Patent Publication Number: US-2018036746-A1

Title: Filter and Cyclone Filter System

Description:
TECHNICAL FIELD 
     The invention relates to a filter and a cyclone filter system with such a filter for removing particulate matter from a gaseous fluid such as, for instance, the intake air of a combustion engine or the interior ventilation of a cabin, in particular a motor vehicle. The filter comprises a filter element having a filter media which is arranged in a ring-shaped fashion around the longitudinal axis of the filter element and a pre-separator sleeve which seats on the filter element and which has several perforations or flow openings for the gaseous fluid. The pre-separator sleeve has at least one guide vane for the gaseous fluid which extends radially outwards from the pre-separator sleeve. 
     BACKGROUND 
     A cyclone filter system comprising a filter housing and an aforementioned filter is known from US 2015/0068169 A1. The pre-separator sleeve of the filter is provided with multiple guide vanes which are arranged in a strictly circular fashion around the pre-separator sleeve. Said guide vanes are designed to direct the gaseous fluid in a spiral or cyclone-like motion around the filter for a pre-separation of particles contained in the gaseous fluid before entering the filter media. The gaseous fluid is preferably introduced radially or tangentially to the filter and strikes the guide vanes arranged on the outer periphery of the pre-separator, whereby the gas flow preferably undergoes deflection and acceleration, which leads to the separation of coarse contaminants such as dirt and dust particles as well as water droplets from the gaseous fluid. The contaminants are thrown particularly tangentially outward and can optionally be discharged from the housing via a discharge opening. After passing through the pre-separator, the gas flow is fed to the filter element that seat is within the cylindrical pre-separator. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a filter as well as a cyclone filter system which shows a further enhanced pre-separation capability. 
     According to the invention, the filter for removing particulate matter from a gaseous fluid comprises a filter element with a filter media which is arranged in a ring-shaped fashion around the longitudinal axis thereof. The filter has a pre-separator sleeve which seats on the filter element and which has several flow openings or perforations, wherein, on an outside surface of the pre-separator sleeve, there is arranged at least one guide vane which extends radially outwards from the pre-separator sleeve and which is wound around the pre-separator sleeve in a helical fashion. Due to the helical guide vane, the gaseous fluid to be filtered can be more effectively guided as a swirling or helical flow or stream around and along the filter in the longitudinal direction thereof such that particulate matter or water droplets contained in the gaseous fluid are more efficiently separated from the gaseous fluid prior to entry of the filter. This results in a considerable improvement in filter life. Further, the filter according to the invention does not require an increased mounting space and can be readily used in filter housings of existing cyclone filter systems. The pre-separator sleeve may contact the filter media of the filter element in a radial direction or may be spaced from the filter media in a radial direction. The pre-separator sleeve, preferably, has an axial length that corresponds to or essentially corresponds to the length of the filter element, particularly a shorter length. Preferably, the helical guide vane shows no interruptions such as gaps, holes, dents, recesses or the like. 
     According to a preferred embodiment of the invention, the pre-separator sleeve has a non-perforated first end portion. The said non-perforated end portion thus has no flow openings located in the wall of the sleeve and can serve as a reception zone or baffle for the gaseous fluid that is fed to the filter during use to prevent the fluid from a direct entry into the filter prior to a cyclonic pre-separation of contaminants in the gaseous fluid. The gaseous fluid stream can thereby be more effectively forced in a spiral direction around the filter to form a cyclone flow under guidance of the sleeve&#39;s helical vane. 
     During operation of the filter, a circulating flow of the gaseous fluid in a circumferential direction around the filter, in other words a continuous looping of the gaseous fluid, in particular in the region of the abovementioned non-perforated end portion of the pre-separator sleeve, needs to be prevented for an efficacious pre-separation of coarse contaminants prior to filtration of the gaseous fluid. The non-perforated end portion of the pre-separator sleeve may, therefore, have a flow locking means which serves to prevent such an unwanted recurrent travel of the gaseous fluid in a tight circle around the filter. The flow-locking means, according to a preferred embodiment of the invention, is formed by a branch of the guide vane in the non-perforated end portion of the sleeve. The branch preferably has an arcuate form and runs essentially in an axial direction to block an unwanted circling flow of the fluid. 
     According to a preferred embodiment of the invention, the helical guide vane extends over a major portion of the total length of the pre-separator sleeve. Thereby, the overall length of the filter can be effectively used for a cyclonic pre-separation of contaminants from the gaseous fluid. 
     The hollow pre-separation sleeve can be made of metal or sheet metal; optionally, a plastic material, particularly thermoplastic material such as PE used in the injection-molding process, can also be considered. This allows for a cost-efficient manufacture of the pre-separation sleeve with minimum wall thickness to ensure a maximum pre-separation gap between the filter and a filter housing in a radial direction. The helical vane is advantageously directly molded on the pre-separation sleeve. 
     The pre-separation sleeve, according to the invention, may have a reinforcement ring. This allows for a very low wall thickness of the pre-separation sleeve. Apart from the cost benefits associated therewith, the reinforcement ring improves the stability of the filter element, even under challenging working environments. The reinforcement ring is advantageously directly molded on the pre-separation sleeve such that no additional manufacturing steps are needed. Also, said reinforcement ring allows use of an available mounting or installation space for the filter within a filter housing for the filter element. 
     According to a preferred embodiment of the invention, the helical guide vane, in the longitudinal direction, extends to or essentially extends to a reinforcement ring of the pre-separator sleeve. The reinforcement ring may extend in a radial direction away from the pre separator sleeve at an end portion which, in an axial direction, is located opposite of the on-perforated end portion of the pre-separation sleeve. 
     According to a further embodiment of the invention, the helical vane has a base section which is connected to the pre-separator sleeve and which extends away from the pre-separator sleeve in a radial direction and an angled end section which is joined to the base section. This embodiment allows for a further acceleration of flow of the gaseous fluid and thus an improved separative capacity of the pre-separator sleeve. 
     According to a further preferred embodiment of the invention, the flow openings or perforations of the pre-separator sleeve can be covered by the helical vane in a radial direction such that the incoming fluid gas stream to be filtered can be forced to make a full turn in an axial direction before entering the filter. Thereby, the pre-separating efficiency of the filter can be even further increased. The aforesaid end portion of the guide vane is preferably arranged parallel or essentially parallel to the outer surface of the pre-separator sleeve. 
     The helical vane preferably has a radial extension which is at least 10% of the external diameter of the pre-separator sleeve. This reduces an unwanted straight axial overflow of the guide vane by the gaseous fluid. 
     The cyclone filter system according to the invention serves for removing contaminants, in particular particulate matter, from a gaseous fluid. The cyclone filter system comprises a filter housing having a fluid inlet port and a fluid outlet port and a filter as described above which is positioned inside the filter housing. 
     According to a preferred embodiment of the filter system, the fluid inlet port is arranged on a side wall of the filter housing to allow for a radial or tangential flow of the gaseous fluid to the filter. In case that the pre-separation sleeve of the filter features the aforementioned non-perforated end portion, the filter is advantageously positioned inside the filter housing such that the said end portion of the pre-separation sleeve is located next to the inlet port of the filter housing. The inlet port in this case thus leads to the non-perforated end portion of the pre-separation sleeve. 
     The outlet port of the filter housing is preferably arranged on an end face of the housing which is preferably adjacent to the fluid inlet port thereof. A flow length of the gaseous fluid within the filter housing can thereby be maximized. 
     According to a further embodiment of the cyclone filter system, the filter housing forms a dirt chamber for particulate matter separated from the gaseous fluid by the pre-separator sleeve which is arranged in the axial direction at an opposite end of the fluid outlet of the housing and which, preferably, extends in a radial direction thereof. The contaminants separated from the gaseous fluid can be thus stored to prevent an unwanted reentry of the contaminants into the gaseous fluid stream. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various other features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference numerals characterize the same or similar parts throughout the several views, and wherein: 
         FIG. 1  is a sectional view of a cyclone filter system with a filter configured in accordance with the present invention; 
         FIG. 2  is a perspective view of the filter of the filter system of  FIG. 1 ; 
         FIG. 3  is a different perspective view of the filter of  FIG. 2 ; 
         FIG. 4  is a front elevation of a pre-separator sleeve of the filter of  FIG. 2   
         FIG. 5  is a perspective view of an alternative embodiment of a pre-separator sleeve for the filter of  FIG. 1 ; 
         FIG. 6  is a perspective view of a further embodiment of a filter; and 
         FIG. 7  is a sectional view of a further embodiment of a filter system with the filter of  FIG. 6 . 
     
    
    
     DESCRIPTION OF THE DISCLOSURE 
       FIG. 1  shows a cyclone filter system  10  for cleaning a gaseous fluid  12 , i.e. the combustion air that is fed to the cylinders of a combustion engine (not shown). The filter system  10  has a filter housing  14  embodied as a cyclone that is hollow and cylindrical. The filter housing  14  has a longitudinal axis  16 , a lateral inlet port  18  over which the uncleaned gaseous fluid  12  flows radially or tangentially into the housing  14  and an axial fluid outlet port  20  located centrally at a one end  22  of the housing  14 . The filter housing  14 , preferably at its other end  24 , forms a dirt chamber  26  for particulate matter or water droplets separated from the gaseous fluid  12  which can, in particular extend in a radial direction thereof. 
     There is a filter  28  arranged inside the filter housing  14 . The filter  28  comprises a hollow cylindrical filter element  30  with a filter medium  32  arranged in a circular fashion around the longitudinal axis  34  of the filter element  30 . The filter medium  32  may be starpleated in order to maximize the effective surface area thereof. Also, the filter medium  32  may be disposed between two end plates  36 . There may be provided a grid-shaped support tube  38  for a radial support of the filter medium  32 . The filter medium  32  is flowed through radially from the outside to the inside by the gaseous fluid  12  to be filtered. 
     The filter element  30  is seated within a hollow cylindrical pre-separator sleeve  40  which, on its outside surface  42  has at least one guide vane  44  for the gaseous fluid  12  which extends from the pre-separator sleeve  40  in a radial outward direction. 
     The pre-separator sleeve  40  extends from a first end portion  46  to a second end portion  48  thereof. The first end portion  46  serves as a baffle for the gaseous fluid. The first end portion  46  is non-perforated. The non-perforated first end portion  46  is located right next to the fluid inlet port  18  of the filter housing  14  such that an inflow of the gaseous fluid  12  is fed right against the said non-perforated end portion  46 . Bordering the non-perforated end portion  46  in an axial direction, the pre-separator shows a longitudinal middle portion or segment  50  with a multitude of perforations  52 . The perforations  52  allow for a radial entry of the gaseous fluid  12  into the filter  28 . 
     The pre-separator sleeve  40  has a smaller outer diameter  54  than the inner diameter  56  of the filter housing  14 , so that an annular space  58  is formed between the wall of the housing  14  and the pre-separator sleeve  40  in which the inflowing, uncleaned gaseous fluid  12  can disperse. The pre-separator sleeve  40  is preferably made of plastic, particularly injection-molded thermoplastic plastic, or metal. The pre-separator sleeve  40  may have at least one stiffening or reinforcement ring  60  which is preferably located at the second end portion  48  located opposite the said non-perforated end portion  46 . The at least one reinforcement ring  60  extends in a radial direction away from the pre-separator sleeve  40  and allows for a minimal material thickness of said sleeve. 
     The gas entering the annular space  58  undergoes swirling supported by the guide vane  44  and undergoes deflection in a radial direction towards the inside  62  of the filter element, whereby coarse contaminants that are being carried along in the gaseous fluid, for example dirt particles or water droplets, are thrown tangentially outward and thus separated from the gaseous fluid  12  flow. 
     As the gaseous fluid  12  continues to flow, it enters the filter  28  via the perforations  52  provided in the pre-separator sleeve  40 . After passing the filter medium  32  of the filter element, the thus filtered gaseous fluid  12  is then discharged axially from the inner space  62  of the filter element  30  via an axial outlet  64  of the filter fluidly connected to the axial outlet port  20  of the filter housing  14 . It needs to be noted that there may be provided a further inner annular space between the pre-separator sleeve  40  and the filter medium  32  of the filter element  30  on the raw side of the filter element  32 . In other words, the pre-separator sleeve dos not necessarily need to directly contact the filter medium in a radial direction. 
       FIGS. 2 and 3  show different perspective representations of the filter  28  from the exemplary embodiment according to  FIG. 1 . The guide vane  44  of the pre-separator sleeve  40  is wound around the pre-separator sleeve  40  and its longitudinal axis  34  in a helical fashion. The helical guide vane preferably has no interruptions, in particular gaps or recesses. The helical guide vane  44  can extend from the baffle or non-perforated first end portion  46  of the pre-separator sleeve  40  over a major portion of the total length  66  of the pre-separator sleeve  40 . 
     Further, in the present embodiment shown in  FIGS. 1 to 3 , the helical guide vane  44  forms more than one full turn or winding on the pre-separator sleeve. It is needless to say, that the guide vane  44  may even form two full turns or windings on the pre-separator sleeve, in particular depending on the total length of the sleeve and the expected maximal flow of the gaseous fluid during use of the filter. The helical guide vane  44 , in the longitudinal direction, extends to or essentially to the reinforcement ring  60  of the pre-separator sleeve  40  which extends in a radial direction away from the pre-separator sleeve  40 . 
     As can be best seen from the individual depiction of the pre-separator sleeve  40  shown in  FIG. 4 , the helical guide vane  44  has a radial extension which is at least  10 % of the outer diameter  54  of the pre-separator sleeve  40 . 
       FIG. 5  shows a modified embodiment of a pre-separator sleeve  40  for the filter  28  shown in  FIGS. 1 to 3  which is provided with an additional flow locking means  68  for preventing a circulating flow of the gaseous fluid in a circumferential direction of the non-perforated first end portion  46  of the pre-separator sleeve  40 . The flow-locking means  68  may be preferably formed by a, in particular arcuate, branch of the helical guide vane  44 . 
       FIG. 6  shows a modified embodiment of the filter  28  with the helical guide vane  28  having a base section  44   a  extending away from the pre-separator sleeve  40  in a radial direction and an angled end section  44   b  which is directly joined to the base section  44   a.  The angled end section  44   b  extends in an axial direction and is aligned in a parallel or essentially parallel fashion with respect to the outside surface  42  of the pre-separator sleeve  40 . 
       FIG. 7  shows a sectional view of a further cyclone filter system  10  with a housing  14  and the filter  28  of  FIG. 6  arranged therein. The flow openings or perforations  52  of the pre-separator sleeve  40  are arranged one behind the other in a helical fashion which corresponds to the three dimensional course of the helical guide vane  44 . The flow openings  52  are covered by the helical guide vane  44  in a radial direction. The helical guide vane thus forms an outer radial side cover for the perforations  52  of the pre-separator sleeve  40 . Of note, there is a common helical inlet or opening  70  formed in between the angled end section  44   b  of the helical guide vane  44  and the outside surface  42  of the pre-separator sleeve  40 . In the embodiment shown, the gaseous fluid  12  is not only swirled when flowing from the inlet port  18  of the filter housing around the filter  28  but is further deflected in an axial direction before entering the helical inlet opening  70  and reaching the perforations  52  of the pre-separator sleeve  40 . This allows for a further improvement of the pre-separating efficiency of the cyclone filter system  10  and filter  28 , respectively.