Patent Publication Number: US-2015059303-A1

Title: Filter Element and Filter System

Description:
TECHNICAL FIELD 
     The invention relates to a filter element with a sealing element and a filter system with such a filter element. 
     BACKGROUND 
     A filter element is known from U.S. 2008250766A which has a sealing element arranged on its outer side. The sealing element consists of polyurethane that is poured on the outer side and cured there on site. 
     It is one object of the invention to provide a filter element with a sealing element that has favorable demolding characteristics. 
     Another object of the invention is to provide a filter system with such a filter element. 
     The abovementioned objects are achieved according to one aspect of the invention through a filter element with a filter body and a substantially axially sealing element that is arranged on a peripheral surface of the filter body, particularly foamed to the peripheral surface, the sealing element having a first sealing surface and a second sealing surface that are positioned opposite each other in the axial direction with an axial gap, and the sealing element having a contour between the sealing surfaces on its periphery in which a contour segment respectively adjoins the sealing surface at an obtuse angle and the two contour segments abut at a joint. 
     Advantageous embodiments and advantages of the invention follow from the other claims, the description and the drawing. 
     SUMMARY OF THE INVENTION 
     A filter element is proposed which has a filter body and a substantially axially sealing element that is arranged on a peripheral surface of the filter body, particularly foamed to the peripheral surface, the sealing element having a first sealing surface and a second sealing surface that are positioned opposite each other in the axial direction with an axial gap, and the sealing element having a contour between the sealing surfaces on its periphery in which a contour segment respectively adjoins the sealing surface at an obtuse angle and the two contour segments abut at a joint. 
     The person skilled in the art can expediently select an appropriate angle for a given housing in order to design the sealing surfaces such that they are sufficiently large and to adapt to the desired configuration of the filter system. 
     The sealing element is advantageously made of polyurethane. With its angular contour, the sealing element can easily be demolded from a casting mold that is used when applying the sealing element to the filter body. At the joint, which forms a kink running around the outer periphery of the sealing element, for example, a suitable seal in the casting mold can prevent flash from forming at the joint during foaming that would otherwise have to be tediously cut away by hand. Such flash can easily form, for example, at the edge of the sealing surface during the foaming of polyurethane if a right angle is formed between sealing surface and contour. By preventing such flash, the cycle time during the manufacture of the filter element can be shortened and damage during reworking of the filter element prevented, since this reworking can be omitted. 
     According to one advantageous embodiment, the joint can be arranged off-center with respect to the axial gap between the sealing surfaces. This can further simplify the manufacture and demolding of the sealing element compared to a joint that is arranged symmetrically with respect to the sealing surfaces. The mold, which prescribes the shape and size of the sealing element, is usually filled up to a level above the middle, and the polyurethane mass already begins foaming during filling of the casting mold. 
     According to one advantageous embodiment, one sealing surface can be shorter in the radial direction than the other sealing surface. Advantageously, a desired asymmetrical arrangement of the joint can be achieved more easily in this way and an angle between sealing surface and contour segment appropriately selected. 
     According to one advantageous embodiment, the joint can be further removed in the axial direction from the sealing surface that is shorter in the radial direction than from the sealing surface that is longer in the radial direction. The sealing element can thus be removed more easily from the casting mold. Particularly, the joint can be removed from the sealing surface that is shorter in the radial direction by at least 50% of the axial gap from the other sealing surface. 
     According to one advantageous embodiment, the obtuse angle can be between 100° and 140°, preferably between 110° and 112°. This rsults in a favorable inner contour of the casting mold. 
     According to one advantageous embodiment, at least the sealing surface that is longer in the radial direction can abut against the peripheral surface in a substantially spur-free manner. This saves material and reworking of the sealing element. This can be achieved in a simple manner by means of a suitable insert in the casting mold, for example. 
     According to one advantageous embodiment, a spout can extend from the sealing surface that is shorter in the radial direction and abut against the peripheral surface. This spout is advantageously short. 
     According to one advantageous embodiment, the filter element can be flowed through along its longitudinal axis. For this purpose, it is preferably formed of a wound semi-finished product made of a smooth layer and a corrugated layer lying on that of a filter medium such as paper, the channels formed between smooth and corrugated later being mutually sealed by tracks of hot melt adhesive, for example, so that the air to be filtered that flows into a channel must travel from this channel that is sealed at its end through a layer of the filter medium into an adjacent channel than is closed at its beginning, thus filtering the air. The wound body formed in this way forms two parallel, opposing inflow and outflow surfaces. Preferably, the sealing surfaces lie radially outside of the inflow and outflow surface and/or parallel thereto. In the case of a seal that is foamed to the filter body, the seal can be foamed directly to the outermost layer of a smooth layer. One of the sealing surfaces is also preferably flush with one of the inflow surfaces. 
     According to another aspect of the invention, a filter system with a housing and a filter element according to the invention is proposed, the filter element being arranged replaceably in the housing. By virtue of the replaceable filter element, the filter system is a good value. 
     The use of such a filter system as an air filter is especially advantageous. An economically priced air filter can be produced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional advantages follow from the following description of the drawing. The drawings show exemplary embodiments of the invention. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also view the features individually and group them together into expedient additional combinations. 
         FIG. 1  shows, as a cutaway of a filter system, a section through a filter element with a filter body and a sealing element according to one embodiment of the invention foamed to it; 
         FIG. 2  shows, in a sectional view, detail of a foamed-on sealing element according to one embodiment of the invention; 
         FIG. 3  shows detail of a casting mold with sealing element 
     
    
    
     DETAILED DESCRIPTION 
     In the figures, same or similar components are designated with the same reference symbols. The figures merely show examples and must not be understood as being limitative. 
       FIG. 1  shows, in a sectional view, a cutaway of a filter system  200  with a two-part housing  130  and a filter element  10  arranged therein with a sealing element  100 .  FIG. 2  shows the sealing element  100  in detail. The filter element  10  is, for example, an air filter with a filter body  20  which can be formed, for example, from paper as a filter medium. A sealing element  100  is arranged on the filter body  20  on its peripheral surface  22  in the radial direction  40 . 
     The sealing element  100  is a substantially axially sealing element  100  made, for example, of polyurethane and foamed to the peripheral surface  22 . The sealing element  100  has a first sealing surface  102  and, spaced apart from that in the axial direction  50 , a second sealing surface  104  that are positioned opposite each other with an axial gap  30 . 
     The filter element  10  is inserted into the housing  130 , for example into a lower housing part with a radially projecting sealing surface  134 . The upper housing part with a radially projecting sealing surface  132  is placed on top, so that the sealing element  100  is positioned with its sealing surfaces  102 ,  104  between the sealing surfaces  132 ,  134  of the housing  130 . The housing  130  is closed and sealed through placement of a clamping ring (not shown) around the outwardly protruding sealing surfaces  132 ,  134  and tightened, thus pressing the pairs of sealing surfaces  132 ,  102  and  134 ,  104  against each other. 
     Between the two sealing surfaces  102 ,  104 , the sealing element  100  has on its periphery a contour  110  in which a contour segment  112  adjoins the sealing surface  102  and in which the opposing sealing surface  104  adjoins the contour segment  114  at an obtuse angle α and β, respectively. The two angles α and β can be equal or different. It is advantageous if the obtuse angle α or β is in the range from greater than 90° to 150°, particularly from 100° to 140°, especially preferably in the range from 110° to 112°. When installing the filter element  10 , it is difficult to position in the housing, particularly in the case of relatively large filter elements having a diameter of over 50 cm. The contour according to the invention reduces the danger of the sealing element  100  coming to rest with one of the sealing surfaces on one of the peripheral edges of the housing parts, thus damaging the sealing surface. The contour enables the oblique surfaces to slide on the housing contour and also provides a centering aid, so that a uniform sealing effect can be achieved all around. 
     One sealing surface  104  is shorter in the radial direction  40  than the other sealing surface  102 . 
     The two contour segments  112 ,  114  protruding at an obtuse angle α or β from the sealing surfaces  102 ,  104  abut against each other at a joint  116 . The joint  116  is arranged off-center with respect to the axial gap  30  between the sealing surfaces  102 ,  104  and is, for example, further removed in the axial direction  50  from the sealing surface  104  that is shorter in the radial direction  40  than from the sealing surface  102  that is longer in the radial direction  40 , for example by at least 50% of the axial gap  30  from the other sealing surface  102 . 
     The sealing surface  102  that is longer in the radial direction  40  abuts against the peripheral surface  22  in a substantially spout-free manner, whereas a spout  106  protrudes in the axial direction  50  from the sealing surface  104  that is shorter in the radial direction  40  and abuts against the peripheral surface  22 . The spout  106  is formed during the casting or foaming-on of the sealing element  100  against the filter body  20 . 
       FIG. 3  shows detail of a casting mold  300  with sealing element  100  during the manufacture of the sealing element  100 . The casting mold  300  has a lower shell  304  and an upper shell  302  that are placed tightly around the filter body  20 . An insert  310  in the form of a seal is inserted at a joint  306  between the shells  302 ,  304 . The lower shell  304  is sealed against the filter body  20  with an insert  314  in the form of an elastic O-ring. This insert  314  advantageously limits the flashing of the polyurethane during foaming that forms the spout  106  of the sealing element  100 . 
     An annular insert  312  is inserted in the upper shell  302  at the transition to the filter body  20  that prevents the foaming polyurethane introduced into the casting mold from forming a spout and ensures that the corresponding sealing surface of the sealing element  100  abuts against the filter body  20  without flash, for example practically perpendicularly.