Patent Publication Number: US-2022219106-A1

Title: Filter Insert for Installation in a Liquid Separator, Liquid Separator, Method for Providing the Aforementioned Filter Insert as well as Use of the Filter Insert in a Liquid Separator

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims a priority date of 12 Jan. 2021 based on prior filed German patent application No. DE 10 2021 100 413.6, the entire contents of the aforesaid German patent application being incorporated herein by reference to the fullest extent permitted by the law. 
     BACKGROUND OF THE INVENTION 
     The invention concerns a filter insert for installation in a housing, in particular in a pressure-resistant container, of a liquid separator, comprising
         at least one separation element configured as a hollow cylindrical coalescer configured for separation of liquid, in particular of oil and/or oil aerosol from a gas flow, and   a flange arranged at an end face at the separation element that can be arranged exchangeably between a cover of the housing and a cylindrical body of the housing, wherein the flange comprises at its radially outer rim a support surface that is configured to be supported on an upper support region of the housing facing the cover.       

     The invention concerns also a liquid separator comprising a housing with a housing opening, a cylindrical housing body, and a cover configured for closing the housing opening, and a filter insert arranged in the housing. 
     The invention further concerns a method for providing a filter insert of the aforementioned kind for installation in a liquid separator of the aforementioned kind. 
     Liquid separators, for example, air/oil separator elements for separating oil aerosol from air, can be employed, for example, for separating oil from compressed air in compressed air systems which are supplied by an oil-lubricated connection element, for example, a compressor or a vacuum pump. Such a liquid separator comprises a filter insert configured for separating oil from air and a pressure-resistant container of the connection element. 
     The air laden with oil flows via a raw air inlet into the pressure-resistant container in order to flow subsequently through the filter insert, which comprises at least one filter element or separation element configured for separating oil from raw air, for example, a main separator and an after separator, and to finally leave the housing in the purified state via the clean air outlet. 
     The filter insert functions according to the coalescence principle. The at least one hollow cylindrically configured filter element is configured as a hollow cylindrical coalescer that combines the fine oil droplets to larger oil drops that, due to gravity, precipitate downwardly in the air/oil separation element and downstream thereof. The precipitated oil drops are drained by means of at least one drainage line or at least one drainage tube. 
     The printed publication DE 10 2014 002719 A1 discloses a filter insert of the aforementioned kind. In this filter insert, the flange is shaped stair-like in longitudinal section and comprises two stair-like steps. The radially outer stair-like step is positioned with its two surfaces arranged at a right angle relative to each other directly at the cylindrical housing body so that the filter insert is arranged centered in the housing body. The radially inner stair-like step covers the separation element. 
     In predetermined servicing intervals, the separation element is to be exchanged. In this context, the length of the servicing intervals varies depending on the configuration of the separation element or depending on the configuration of the liquid separator. 
     The invention has the object to further develop a filter insert of the aforementioned kind as well as a liquid separator of the aforementioned kind in such a way that the filter insert can be installed in a particularly simple and error-free way in the housing of the liquid separator. In particular, it is to be differentiated whether the filter insert is configured for installation in the liquid separator. For example, it is to be ensured that the filter insert can be operated only in a liquid separator that matches it. 
     SUMMARY OF THE INVENTION 
     This object is solved by a filter insert of the aforementioned kind that is characterized in that the flange comprises at least one guide structure configured for determining the position of the flange on the support region, wherein the guide structure is at least one groove-like axial elevation of the flange projecting away from the end face of the separation element that is configured to receive substantially with precise fit at least one counter structure correlated with the liquid separator. 
     This object is solved by a liquid separator of the aforementioned kind that is characterized by comprising a filter insert in accordance with the invention arranged in the housing. 
     Advantageous embodiments and expedient further developments of the present invention are characterized in the respective dependent claims. 
     The present invention is based on the flange of the filter insert comprising at least one guide structure which can be engaged by at least one counter structure of the liquid separator that is complementary to the guide structure. In this context, guide structure and counter structure are configured in the manner of a lock-and-key principle. The guide structure of the flange is a groove-like axial elevation of the flange that is projecting away from the end face of the separation element. This type of the guide structure has the effect that the support surface of the flange can be arranged on the support region of the housing only when the guide structure and the counter structure are arranged so as to spatially match each other, in particular when the counter structure engages the guide structure. In this manner, it can be ensured that only a matching filter insert can be used in a specific liquid separator. 
     In the present invention, due to the shape of the guide structure, the housing cover can be arranged in a closing manner on the housing body only when the guide structure and the counter structure are arranged so as to spatially match each other. The housing opening thus cannot be closed by the housing cover when the flange is arranged between the housing cover and the housing body and in this context the guide structure and the counter structure are not arranged so as to spatially match each other because then the counter structure keeps the support surface of the flange at a distance from the support surface of the housing body. 
     In order to reliably prevent collection of condensed water in the guide structure, the latter is advantageously configured open toward the support region of the housing in the position of use of the flange. 
     In a particularly advantageous embodiment of the present invention, the guide structure is an annular elevation of the flange arranged concentrically about a central cutout of the separation element. This has the advantage that the guide structure is configured such that the separation element is centered upon insertion of the filter insert into the housing of the liquid separator. In this context, the central cutout of the separation element can be configured as an outflow opening. The radially inner rim of the flange can be designed to delimit the outflow opening of the filter element. For example, the flange can be formed of sheet metal that comprises a central cutout and whose inner rim bordering the cutout is crimped. 
     The counter structure of the liquid separator that can be arranged in the guide structure can be arranged concentrically at the cylindrical housing body. This has the effect that, by means of a spatially matching arrangement of the guide structure and of the counter guide structure relative to each other, the separation element can be arranged centered in the housing or can be arranged coaxially to the cylindrical housing body. 
     In a liquid separator in which the air laden with oil flows spirally through an annular gap arranged between housing body and filter element before it enters the separation element, a person of skill in the art will be particularly appreciative when the guide structure aids in centering the separation element in the housing body because in such a liquid separator centering of the separation element is required so that the separation element is uniformly exposed to the incoming gas flow. 
     In a particularly advantageous embodiment of the present invention, thus
         the support surface of the flange is arranged radially displaced relative to the separation element such that the separation element can be arranged at a distance from the cylindrical housing body, wherein between the cylindrical housing body and the hollow cylindrical separation element an annular gap is formed that can be flowed through spirally by the air laden with liquid flowing through the housing body,   the guide structure is an annular groove-like elevation of the flange that is concentrically arranged about a central cutout of the separation element, and   the counter structure is a groove-like counter elevation of the housing body concentrically arranged at the cylindrical housing body of the liquid separator and/or a concentrically configured groove-like counter elevation of an air guide element arranged in the housing body.       

     In an advantageous embodiment of the present invention, the guide structure is shaped such that it projects past the support surface of the flange in the axial direction. For example, the guide structure can project past all other regions of the flange in the axial direction. The guide structure can thus be a region of the flange which comprises the largest axial distance from the separation element. In this way, a counter structure interacting with the guide structure can also be arranged in the housing cover. In this manner, by means of the guide structure, the position of the flange relative to the housing cover can also be determined in addition to the position of the flange relative to the housing body. 
     Independent thereof or in combination therewith, in an advantageous embodiment of the present invention at least one seal element is captively arranged at the support surface of the flange. In this context, the seal element is arranged such at the support surface that, in the position of use of the filter insert, it is arranged between the flange and the housing of the liquid separator and seals the housing relative to the ambient pressure. Providing a seal element at the support surface of the flange in the present invention has the advantage that, upon insertion of the flange into the liquid separator, the seal element can be arranged in its correct sealing position by means of a spatially matching arrangement of the guide structure of the flange and of the counter structure of the liquid separator to each other. During insertion of the filter insert into the liquid separator, the guide structure thus assists in guiding the seal element into its correct sealing position. In that the guide structure prevents a wrong insertion of the seal element, it increases the operational safety of the liquid separator. 
     The seal element can be, for example, a flat seal, an O-ring or an L-shaped seal ring. In particular, the seal can be designed L-shaped in longitudinal section and can be arranged at the radially outer rim of the flange. 
     Advantageously, the seal element is a fixed component of the filter insert, in particular is captively arranged at the filter insert. This facilitates working steps upon exchange of the filter insert because in this way no separate seal exchange is required. 
     In an advantageous embodiment of the liquid separator according to the present invention,
         the support surface of the flange in the closed state of the housing is clamped between the housing cover and the housing body,   at least one flange cutout is arranged at the housing configured for receiving the support surface, and   the radius of the flange is smaller than the radius of the housing in such a way that, in the closed state of the housing, the housing cover is resting directly on the housing body at a radially outer region of the housing bordering the flange cutout.       

     The liquid separator comprises advantageously a raw air inlet arranged tangentially at the cylindrical housing body that is connectable to a liquid-lubricated connection element of a compressed air system, in particular to an oil-lubricated compressor, and that is configured to enable inflow of compressed air, laden with liquid and originating from the connection element, tangentially into the cylindrical housing body. 
     Moreover, the liquid separator comprises advantageously an annular gap that is arranged between the cylindrical housing body and the separation element of the filter insert. In this context, the liquid separator is configured such that the air flowing in through the raw air inlet flows spirally through the annular gap and flows into the separation element of the filter insert in a region facing away from the cover. 
     The counter structure of the liquid separator as well as the support region of the housing body can be arranged at a region of the cylindrical housing body facing the flange in the position of use. This has the advantage that the guide structure and the counter structure upon insertion of the filter insert into the liquid separator interact such that the distance of the separation element from the housing body is determined, in particular the separation element is centered in the housing body. 
     Optionally, at least one air guide element configured for guiding the air flowing through the housing body, in particular an air baffle, can be arranged between the housing body and the separation element. The air guide element is thus arranged upstream of the separation element in the cylindrical housing body in the flow path of the air laden with liquid. 
     The air guide element can be an element which is independent of the housing body. Upon insertion of the air guide element into the housing body, it is important to center it properly because
         the distance between the housing body and the air guide element defines the degree of preseparation of the liquid separator, and   the distance between the air guide element and the separation element defines the velocity at which the air laden with liquid flows into the separation element.       

     It is thus required to properly center the air guide element in the housing body so that the desired preseparation degree is achieved and inflow at the separation element is uniform. 
     As a supplement or as an alternative to the housing body, the counter structure of the liquid separator can be arranged in a region of the air guide element that is facing the flange in the position of use. In this embodiment, the guide structure of the flange is arranged at the counter structure of the air guide element and the counter structure of the air guide element is arranged at the support region of the housing body. An arrangement of the counter structure at the air guide element has the advantage that the guide structure and the counter structure upon insertion of the filter insert into the liquid separator interact with each other such that the distance of the air guide element from the separation element is determined. Therefore, no erroneous positioning of the separation element relative to the air guide element can occur. 
     The present invention concerns moreover a method for providing a filter insert of the aforementioned kind for installation in a liquid separator of the aforementioned kind. 
     The present invention concerns finally the use of a filter insert of the aforementioned kind in a liquid separator of the aforementioned kind, for separation of oil from compressed air, wherein the liquid separator is correlated with a compressed air system that is supplied by an oil-lubricated connection element, for example, by a compressor or by a vacuum pump. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       As already discussed above, there are various possibilities of configuring and further developing the teaching of the present invention in an advantageous manner. For this purpose, on the one hand, reference is being had to the independent and dependent claims, and, on the other hand, further embodiments, features, and advantages of the present invention will be explained in more detail in the following inter alia with the aid of the two embodiments illustrated in the  FIGS. 1 to 10 . 
         FIG. 1  shows in longitudinal section illustration an embodiment for a filter insert according to the present invention which is provided according to the method according to the present invention. 
         FIG. 2  shows in perspective illustration the filter insert of  FIG. 1 . 
         FIG. 3  shows in longitudinal section illustration a first embodiment for a liquid separator according to the present invention, wherein the liquid separator comprises the filter insert of  FIG. 1 . 
         FIG. 4  shows a detail view of the flange region of the liquid separator of  FIG. 3 . 
         FIG. 5  shows in longitudinal section illustration a second embodiment for a liquid separator according to the present invention, wherein the liquid separator comprises the filter insert of  FIG. 1 . 
         FIG. 6  shows a detail view of the flange region of the liquid separator of  FIG. 5 . 
         FIG. 7  shows a longitudinal section of an exploded illustration of the liquid separator of  FIG. 3 . 
         FIG. 8  shows a longitudinal section of an exploded illustration of the liquid separator of  FIG. 5 . 
         FIG. 9  shows in perspective exploded illustration the liquid separator of  FIG. 3 . 
         FIG. 10  shows in perspective exploded illustration the liquid separator of  FIG. 5 . 
     
    
    
     Same or similar configurations, elements or features are provided in the  FIGS. 1 to 10  with identical reference characters. 
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     For avoiding superfluous repetitions, the following explanations with regard to the configurations, features, and advantages of the present invention (in so far as not disclosed otherwise) refer to the liquid separator  200  illustrated in  FIGS. 3, 4, 7, and 9  as well as to the liquid separator  202  illustrated in  FIGS. 5, 6, 8, and 10 . 
     The filter insert  100  illustrated in  FIG. 1  comprises a hollow cylindrical separation element  10  that is configured to separate oil and/or oil aerosol from a gas flow by means of the coalescence principle. The separation element  10 , as illustrated in  FIG. 1 , can comprise a plurality, for example two, filter layers which can be formed of the same or of different materials, for example, of glass fiber and/or of plastic material, for example, of nonwoven. 
     As illustrated in  FIGS. 7 to 10 , the filter insert  100  can be installed exchangeably in a pressure-resistant housing of a liquid separator  200 ,  202 . For installation in the housing of the liquid separator  200 ,  202 , the filter insert  100  comprises a flange  20  arranged at the end face at the separation element  10  and clamped between a cover  30  and a cylindrical body  40  of the housing of the liquid separator  200 ,  202 . The cover  30  can be removed, in particular can be screwed onto the pressure-resistant container. 
     The housing of the liquid separator  200 ,  202  has a raw air inlet  70  which is arranged tangentially and which is connected to a connection element, for example, to a compressor screw. When presently reference is being had to tangential, radial, axial, coaxial or circumferential or the like, this relates to, if nothing different is mentioned, the longitudinal axis of the liquid separator  200 ,  202 . 
     By means of the raw air inlet  70 , compressed air laden with oil aerosol enters the housing of the liquid separator  200 ,  202  and flows then spirally through an annular gap  60  that is arranged between the housing body  40  and the separation element  10  before it flows in a lower region facing away from the cover  30  into the separation element  10  of the filter insert  100  and then flows radially through it from the exterior to the interior. 
     The purified clean air flows in axial direction out of the housing of the liquid separator  200 ,  202 . For discharging the clean air, the housing cover  30  comprises a central clean air outlet  72 . The flange  20  is arranged coaxially to the clean air outlet  72  of the liquid separator  200 ,  202 . 
     In longitudinal section, the flange  20  comprises two stair-like sequentially arranged steps. The axially extending region  26  of the radially inner step is contacting the central cutout of the hollow cylindrical separation element  10 . The radially extending region  27  of the radially inner step covers the end face of the separation element  10 . At the radially extending region  29  of the outer step, the flange  20  comprises at least one guide structure, namely a groove  24 , for securing the position of the flange  20  on the housing body  40 . This groove  24  centers the filter insert  100  in the housing body  40 . 
     At the outer rim of the radially extending region  29  of the outer step, a seal element  50  is arranged for sealing the housing  30 ,  40  relative to the ambient pressure. 
     The oil that is separated by the separation element  10  of the filter insert  100  collects in the interior of the cylindrical filter insert  100  at a bottom-side end disk  90 , in particular in an oil collecting region  92  of the bottom-side end disk  90  that is arranged radially within the filter insert  100 , and can be discharged, for example, through a drainage tube element (not illustrated) and returned to the connection element. 
     At the bottom of the housing body  40 , oil collects in a bottom-side oil collection volume  110  that is separated by a preseparation action of the housing, in particular by gravity and by centrifugal force for tangential inflow of the raw air. The pre-separated oil collecting in the oil collection volume  110  can also be returned to the connection element, for example, by a liquid outlet (not illustrated) configured for draining the liquid collecting in the housing. 
     The groove  24  defines the position of the flange  20  on the upper support region  42  and thus also the arrangement of the separation element  10  relative to the housing body  40 . In order to be able to determine the position of the flange  20  on the support region  42  of the housing body  40 , the groove  24  is at least one axial elevation of the flange  20  that is projecting away from the end face of the separation element  10  and is configured to receive substantially with precise fit at least one counter groove  44  correlated with the liquid separator  200 ,  202 . In cross section, the groove  24  is n-shaped. As is illustrated in  FIGS. 3 and 5 , the groove  24  is arranged displaced radially as well as axially relative to the separation element  10 . 
     The counter groove  44 , as illustrated in  FIGS. 3, 4, 7, and 9 , can be arranged at an air baffle  80  which is arranged at the housing body  40 . Such an air baffle  80  must be centered well relative to the filter insert  100  because
         the dimension of the annular gap  60  between the housing body  40  and the air baffle  80  defines the acceleration of the air flowing through this annular gap  60 , and   the dimension of the annular gap  60  between the air baffle  80  and the separation element  10  determines whether the air flows uniformly into the separation element  10 .
 
When the counter groove  44  is arranged at the air baffle  80 , the groove  24  assists in centering the air baffle  80  relative to the separation element  10  when inserting the filter insert  100  into the housing.
       

     In addition to this or as an alternative thereto, the counter groove  44 , as illustrated in  FIGS. 5, 6, 8, and 10 , can be arranged at the housing body  40 . This has the advantage that the groove  24  assists in centering the separation element  10  relative to the housing body  40  when inserting the filter insert  100  into the housing. 
       FIGS. 4 and 6  show a detail view of the flange  20  in the housing of the liquid separator  200 ,  202 . The flange  20 , more precisely, a support surface  22  of the flange  20  arranged at the radially outer rim of the flange  20  is positioned directly on the housing body  40 , namely on an upper support region  42  of the housing body  40  facing the cover  30 . A seal ring  50  that is L-shaped in longitudinal section is resting on the support surface  22 , and the cover  30  is resting on the L-shaped seal ring  50 . 
     The cover  30  has a flange cutout  32  configured for receiving the support surface  22 . Moreover, the support region  42  has a flange cutout  46  configured for receiving the support surface  22 . The flange cutout  46  of the housing body  40  and the flange cutout  32  of the cover  30  form together a seal chamber  46 ,  32  in which the L-shaped seal ring  50  is arranged such that the seal chamber  46 ,  32  is sealed relative to the environment, i.e, relative to the atmospheric pressure. 
     The groove  24  aids in positioning the seal  50  upon insertion of the filter insert  100  into the housing of the liquid separator  200 ;  202  because, by means of the guiding action provided by the groove  24  and the counter groove  44 , the seal  50  can be inserted into the seal chamber  46  in the manner of a loose fit. 
     The flange cutout  32  of the cover  30  is designed such that the groove  24  can be arranged only in the flange cutout  32  of the cover  30  when the groove  24  is arranged spatially matched to the counter groove  44 . In this context, the axial extension of the flange cutout  32  of the cover  30  corresponds substantially to the axial extension of the groove  24 . This has the effect that the cover  30  can be arranged on the housing opening in a closing manner only when the counter groove  44  engages the groove  24 . 
     In a radially outer region of the housing which is bordering the seal chamber  46 ,  32 , the cover  30  and the housing body  40  are resting on block. 
     The embodiments of the present invention illustrated in  FIGS. 1 to 10  have the advantage that by the interaction of the groove  24  and the counter groove  44  upon insertion of the filter insert  100  into the housing a guiding action is provided which has the effect that
         the separation element  10  is centered relative to the housing body  40  and/or to the air baffle  80 ,   the seal element  50  is arranged in its seal seat, and   the filter insert  100  can be installed only in a housing that is matching it.       

     LIST OF REFERENCE CHARACTERS 
     
         
           10  separation element configured for separating oil and oil aerosol from air by means of the coalescence principle, in particular hollow cylindrical coalescer, for example, of glass fiber and/or of plastic material, for example, of nonwoven 
           20  flange, in particular end face end disk, of the filter insert  100  for supporting the filter insert  100  between the cover  30  and the housing body  40  of the liquid separator  200 ,  202   
           22  support surface of the flange  20  (compare  FIG. 1 ) 
           24  guide structure or differentiation structure or positioning structure, in particular groove, for example, n-shaped groove 
           26  axially extending region of the radially inner step of the flange  20   
           27  radially extending region of the radially inner step of the flange  20   
           28  axially extending region of the radially outer step of the flange  20   
           29  radially extending region of the radially outer step of the flange  20   
           30  cover or housing cover, in particular pressure container cover or pressure storage container cover, for example, housing socket 
           32  flange cutout of the cover  30  for receiving the support surface  22   
           40  body of the housing or housing body, in particular cylindrical pressure-resistant housing body or pressure container bottom part or pressure storage container bottom part 
           42  support region, in particular support surface, of the housing body  40   
           44  counter structure, in particular counter groove 
           46  flange cutout of the housing body  40  for receiving the support surface  22   
           50  seal element, in particular seal ring L-shaped in longitudinal section 
           60  annular gap arranged between cylindrical housing body  40  and hollow cylindrical separation element  10   
           70  raw air inlet for letting in raw air, originating from the connection element and laden with liquid, into the housing body  40   
           72  clean air outlet for letting out compressed air purified by the liquid separator  200 ,  202   
           80  air guide element, in particular air baffle, for example, shield 
           90  bottom-side end disk or bottom-side end cap or bottom element for covering the hollow cylindrical bottom side of the filter insert  100   
           92  liquid collection region, in particular oil collection region, which is correlated with the bottom-side end disk  90 , arranged radially inside of the separation element  10 , and configured for collecting the liquid separated by the separation element  10  (compare  FIGS. 3 and 5 ) 
           100  filter insert 
           110  liquid collection volume, in particular oil collection volume or oil collection chamber, for collecting liquid separated by preseparation, in particular by gravity and/or by centrifugal force for tangential inflow of the raw air into the housing body  40  (compare  FIGS. 3 and 5 ) 
           200  liquid separator, in particular compressed air dehumidifying device, for example, air/oil separator element, first embodiment (compare  FIGS. 3, 4, 7, and 9 ) 
           202  liquid separator, in particular compressed air dehumidifying device, for example, air/oil separator element, second embodiment (compare  FIGS. 5, 6, 8, and 10 )