respectively, that should be on the downstream side (or upstream side) with regards to the direction of the flow of gaseous medium, i.e. air or some other gas, through the filter unit. In other words, the filter unit may arranged in a filter bank with a certain side of the filter unit oriented in either of the downstream and the upstream direction, or the filter element (i.e. the mounting frame) may be received by the holding frame such that the filter element is arranged with a certain side of the filter element oriented in either of the downstream and the upstream direction. In particular, the strength of the engaging end can be combined with a sufficient bias of the resilient member, such that holding frame is secureably held in a coupled position in the mounting frame also when forced against the biased engaging end by forces from a flow of gas through the filter unit. This can be supported by arranging the coupling element to impede also lateral movements as described above, minimizing the risk of disengagement of the coupling element due to lateral movement. The second receiving surface portion may be located directly or indirectly on a front (or back) surface of the frame that the second receiving surface is provided on, or in other words, constitute a surface portion of the frame in question. By indirectly located it means that one or more intermediate components may be arranged between the second receiving surface portion and the frame that the second receiving surface is provided on (thus the second receiving surface portion may not necessarily be integral with the frame that the second receiving surface is provided on). The second surface portion may also or alternatively be provided on a protruding flange or there may be several second receiving portions located on a respective flange portion. The resilient member may be arranged such that the abutment portion is biased against the at least one second receiving surface portion. In this manner, the coupling between the holding frame and the mounting frame may be effectuated in an increasingly sealingly manner. This may further improve the capacity of the filter unit, in particular the coupling between the mounting frame and the holding frame, to handle (i.e. to cope with without suffering from mechanical damage) relatively large forces acting on the filter unit. Such forces may for example be caused by a strong flow of gaseous medium, e.g. air or any other gas, that is flowing through the filter medium.

The amount of the bias may be selected according to user needs and/or capacity or application requirements. In other words, the resilient member may be arranged such that the abutment portion is biased towards the at least one second receiving surface portion with a bias sufficient for user, capacity and/or application requirements.

In the context of some embodiments of the present invention, by "longitudinal direction" it is referred to a direction that is parallel to the normal of a surface portion of the filter media, or in other words, generally along a downstream or upstream direction of with regards to the direction of the flow of gaseous medium, i.e. air or some other gas, through the filter unit.

In the context of some embodiments of the present invention, by "lateral direction" it is referred to a direction that is generally perpendicular to a longitudinal direction.

According to an exemplifying embodiment of the present invention, the mounting frame may be receivable within the holding frame. Such a configuration may for example increase the mechanical strength of the frame arrangement of the filter unit. As discussed above, the mounting frame, once received by the holding frame, may be closely coupled to (e.g., abutting against), e.g., side surfaces of the holding frame. Alternatively or optionally, at least portions of the mounting frame, once received by the holding frame, may be relatively loosely coupled to, e.g., side surfaces of the holding frame (e.g. allowing for a predetermined amount of play between the at least portions of the mounting frame and the holding frame).

The at least one coupling element may for example be mounted within the holding frame.

The resilient member may be arranged on the holding frame, and the at least one first receiving surface portion may be provided on the mounting frame. For example, according to an exemplifying configuration the mounting frame may at least partially comprise a square or rectangular cross section and the first receiving surface portion may be located on a front surface of the mounting frame. Alternatively or optionally, the mounting frame may at least partially comprise a square or rectangular cross section and the second receiving surface portion may be located on a side surface of the mounting frame.

Such configurations as described immediately in the foregoing may for example increase the mechanical strength of the mounting frame. As discussed above, alternatively or optionally, at least portions of the mounting frame/holding frame may comprise cross sections having arbitrary shapes or shapes chosen on the basis of user needs and/or capacity requirements (e.g. on the basis of the desired or required mechanical strength and/or stability of the mounting frame/holding frame). According to yet another exemplifying embodiment of the present invention, the holding frame may comprise at least one projection for receiving the mounting frame (thereon). The resilient member may be arranged such that the mounting frame is biased against the at least one projection in at least one longitudinal direction such that the mounting frame is locked between the engaging end and the at least one projection. Such a configuration may facilitate mounting of the mounting frame (e.g., the process of receiving the mounting frame) on, or within, the holding frame in that the mounting frame may be at least partly supported on the one or more projections in its mounted (received) position. In this manner, the mechanical strength and/or stability of the frame arrangement of the filter unit may be increased. The amount of the bias may be selected according to user needs and/or capacity or application requirements. In other words, the resilient member may be arranged such that the resilient member provides the mounting frame with a bias against the at least one projection sufficient for user, capacity and/or application requirements. The biasing force may be provided by the resilient member biasing against the first receiving surface portion.

The at least one projection may comprise at least one flange, or rim or flange-like projection, integrally arranged with the holding frame such that the holding frame comprises an at least partially L-shaped cross section. In this manner, there may be achieved a holding frame comprising at least one projection for receiving the mounting frame that can relatively easily be manufactured (e.g. by welding together a number of bended plates or the like such as to form the holding frame having a projection for receiving the mounting frame. Such a configuration may provide a relatively high mechanical strength to the holding frame of the filter unit. The projection, or flange, need not necessarily be integral with the holding frame, but can rather be constituted by a suitable member coupled to the holding frame, for example such that the mounting frame coupled to the projection, or vice versa, comprises an at least partially L-shaped cross section. The resilient member may for example be constituted by a ribbon, or strip, of metal that has been bent in such a way as to form the geometrical configuration of the resilient member. The resilient member may for example comprise a suitably arranged (e.g. bent) leaf spring member (also known as plate spring member). The at least one coupling element may be integrally formed from a plate-shaped element. In this manner, a coupling element to be used in the filter unit according to the embodiment may be manufactured in a relatively easy and cost-effective manner. Such a coupling element may provide a relatively high mechanical strength. In turn, the coupling between the holding frame and the mounting frame may be strengthened.

For example, the resilient member may be constituted by a plate spring member formed from a portion of the plate-shaped element and/or the enaging end of the resilient member may be constituted by an abutment member, or stopping member, that may be formed by suitably bending a portion of the plate-shaped element.

By such configurations, there may be provided an improved flexibility and adaptability with regards to user needs and/or capacity requirements. For example, the resilient member and/or the engaging end may in general be arranged such that they provide different degrees of stiffness, mechanical strength and/or resiliency.

According to an exemplifying embodiment of the present invention, the coupling mechanism may comprise a plurality of coupling elements, wherein each of the plurality of coupling elements may be arranged on one of the holding frame and the mounting frame at predetermined coupling positions.

According to an exemplifying embodiment of the present invention, the filter unit may comprise a gasket, sandwiched between the mounting frame and the holding frame, for inhibiting passage of liquid medium between the holding frame and the mounting frame.

The gasket may for example be coupled to the at least one projection, or flange, or rim.

The resilient member of the coupling element may be biased in at least one longitudinal direction such that coupling between the mounting frame and the holding frame causes the gasket to be compressed at least a predetermined distance in the at least one longitudinal direction. In this manner, a varying degree of sealing between the mounting frame and the holding frame may be achieved. The amount of bias, and thus the degree of sealing, may be chosen on the basis of user, capacity and/or application requirements. In some applications, the bias may for example be set such that the predetermined distance may be about 3 mm.

According to another exemplifying embodiment of the present invention, the filter unit may comprise an actuator. The holding frame may comprise at least one through-hole for slidingly receiving the actuator therein. The actuator may comprise an actuation end and an engaging end for engaging a receiving surface portion of the mounting frame. The actuator may be arranged such that when a force is applied to the actuation end at least a portion of the mounting frame may be caused to be displaced. In this manner, release of the coupling between the holding frame and the mounting frame may be facilitated. Thus, a portion of the holding frame within a through-hole may be used as a point, or pivot, about which the actuator turns at the application of a force on the actuation end of the actuator receivable within the through-hole. The actuator may for example comprise an elongate, rigid member such as a metal bar. Other types of actuators are possible. In this manner, a user may even easier and/or quicker replace a filter element in a filter unit.

The present invention is not limited to a coupling mechanism comprising one or more coupling elements as have been described in the foregoing, but rather encompasses embodiments wherein the coupling mechanism alternatively or optionally comprises one or more coupling components or elements different from the coupling element that has been described in the foregoing, or a combination of the coupling element described in the foregoing and some other type(s) of coupling component or element. For example, the filter unit may comprise an abutment member provided on one of the mounting frame and the holding frame at a location on the filter unit for receiving an end of the other frame such that longitudinal motion of that end is impeded, while coupling between the mounting frame and the holding frame is effectuated at one or more other locations on the filter unit by means of one or more coupling elements such as have been described in the foregoing. Further objects and advantages of the present invention are described in the following by means of exemplifying embodiments.

Brief discussion of the drawings Exemplifying embodiments of the invention will be described below with reference to the accompanying drawings, in which:

Fig. 1 is a schematic perspective view of a filter element in accordance with an exemplifying embodiment of the present invention;

Fig. 2 is a schematic perspective view of a filter unit according to an exemplifying embodiment of the present invention;

Fig. 3 is a schematic perspective view of a portion of a holding frame in accordance with an exemplifying embodiment of the present invention; Fig. 4 is a schematic perspective view of a portion of a filter unit in accordance with an exemplifying embodiment of the present invention;

Fig. 5A is a schematic side view of a coupling element in accordance with an exemplifying embodiment of the present invention; Fig. 5B is a schematic perspective view of the coupling element shown in Fig. 5A;

Fig. 6A is a schematic perspective view of a holding frame in accordance with an exemplifying embodiment of the present invention;

Fig. 6B is a schematic perspective view of an actuator according to an exemplifying embodiment of the present invention; and

Fig. 7 is a schematic block diagram of a filter bank according to an exemplifying embodiment of the present invention.

In the accompanying drawings, the same reference numerals denote the same or similar elements throughout the views.

Description of exemplifying embodiments

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplifying embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and fully convey the scope of the invention to those skilled in the art. Furthermore, like numbers refer to like or similar elements or components throughout.

Referring now to Fig. 1 , there is shown a schematic perspective view of a filter element 100 in accordance with an exemplifying embodiment of the present invention. The filter element 100 comprises a mounting frame 101 comprising four peripheral mounting frame portions 101a, 101 b, 101 c, 101d forming a rectangular frame structure.

Although the embodiment depicted in Fig. 1 comprises a mounting frame having a rectangular outline, the form of the mounting frame (and the form of the holding frame [not shown in Fig. 1 , see Figs. 2-4] as described in detail in the following) may have any shape, e.g. polygonal, circular, etc., according to different embodiments of the present invention The particular shape may be adapted to user needs and/or application requirements (e.g. the installation space where the filter unit is to be installed). It follows that the mounting frame may comprise an in general arbitrary number of interconnected peripheral mounting frame portions depending on the particular shape of the mounting frame. Such mounting frame portions may for example be welded together such as to interconnect them. According to the embodiment depicted in Fig. 1 , the filter element comprises a plurality of filter pockets 102 (of which only some are indicated by reference numerals in Fig. 1 ) having openings 103 (of which only some are indicated by reference numerals in Fig. 1 ), which may admit gaseous flow that is to be passed through the filter unit. The filter pockets 102 may be made of any suitable filter media 104, such as microfiber glass media, blends of cotton and polyester, synthetic fibres, etc. The selection of type of filter media may be made on the basis of user needs and/or capacity requirements. The filter media connected to the mounting frame may not necessarily be shaped as filter pockets - Fig. 1 is only by way of example. The present invention rather encompasses embodiments comprising filter media connected to the mounting frame shaped in various ways according to user needs and/or capacity requirements.

Referring now to Fig. 2, there is shown a schematic perspective view of a filter unit 200 according to an exemplifying embodiment of the present invention. The filter unit 200 comprises a filter element 201 , similar to and having similar function as the filter element 100 described with reference to Fig. 1. The filter element 201 is shown from a view that is rotated with respect to the view of the filter element 100 described with reference to Fig. 1. The filter unit 200 further comprises a holding frame 202, comprising four peripheral holding frame portions 202a, 202b, 202c, 202d forming a rectangular frame structure, for receiving the mounting frame 203 of the filter element 201.

The filter element 201 and the holding frame 202 are shown in a non- coupled state, i.e. a state in which no (releasable) coupling between the mounting frame 203 of the filter element 201 and the holding frame 202 has been effectuated. The holding frame 202 further comprises a coupling mechanism, generally referenced by the reference numeral 204, for releasably coupling the mounting frame 203 and the holding frame 202 to each other. The coupling mechanism 204 may comprise at least one coupling element 205 (schematically drawn in Fig. 2) for effectuating the releasable coupling between the mounting frame 203 and the holding frame 202. Such coupling elements are further described in the following with reference to Figs. 3, 4, 5A and 5B.

With further reference to Fig. 2, the holding frame may comprise a projection, for example constituted by a flange 206, for receiving the mounting frame 203.

Referring now to Fig. 3, there is shown a schematic perspective view of a portion of a holding frame 300 in accordance with an exemplifying embodiment of the present invention. As depicted in Fig. 3, the holding frame 300 may comprise a projection, for example a flange 301 , for receiving a mounting frame (not shown in Fig. 3, see Figs. 1 , 2 and 4) comprising filter media connected to the mounting frame. In this manner, the holding frame 300 may exhibit one or more portions having an L-shaped cross section, as illustrated in Fig. 3.

The portion of the holding frame 300 shown in Fig. 3 comprises a coupling element 302 that may be fixedly connected to the holding frame 300 by means of connection elements such as screws 303 or the like. Alternatively or optionally, the coupling element may be connected to the holding frame by means of a punching or the like (not shown in Fig. 3) punched in the holding frame, where the punching or alike cooperates with a hole or recession in the coupling element such as to connect the coupling element to the holding frame.

Such as indicated in Fig. 3, the portions having an L-shaped cross section may be arranged such that the flange 301 is pointing in a direction generally towards a portion of the holding frame (in other words, pointing at a location within the holding frame). Alternatively or optionally, one or more projections may be arranged such that they point or is aligned in a direction generally away from the holding frame.

With further reference to Fig. 3, the coupling element 302 may comprise a resilient member 304 comprising an engaging end 304a for engaging at least one corresponding first receiving surface portion (cf. Fig. 4) on the mounting frame (not shown in Fig. 3). The engaging end 304a may engage with the at least one first receiving surface portion by a snapping action for releasably coupling the mounting frame and the holding frame 300. The resilient member 304 may comprise an abutment portion 304b for abutting against at least one corresponding second receiving surface portion (cf. Fig. 4) on the mounting frame for further impeding movement of the mounting frame in at least one lateral direction. With further reference to Fig. 3, the mounting frame and the holding frame 300 may be releasably coupled to each other by pushing the mounting frame longitudinally towards the holding frame 300, wherein the first receiving surface portion travels (or slides) past the resilient member 304 until the engaging end 304a is brought into engagement with the at least one first receiving surface portion by the snapping action. In other words, the first receiving surface portion may travel or slide past the resilient member 304, which may cause a gradual build-up of an elastic force on the resilient member 304, which elastic force, once the first receiving surface portion has travelled past the resilient member 304 or past some predetermined portion of the resilient member 304, causes the engaging end 304a of the resilient member 304 to "snap" into engagement with the first receiving surface portion. This is further clarified with reference to Fig. 4 in the following description. The filter unit may comprise a gasket for inhibiting passage of liquid medium between the mounting frame and the holding frame. Such a gasket may for example be sandwiched between the mounting frame and the holding frame. With further reference to Fig. 3, such a gasket 306 may for example be arranged on at least a portion of the projection (flange) 301. Referring now to Fig. 4, there is shown a schematic perspective view of a portion of a filter unit 400 in accordance with an exemplifying embodiment of the present invention. The elements and components depicted in Fig. 4 are similar or identical to and have functions similar or identical to the elements and components depicted in Fig. 3. The filter unit 400 comprises a holding frame 401 within which a mounting frame 402 has been received. Filter media (not shown in Fig. 4, see Figs. 1 and 2) may be connected to the mounting frame 402, for example for separation of contaminants from a gaseous flow that is directed through the filter unit 400. The gaseous flow may for example comprise air. In general, the gaseous medium can comprise any gas, depending on application.

With further reference to Fig. 4, the depicted portion of the holding frame 401 comprises a coupling element 403 that may comprise a resilient member 404 having an engaging end 404a for engaging at least one corresponding first receiving surface portion 402a on the mounting frame 402. The engaging end 404a engage with the at least one first receiving surface portion 402a by a snapping action for releasably coupling the mounting frame 402 and the holding frame 401 to each other such that movement of the mounting frame 402 in at least one longitudinal direction is impeded. The resilient member 404 may comprise an abutment portion 404b for abutting against at least one corresponding second receiving surface portion 402b on the mounting frame 402 for further impeding movement of the mounting frame 402 in at least one lateral direction. The abutment portion 404b is not necessary, but advantageous.

As the skilled person realizes by the foregoing description, by one or more of such coupling elements the mounting frame 402 and the holding frame 401 may thus be coupled together via a snapping action. Contrary to the configurations depicted in Figs. 3 and 4, a coupling element may alternatively or optionally comprise one or more resilient members that are arranged on the mounting frame, wherein each resilient member has an engaging end for engaging at least one corresponding receiving surface portion on the holding frame. Referring now to Fig. 5A, there is shown is a schematic side view of a coupling element 500 in accordance with an exemplifying embodiment of the present invention, which coupling element 500 may be comprised in the coupling mechanism (cf. Fig. 2) for releasably coupling the mounting frame and the holding frame together (neither the holding frame nor the mounting frame is shown in Fig. 5A) by a snapping action. The coupling element 500 comprises a resilient member 501. The resilient member 501 comprises an engaging end 501 a for engaging at least one corresponding first receiving surface portion (cf. Fig. 4) on the other frame by a snapping action, when mounted on one of the frames. When the coupling element is mounted and operated, the first receiving surface portion cooperates with the engaging end 501 a such that a releasable coupling between the mounting frame and the holding frame may be obtained, wherein movement of the mounting frame in at least one longitudinal direction is impeded.

With further reference to Fig. 5A, the coupling element 500 may comprise a connecting portion 503 arranged for enabling connection of the coupling element 500 to one of the mounting frame and the holding frame. For this purpose, the connecting portion 503 may be provided with circular through-holes 503a for receiving connection elements such as screws or the like (not shown in Fig. 5A). Alternatively or optionally, the connecting portion 503 may be provided with a hole 503b or recession (not shown) in the coupling element 500 that may cooperate with a punching or the like provided in one of the mounting frame and the holding frame, such as to connect the coupling element 500 with the mounting frame or the holding frame, respectively.

The connecting portion 503 may be integral with the resilient member 501 or a separate part fixed to the resilient member 501. With further reference to Fig. 5A, the resilient member 501 may comprise a second engaging end 501 c that may be arranged on, or be coupled to directly or via some other component(s), a cooperating third receiving surface portion (not shown in Fig. 5A) of one of the mounting frame and the holding frame. By such a configuration the mechanical strength and/or stability of the coupling element 500 may be further improved. The second engaging end 501 c may abut against a cooperating receiving surface portion.

Referring now to Fig. 5BA, there is shown a schematic perspective view of the coupling element 500 shown in Fig. 5A. The same reference numerals denote the same or similar elements or components, which have same or similar functions, throughout Figs. 5A and 5B.

Referring now to Fig. 6A, there is shown a schematic perspective view of a holding frame 600 in accordance with an exemplifying embodiment of the present invention. The holding frame 600 may comprise four peripheral holding frame portions 600a, 600b, 600c, 60Od forming a rectangular frame structure, for receiving the mounting frame of a filter element (not shown in Fig. 6A), such as has been described in the foregoing. The holding frame 600 may comprise a projection, for example a flange 601 , for receiving the mounting frame. The holding frame 600 may comprise at least one through- hole 602 for slidingly receiving an actuator therein (see Fig. 6B and the following description referring thereto).

Referring now to Fig. 6B, there is shown a schematic perspective view of an actuator 603 according to an exemplifying embodiment of the present invention. The actuator 603 comprises an actuation end 604 and an engaging end 605 for engaging a receiving surface portion of the mounting frame (not shown in Fig. 6B). The actuator 603 may be arranged such that a force applied to the actuation end 604 causes at least a portion of the mounting frame to be displaced, whereby release of the coupling between the holding frame 600 and the mounting frame may be facilitated. Referring now to Fig. 7, there is shown a schematic block diagram of a filter bank 700 according to an exemplifying embodiment of the present invention, comprising a plurality of filter units 701 according to an exemplifying embodiment of the present invention such as have been described herein.

Although the features, components and elements of embodiments of the present invention have been described in the foregoing description by means of exemplifying embodiments in particular combinations, each feature, component or element can be used alone (without the other features, components and elements of the exemplifying embodiments) or in various combinations with or without other features, components and elements of embodiments of the present invention. While the invention has been illustrated and described in detail in the appended drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplifying and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A filter unit (200; 400; 701 ) for separation of contaminations from a gaseous flow, the filter unit comprising: a filter element (100; 201 ) comprising a mounting frame (101 ; 203; 402) and filter media connected to the mounting frame; a holding frame (202; 300; 401 ; 600) for receiving the mounting frame; and a coupling mechanism (204) for releasably coupling the mounting frame and the holding frame to each other; wherein the coupling mechanism comprises at least one coupling element (205; 302; 403; 500), comprising a resilient member (304; 404; 501 ) arranged on one of the holding frame and the mounting frame, the resilient member comprising an engaging end (304a; 404a; 501a) for engaging at least one corresponding first receiving surface portion (402a) on the other frame, and wherein the engaging end engages with the at least one first receiving surface portion by a snapping action for releasably coupling the mounting frame and the holding frame to each other such that movement of the mounting frame in at least one longitudinal direction is impeded.

2. A filter unit according to claim 1 , wherein the coupling mechanism is such arranged that, when the mounting frame is pushed longitudinally towards the holding frame, the first receiving surface portion travels past the resilient member until the engaging end is brought into engagement with the at least one first receiving surface portion by the snapping action.

3. A filter unit according to claim 1 or 2, wherein the resilient member is arranged such that the engaging end is biased towards the at least one first receiving surface portion.

4. A filter unit according to any one of the preceding claims, wherein the resilient member further comprises an abutment portion (304b; 404b) for abutting against at least one corresponding second receiving surface portion (402b) on the other frame for further impeding movement of the mounting frame in at least one lateral direction.

5. A filter unit according to claim 4, wherein the resilient member is arranged such that the abutment portion is biased against the at least one second receiving surface portion.

6. A filter unit according to any one of the preceding claims, wherein the mounting frame is receivable within the holding frame.

7. A filter unit according to claim 6, wherein the at least one coupling element is mounted within the holding frame.

8. A filter unit according to claim 6 or 7, wherein said resilient member is arranged on the holding frame and the at least one first receiving surface portion is provided on the mounting frame.

9. A filter unit according to claim 8, wherein the mounting frame at least partially comprises a square or rectangular cross section and the first receiving surface portion is located on a front surface of the mounting frame.

10. A filter unit according to claim 8 as appended to claim 4 or 5, wherein the mounting frame at least partially comprises a square or rectangular cross section and the second receiving surface portion is located on a side surface of the mounting frame.

11. A filter unit according to any one of the preceding claims, wherein the holding frame comprises at least one projection (206; 301 ; 601 ) for receiving the mounting frame and wherein the resilient member is arranged such that the mounting frame is biased against the at least one projection in at least one longitudinal direction such that the mounting frame is locked between the engaging end and the at least one projection.

12. A filter unit according to claim 11 , wherein the at least one projection comprises at least one flange (206; 301 ; 601 ) integrally arranged with the holding frame such that the holding frame comprises an at least partially L-shaped cross section.

13. A filter unit according to any one of the preceding claims, wherein at least one coupling element (205; 302; 403; 500) has been integrally formed from a plate-shaped element.

14. A filter unit according to claim 13, wherein the resilient member

(304; 404; 501 ) is constituted by a plate spring member formed from a portion of the plate-shaped element and/or the engaging end of said resilient member is constituted by a abutment member formed by bending a portion of the plate-shaped element.

15. A filter unit according to any one of the preceding claims, wherein the coupling mechanism comprises a plurality of coupling elements, each of the plurality of coupling elements being arranged on one of the holding frame and the mounting frame at predetermined coupling positions.

16. A filter unit according to any one of the preceding claims, further comprising a gasket (306), wherein the gasket is sandwiched between the mounting frame and the holding frame for inhibiting passage of liquid medium between the holding frame and the mounting frame.

18. A filter unit according to claim 17, wherein the resilient member of the coupling element is biased in at least one longitudinal directionsuch that coupling between the mounting frame and the holding frame causes the gasket to be compressed at least a predetermined distance in the at least one longitudinal direction.

19. A filter unit according to any one of the preceding claims, further comprising an actuator (603), wherein the holding frame comprises at least one through-hole (602) for slidingly receiving the actuator therein, the actuator comprising an actuation end (604) and an engaging end (605) for engaging a receiving surface portion of the mounting frame, the actuator being arranged such that when a force is applied to the acutation end at least a portion of the mounting frame is displaced, thereby facilitating release of the coupling between the holding frame and the mounting frame.

20. A filter bank (700) comprising a plurality of filter units (200; 400; 701 ) according to any one of claims 1 -19 arranged in an array configuration.

21. A coupling element (205; 302; 403; 500), comprising a resilient member (304; 404; 501 ) having an engaging end (305; 405; 502), for use in a filter unit (200; 400; 701 ) according to any one of claims 1 -19.

22. An actuator (603) for use in a filter unit (200; 400; 701 ) according to claim 19.